Re: Unsmoothed car battery charger - is it crap?

We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember "JosephKK" saying something like:

That's a perfectly ordinary home-use 4A charger, of which millions were made. As charging state rose, the current fell and it took ages for the battery to start bubbling, usually a day or so. Still best to have it on a timer, I would agree, but 4 hours per session is nonsense.

In message , Grimly Curmudgeon writes

|Septics, eh ?

By the time the battery is visibly bubbling you have damaged irreparably.

I believe that this depends on the specific battery type.

As I understand it, classic lead-acid flooded storage cells are often deliberately given a periodic "equalizing charge", at a voltage high enough to cause electrolysis and bubbling. This mixes up the electrolyte, reversing the stratification of water and acid which can occur in these cells. One then adds some water to replace what was lost in gas form due to the electrolysis. Done properly this doesn't seem to damage batteries designed for it.

This shouldn't be done to gel cells (or AGM cells, I imagine)... I believe it *will* damage those.

I'm not sure how tolerant modern "no-maintenance" grid-plate car batteries are to this sort of overcharge.

ALL lead acid batteries (not gel cells) bubble while charging. That is the normal process. That is why you keep sparks away from charging batteries. It is a normal process.

Where did you get that nonsense? One of the benefits of equalizer charging is that it will form bubbles of gas that helps to stir the electrolyte and mix it to a more uniform concentration.

We deliberately do this to a lot of different lead acid batteries.

What *really* hurts a battery is overheating it or discharging it so low that you reverse one or more cells. But charging to the point of gassing is not a serious problem.

daestrom (former submarine battery-charging electrician)

I used to rock my batteries several times before a charge session.

Let's have the "placing a lead acid battery on a concrete floor will discharge it" discussion.

Maybe we should submit that one to Myth Busters.

| I used to rock my batteries several times before a charge session. | | Let's have the "placing a lead acid battery on a concrete floor will | discharge it" discussion. | | Maybe we should submit that one to Myth Busters.

I wanna see some batteries explode! Can they get 1000000 amps through it?

Maybe we can get them to go after the world record for size of a Tesla coil.

They'd probably have to have a sub-station put in.

I remember my parents always opening the fillers on the top of the battery to let the gas out. (why I don't know, they vent when you charge them on the car anyway)

Then they got one of those fancy auto vent batteries with the lift up vent cover.. they decided that they needed to lift that when charging it. Came back to a floor covered in battery acid as lifting the strip closed the vents, really intelligent design that.

So gassing can do a lot of harm if the user expects different behaviour to what happens.

Gassing doesn't do harm. Dumb users do harm. Just like with guns.

We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember "JosephKK" saying something like:

Umm.. lemme see. How many years have I been involved with automotive batteries? Many.

How many batteries have I wrecked by overcharging them? None.

How many batteries have I seen bubbling? Quite a few.

Note that I don't particlarly recommend leaving the battery on a charger until it's bubbling vigorously, like a deep-fat frier, but if it happens it happens and so far it's not damaged any flooded lead-acid cells I've had. Anyway, that's why I have them on a timer.

The only time I've ever seen a battery damaged by overcharging was when the voltage regulator failed on a friend's car in a way that the output was much higher than it should be, and it boiled almost all the water out.

I was very close to that once I reckon, with a motorcycle battery, when I neglected to remove the vent plug before charging. The whole case was bulging ominously by the time I noticed.

Every low maintenance wet battery I've seen has a vent to stop this happening. Often with a plastic tube attached to vent the fumes out of harm's way. Genuine SLA have a vent too - but no 'vent plug'

In article , Dave Plowman (News) writes

This was a small (easy to overcharge and froth) basic liquid lead/acid battery, a Yuasa YB3L, IIRC. All cells breathe to a vent at the side, then a plastic tube downwards. When it is supplied wet, this vent is plugged for obvious reasons, and it is easy to forget to remove it before the initial trickle charge I used to give them.

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session

That is not the style, action, or purpose of an equalizing charge. No bubbling is involved in anything i have found on equalizing charging.

"JosephKK"

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charging=20

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The bubbling is mainly released hydrogen. This results in an unwanted excess of sulfate ions. You should be able to figure it out from there.

Interesting - thanks. I've seen articles posted which assert that the equalizing and de-stratification does involve some amount of gassing... and now that I look, I see other references which either don't mention gassing during equalization charge or which state that a proper equalizing charge should be prolonged, slow, and should definitely _not_ cause gassing.