I Think My Batteries Are Bad

[Gadget Man]

My inverter/charger died last week. I ordered a new one but UPS hasn't delivered it yet. My house battery bank consists of four Trojan 6V golf cart batteries.

Five hours after my inverter/charger died, I checked my house battery voltage level and each battery showed between 6.4 & 6.3V. I turned off the battery switch to preserve the batteries until my new inverter/charger arrived. I checked them again yesterday and they were at 6.2V each, which I realize is dangerously low. I have an automotive battery charger with a 6V deep cycle option. I connected the charger to one of the batteries (after disconnected the parallel cables), and let it charge overnight. My charger showed that the battery was getting 6 amps. I went out this morning, 15 hours later, and the charger showed that it was still giving the battery 5 amps. Am I correct in assuming that it should have received a full charge in 15 hours?

I disconnected the charger, and re-checked the battery voltage. It registered 6.8 volts. I checked it again 6 hours later and it was down to 6.5 volts.

My inverter/charger was always connected to shore power. The batteries are only 18 months old. I have a sinking feeling that they're already kaput. What do you guys think?

Craig

[GaryKD]

Hi Craig P,
Don't sink too low just yet. Consider the following steps, while waiting for the new part.

1. Connect all the wires to the coach batteries.
2. Find the positive and negative wires that go to the coach.
3. There should be 12 VDC across these two connections.
4. Install your charger on these two connections and let it run over night.
5. Forget what the charger says, disconnect the charger and take your VDC reading across the two terminals you just used. Monitor these two terminals. The only thing you're concerned about is the VDC available to the coach.
6. If the total 12 VDC VDC still drops too quickly for your comfort then:
7. If the batteries are flooded, get a hydrometer and check each cell (only if the batteries are at full charge.
If that shows no problem, then:
8. Disconnect all the batteries from each other and the coach. Monitor each battery's discharge rate when standing by itself.
9. Lastly, get a stress test tool (under $100.). You can stress test each battery and determine if one is bad. Next to the VOM, this is a close second to the most valuable tool I carry. It has saved many members of the camping clubs I belong to from spending $s they do not need to spend. The batteries must be in a stand alone (no connections) when stress tested.
10. While everything is disconnected, clean all the terminals and wire connections.

[krautkamper]

I wouldn't panic until you get your new converter and observe the behavior. You don't know what your old converter was doing the weeks before it died and the car charger you are using may not be getting the voltage up high enough. The T-105 battery needs 7.4 volts bulk charge voltage. Those batteries are 225 AH I believe. If you ran 5-6 amps for 15 hours you gave it 70-80 AH. At 50% dead it may have not been completely charged. Which converter did you order? I had a hard time finding one that produced a 14.8V bulk voltage. I used the IOTA.

[wb7auk]

I agree do not panic I doubt your charger is able to do the job you converter/charger
does.
A 5 amp charge into those batteries is nothing and will take many hours if they are
low. I would expect 24 or more hours to bring one up to full charge if it is 50 percent
or less at the start with a charger output of 5 amps.

[Gadget Man]

Thanks for the helpful replies guys.

I wired the batteries back up and hooked my charger up to the battery cables that go to the inverter/charger. I assume since the voltage coming off of these cables is 12V, I should set my automotive charger at 12V instead of 6V....

I'll check them again in 24 hours.

My old inverter/charger was a Xantrex Freedom 458. On the advice of several members of this forum, I'm replacing it with a Magnum MS-2012 PSW.

Craig

[RLKBOB]

Did you check fluid levels in the batteries?

[Gadget Man]

Originally Posted by RLKBOB

Did you check fluid levels in the batteries?

Yes, they're good. I have a Pro-Fill system and religiously top them off monthly.

Craig