Charge gel cell with car charger?

You answered your own question. As long as the battery doesn't heat up on a big charge you're probably OK. Trickle chargers can do more harm than good. I'd find a smartcharger with a "lead-acid" setting.

"dave"

The pressure builds up inside until something gives - then you have bits of battery and acid all over the place.

Voltage & current limited charging is the only safe and sensible way.

... Phil

They have vents.

Which are NOT meant for overcharge relief.

I didn't say they were. I was speaking to the "bits of battery and acid" prediction above.

And that's news?

I've seen the results of several car batteries exploding. Maybe your head should be under the hood when one blows.

Why is everyone so rude around here?

Why are you here?

Everyone is quite an exaggeration, but this isn't the kiddy's sandbox. If you want to be spoon fed, go to news:sci.electronics.basics

This group is intended as a place to kick around design ideas, not baby-sit beginners. If you think this place is rude, you'd never survive a design review.

I am here for entertainment, mainly. most of the substantive stuff is over my head, but the lead-acid battery is on the FCC exams you take for an advanced license, plus I used to maintain a fleet of trucks at a construction company, where I also serviced 2-way radios and 5 mW surveyor lasers.

I wasn't saying you said something wrong. I was merely iterating that those vents are not for charging pressure relief, per se.

No shit, dumbfuck.

No shit, dumbfuck.

But you very likely have no clue as to why.

It is also a FACT that a battery at 12 Volts is NOT discharged as you claimed, DORK.

It has nothing to do with rudeness, it has to do with your lack of accuracy.

I don't need a primer from a dipshit who cries like a wimp when he gets corrected.

And almost everyone knows that rechargeables and alkalines are not at the same voltage.

AND, asshole, they are NOT "1.5 Volt NiCads". They ARE 1.2 volt NiCads.

so, I am "rude", but YOU are "stupid".

"dave"

An acquaintance had a 12V gell battery like the one pictured explode violently while doing just what the OP here is contemplating. He was sleeping nearby at the time an got one HELL of a scare !!!!

Makers all warn against using unregulated ( ie raw, rectified AC ) chargers with gell or SLA batteries.

BTW:

Makers also warn against shorting the battery and often quote a max safe discharge current.

The penalty for ignoring this advice is a dead battery when the deliberate (weak link ) fuse inside goes open.

.... Phil

Until you load it.

Unloaded, an old xformer/rectifier battery charger always had significantly higher voltage without a battery on it. BIG ripple!

But once a battery is charged and even peaked out, that higher voltage peak can blow the damned things up, so all charging sessions had to be monitored to keep them from exploding. Then better chargers came out.

Now, I wouldn't be surprised if there wasn't one you could operate or observe with your iPad. There are Wi-Fi and/or bluetooth handheld meters now. That would be enough to know when to go shut it off.

From my first comment on the thread:

"I'd find a smartcharger with a "lead-acid" setting."

_______________________________________________________________________

"Smartcharger" being a generic term for a charger than knows what it is charging and the best way to charge it.

I have no doubt that you know way more than I do, but your actions betray a profound insecurity. I prefer being "stupid" to the obvious heavy burden of knowing enough to justify insults and abuse.

"An absorbed glass mat battery has the electrolyte absorbed in a fiber-glass mat separator. A gel cell has the electrolyte mixed with silica dust to form an immobilized gel.

While these batteries are often colloquially called sealed lead?acid batteries,

they always include a safety pressure relief valve.

As opposed to vented (also called flooded) batteries, a VRLA cannot spill its electrolyte if it is inverted."

-

For NORMAL battery utilization. NOT a vent for charging pressure relief.. The device and or person doing the charging has to keep the process below any overt gassing level.

OK. My only other point was that 12 Vdc nominal is never 12 Vdc, except when the battery is severely discharged. A lot of mobile equipment will not work properly on 12 Vdc.

"A car battery is considered charged at 12.4 volts or higher. It is considered discharged when it's at 12.39 volts or less."

-

You are allowed to nag precise, and I am too.