Guest Automatic 5/10 Amp Charger

[0533]

I am replacing my current charger (non automatic) with a new Guest fully automatic one.

Like everything else I get involved with i thought the install would be a no brainer (I an sure it is for the rest of you) but now I am second guessing the install.

I have 4 brand new chassis batteries and for the sake of a few $$'s I do not want to fry them because I made an install mistake.

Here is what is stalling me out. The old charger has 2 leads that are connected to a negative battery post (different battery) and the other connected to a positive post on another battery in the bank of 4.

The new Guest comes with 4 leads, 2 POS. and 2 NEG. leads.

Question: What batteries do I connect these leads to, does it matter, Should I connect them to separate NEG/POS terminals on any 4 batteries or to both NEG/POS terminals on any to batteries. Check out the diagram from Guest for 24V installs. It seems different than what I had expected.

See Link: http://www.marinco.com/product/10-amp-dual-battery-chargepro-charger

This should be very easy but I am reluctant to make the connections without a second opinion.

I am also having difficulty uploading images to the forum today as well, maybe I should not be doing important stuff.

[0533]

Image diagram

We have 4 chassis batteries, this diagram shows the 4 leads 2 POS and 2 NEG connected to 2 batteries 1 NEG and 1 POS connected to 2 batteries. How would this application work for 4 batteries, can I just connect the 4 leads to 1 POS on 1 Battery, 1 NEG on another battery??? repeat the same for the other 2 leads or do I need to attach the pairs POS?NEG to 2 separate batteries??

I hope I am not confusing anyone.

[MangoMike]

Hi Bruce,

I have the same charger.

Here's a diagram I worked hard at to show the hook up.

4703

The two center wires from the charger just wire nut together, don't bother attaching to batteries.

Mike

[Gary & Peggy Stevens]

Bruce, MangoMikes diagram is exactly what I used to connect my Guest Charger.

It has worked flawlessly, since I got the wiring issue all sorted out. You'll be glad you have this installed in your system.

Be sure the Guest Charger is plugged into a hot plug that runs off of either shore power or Gen set, not just when you turn on a timer. I had to replace my existing 60 minute timer with an on/off switch for the system to function properly, but it has worked great since then.

Gary S.

[GDeen]

Warning, stupid newbie question......

What is the purpose of a "guest charger?" Just what it implies - charging other things like your car?

[Gary & Peggy Stevens]

Warning, stupid newbie question...... What is the purpose of a "guest charger?" Just what it implies - charging other things like your car?

Gordon there are No Stupid Questions, or believe me I would have taken the prize for asking them several times over.

The Guest Charger keeps the (4) Chassis Batteries charged properly when it is parked. If your plugged into shore power at a park, or running the gen set in an overnight situation dry camping, the chassis batteries are being maintained properly.

Jon, did I answer that correctly? :o

Gary S.

[0533]

Thanks Mike.

They all have inline fuses, should I disconnect the fuse when I wire tie the inner ones together? My guess is get rid of the inline fuse. I will leave the one to the main POS that I connect to the batteries.

Again thanks, I am somewhat surprised that Guest does not offer this diagram on its website for this unit. The manual did not offer this option either. Where did you find the diagram?

PS> Gary I do have a timer that will be removed, the A/C power outlet (both Shore/Gen) can be turned on at the dash, I will keep it on at all times to allow it to work when needed. Question: I guess it might come on while running down the road while on the genset as the 270 alternator turns off when the gen side is on while running along, no demand from the house side on Marathon single alternator buses. Interesting solution, could this offset the need for a second alternator??? Jon will know the answer, bet he is out having pizza and Mussels somewhere

PS> Gordon: Even if you turn off the chassis battery 12/24 volt shutoff there are wires from the chassis batteries that go directly to the DDEC, most owners leave the 12/24 on so they can have access to air for leveling?? and all else chassis related. If the coach sits without running for long periods the battery will run down unless you have a charger. The Auto Charger is the best solution (I had a manual timer version)

Bruce

[tdelorme]

Gordon, "Guest" is the name of the company that makes the unit Bruce and others have installed.

[GDeen]

Gordon, "Guest" is the name of the company that makes the unit Bruce and others have installed.


