350C Battery Issue

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Stan Disbrow
350 crawler
350 crawler
Posts: 2627
Joined: Fri Jul 15, 2005 3:13 pm
Location: Raleigh, NC

350C Battery Issue

Post by Stan Disbrow » Tue Sep 11, 2018 6:43 am


This covers a lot of things, not just the 350C. It is simply that this occurred on my 350C last Sunday.

Hadn't run it in three weeks. Went to start it, pushed the button and....nothing. Hmmm. Switch back off, then on. Heard the IP solenoid. Push the button and....clicky click. Hmmm. Now that is different than 12 seconds ago. Time for Mr Multimeter!

He says: 11.5 volts, then it rises to 11.6 in about a second. Then to 11.7 in another second. Yes, voltage rising at 1/10 of a volt per second. This is different! Different enough I sit there and watch it rise up to 12.6 volts. Hit the button. Crank! And, start right up.

Note, I never said anything about hooking up a charger. This charged itself. Hmmm, once again! Has to be a plate sulfation issue. Acid eating a film on the plates and my pulling a load broke the film up so the chemical action was able to progress.

But, not quite. Running, the ammeter showed a high charge rate. But, the voltmeter did not. It sat right there at 12.6 volts. After 15 minutes, it ran up to 13.0 volts but stopped there. Energy was passing into the batteries and....disappearing.

Shut it down. It dropped right back to 12.6 volts. Now, an interesting aside is, 12.6v is the nominal reading for a 12v battery. With the machine off, and a 12.6 reading, one can think the battery is OK. Ordinarily, one would be correct.

Now, the extra piece of data is, this has two batteries in parallel. Time to un-parallel them. And, one stays at 12.6 volts and the other begins dropping. Time for Mr Charger! Using this, the good battery rises up to 13.6 in a couple minutes at 5-6 amps. The bad battery rises right away to 14.4 volts but also shows no current flow.

Time to yank these things out. The bad battery has an acid film. A little water and baking soda fixes that. And the battery box as well. The good battery has no film, but does show some bulging of the outer case. Both batteries were sold in January 2006. Well, they were excellent batteries to go so many years.

Finally, popped the caps. They were all low on water. The bad battery was down below the plates on the center two cells. There was the drain. They dragged the good battery down, but when I loaded it, it responded chemically. The bad battery never would. Those two sick cells took most of the charging energy and boiled. Hence, the acid film.

Two new batteries and all is well once again.

I write all this, because it was rather odd and someone might run into this.

There's No Such Thing As A Cheap Crawler!

Have: '58 JD 420c 5-roller w/62 inside manual blade
Have: '78 JD350C w/6310 outside manual blade
Useta Have: '68 JD350, '51 Terratrac GT-25
Also Have: 1950 M, 2005 x495, 2008 5103 (now known as 5045D)

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