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I have an 02 Civic SiR (Canadian model) with a maintainable battery. I check and refill the electrolytes every few months with distilled water. The battery is about 4 years old.

I use a Battery Tender (float charger) with a wiring harness installed on the battery to easily attach the charger, which I do most nights in winter. I only have outdoor parking and batteries lose voltage very quickly when it's -30C!

I get white corrosion build-up around the terminals and the tie-down bracket that seems to accumulate rather quickly. I cleaned it only a few weeks ago and it's already built-up again.

Does charging increase the rate of accumulation? Does the fact that it's a maintainable battery affect this in any way? How can I prevent or reduce this?

battery with corrosion buildup

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I check and refill the electrolytes every few months with distilled water.

There's no earthly reason for you to need to do that.

I use a Battery Tender (float charger) with a wiring harness installed on the battery to easily attach the charger, which I do most nights in winter.

Oh, wait, I take that back.

The problem is, your alternator is a 3-stage charger that knows exactly how to charge your battery without overcharge.

Your battery tender is a cheapie (let me guess, Canadian Tire) that just blasts energy into your battery without the slightest clue or care of overcharging.

See, the battery doesn't need to be charged; it's already 100% charged when you park it. What the battery needs is to be warm. Warm batteries have much more cranking amps than cold ones. What your battery "tender" is doing is heating the battery, by overcharging it.

Hence, all the splashing.

And the problem is, you're adding water back in, but what's coming out is obviously not merely water. The overcharging is causing it to gas off and sputter up the essential chemicals from the battery itself, i.e. the acid. I bet it neutralizes very nicely with baking soda, yes? It's battery acid. That belongs inside the battery, not splashing out.

You're needing to add water because you're boiling off water (and sputtering out acid to boot) because you're overcharging it. And what makes you think the battery tender works is the side-effect of overcharging: heating the battery.

If you want a battery tray heater, then get a battery tray heater.

By the way, if that was not a maintainable battery, the water still would have boiled off, but you would not have been able to replace it. You're not allowed to overcharge non-maintainable batteries!

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  • Are you not familiar with battery tenders? They're specifically designed to maintain a charge without overcharging. – autobottodoggo Feb 28 at 15:24
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    @autobottodoggo So they say. I certainly sympathize with trusting that marketing claim, but given the stack of evidence here, the most likely explanation here is that one is not meeting its promises. Does your battery behave like this when you don't use the tender, i.e. in summer? – Harper - Reinstate Monica Feb 28 at 17:51
  • I didn't take note of it in summer, but I'll keep an eye on it this year. – autobottodoggo Feb 28 at 21:40
  • @harper-reinstate-monica: I've had my battery disconnected from the charger for several weeks now and I'm still getting same rate of build-up. – autobottodoggo Apr 5 at 23:27
  • @autobottodoggo Thanks for following up. I will change my mind on that particular topic. However, as to your problem that is a mystery. Perhaps the battery is having problems (4 years seems a little early) -- or could the alternator be overcharging the battery?? – Harper - Reinstate Monica Apr 5 at 23:33

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