Battery Basics ??

Paul,

You need the generator running or shore power to power the circuit to the engine block heater. Best to my knowledge that it does not run off the inverters.

Gary - we like that detail.

Mike

Yeah, I'm connected to shore power... wouldn't do well to have battery chargers connected to the inverters!

Well, as I'm continuing along my trek to disconnect and charge each battery in turn, as I removed the nuts from the battery posts of battery #3, the ends of the cables attached to one of the posts just crumbled into nothing.

So, it looks like I get to play electrician tomorrow. I need to replace a short, say 8" or so, battery cable that acts as a jumper, and replace the ends to a couple of wires from the wiring harness that now have no connector on them to attach to the battery post.

If I have to keep doing this level of maintenance, I'm gonna need to press Janice into duty with the stainless polish...I'm getting behind in the polishing schedule and Lew has been chastising me about the water spots and finger prints...

I didn't steal your post chicken boy, he MAY NOT have a 110V block heater!;)

Well, it looks like I'm getting closer to being finished. All 4 batteries are charged up and I'm in the middle of replacing some of the questionable cables.

Any suggestions as to handle these destroyed connectors? They attach to a negative terminal and are part of a wiring harness.

What's the best way to handle this repair?

A battery distributor can make new cables for you, or you can make your own. The ends are available at welding supply stores or battery specialists and the tool to crimp the ends is a simple punch and die type fixture that you insert the cable end in and hammer it to make the crimp.

The black insulation over the end terminal is just heat shrink tubing.

I'll need to replace the ends/connectors. They actually have 2 wires each, which aren't clear in the photo, and the wire disappears into a wiring harness cable wrap.

Hopefully, once the old ends are cut off, I'll have enough wire to reach the terminal.

Is it better to twist the 2 wires together before crimping on the end, or place them parallel to each other (the way they are now) and crimp the center?

I hope a smart electrical guy would answer this, but if it was me I would twist them. I am not sure you need the big battery type terminals since you might find suitable sized ring terminals.

What I now realize is that if those are connected to your bus batteries I'll bet you the Happy Meal Joe owes me for the nitrogen thing that is the phantom load draining your bus batteries. Chase them down and figure out why someone connected them to the batteries instead of the terminal posts in the bus rear junction box.

I was wondering the same thing about those wires, Jon. I get suspicious when there's anything but battery cables attached directly to the batteries.

If you think the ends of those wires look bad, you should have seen the battery cable that I replaced! The copper-colored cable in the photo is a new replacement, which was made up at a local battery place. I also replaced a couple of others that looked tired while I had everything apart.

I agree Jon, I don't like to see anything connected to the chassis batteries. The chassis batts are to important to have anything to them. If its a connection to the house batts that the converter did I would put a disconnect right at the batts.

Paul, can you find where those cables go?

I'm going to try my best to track them down. Right now, they just kind of "disappear" into a wiring harness. There's these 2 pair connected to each terminal of the battery in the photo.

For what it's worth,the negative 2 pair are black and the positive 2 pair are yellow. This probably only means something to whoever installed them.

My first instinct is to replace them and then see if the bus starts and runs OK. Then, I'll spend some more time tracking them down.

Could they be part of the Detroit or Allison systems? I wasn't sure if either the engine or trans required a direct connection such as this.

If it's merely for some accessory, I'll feel much better tinkering with it.

In the mean time, I'm also going to concentrate on a method to keep the chassis batteries charged while plugged into shore power.

Do these extra wires go to a single battery, i.e. black to negative, and yellow to positive? if so, this is most likely some 12v add-on?

Yes, these extra wires go to a single battery. There are 2 pair and look identical.

So, I agree that a 12v accessory is a likely candidate.

Now then, since the negative leads are disconnected, I should have a 12 volt something that doesn't work, right?

I had high hopes for the CB, but it powered up fine. I also have both the 12 volt and 24 volt disconnects "off", so I'm sure how that enters the mix of variables.

ph-

while you're at it: it appears from the pic in post #45 there is a steel washer under the big cable ring connector. you need to remove this. the connector needs to touch the lead post. steel doesn't have the conductivity of copper or lead and wil cause a large voltage drop at high current, like when you're starting.

of course, if there's no washer there, as rose rosannadanna would say, "never mind".

wmm

Thanks for the tip. Actually, that's the base of the battery post, but I'm glad to keep learnin'...

