New Dude - Battery Question

[Cjohnson]

Howdy.

Just purchased a used 2018 GD M-327. I've been running the unit on my property with a small generator. Looks like I was confused on which way to turn the Battery Disconnect, so when I went to put the slide out tonight I found the battery dead. Ran the genny, and didn't get much of a charge on the battery.

A couple of questions...

1. Should I have the disconnect off when running generators? I read somewhere that they fry the battery. Mine are Honda EU2000/2200 invertor models
2. Should the battery be charging while the generators are running (disconnect ON)?

The battery is a FVP M24-7DC.

thx,
CJ

[jkwilson]

The battery is charged via the converter. The disconnect removes the battery from the converter so it isn’t charged.

[boyscout]

Just purchased a used 2018 GD M-327. I've been running the unit on my property with a small generator. Looks like I was confused on which way to turn the Battery Disconnect, so when I went to put the slide out tonight I found the battery dead. Ran the genny, and didn't get much of a charge on the battery.

1. Should I have the disconnect off when running generators? I read somewhere that they fry the battery. Mine are Honda EU2000/2200 invertor models
2. Should the battery be charging while the generators are running (disconnect ON)?

Welcome to the forum.

Per @jkwilson, the generator doesn't charge the battery so it can't "fry" the battery. Generator provides shore power to the converter, and the converter has a multi-stage charging system to charge the battery. The battery "disconnect" switch must be on to allow the battery to charge.

When you turn it off the battery "disconnect" switch doesn't disconnect the battery completely. Things such as smoke and propane alarms, trailer brakes, and the leveling system remain inline, drawing about 1/2 an amp of power, so even with the "disconnect" turned off the battery will drain flat in a few weeks.

Sounds like your battery did drain flat. Lead-acid batteries should not be drained more than about 50% of their capacity. Draining flat usually damages them such that they'll never again give full performance and sometimes they won't take much of a charge at all. Most places that sell batteries can test yours to tell you if it's damaged.

[Cjohnson]

The battery "disconnect" switch must be on to allow the battery to charge.

Perfect! Thank you. I was typically not turning on the disconnect when running on the genny. After a couple of weeks, the battery dropped so low that it required a charge. Makes sense now. I store the camper quite a bit so will consider installing a full disconnect at the battery itself.

[DaveMatthewsBand]

...the generator doesn't charge the battery so it can't "fry" the battery. Generator provides shore power to the converter, and the converter has a multi-stage charging system to charge the battery...

Just FYI OP might have been referring to accounts of the WFCO converter/charger that comes in all the Grand Design trailers.
They actually have been known to “fry” lead acid batteries. Which is why a lot of owners ditch the WFCO and upgrade to a Boondocker model or Progressive.

Also, our smoke detector and carbon monoxide detector are powered by independent 9-volt batteries, not the trailer battery. Only the propane detector is run off the trailer battery.

Also, the 50% thing is a myth according to Jeff.


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[boyscout]

Just FYI OP might have been referring to accounts of the WFCO converter/charger that comes in all the Grand Design trailers.
They actually have been known to “fry” lead acid batteries. Which is why a lot of owners ditch the WFCO and upgrade to a Boondocker model or Progressive.

Also, our smoke detector and carbon monoxide detector are powered by independent 9-volt batteries, not the trailer battery. Only the propane detector is run off the trailer battery.

Also, the 50% thing is a myth according to Jeff.

The pandemic gives us plenty of time to split hairs Ed.

I wrote that the generators that the OP was asking about weren't going to fry the battery because they don't charge the battery directly.

Yes, there are reports of people having battery damage after extended time plugged in, especially if the trailer isn't being used. We don't know now many of those cases involved reduced electrolyte levels in the battery - the most-common lead-acid batteries need to be checked at least monthly. The WFCO converter is not the best-quality device around, but OTOH there are literally hundreds of thousands of WFCO owners (including us) who are years into using them a LOT without frying their batteries.

Our smoke detector is powered by 9V battery too, others have reported that theirs runs off the trailer battery. The point that was being made was that most of these trailers have some measure of current loss from various devices even when the battery "disconnect" switch is turned off - I've seen draws ranging from 0.4 to 0.6 amps in our trailer - because these devices are on circuits that remain connected to the battery even with the "disconnect" switch is off.

As for the 50% max recommended discharge level being a myth, "Jeff" may be someone you have every reason to respect but I'm inclined to take the advice of battery manufacturers.

[DaveMatthewsBand]

...
As for the 50% max recommended discharge level being a myth, "Jeff" may be someone you have every reason to respect but I'm inclined to take the advice of battery manufacturers.

Lol

You mean you’re inclined to propagate what everyone else says about the 50% rule without doing any research of your own.

After John @jkwilson (who has tested literally thousands of them) brought it up I went out and looked and couldn’t find anything from a battery manufacturer specifically saying it would damage them.

EXIDE is one of if not THE largest battery manufacturer in the US. Most of the lead acid batteries you buy are made by EXIDE. Look on their website under “How to properly maintain your battery” they state in writing... “batteries are designed to discharge up to 80% of their total stored energy.”



lol


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[WhittleBurner]

Lol

You mean you’re inclined to propagate what everyone else says about the 50% rule without doing any research of your own.

After Jeff @JColeman (who has tested literally thousands of them) brought it up I went out and looked and couldn’t find anything from a battery manufacturer specifically saying it would damage them.

EXIDE is one of if not THE largest battery manufacturer in the US. Most of the lead acid batteries you buy are made by EXIDE. Look on their website under “How to properly maintain your battery” they state in writing... “batteries are designed to discharge up to 80% of their total stored energy.”



lol


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There are only 3 flooded battery manufacturers and 4 AGM battery manufacturers.

[JColeman]

I think @DaveMattewsBand has me mistaken for someone else.

While I am certainly worthy of universal respect, it is more for my incredibly precise and true opinions in all things meaningful other than electrical engineering.

-jeff

[DaveMatthewsBand]

I think @DaveMattewsBand has me mistaken for someone else.

While I am certainly worthy of universal respect, it is more for my incredibly precise and true opinions in all things meaningful other than electrical engineering.

-jeff

Come on now, you're just being modest (once again).
My mistake though. It was @jkwilson
I edited my post above!