I rest my case....thanks Ted.

[0533]

Who's a guest, I thought all users on this forum were members?? Who's on first?

My fault, sorry will try and be more specific in the future, doesn't happen often in my case.

[truk4u]

Here's how I have done the Guest Chargers:


4704

This charges all 4 batteries as 12v, using the 2 pair cabled in parallel. Is this better than Mango's? Beats me, but there has been issues previously with Marathon and 24 volt chassis chargers, although I don't remember the details.

[MangoMike]

Thanks Mike.

They all have inline fuses, should I disconnect the fuse when I wire tie the inner ones together? My guess is get rid of the inline fuse. I will leave the one to the main POS that I connect to the batteries.

Again thanks, I am somewhat surprised that Guest does not offer this diagram on its website for this unit. The manual did not offer this option either. Where did you find the diagram?


Bruce

I would get rid of the inner fuses, unless someone has a better reason to keep them.

I did the diagram in Adobe Illustrator.

MIke

[JIM KELLER]

I installed mine per truk's wiring diagram

[0533]

This is interesting.

I installed the batteries the way Mango said to, joined the Inner POS and NEG to each other (left the 2 fuses in line) There are in fact 3 fuses, 2 POS and one NEG fuses. I could see no harm in leaving them inline, after all if they blow something is wrong.

I tested each set with meter, both as 12V and 24V, all seems good, they were charing, went to RED for a few minutes then to RED & GREEN for the finish charge. The batteries were reading 27.5 on the finish RED/GRN 13.75 on 12V, seems about right.

Tom: You certainly are a game changer with your diagram. I am afraid I do not exactly understand how they would charge as though each was 12V with this connection. Doesn't the first 12V connected to the second battery bank create a 24V setup anyway?? How would each get there 12V charge?? I am no electrical engineer, but can flow directions.


This is your setup? Do you have the same charger??

maybe it works either way. Your setup is one of the options for a 24V setup when there are 2 12V batteries, but I cannot exactly figure out the rest of the charging pathway with your connection.

The directions that Guest provides offers no diagram for 4 battery 24V setup, a bit screwy considering they promote RV's in their literature. guess most RV's are 2 chassis battery setups.

[0533]

Can anyone else confirm Mike's or Tom's installs for their buses using the Guest 10Amp, 5/5 charger. It appears that both work.

Also Tom mentioned that Marathon was having some issues with their hookups, anyone know about this?

How is it possible to hookup all four batteries as 12V?

[Jon Wehrenberg]

Bruce,

Please take the following as constructive. If you have to ask those questions I would urge you to get someone with a basic understanding of electric to hook the charger up to your bus.

The charger is intended for your chassis batteries and they must remain as a 24/12 volt configuration. If you attempt to try to hook up all your batteries as a 12 volt set up you are in effect re-engineering the Prevost chassis.

[phorner]

"on the finish RED/GRN"

On my Guest charger, the finish/float charge is indicated by a single green light.

FWIW, Truk installed mine and it has worked flawlessly for nearly 2 years now.

[0533]

Here's how I have done the Guest Chargers:


4704

This charges all 4 batteries as 12v, using the 2 pair cabled in parallel. Is this better than Mango's? Beats me, but there has been issues previously with Marathon and 24 volt chassis chargers, although I don't remember the details.
Thanks Jon, That is my exact point. I did hook them up as 24V, I am confused by Tom's (Truk's) post and comments. I assume this is another way to make a 24V hookup is all and wanted to get confirmation.

Please read both Tom's and Mikes (Mangos) posts, each has a different way of making the connection. Each has a different approach. I was not asking whether it should be 12 or 24 but rather if it matters which approach.

I used Mango's approach.

I do understand the difference between 12 & 24 volts but wanted to get confirmation before heading off into space.

Bruce

[Jon Wehrenberg]

Bruce,

They are both correct. Truk and Mango took different roads to go the same place.

Mango in essence charges the batteries as a 24 volt set exactly like your bus alternator does, Truk charges two 12 volt sets.

Your battery equalizer sorts out either system balancing the voltages.

