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Topic: Coaches with miswired house batteries (Read 847 times) previous topic - next topic - Topic derived from Re: House batteries n...

Coaches with miswired house batteries

Quote from: Skillagalee –
U320 with 3 lifeline 8d AGM house batteries.

FOT said the batteries were hooked up wrong and only drawing on one battery. 

Quote from: Carol & Scott –
We recently encountered something similar.  It appears that our batteries were wired incorrectly and 2 out of the four 8a8ds were sick. 


So we have 2 coaches with batteries wired incorrectly.  Do we have any info on where these installations were done?  It would help others in the future to know this since batteries are not cheap.

Re: Coaches with miswired house batteries

Reply #1 –
In an effort to answer Michelle's question, I offer the following:

Based on PO's records our 4th battery was installed at MOT.  The 4th battery was added to the middle of the string.  We replaced 3 of the 4 batteries with Lifelines and that is what we are currently using - 765 amp hours of total charge available or 382 amp hours to use 50% of the total available.  So far in our limited dry camping experience the 3 8as have been performing well.

Our LP tank had been removed and that is where the 4th battery was installed.  The battery cables were attached to the existing 3 8a8d  bank.  It appears that if the 4th battery was wired into the bank correctly either using buss bars and equal cable lengths or to the beginning or end of the string, the 4th battery and the bank probably would be functioning properly.  Increasing the battery bank may also requires the gen to run longer to replace the charge spent while not plugged in or running the gen set.  It depends on how many amps you use while dry camping.

(Am considering how to add additional house battery capacity.  At the moment leaning toward adding two L16s and a separate inverter for the res. refer.  and adding about 960 watts of solar with appropriate controllers to assist charging the battery banks.  The 2 L16s will live in the area where the LP tank resided.  The addition of solar should allow us to run the gen set less often.)





Re: Coaches with miswired house batteries

Reply #2 –
My question to add to Michelle's ( the Jeffe) would be " how were these batteries actually wired to be incorrecttly done?"
A simple drawing is all we need (or photo) so that other members can simply look at it and decifer if theirs are ok.
I have a buss bar setup so simple to add to.
JohnHm

Re: Coaches with miswired house batteries

Reply #3 –
I have a drawing of how our batteries were wired.  Will try to find it and take a  pic to post.  Busy today so will try to get up this PM.

Re: Coaches with miswired house batteries

Reply #4 –
It is almost impossible to mis-wire multiple house batteries, as long as all negative terminals are connected together and all positive terminals are connected together.
But there are lot ways to not optimize them: terminal & connections not sparkling clean, connecting the main cables to the same battery, dirty batteries, etc.
Also parallel-wired batteries, even if all is perfectly wired, often to not equally share in the load and charging, and nothing can force them to equally share.  So one battery may get more 'worn-out' than the others.

Re: Coaches with miswired house batteries

Reply #5 –
If you have a DC clip on amp meter and can access the battery wiring, it is possible to check what each battery is doing. Put a heavy load on the inverter, say a griddle that draws 1200 watts, this will be approx 100 amps at 12 volts. The exact value isn't important. Using the formulas in the attached diagram, compare the batteries, healthy batteries should provide approximately equal current under load.

Re: Coaches with miswired house batteries

Reply #6 –
Quote from: prfleming –
If you have a DC clip on amp meter and can access the battery wiring, it is possible to check what each battery is doing. Put a heavy load on the inverter, say a griddle that draws 1200 watts, this will be approx 100 amps at 12 volts. The exact value isn't important. Using the formulas in the attached diagram, compare the batteries, healthy batteries should provide approximately equal current under load.

In your middle picture would it not be for the third battery amps  C-(A+B)