House Batteries

[truk4u]

I agree, there is no doubt each inverter manufacturer handles the job a little different.

With the Magnum's, after driving, the batteries are well charged and mine immediately goes to bulk, then absorbtion and float rather quickly. The entire process takes less than 1 hour, but I haven't kept exact time. Before I hook to shore after driving, I turn off the chargers and turn them back on later after all the power needs sort of get worked out. There's no hurry for the chargers, so I wait.

Cycles are the big question in battery life. How you use your bus determines the cycles based on your particular charge parameters. Here's a few numbers to think about using Lifeline's AGM data:

Expected Life Cycle - 5000

Discharge - Voltage - Life Cycle
50% - 12.20 - 1000
75% - 11.75 - 600
100% - 10.50 - 375

So in theory, if I am diligent about my new batteries discharge rate not exceeding 50% (12.2 volts), I can expect about 1000 cycles. I will use more cycles than the guy who uses 75% (11.75 volts) and gets 600 cycles, but will I reach the end of my battery life before he does? I will also use the generator more often and use more fuel, but using the gen more in my opinion is a good thing.

Now I throw my auto-start into the picture and with the Liberty Watch Dog default start voltage of 11.15, approximately 90% discharge, I now only have about 440 life cycles. Batteries are very expensive!

I'm sticking with 12.2 per Lifelines recommendation, manually controlled of courseand hope it all works out.

[Joe Cannarozzi]

Jack the way your bus forces a charge on full batteries after a long drive, that's not right. What is Liberty's explanation for that?

Ours functions just like Toms.

I do not turn off the inverter when first hooking into shore/gen like Tom but with the batts charged up the inverter will really quickly go thru its cycle and into float. When we leave town I do not turn the inverter off till we get home.

Jon we are not able to adjust our charge rate on our older Heart in the back of the remote but have to do it directly on the front of the inverter itself and it is downstairs behind a wall, behind the freezer. Again because of the fully charged condition of the batts any time we end a day I have never adjusted ours down, it has been a non-issue.

Winter forces me to manage power more than summer.

The only time I can get the inverter to ramp up to 30 amp rate is if we are dry camping we have been running off of it for 8 hr or so and when I start the gen I want to see 30 amp anyway, not 5.

It's great to have all these choices. If we had the convienience to adjust our charge rates like you we probably would but even so it does a pretty good job all on its own. Jon could you adjust your 87 at the remote too?

I think these 15 and 20 K power plants and large corrisponding inverters/dc capacity are one of those things that set us apart.

[phorner]

It sounds like the inverter manufacturers that provide control panels that can control generator auto start do a very good job and allow for the precise setting of start/stop parameters.

Maybe it would be beneficial to explore the possibility of replacing the converter's auto-start system with the one offered by the inverter manufacturer?

My old system would allow me to set the auto start at 90% capacity and stop at float charge. The display would also tell me how many hours to go based on the existing current draw. It worked flawlessly.

It might be simpler to research this retrofit rather than re-engineer the converter's system.

Any thoughts?

[ajducote]

On my 99 Royale, I wired one of the inverters to control the generator auto start. You can set times and voltage points for bulk, absorption and float.
It was a job to get the wiring figured out. I will try and find the wiring diagram I created and post it.
Works much better then the auto start that was installed by the converter.

[BrianE]

Andre,

It was news to me that the autostart system in our Royale #265 is not controlled by the Trace panel. The differences in systems between the Royale and our old Liberty have kept me busy enough without worrying about the autostart system which I have never used in either coach. The current thread has however kept my attention about battery charging and your comments definitely woke me up.

I just spoke with Glen Burden at Royale Phoenix and asked him to review the autostart system for me. He confirmed your info and told me the autostart low battery cut in is preset and not controllable at 11.4 volts. He also told me he has a diagram for accomplishing what you did in allowing the Trace inverter to control the autostart and charge parameters. He recalled a relay and 110v line was needed in the circuit to make it work and that he would dig the diagram up and send it to me. It will be interesting if it is similar to your setup.

Many thanks for the heads up. As always POG is a great tech resource as well as a place to meet good friends, sheep-lovers, annal mechanics, and taco freaks.