Personally I like Mike's method due to the simplicity, but Tom's method is charging the two parallel 12 volt sets and accomplishes the exact same thing. This is a guess because I don't have access to the charger information but I suspect they will produce exactly the same rate of charge so there are no performance considerations which might make one set up more advantageous.

Having said the above if I had the charger installed on my bus (I have a different one installed when the bus was converted) I would never use it as a maintenance charger, but would use it to restore the batteries to full charge only periodically.Doesn't your bus tie your inverters (when used as chargers) into your chassis batteries? And why would you consider a second alternator? It will not make your bus any more reliable, and in fact doubles your chances of an alternator failure?

[BrianE]

Spoken like a confirmed single engine pilot Jon. Me too. :)

[truk4u]

Paul is correct, if your green/red light are on together, there's something wired wrong. It should take about 12 hrs to get from red to float (green) the first time you plug it in. All of this is assuming you bought the 10 amp 2611.

I simply wire them to use the 12v function by charging two sets of batteries (that's 4 batteries) hooked in parallel by the two Guest leads that in turn charge all four batteries.

Forget what I have done if your confused and stick with Mango's deal, but you have something wrong if your green/red.

[Danss]

I hooked mine up per Truk's diagram. Works great! Dan

[Jon Wehrenberg]

Bruce,

This is not apples and oranges.

Both Mango and Truk accomplish the same thing. Mango makes the charger a 24 volt charger using his method. Truk keeps the charger as a two circuit 12 volt charger. But both are doing exactly the same thing. Pick one and do not deviate.

Either connect to the batteries at the 24 volt posts and use Mango's, or hook up to the 12 volt (2 sets of 2 batteries) and use Truk's.

If your bus is set up so the house inverters are maintaining a charge on the chassis batteries via some interconnection between the two sets, step back, and reconsider why you are using the charger, and if you still decide to use it, making two sources independent of each other charging your batteries, you need to verify that no voltages are other than what they want to be. If you fail to do that I see more battery purchases in your future.

Ka-ching.

[truk4u]

Good point by Jon! Do not run the charger via your inverters, that caused wierd things to happen on my Marathon like the house lights pulsating. You must use a dedicated 120 volt power source such as the block heater that will not run through the inverter.

[Jon Wehrenberg]

I wasn't talking about that, but was going by Bruce's post a while back that indicated he had some type of set up that can tie his house and chassis battery systems together.

But you are correct. Tying a charger to inverters is akin to trying to pick yourself up off the floor by pulling up on your socks.

[0533]

Ok, let me respond to each:

first lets be completely clear on what unit and how the lights should read out and what each means at what point during the charge, see diagrams.

The lighting diagram indicates that when the Red/Grn are on together the batteries are at the "Finishing" stage no a problem , I do not believe.

Let me respond to Jon's Questions: The chassis batteries are getting charged via the regulator when the House side is calling for a charge while on inverter power only (no shore/Generator) running down the highway. The regulator is set to max out at 27V and the chassis side works nicely under these conditions. The Isolator and the battery balancers are at work as well, no issues here

[truk4u]

The batteries were reading 27.5 on the finish RED/GRN 13.75 on 12V, seems about right.

If it's steady green your good, the above is what you said..

[0533]

Your right Tom, those are my readings.

I think I am good to go.

My concern in the first place came about as a result of 2 reasons. I use my genset some times while running down the road, noticed the chassis side voltage dropping (settling down to the uncharged values), finally realized the alternator/regulator does not charge the chassis side when the genset is on, as there is no demand from the house batteries to the regulator/alternator because they are charged from the genset.

PS> there is no inter connect between the house and chassis side, used to be when I had the old isolator that had the ability to allow the owner to push a switch at the dash, and allow for a momentary connection to the house side to supply starting power to the dead chassis batteries. This isolation failed and fryed my chassis batteries over time.

it is a bit screwy (Marathon created this connection for single alternator buses), So while out last summer decided to pick up a battery charger in Angola while having a broken window changed, but it was not automatic, all they had available, big pan in the Ass.

I also noticed that my chassis batteries were running down too quickly while sitting, and without an automatic charger it is impossible to know when to address the need.

