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Topic: The tired battery topic again (Read 374 times) previous topic - next topic

The tired battery topic again

My AMGs have died  >:( , my fault, but they're dead. Reading about 8V and charger (XC2000) wont start. I'm considering LiFePo batts but I'm concerned that they can't start the gen due to lower cranking amps available from Li batts (schematic shows gen starter is hooked to house batts). Anyone here have any concerns or advice on this? BTW I don't currently have solar and I'm pretty much tapped out on $$$ due to other repairs I'm making so please don't suggest ripping everything out and starting over.

Regards
John
Never trust a skinny cook!!!

2001 U270 Build 5833

Re: The tired battery topic again

Reply #1 –
I did this swap about two years ago.  LiFeP04 batteries are not a drop in replacement (yet) and require a bit of research and planning to get right.

However, the good news is that my 3x 100AH Chins brand (Amazon) start my 10KW Powertech generator just fine.  IIRC, the batteries want up to 100 amps of draw each, but provide a peak of 300A each for short intervals.

I was planning to use the extra space for a small AGM starting battery, but it turned out I didn't need it.
Rick and Donna
1997 U320 4000 WTBI Build 5152 "Molesley"

Re: The tired battery topic again

Reply #2 –
Why not try a charger with a desulfanator function and try and bring the batteries back,what exactly did you do or did'nt do,why
not just get less expensive batteries and care for them properly.
96 U270 BUILD 4810
85 380SL
Drummonds TN.

Re: The tired battery topic again

Reply #3 –
Quote from: John44 –
Why not try a charger with a desulfanator function and try and bring the batteries back,what exactly did you do or did'nt do,why
not just get less expensive batteries and care for them properly.

I agree.  Use a "stupid"/automotive charger, jump from another vehicle, or even coach's alternator to bring the house bank back up to voltage where your on-board will charge them.  When fully charged, use the "stupid"/automotive charger to bring voltage up to high 15 VDC.

Be sure to disconnect all coach 12 VDC loads when you do this last part as some PC boards may be sensitive to high voltage.

THEN evaluate the batteries.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: The tired battery topic again

Reply #4 –
AGM's work great when properly charged and maintained.
1996 U295-36, Cummins 300hp, 8.3. Build number 4864. Vin number 1F97D536XTNO54271. Purchased October 31, 2019.

Re: The tired battery topic again

Reply #5 –
Stupid charger for sure. Also the generator takes very little to start at a lower required voltage. I started my generator for a year with a junk old optima battery.

Re: The tired battery topic again

Reply #6 –
Quote from: John44 –
Why not try a charger with a desulfanator function and try and bring the batteries back,what exactly did you do or did'nt do,why
not just get less expensive batteries and care for them properly.

I was stupid and let them sit unattended. Even with the DC disconnect there must have been some drain on them. This is a new coach for me so it could also be that they were not in good shape to begin with. From now on I'm going to disconnect the batts entirely when the coach is in storage regardless of the solution I come up with. Can you recommend a BC brand with desulfanator? 
John
Never trust a skinny cook!!!

2001 U270 Build 5833

Re: The tired battery topic again

Reply #7 –
Quote from: wolfe10 –
I agree. ... or even coach's alternator to bring the house bank back up to voltage where your on-board will charge them.
THEN evaluate the batteries.

So just start the engine and enable the boost?
John
Never trust a skinny cook!!!

2001 U270 Build 5833

Re: The tired battery topic again

Reply #8 –
Quote from: jlallen –
So just start the engine and enable the boost?

Shouldn't even need to do that, as the alternator automatically charges both chassis and house battery banks.

Turning on boost  will speed up charge of the house batteries (by taking a lot of amp VERY QUICKLY) from the chassis bank. May cause voltage spikes with the chassis battery at full charge and house battery deeply discharged. I would not do it that way.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020
 

Re: The tired battery topic again

Reply #9 –
John, if you replace your house AGMs with Lithium you won't have any trouble starting your generator. If you did, you could hit the boost switch and "add" your bank of start batteries to the party. If that doesn't spin your generator like a top, you have other problems.

Meanwhile I would definitely try to revive your coach batteries as recommended by reply 2 & 3 et al. That should keep you going without shelling out any money.

Personally, I feel the price of lithium batteries has come down to the point that it doesn't make much sense to purchase new AGMs. They are half the weight, almost double the useable capacity, recharge to 100% much faster, and provide superior voltage stability under load. A Victron Orion B2B will protect your alternator and a Victron shunt will give you great info on where your 12 volts disappear to and how quickly they can be replaced. You don't need solar to reap those benefits.
1998 36 foot U270 Build No. 5328 WTFE, 900 watts solar, Victron controller, B2B, bat monitor, 600 AMPH lithium with 2018 Chevy Colorado toad, SKP #110239, Motorcade #17781, 2021 Escape 17B for when Coach is broken down and campsites are too small, retired and full-timer since Dec. 2020. Part of RV family since 1963.