Paul,

To help understand the situation those wires are creating an imbalance by being connected as you describe. They will pull a single battery down and that will drag the rest with it.

Just for the hell of it, leave them off and if anything on the coach does not work then worry about it.

I would chase those wires down. I have several small yellow wires attached to my batteries as well and it was done by the convertor. These are what are called parasitic loads which go direct to the batteries so certain electrical systems do not get turned off. Also, I have wires attached from my battery charger. So, verify before changeing your wiring. The terminal ends (ring type) can be purchased at any auto store, they look like #6 guage because of the two #10 copper wires. I would strip back about 1 inch and twist the copper a couple of times, slip them into the terminal and crimp with a crimp tool or with a pair of dikes. (2 crimps). Also, slide on a piece of suitable size shrink tube prior to crimping.

Gary,

Your comment about wires attached directly to the batteries took me by surprise. Are they attached to the chassis batteries, and are you sure Liberty did them?

I can fully understand if the converter attaches loads to the house batteries. That is their domain, and we would have to assume they had a reason. But the downside of that is that the coach can never be turned off, meaning any coach storage will require shore power because without it those parasitic loads will kill the batteries.

By appearance, they do look like they were installed by Liberty.

What do the 12 and 24 volt disconnects actually "disconnect"? I'm thinking this is a Prevost feature and should be the same function from bus to bus, regardless of converter?

So far, I've only found the driver's seat inoperable with those wires disconnected, but the passenger seat works OK. That doesn't make sense to me, but then again, so far not much has...

The chassis shut off switches, 24 volt is for the battery bank, and the 12 volt is the tap from the battery bank for the DDEC.

I admit my experience with Liberty is limited to 2 coaches, but I am troubled that a parasitic draw would be added to a coach to FORCE the owner to always have shore power available so the batteries could be charged at all times. Does not sound right. Actually is sounds like someone added it without thinking through the consequences.

Passenger seat is electric and comes from the house circuits. Driver's seat is air and if the aux pressure is zero it will not work.

Only problem is... the batteries died while continuously plugged into shore power.

That's what has me concerned. If I lose the chassis batteries while maintaining power to the coach, something has to be wrong.

The coach sat for about 3 weeks, house power connectd all the time, since the last start-up, and the chassis batteries were dead.

Since we live in the bus full-time, I have no objection to keeping it plugged in when the alternator isn't keeping things charged up.

Paul,

You can be plugged into shore power, but if there is no battery charging provision on your chassis batteries they are going to go dead because of the parasitic load. That is why they are a bad thing.

I have sat for at least 3 months, with my chassis switches ON, no charger for the chassis batteries, opening bay doors on occasion (drawing power from the batteries due to lights which I think are chassis) and still had plenty of battery power to start the coach. The object is to get your coach to a point where you do not have to worry about dead batteries. In fact judging by the size of the wires that parasitic load is not a tiny one if it is on a circuit that is hot at all times.

I have zero issues with loads being connected to either set of batteries if two conditions are met, neither of which appears to be the case with your coach. First, the circuit is fused or protected at the batteries. Every inch of wire between the circuit protection and the battery post is an unfused hazard. Second, the circuit is not "on" except when you turn it on so you can control if it draws down your batteries. If an unprotected or poorly protected circuit is on all the time (fuse no further than 18" from the battery post) you not only have a current draw you have a potential fire hazard.

I went through this issue on my previous coach where a previous owner did some shade tree engineering and hooked the Racor heater element directly to the batteries. The thing that made it impossible to quickly locate was it wasn't drawing current until the internal thermostat called for heat, so I couldn't find the current draw until it got cold. The only thing I beleive to be directly from any of my batteries now is my CB and I have no clue why, but it is called out in my owner's manual to be that way.

Paul, just to review, you have the chassis batteries charged, the bus starts and everything is fine, the bus charging is ok, except you need to replace the ends on the two cables in the photo?