I am pleased with this install as my batteries are all brand new, am not interested in frying them with incorrect power.

[Jon Wehrenberg]

If running your generator while the engine runs stops the charging current from reaching your chassis batteries you have a problem or a serious design issue.

In either case, whatever the cause something is screwed up. It is screwed up big time because I can be hooked to shore power, running my engine, and with the generator running and my batteries are receiving the current they need. And so are everyone else's unless Marathon does something totally unique. And if they really designed it to work that way I would be very concerned about what they were thinking.

[truk4u]

Bruce, I'm really confused now!:confused: My 97 Marathon had one 270 amp alternator that charged the chassis batteries while running and charged the house via the inverters. Running the gen while under way with the bus did not take the chassis battery charging away from the alternator. The transfer switch would provide AC power from the gen to the house through the inverters (no bypass switch on mine), but would not knock off the chassis charging function of the 270 amp alternator. With the bus not running, the gen or shore power would provide the AC through the inverters for the house, but would not charge the chassis. My gen also was stand alone, no charging except while running or receiving the solar panel juice.

What you are saying, is if you were running at night with all lights on with the gen running, you would eventually run your chassis batteries dead! Something is really wrong with that picture!

The only reason I added the Guest was to periodically bring the chassis batteries up to full charge if setting in the barn for an extended period.

I'll just defer to you and Jon so as not to confuse the issue further.

[Jon Wehrenberg]

I'm already seriously confused.

I thought the trip to Prevost to replace the isolator cured that problem.

There is something wrong, wrong, wrong.

[0533]

Jon: Lets review why this occurs on Marathon single alternator setups, which is my case.

My regulator gets its signal for the need for alternator power (single 270 amp alternator) from the house side. The regulator senses its need to deliver a charge from the house side. The electrical connection has been MOVED by Marathon from the 12/24 volt chassis switch at the drivers side rear door entry (where we all turn off the chassis side) to the house side shutoff just above at the same door location. Therefore when the generator is on, or the shore power is on while the engine is running the regulator will not sense a need for a charge as the house batteries are getting their charge from the generator or shore A/C power. therefore no charge will be sent to the chassis batteries regardless whether they are needed. This would only occur in this event, no problem when GEN/Shore is off.

The thought at Marathon was to provide the owner with a way to operate the bus using only the 270 AMP alternator to charge the house batteries without the need for the Gen/shore A/C source charging the house batteries keeping the house batteries charged at the proper levels saving fuel and the gen hours for use only at a dry camping situation I guess.

It is a pretty simple system if you view in these terms. The problem comes in if you find a need to run the generator while driving down the road. This will cut off the charging cycle to the chassis side.

So with this in mind, I use my OTR air while running along and rely on the alternator to charge the house batteries when the regulator senses a need.

I would be curious to know how Liberty handles this situation, especially when the coach is running down the highway without the GEN on and a load on the house batteries. What senses in this case, I guess if you have the inverters on auto start this would accomplish the same goal. How are other Marathon single alternator setups installed.

In my case, all I would have to do would be to move the wire from the regulator from its current location (House shutoff) over to the chassis shutoff, very simple change over.

PS> The isolator was a separate issue from this and it is solved. The Guest charger is only for charging the batteries while it sits for extended periods, nothing to do with any operational charging issues. my chassis batteries get a full charge while running down the road when the alternator is functioning.

PSS> If the regulator senses a power need from the house side, how would it function any other way than what I have presented??

[phorner]

Bruce,

Our Liberty set-up is pretty simple. There are 2 alternators. One handles the house batteries, the other the chassis batteries.

If either alternator fails, or both for that matter, (with the Guest charger installed) I can run the generator and still charge the batteries through the inverter/chargers.

I am at a loss regarding your system.

Wish I had more to offer you.....

[phorner]

Also, Bruce,

Your post makes it sound as if your single alternator senses only the house batteries while running down the road, and sends charging current accordingly.

If that is the case, how do you ever charge the chassis batteries? Under what conditions does your alternator send charging current to your chassis batteries as opposed to your house batteries?

