Reversed Polarity

[freeheel4life]

Not on a Tige, but had a boat come in for wint that the owner had pulled battery and put on a tender (good boat owner). Went to suck oil with my pump rig and it started blowing bubbles in the pan. Struck me as odd so pulled out the meter. Sure enough, battery had managed to reverse polarity, or tender managed to reverse polarity is my theory. This is all assumed as customer is "sure" he didn't have battery tender hooked up incorrectly. Put in new battery and verified alternator outputs and grounds were all good(approx. 1v drop from Alt to Batt not ideal but not worried about that right now). Boat runs fine and all seems normal.
Anyone else ever run across this problem before?? I would assume battery would have to be fully discharged in order to switch its polarity via a tender. Any other ideas how this may be possible besides the tender theory??
Certainly a first for me so thought I would see what IDboating, Mike, and others have to say.

[tigemech]

I have seen this happen before, customer most likely hooked up the charger wrong. They will never admit it. Id sell him a new battery, and im sure it wont happen again as he knows what he did, and wont likely do it again.

[chpthril]

Ive never experienced personally, but have known a case of it, and yep, started with recharging of a dead battery.

I think ive got a core battery at the shop. may put it in a plastic tub, set it outside and put a low charge on it with the cables reversed just to see it for myself

[ericinmich]

Just did some googling, I guess it can be done if battery is flat and it gets hooked up the wrong way.

Battery is ruined either way!

[freeheel4life]

Ive never experienced personally, but have known a case of it, and yep, started with recharging of a dead battery.

I think ive got a core battery at the shop. may put it in a plastic tub, set it outside and put a low charge on it with the cables reversed just to see it for myself

Lol, I've been debating hooking this reversed battery up to a blower I have sitting in the shop, discharge it then see if I can't get it to flip after a long 2A charge. If I do I will test it's CCA with my overpriced Snap On tester as well.

[SONIC]

Lead acid batteries are normally toast if fully discharged, I'd be curious to see what happens if you charge it up as is (backwards) and load test it to see if it is actually holding a charge or if it's just a surface charge.

[tigemech]

Ive actually seen it a few times, and its usually either, "my brother in law charged the batteries", or "I think I had it hooked up right" lol. Its like come on just admit it not like im going to care or judge you for it, accidents happen.

[freeheel4life]

Lead acid batteries are normally toast if fully discharged, I'd be curious to see what happens if you charge it up as is (backwards) and load test it to see if it is actually holding a charge or if it's just a surface charge.

Will let you know results. Don't have a carbon pile tester that can put a load on it but have my fancy snap on tester that reads CCA capacity. Find it is usually accurate as long as you are taking reading directly from lead post and not stainless studs. Took a half day as wint season is finally slowing down a bit and spent most of my half day off at the DMV so this project didn't proceed at all today.

[KoolAid]

I have seen lithium 18650's do that a lot. Never seen a lead acid battery do that but I can see it happening lol!

[chpthril]

Well, thought I had a core that was no good. It came out of my Kicker display back in January cause the woofer amp was cutting out do to low voltage when i hammered on it. Installed an AGM that I had and solved problem. Set old battery in battery rack as a core. Been sitting since Jan and its still holding 12.4V.

I may go ahead and sacrifice it anyway as one of the threaded studs is ripped out so Interstate wont take it as a core anyway. thats I was using it in my display.