I reconnected the damaged wires and fired up the bus. Good news is it started.

But, I'm getting readings from the Liberty gauges of 15 and 27 volts, respectively, including 15 or more volts for the house batteries.

With the high house battery voltages, the inverters are in a fault stage of some sort.

Shore power is disconnected at the breaker in the 1st bay.

Can you leave the cables with the bad ends disconnected to see if your still getting draw down on your chassis batteries. If you can do this in the dark, touch the bad positive cables, almost a striking against the post to see if you have much draw or if you have a DC amp meter that would be the best to check draw.

I think I would leave them disconnected for a few days to see what's going on with those cables.

Paul,

The 27 volt chassis voltage is OK. I would expect to see it climb to around 27.7 or thereabouts as the batteries get fully charged.

The 15 volt for the house is a little high unless the inverter went into equalize mode. Is your equalizer hooked back up? 13.8 to 14.2 would be around where I would expect to see the house when the inverters are maintaining the charge on fully charged batteries.

Why is the shore power off in the coach and not in the campground the power outlet? If you are trying to verify everything is OK you want to make sure all switches and devices are in the normal mode.

Jon,

I shut the power off at the breaker in the bus bay simply as a matter of convenience. I subsequently then shut down the breaker in the resort power pedestal.

One thing that I've learned is that the inverters do not like to have me start the bus while connected to shore power. For some reason, when I do this, it acts as if the house batteries are getting over charged (which, I guess they are, since both the inverter/chargers are working as well as the alternator at that point) so I have to remember to disconnect from shore power before starting the engine.

I did notice that the dash engine monitor clock display went back to a flashing 12:00 after I had shut down the 12 and 24 volt disconnects, which indicates to me that this "draw" can be eliminated by using the disconnect switches. But that should, in my opinion, draw very little current and shouldn't have been enough to kill the chassis batteries in less than a month.

I'm sure things will be better once I have everything down to a set procedure and gain more experience in using the bus.

It was a real eye-opener to turn that ignition key and have absolutely nothing happen!

Is there a good way to measure the current draw from the chassis batteries while parked and in a "shut down" (both disconnects in the off position) mode? If so, that seems to be a good starting place to figure out what I need to do next. My ultimate plan is to install the battery charger that you recommended, which should arrive in the next week or so.

You can use a clamp type meter that measures DC current (Fluke 336A for example) or a multimeter that has a current measuring capability. If the draw is greater than 10 amps that will exceed most meters, but not the clamp type.

I'd have to get more familiar with your coach because some stuff doesn't sound right. Both the inverters and engine driven alternator sense current and regulate the voltage so you could have three chargers on there and the battery voltage is unlikely to exceed a certain preset value. That is why I questioned if the inverters went into equalize which is a higher voltage than the bulk charge voltage, and which the inverters are capable of doing. It is not a bad thing if that is what happened, but it is a bad thing if the voltages are out of control.

On your bus the house should have a dedicated alternator specifically for the house. If the higher voltage is present when the bus is runnning I would be very suspicious of the alternator or the voltage regulator (most likely).

Paul, when you have the bus engine off and you go to the dash, can you see the volts of the chassis batts? My thinking is if you can then watch the chassis battery volts over a period to see if they are dropping. Ours doesn't loose volt while just sitting, but I normaly flip the disconnect. I still would leave the cables with the bad ends off, I have a feeling they are coming from the house batteries.

It would sure be fun to be parked next to you, so we could see for sure what your dealing with.

Thanks for all the help.

Dale, if you really wanna have fun, Lot 24, right next to me in Outdoor Resorts, is available!

The mystery wires that had the bad connections have all the appearances of an "original" installation.

So, I'll continue tomonitor the situation. At least I know what I need to do to get the batteries charged if need be.

I've schedulled a service appointment to have everything checked out and to have my handiwork on the replacement cable ends inspected.

Paul,

One concern I have in reading through this thread. I think there were two misunderstandings in your posts, which I'd like to try to clarify.

As Jon has pointed out, most draw items, like clock, radio etc, should all be driven off the house batteries, NOT your coach/chassis batteries.

Basically the coach/chassis batteries should ONLY be used to start the bus, and nothing else.