[jack14r]

On my 2001 Marathon the OTR was wired to the house batteries with a 270 amp alternator charging them,the coach batteries had a 100 amp alternator charging them.On both Liberty's I have owned there is a single 270 amp alternator that will charge the coach or house batteries,also the OTR is wired to the coach batteries.I don't know how the sensing works but at times I can see on the gauges both sets of batteries being charged at the same time.

[Ray Davis]

So Bruce, if I understand what you're saying with regards to Marathon moving where the system senses the voltage to determine how much charge to provide out of the alternator, it would seem that any of us with a Marathon coach should be able to test this, and note battery voltages both with and without generator when running the engine?

I'll try to remember to make that test next time I'm out in the bus.

Ray

[Jon Wehrenberg]

Bruce........

Lets get basic here for a minute.

Your 24V alternator charges the entire coach when the engine is running. The alternator sends current through the isolator whose sole purpose is to prevent one set of batteries from pulling down the other set of batteries. In your coach and mine we can have the house batteries fully discharge, and the chassis batteries will still have a full charge, or vice versa.

Your 24V alternator voltage regulator has been set up to sense house current. There may have been a reason for that, but as you now know that reason was ill conceived. If you want you can go the expensive route and put in a second alternator, with a second regulator and increase the chances of a regulator or alternator failure in the future.

If you want to cure the problem you have with the chassis batteries not getting any charge when the bus engine and generator are running the solution is simple. Take the sense wire off the house circuit and instead sense the chassis batteries. In that way the problem goes away.

I don't know your coach. I don't know what loads you can have on the house batteries while you drive, or what conditions you determine are necessary to run the generator. None of that matters. If you want to end you problem I can talk you through making one wire connection to make your problem go away. By making this change you can get experience with it and determine if it makes the problem you are having go away, or if it transfers the issue to the house curcuits or if there is another piotential problem I am not anticipating.

Paul has a 12 volt house and a 24 volt chassis so his use of 2 alternators is because he is charging two different voltages. He has true bus air (some call converter installed AC bus air but it is not Prevost OTR with heavy DC loads) so he needs to have the big alternator, but his house battery system is a three battery in parallel set up making it an ideal candidate for a second alternator.

[Ray Davis]

Correct me if I'm wrong here, but at least with my Marathon's, they are wired such that the while driving the inverters can each run one A/C. This is assuming that the alternator is charging the house batteries while driving.


So, perhaps this makes an assumption that you should rarely need to run the generator while driving down the road, i.e. you should have dash air, and up to two cruise air or roof airs available from the engine. An A/C select button allows you to chose which A/C on an inverter is actually powered up.

Obviously, you could still run the generator, but perhaps that would cause the lack of charging to the coach batteries. I would think that if you limit the generator use in this case, then perhaps that was an intended trade-off?


Ray

[0533]

Also, Bruce,

Your post makes it sound as if your single alternator senses only the house batteries while running down the road, and sends charging current accordingly.

If that is the case, how do you ever charge the chassis batteries? Under what conditions does your alternator send charging current to your chassis batteries as opposed to your house batteries?
The regulator is sensing the house load, and directs the alternator accordingly.

The regulator is adjusted to a Max Output of 27.

There is an isolator and equalizer. The chassis batteries will receive an equivalent charge up to the Max Output of the regulator I believe.

There is only one sensor from the regulator on all Prevost car regulators, it simply depends on where you place the sense wire. In this case its the house side (not through the inverters i might add) but at the Main shutoff in the back of the bus.

[0533]

Jon: let me answer in your text copy below.

Bruce........

Lets get basic here for a minute.

Your 24V alternator charges the entire coach when the engine is running. The alternator sends current through the isolator whose sole purpose is to prevent one set of batteries from pulling down the other set of batteries. In your coach and mine we can have the house batteries fully discharge, and the chassis batteries will still have a full charge, or vice versa.

Yes the alternator will charge both the house and Chassis at the same time (as long as the genset or shore power is not on)

Your 24V alternator voltage regulator has been set up to sense house current. YES There may have been a reason for that, but as you now know that reason was ill conceived. If you want you can go the expensive route and put in a second alternator, with a second regulator and increase the chances of a regulator or alternator failure in the future.

I have considered this option or to simply move the sense wires back to the chassis side and forego the alternator.


