Forza 34 T - Chassis Batteries keep dying

[Tin Trekkers]

Hello Folks,
We picked up our new-to-us 2018 Forza 34T in January and took it south for about 6 weeks.
We had a couple minor issues - mostly related to getting to know the ins and outs of a new coach...and the owner's manuals are pretty vague and non-specific with information.

So maybe this is a newbie question...

Since we have been back home we have taken it out a couple times with no problem except the initial engine start. Basically, after it sits for 10 - 14 days, we cannot start the engine, even with the house battery boost.
AAA has given us a couple of jumps. They checked the chassis batteries and said they are OK.

So what do we need to do here?

When it is sitting in the driveway we shut off the house battery switch and the chassis battery switch. Before we try to start the engine, we turn them both on.
We have had other RVs but this is our first diesel pusher.
Is it normal to need to start the engine once a week or so?
Should we be keeping a trickle charger on the chassis batteries?

Are we doing something wrong?
Any advice would be most appreciated.

Thanks in advance,

[Ranger Smith]

If it were me what I do is leave the batteries on and I run a cord out to the rv and let the charger/converter in the rv keep the batteries maintained. There are some parasitic voltage drains that will kill the batteries

[CapeCodRob]

If your 18 34t is like my 19 38f the steps will be powered even with the battery switch off.

We picked up our new to us 19 this past October, the batteries being of 2018 vintage I bit the bullet and changed the engine batteries. Your 18 may have a 2017 chassis and 2017 batteries. I’d replace the engine batts and monitor the house batteries. That’s what I’m doing.

I also shut my switches off in storage and check the voltages every other week. I’ve also set the AGS to start the gen set for low voltage. Don’t know if that’s an option for you.

Other than that, hope you’re loving the new rig.

[Morich]

First point is to know that most RV will have drains on the batteries, even with the disconnect switches off, so we need to have some way to keep them charged.
On the chassis/start battery some of those drains are the ignition, any automatic things like locks, radio preset, etc.
On the coach batteries there are the safety items like steps, propane and CO detectors.

Most people do one of two things. If they have power handy and keep the RV plugged and let the converter charge the coach batteries and thenmake sure they have, or add, a small devise called a Trik-L-start or other items which connect between the two battery sets and let the start get a bit of charge as the coach is charged.

A second method to prevent battery drain ruining the batteries is to add a small disconnectat the negative post of the battery and open both battery strings there.
One simple method is adding some switch of this type:

https://www.harborfreight.com/batter...AaAqmLEALw_wcB

There are lots of other types and styles of switch if the batteries are hard to access, so somethought to what works best is needed.

Other folks just use a strap between the positive posts of one coach to one start if they are already chargingthe coach .

[creativepart]

Take a look at the "Amp-L-Start" product (it's the big brother of the Trik-L-Start that Richard mentioned). It costs $80 and is easy to self-install. It will keep your chassis batteries charged by sharing power from the House bank.

AMP-L-START Starting Battery Charger/Maintainer - Overview Page

It is possible that one of your Chassis batteries is weak - or maybe both are weak. I wouldn't take AAA's word on a jump service to really know the condition of those batteries. It's very possible a previous owner damaged them beyond repair.

You could remove them and take them to an auto parts store for load testing. They might charge up fine... but then not be able to hold that charge for starting.

[Tin Trekkers]

Some good information from all.

Think it's time to have the chassis batteries checked and possibly replaced.

Then we can go from there...

We park it in a lot across the road from the house so electricity is not available for a trickle charger. The Amp-L-Start might be an option or the battery disconnect switch.

Our neighbor suggested a solar powered trickle charger but our lot is wooded and we're not sure it would get enough sun.

Thanks for weighing in, folks!

[Campering]

I second the negative or ground post disconnect that Morich suggested. On our coach the chasis battery is getting old and gets weak if not charged or the engine is not run after four to six weeks. I attribute it to parasitic drain because if I open the ground connection I can let it set all through the winter storage time frame, and it will start with good energy in Spring. I know that with a new chasis battery I would get by for a longer time period without disconnecting the ground.

[Chop]

We have a 2019 Winnebago Forza 34T that we bought new in July 2019. Within the first 2 years, I replaced both the house (first) and the chassis batteries (much later). The house batteries I replaced in late 2020. For some reason they stopped working but the date on the batteries was early 2018. The battery company replaced all at no charge to us except labor. The chassis batteries I replaced about a year later when they were lagging during starting.

Both times I went and got them tested at the RV dealer near us. I think because the RVs sit so long that sometimes that the batteries get stressed to much. Test before replacing.

Also, there should be a inverter on/off switch in on of your cargo bays. That will turn off most everything. Finally, do you know how to use the house batteries to jump the chassis batteries? There is a switch on the dash that you can use to do that. Saves you from calling AAA.

[BarryLS]

The disconnect is fine, but it's also pretty easy to just remove the neg cable from the battery post. That's what I do.

[thataway4]

I pull the ground to the engine start battery. That way it cannot drain. You could put a switch on it. Agree that many coaches have parasitic draw even with Positive switch off--look for wires coming off the battery before the positive switch.