The other important thing to understand is that unless you've added a charger back in your engine bay, the ONLY time the chassis batteries are being charged is when your engine is running. Default condition on these busses is that there is NO charger on the chassis batteries.

Plugging in to shore power will NOT charge your chassis batteries.


Ray

Paul,

Not to beat a dead horse, I'm just trying to help, but if you have a dead cell or two the charges will charge like crazy and never get to the float. I mentioned this before and asked if you load tested them while they were removed, but you didn't say anything. Also, if your chassis batteries are AGM, make sure your charger is not Equalizing, bad thing to do.

Tom, do you think that there are those who use AGM in the chassis? I don't think I have seen that before.

Dale,

That is a question for Paul to answer. I know of several coaches now where the owners have gone to AGM.

Tom is on the money about equalizing and that is why I am asking about it and suggesting close monitoring of the system. I am still really bothered by those parasitic loads. They spell trouble.

The chassis batteries are standard wet cell batteries. Although I don't have the equipment to load test them, my charger is a digital, high frequency model that is supposed to give me a fault code if there is a bad cell, short, or similar problem.

Since it went to float charge and there were no fault codes, I'm relatively confident that the batteries are OK.

As I have learned, there is apparently no provision for charging the chassis batteries other than the alternator while the engine is running. Since I didn't"t have the disconnects in the "off" position, this whole episode may just be a case of pilot error in allowing the batteries to drain over a period of about 3 weeks.

However, this adventure did allow me to find some badly damaged cable ends which have been replaced and I've decided to add a charger for the chassis batteries. The ultimate result will hopefully be a more reliable coach which is better understood (and better maintained) by the owner.

Haven't given up yet!!

Paul,

This is important......it would not matter if you had the battery disconnects for the chassis "off".

We are trying to tell you that those wires connected to your batteries ARE NOT going through the disconnect switches, and until you leave them disconnected, or find out what they are for, and you can be assured they are not pulling power you can almost bet that even if you turn off the battery disconnect switches your batteries are still going to end up dead.

Unless you want to leave a charger on them forever.

Paul, just the thought of the chassis batteries going down unless you throw the disconnect should alarm you a little. As Jon pointed out the chassis batteries could be left in the road ready position for some length of time, like your automobile.

Dale - Yep, my Marathon had AGM's in the chassis. I wouldn't go to AGM's in the chassis, but someone previous to me did it.

Paul - Since my chassis is the same year as yours, although not a Liberty, when I start up and drive, my chassis alternator puts 14.2 volts into the chassis batteries for about 1 hour and then tapers off to 13.2. My regulator is adjustable and those numbers are recommended by the Lifeline Regulator documents. I mention this only to kind of give you a reference number if your setup is similar. As I mentioned, I just installed a Quest 3 stage charger for the chassis batteries, although like Jon, mine stays up without any measurable loss over time, but I'm anal about keeping them topped off. I have a digital dash in the CC and it seems to like all the juice it can get at startup. If you want pictures, let me know. Sounds like your batteries are good if it went to float, but I don't understand how your charger can check a cell without putting a load on it. Lots of new stuff out there, so I'm probably behind the curve.

Hang in there....;)

Jon. I will review those yellow wires tomorrow and let you know what they are energizing. My thought about Pauls batteries going dead may have to do with the burnt connections. He would not have been getting a charge when the engine was running with loose or bad connections. The burnt ends confirm he had a load heat up on the ends which means he had a tremendous amount of load heating up at the terminals. This may have been going on for quite some time. Therefore the batteries were dead because they were not getting charged.

Gary,

Your coach is new enough to be able to possibly trace how some things came about. Attaching anything directly to the batteries, and thus by-passing the power disconnect switches is bad practice and dangerous if those attachments are unfused.

Not knowing the history behind those kinds of things almost mandates that the owner investigates and finds out where they go just to be sure there is a good reason behind why they are there. One thing that I can envision as making sense for wires directly to batteries would be an owner installed charger, but other than that I'm at a loss to think of anything that wouldn't be better coming from one of the DC posts inside the front or rear electrical boxes (with a fuse or circuit breaker in close proximity).