If you want to cure the problem you have with the chassis batteries not getting any charge when the bus engine and generator are running the solution is simple. Take the sense wire off the house circuit and instead sense the chassis batteries. In that way the problem goes away.

Yes I agree But I sort of liked the idea for a while as it seemed to offer a solution instead of using the generator. I must admit that sometimes I do not like running my genset because the exhaust is on the roof and leaves a mess sometimes, especially if it rains after a long genset usage. The benefits of having the exhaust on the roof probably better overall. Different issue.

I don't know your coach. I don't know what loads you can have on the house batteries while you drive, or what conditions you determine are necessary to run the generator. None of that matters. If you want to end you problem I can talk you through making one wire connection to make your problem go away. By making this change you can get experience with it and determine if it makes the problem you are having go away, or if it transfers the issue to the house curcuits or if there is another piotential problem I am not anticipating.

Thanks, I assume it is to simply move the regulator wire to the chassis main shutoff?? If so I might well do this, and set the genset back to auto start again.

Paul has a 12 volt house and a 24 volt chassis so his use of 2 alternators is because he is charging two different voltages. He has true bus air (some call converter installed AC bus air but it is not Prevost OTR with heavy DC loads) so he needs to have the big alternator, but his house battery system is a three battery in parallel set up making it an ideal candidate for a second alternator.

I understand. Ours is a marathon OTR, smaller works well uses less juice.

Thanks Jon.

I am surprised by this type of install, have asked Marathon Coburg to confirm this, both Marathon Fl. and Prevost Car showed me this install and Marathon Fl concluded that it was the way it was originally setup, there are in fact Marathon #'d wires attached to the Prevost regulator wires. I have to believe there are other Marathon setups like this???
__________________

[Jon Wehrenberg]

Bruce,

Energy is energy is energy. If you run an AC unit from an inverter or a genset, or if it is an engine driven compressor to get the exact same level of cooling requires the same energy. The only difference is in the efficiency losses between an alternator going through an inverter, or a generator's 120VAC output going through the inverter transfer switvch for example.

Assuming your coach regulator voltage set point is what you require based on your type of batteries, I would guess the inverter set point is higher by enough of a margin to effectively tell the regulator to shut off voltage output from the alternator.

Let me answer your previous Liberty question. How does Liberty do it? First, they do not run any house AC units from an inverter. If I want to run a Cruise Air while driving, I need to start the generator.

That in turn powers the Cruise Air, but also makes the inverters chargers. If the bus engine is running the inverters sense house battery voltage, and if the alternator is maintaining a charge on house batteries the inverter charging circuit is putting out minimal charging current.

If you switch your sense wire back to the chassis batteries but try to run a couple of AC units through your inverters at 24 volts your alternator will be putting out about 130 amps just to keep the AC units running. Add in other loads such as charging the chassis batteries to make up for the bus loads like daytime running lights , or to make up for other house loads like the refrigerator and you end up pushing the limits on the alternator. The greater the loads on it the hotter it runs and heat is the enemy.

If you add a second alternator it needs to be big enough so it is not run to its capacity or its life will be shortened.

If your chassis batteries are what your alternator senses (I recommend that) your house will receive the bulk of the charge if the house voltage goes down due to depletion frm AC units. The regulator will not be shut down by a higher inverter charge rate. But don't expect to get it all or for free. If you run AC units from the inverters you send power to the ACs from the batteries but the charge current going into the batteries may not prove adequate to maintain a full charge on the house batteries while they are under such loads. The house batteries and the chassis batteries will receive charging current to some extent however.

There ain't no free lunch.

I don't understand the concept of what you call over the road air. It must be a misnomer. My understanding of over the road air is a full coach Prevost system using a large engine driven compressor with large DC evaporator and condenser motors. With that system there is no need to run anything other than the engine, and it will freeze you out if set to max. The only time I ever need to run the generator while driving is if we want to run heavy loads such as the washer, dryer, other items not on the inverter powered circuits, including cruise airs (which we don't run while driving).

[jack14r]

Jon,The newer Liberties have 3500 watt Outback inverters that will run AC units,but you are right with OTR it is not necessary to use the inverters going down the road.

