Mep804b battery reverse polarity

[RichRiley]

New to me 2010 Fermont mep804b picked up at Columbus yesterday. 13.2 hours on the meter and the engine compartment looks new. All accessory items are still in plastic bags in their stowage compartments including operators TM and maintenance TM. The auction checkout showed that the starter solenoid had to be crossed to start as the starting switch was intermittent and the low voltage light was illuminated. I read the online version of the operators manual and maintenance tech manual and thought that with SS forum help I could probably figure this out so I went ahead with the purchase.
Got her home and hooked up a smart charger after disconnecting battery terminals. Both batteries show reverse polarity! I am going to drain them of voltage and try to rereverse them as the prices of the 6tfm? Batteries are hefty.
Does anyone have similar experience with this phenomenon? Should I expect electronic issues? Should I continue to try a normal startup with these batteries if they can be brought back to correct polarity or do some further test and evaluation? Thanks in advance for any and all thoughts and advice.

 

[155mm]

I am pretty sure you are beating a dead horse on trying to save the batteries, BUT it is always worth a shot.

Slowly discharge with a low amp draw like an old incandescent headlight or marker light, then when you start to recharge, use another good lead acid battery as a buffer between the dead one and charger. I would have had the buffer battery on the charger before hooking to dead one, that way the charger is only putting out like 1/2 amp as a trickle charge.

In the week it takes to discharge/recharge, I would go over the wiring in the genny with a fine toothed comb, making sure there isnt a dead short or something like a starter wired in backwards, or a slave wired backwards. There are lots of if's and and's to get a battery reverse poled.

I dont know if you will have issues, but I dont think I would attempt to use these batteries until I made the machine run with different batteries, when you do hook up different batteries, just remember in the back of your mind, if something is wrong with the genny, it may smoke these batteries as well.

 

[Guyfang]

While you are discharging/recharge the old battery's, get two normal 12 volt car battery's, old, used , junker ones if possible. Just to hook up and test the gen set with. The first place I would check for miswired problem is the terminal board that the battery cables are hooked up to, on the side of the set. Then take the wire diagram in hand, and check the starter, alternater wires. But like 155mm said, good luck. In theory, you don't even need to install battery's. Tape up the battery leads, and slave it off another 24 volt system.

 

[RichRiley]

I went to the local battery dealer and asked his advice, he offered two group 34 (690 cca at zero f ) batteries with a one year free replacement. Their normal warranty is 5 years in a vehicle, but a generator they consider “standby”. Mike went over installation with me to be sure I understood the 24 volt and it went very smoothly. Went through the operators startup procedure in the manual and the genny fired right up. The low voltage light was on so Remembering a former post from guyfang i shut herdown and restarted with holding the switch to start for a few seconds after she lit. Hertz meter wasnt reading but a few taps of the gauge glass fixed that. Everything now functional. As I was going through the original acceptance paperwork from and quarterly test notes from 2010 to 2014 when she was prepared for storage. Apparently 13.2 hours is correct. Seems like a real bargain to me. Thank you all for sharing your knowledge and experience!

 

[RichRiley]

155mm, I still intend to try to rereverse the polarity of the bad battery, she is currently hooked to a marker light that while warm to the touch has no “glow”. When she gets down to 0000.0voltage wise I intend to parallel her with an AGM Deep cycle and try to bring her back. I am somewhat cynical myself but with so much buzz on the web about desulfation what the hey give it a try.
Rich

 

[smokem joe]

Where are you still able to get gen sets out of Columbus?

 

[RichRiley]

Bought it at ritchie bros sale site for govt auctions. Got the battery turned around, but quickly went to no charge then negative charge. Got really hot, was afraid of melting then decided it was not worth the risk of injury. The other battery seems fine will load test tomorrow.

 

[smokem joe]

Very interesting. I didn't know Ritchie was selling out of Columbus. Was it the old gov liquidation site? I'm not surprised you have battery issues. I don't think they left many good batteries in units.