Are my Batteries Shot?

[slabman]

All-electric coach, 8 batteries, 6 volts each, 6 month old coach. Because of an auto gen-set malfunction I have found these guys down to as much as 9.2 volts when in storage for only a week. I have never measured specific gravities of more then 1.10 in any of the cells. Using a stand-along charger, I pumped 60 amps into each pair for a couple hours, followed by 2 more hours at 12 amps. Found only a few sporatic bubbles, but not what I was looking for. Still no change in S.G. After charging, each pair read 12.6 volts, but will drop off in only a couple hours to 11.8v or less.

It appears to me these batts are beyond the stage of serviceability and need replacement. Comments?

[slabman]

All-electric coach, 8 batteries, 6 volts each, 6 month old coach. Because of an auto gen-set malfunction I have found these guys down to as much as 9.2 volts when in storage for only a week. I have never measured specific gravities of more then 1.10 in any of the cells. Using a stand-along charger, I pumped 60 amps into each pair for a couple hours, followed by 2 more hours at 12 amps. Found only a few sporatic bubbles, but not what I was looking for. Still no change in S.G. After charging, each pair read 12.6 volts, but will drop off in only a couple hours to 11.8v or less.

It appears to me these batts are beyond the stage of serviceability and need replacement. Comments?

[RV Wizard]

Have you tried doing an Equalize charge on them? I would recommend that you turn off any 12 volt apparatuses and do so bfore condeming the batteries. It will take about 8 hours of a high voltage and will desulphate the plates. Follow the instructions in the inverter manual and then let us know what you find.

[Bob (WA0MQE)]

I agree with RV Wizard, I equalize my batteries about once a year. Also, keep in mind it could be just one or two of the batteries that have a bad cell in them. The only way to be sure is to disconnect all of them and treat them individually.

[slabman]

I guess I am missing something here. I thought pumping that kind of voltage into them WAS a form of equalizing. As I said, I only saw a few bubbles...like one per second come up out of the cells. I charged the 3 pairs, one pr. at a time and then compared with the un-charged pair. Of course, no other draw was on them while charging....that would defeat the purpose, wouldn't it? No difference in S.G.'s and voltage across EACH pair was an identical 12.43 v., measured with a digital voltmeter. I've charge 'till I am blue in the face and nothing seems to improve the results.

Unfortunately, I was not furnished a manual with my Magnum 2000 inverters, so not sure if they provide for an equalization function. I'm thinking the stand-along charger offered the best control of these procedures.

I had Interstate do load tests on them back in February and they found only one battery was bad, which was replaced with a new one. Now that new one performs in the same manner as the others....no difference in it.

[Ray,IN]

Perhaps a pulse-charger will work to wake them up. This battery tutorial may have some suggestions.

[RV Wizard]

Bob & carol, not sure of which Magnum Inverter you have but this is the manual in pdf format for the ME model: http://www.magnumenergy.com/Literature/Manuals/Inverter...rev.%202%209-03).pdf

It does provide for equalization charging and with the manual you should be able to set it up to do so. Make sure other 12 volt loads are off as some do not take kindly to the 15 volt range.

[slabman]

Yup....that looks like the same animal I have. I'll have to fiddle with it and find the equalize feature. But with all the juce I've been pumping into these batts, I have yet to increase the S.G. over 1.10, so I doubt these batteries can be saved.

[Ray,IN]

If you use a pulse charger remove the battery cables first.