[0533]

First, Jon, I want to thank you for helping, for listening and always making me think.

0533 is a one of kind bus in many ways, it was designed for an experienced 3 Marathon owner who seemed to want the very best, latest and greatest equipment in hopes of creating the better mousetrap. It is special but with a few twists.

Jon wrote: Energy is energy is energy. If you run an AC unit from an inverter or a genset, or if it is an engine driven compressor to get the exact same level of cooling requires the same energy. The only difference is in the efficiency losses between an alternator going through an inverter, or a generator's 120VAC output going through the inverter transfer switch for example.

Which is more efficient?? Does anyone know??



Jon wrote: Assuming your coach regulator voltage set point is what you require based on your type of batteries, I would guess the inverter set point is higher by enough of a margin to effectively tell the regulator to shut off voltage output from the alternator.

This is a good question, I do not know what the inverter set point is, will check. Isn't it also dependent on how quickly the house batteries use up their stored charge. Is this the set point?? If the house batteries fall below 25.5?? or something?



Jon wrote: Let me answer your previous Liberty question. How does Liberty do it? First, they do not run any house AC units from an inverter. If I want to run a Cruise Air while driving, I need to start the generator.

First: I do not have cruise air's on my bus, rather I have 2 RVAC units with 4 compressors, 2 on each side, 2 are for a low setting and 2 are for a high setting. I also have a Marathon OTR . The manual says that one can mix and match, in other words, I can operate the low settings using the inverter power while running down the road or even while sitting without the engine running (few hours). I can also even add the OTR into the mix and have both operating or use OTR alone.


Jon wrote: That in turn powers the Cruise Air, but also makes the inverters chargers. If the bus engine is running the inverters sense house battery voltage, and if the alternator is maintaining a charge on house batteries the inverter charging circuit is putting out minimal charging current.

I am a bit confused here. If your genset must be operating to run your Cruise Air's, and your inverter becomes a charger (same in my case) doesn't your genset charge the house batteries?? How could the regulator/alternator sense the house batteries if they are tied to the chassis side??



Jon Wrote: If you switch your sense wire back to the chassis batteries but try to run a couple of AC units through your inverters at 24 volts your alternator will be putting out about 130 amps just to keep the AC units running. Add in other loads such as charging the chassis batteries to make up for the bus loads like daytime running lights , or to make up for other house loads like the refrigerator and you end up pushing the limits on the alternator. The greater the loads on it the hotter it runs and heat is the enemy.

I am not sure that I am following this train of thought completely, not doubt.
If I move the regulator sense wire back over to the chassis 24V shutoff the regulator (hence the alternator) will sense the need for charge from the chassis batteries, if they do not call for a charge the alternator will not provide much output. I do not see how the alternator will be suppling much of any output to the house side (reverse of my current setup) if I were to operate my AC units in the bus on inverter power. If I did not turn on (Auto Start) the genset the house batteries would drain down eventually as the alternator could not sense a need for a charge to the house.



Jon wrote: If you add a second alternator it needs to be big enough so it is not run to its capacity or its life will be shortened.

My thought was to dedicate a smaller alternator exclusively to the chassis side with a second regulator (I think) that went to the Chassis main shutoff. I would not need the equalizer anymore and maybe the isolator ??? This way the 270AMP would be dedicated to the house side and the smaller to the chassis, might leave the old install in place (isolator and equalizer) in the event of an alternator failure???



Jon wrote: If your chassis batteries are what your alternator senses (I recommend that) your house will receive the bulk of the charge if the house voltage goes down due to depletion frm AC units. The regulator will not be shut down by a higher inverter charge rate. But don't expect to get it all or for free. If you run AC units from the inverters you send power to the ACs from the batteries but the charge current going into the batteries may not prove adequate to maintain a full charge on the house batteries while they are under such loads. The house batteries and the chassis batteries will receive charging current to some extent however.

This would be so if I transferred the sense wire from its current configuration, but I do not see a way to charge the house batteries in this scenario at any rate that could support enough of a charge to maintain AC power in the bus. The chassis batteries would not require enough of a load to offer a big enough, long enough charge for the house batteries. I would need to operate my genset as you do to use any AC in the bus (other than OTR)??


