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Strange battery charger behavior

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coldplugs

coldplugs

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I've had an interesting experience over the past couple days with a battery charger. I rent garage space from a neighbor for winter storage and needed to charge a six volt battery over there. I brought a small DieHard charger/maintainer over and hooked it up. The charger has three indicators - “Charging”, “Battery Charged”, and “Battery Fault”. The fault light means that the connections are reversed or there's a short.

Normally, the Charging light glows for a while, then the Charged light goes on, and shortly afterwards the Charging light goes off.

In this case, the Charging light was flickering rapidly and the Charged light was lit. The Fault light was off. I knew that the battery was dead as a doornail since it showed about 0.5 volts on the meter. I tried this numerous times with the battery connected (to the car) and, later, with it removed from the car.

I brought the charger back home and tried it here, and it worked fine.

I finally brought the battery to my shop, figuring I needed a replacement. Just for the heck of it, I tried hooking the charger up again and this time it worked fine. So the only obvious variable here is the neighbor's electrical supply.

They have a box in their circuit that instantaneously fires up an emergency generator if the power fails – I don't know how it works but it produces a loud hum under normal conditions. I don't know if it affects the quality of their power. I do know that they can run computers etc with no problems.

The battery is now charged so I'm more curious than anything else. Does anyone have any ideas on why this would happen?
 
What does your charger do when connected to a somewhat sulphated battery?

The flickering 'Charging' light sounds suspicious to me, since when you start charging a sulphated battery, the voltage goes to "fully charged" almost instantly. My theory is that each flicker was putting just a tiny amount of charge into the battery, and that combined with the jostling and shaking as the battery was brought to your shop was enough to break through and let it charge normally. The 0.5v would also indicate that at least some level of suphating was present.

Just a WAG, though. Seems unlikely to me that their UPS system pollutes the power enough to affect a battery charger; but I guess it's possible. Modern computers are actually pretty rugged when it comes to noise & spikes on the hot wire; what they hate (if anything) is noise & spikes between neutral and ground.
 
I think you're on to something. Although I've never had a battery recover due to shaking it up a bit, it's certainly possible. I brought it to my place in a small cart behind a lawn tractor over a dirt road and a field so it got shook up pretty good.

I agree that their UPS isn't the likely culprit.

Thanks for the response.
 
coldplugs said:
Although I've never had a battery recover due to shaking it up a bit,
Click to expand...
Long time ago, a friend and I were out in the middle of nowhere trying to start a TR3A that I had just bought. It didn't want to run, and we were using my Oldsmobile as a power source to jump it. Temps were below freezing, and when we finally got tired of standing around in the snow, we hopped in the Olds to head home. But, the Olds' battery didn't have enough oomph left to turn over the 425ci V8!

At my friend's suggestion, we took the battery loose and shook it pretty thoroughly. I can't explain why, but after that treatment the engine cranked and we went home. Nothing particularly wrong with the battery, it wasn't low on electrolyte or anything like that. It continued to work fine at least until the next winter.
 
Which is one definition of uninterruptible power supply.

But that wouldn't explain the loud hum.
 
That is kind of strange, but it could be that the generator is throwing something other than 60hz. I have seen issues here in S. Fl. with people running generators and getting some weird thing happening with refrigerators and such.

Just a thought.
 
Just to close this out...

I was able to charge the battery at my place and it held a charge. I tried at the neighbors again today and everything looked fine. The buzzing UPS was a red herring. The fault was most likely with the battery as TR3driver suggested.

Lights work, starter spins, all is well in 6v land.
 
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