[lonesome george]

Our coach uses a Sun Selector to auto start/stop the generator, the thing works OK and the start and stop voltages can be adjusted by .1 of a volt which is good. The current setting are start at 12.0 and stop at 14.1 from this thread it looks like the 12.0 should be changed to 12.2.
My question is if the inverters can be wired to start and stop the generator why is the Sun Selector, Watch Dog or some other device there in the first place? Is it the covenience of a rocker switch on the Instrument Panel?
For reference our rig has two 4000w Trace inverters, six 8D AGM's and a 20 kw generator.

[BrianE]

George, The advent of the inverter controlled genstart system is relatively new. Why the converters didn't take advantage of the feature when it became available in the mid-90's is anyone's guess. Also the 11. something value the older systems use to trigger autostart works okay with lead acid batteries but obviously isn't okay with AGM's. The 12.0 that your system is set up for is presumed to be just fine according to the Battery thread that just preceded this one.

[Jon Wehrenberg]

In problem solving it is best to eliminate variables or unknowns and in this discussion we are all considering a global problem relating to autostart and battery charging. Apples and oranges.

I see two distinct issues that need to be separated. The first is recognizing the autostart parameters for our repsective coaches. What may be the Liberty Watchdog start/stop parameters may not be the same for any other conversion, or even a Liberty that has been modified.

I think if Jack can discern the start/stop parameters for example we can likely resolve how to modify those while leaving the Watchdog system unaltered. I cannot say that about other autostart features because my understanding of those is worse than what I know about the Watchdog (which is minimal).

The charging cycle for our inverters is another whole issue. Some can be easily changed to reflect our individual needs. Setting inverters up for high power charging is as easy as following the inverter manufacturer's instructions, but in some cases it may require access to the rear of the remote panel. In other cases it might just involve some button pushing from the front, or as Joe points out, gaining access to the inverter itself. There are times when the charging parameters need to be reset, such as when we have power management issues with a 50 amp service and we need to have 3 AC's running along with everything else we need operating. Other times we need a high charge rate on our batteries because we may be pulling a lot of power from the batteries and we need that high charge rate to avoid discharging the batteries.

Some inverters are designed to go to bulk on every inititation of the charge cycle (a warning to owners of gel cell batteries....that's not good) and others may just need to go quickly through the various charge phases only to measure voltages. But part of the charging system also involves the bus driven alternators which are charging to a single specific voltage and DO NOT go into float. As if that is not enough to worry about, recognize that the bus driven alternator can be supplying charging voltage, and if you are running the generator (such as to use AC) the inverters are also charging the batteries. Their voltage output may exceed the bus regulator set point so the resultant voltage may be a bulk rate voltage from the inverters. Confused? Don't be. Just be aware of these things and make absolutely certain the various chargers are set up for your type of batteries (a gel cell battery is as good as dead if you charge it using a lead acid or AGM protocol) and that you clearly understand how your system works.

[Joe Cannarozzi]

D/C Power 101

I am confident I understand float but I would like to know more about the difference between bulk charge and absorption charge?

[Jon Wehrenberg]

Joe,

It's voltage. By the time you read this site you will be volunteering to put on the DC Power 101 seminar.

http://www.windsun.com/Batteries/Bat...ting%20battery

Every single RV owner should read and understand this information. It will pay dividends many times over.

But here is another that has substantial value and information.

http://www.lifelinebatteries.com/rvbatteries.php

If you really want to go further, here is another site that will add to your depth of knowledge.

http://www.wholesalesolar.com/information.html

As an alternative, do what I do. I make stuff up.

This whole topic of batteries, charging, inverters, etc. is central to enjoying an RV. If you are constantly having problems with battery life, maintaining a charge, overloading circuits, or just don't know what you should be checking or looking for, the above information is about as good as it gets. There are no free lunches so we are all forced to compromise. We only have a finite amount of battery power available so we all need to understand how to prolong the battery life, how to conserve battery power, how and when to charge the batteries, what type of batteries are best for our needs, and if we need to modify how we use our available battery power. An alternate source of information is the operating manuals and owner's manuals for everything from our inverters to our chargers to our batteries.