Jon wrote: There ain't no free lunch.

Come to my house Jon, I owe you that much and more.


Jon wrote: I don't understand the concept of what you call over the road air. It must be a misnomer. My understanding of over the road air is a full coach Prevost system using a large engine driven compressor with large DC evaporator and condenser motors. With that system there is no need to run anything other than the engine, and it will freeze you out if set to max. The only time I ever need to run the generator while driving is if we want to run heavy loads such as the washer, dryer, other items not on the inverter powered circuits, including cruise airs (which we don't run while driving).


0533 has 2 ways to have AC running while operating the bus without the need to operate the genset. Marathon OTR, a smaller compressor than the Prevost unit, all else the same I believe?? This unit requires a less energy from the main engine to operate and produces lots of air in the bus. But if it is really hot outside desert hot you can add up to 2 RVAC compressors on the low setting (even add just one if one side of the bus is hotter than the other) and still not require the genset. If you decide to add the second set of compressors (high) you will need to add the genset to operate all unless you are using shore power.
__________________

[Jeff Bayley]

Warning, stupid newbie question......

What is the purpose of a "guest charger?" Just what it implies - charging other things like your car?


The purpose of a chassis battery charger like this is for when you park in South Beach and block an entire lane of traffic on a Friday night and are too smashed to move the bus when you get back from bar hoping. You've left the flashers on, you go to be with the flashers on and when you get up in the morning the chassis batteries need to be topped off in order to start the coach.

Worked great for me and not so much as a single knock on the door from a cop asking me what the hell I was doing there. Maybe he thought I was waiting for Triple A but I was starring at my eyelids.

[Jon Wehrenberg]

Bruce......please understand this. The efficiency of running a generator, or putting heavy loads on the alternator is something that requires someone with some ability to eliminate all variables except the differences between the two methods. That means you need to run the test to determine fuel consumption on a day when temperatures don't vary, the road course is exactly the same, the winds are exactly the same, etc.

You have a bus that is eating money and you seem worried about a few grams per mile of diesel fuel.

Call me when you have completed the test.:D

What I said poorly and you did not understand was my contention that running the A C units off the inverter puts a heavy load on the alternator. Since I have no clue what loads the A C imposes I made the assumption that using the equivalent of two Cruise or roof airs is 130 amps at the 24 volt output of the alternator. Even if the regulator sense wire is on the chassis side the alternator will be putting out juice. At least it does on my coach. My sense wire is on the chassis side, and my house is still charged.

The point I was trying to make but poorly is that I personally think running AC units off inverters (actually house batteries) begins pushing the output of the alternator. In my coach my typical inverter loads are around 5 amps at 120 Volts or 25 at 24. Add in 130 for AC units, add maybe 25 more for whatever the bus uses, add in a few efficiency losses and the alternator is beginning to approach its limits. It may be running at 75% of its rated output. Your engine is working to turn that alternator, using extra fuel. If you want to run the house AC units, crank up the generator and be good to the bus alternator. You will probably use similar amounts of fuel.

If you move the sense wire to chassis the house batteries will still get a charge. Mine does, yours should. If you wish to run the AC units, just monitor the house DC voltages and if the alternator is not putting enough of a charge into the house, running the generator is the response.

If I were to run the generator on my coach while the engine was running here is what would happen. The chassis battreries would be charged at the voltage the regulator is set to. The inverters AND the alternator driven by the engine would both be charging the house, but only the higher set point would prevail once the battery voltage reached the lower set point of the two. If my inverters are set higher, the resultant house voltage would be what they put out. If the regulator had the higher voltage that would be their ultimate voltage. Whichever is the lower voltage will be overridden by the other.

Since the regulator cannot see house voltage because it senses chassis, then it has no idea the inverter voltage may be higher. It just limits the alternator output voltage. If the inverters have a higher setting only the house is affected because the isolator stops current flow back from the house.

With respect to your concerns about house battery voltage when the house is drawing a lot of current, the alternator output will flow toward the area of greatest need. If the house voltage is less than the chassis, it will get the bulk of the charge.