Lead Acid Charger

[Rick Hughes]

I have a relatively new Car Battery Charger (twas a gift) claimed to be electronic 'smart' charger. Took the cover off and found it to be a straight transformer to full wave rectifier set of diodes ... and out to croc leads.

Only 'smart' bit was that it had a 'display pcb of 3 LED's .... one for power, the other 2 just via a zener diode to measure aprox charge voltage - no actual control at all.

Thought as the case, transformer, diodes & heatsinks are fine ... could use this a basis for a proper 3 stage 'SMART Charger'

I have couple of links to full designs, but these use PICs and need programming, which I do not have facility to do. There are really SMART and fully programmable for battery parameters etc. and Deep Cycles batteries .... eg

for my needs ... which is basic low speed charge & float charge. Anybody know of a simpler circuit ... all I need is ability to charge 6 & 12 V batteries, non-deep cycle.

[Harry Bloomfield]

Rick Hughes explained :

Depending on the current output level of the charger...

Look up a circuit for a 2N3055 (which is a high current transistor) using a 1amp 5v regulator with a pot on the control pin to set the output voltage. Add an extra pot and a couple of switches and you should then be able to get a charge voltage and a float charge voltage from it.

[Bill Wright]

Dave's speciality is the prognostication of doom. He was a Mayan in a previous life.

Bill

[Dave Plowman (News)]

Oldest charger I've got - '50s - still has a resistor. Or rather a couple so you can set the charge rate. Approximately.

[Dave Liquorice]

Why bother, wander along to Aldi and pick up one of their 6/12 V battery chargers for less than 15 squid...

Though ISTR some mention of SLA gell battery rather than a wet cell type. These are rather more fussy about charging but these days I'd expect to find a chip that does multi stage charging for SLA's. How else can you buy one for a tenner?

[Dave Plowman (News)]

I bought quite a few of those Lidl chargers when they came out as Xmas presents, so maybe 5 years ago. At least two have failed, including one of mine. So I'd say ok for occasional use, but I'm not sure how well they'd last long term.

[Rick Hughes]

but are they any better ... do they give genuine 3 stage charging.

want to end up with correct float condition.

[Jaime Dixon]

On Friday, December 28, 2012 9:05:27 PM UTC, Rick Hughes wrote... Anybody know of a simpler circuit ... all I need is ability to charge 6 & 12 V batteries, non-deep cycle.

Similar prob:? --2 year illness meant no charging of two gardening strimmer and cutter batteries. They now dead and dont respond to chargers. Would e.g. a 210 shot (like a defribulator) or similar do it? Or are the batt's dumpers?

[Dave Liquorice]

What technology are the batteries?

[meow2222]

and cutter batteries. They now dead and dont respond to chargers. Would e.g. a

210 shot (like a defribulator) or similar do it? Or are the batt's dumpers?

If they're lead acid, I've heard of people applying relatively high voltage to them to get them going again, but it needs current limiting, multiple cycling and you don't get good capacity in the end.

NiCd and NiMH are practically unrepairable. There are 2 ways to fix them, but neither is really practical.

Lithium I'm not familiar with any repair mthods

NT

[Tim Lamb]

Oh. I am attempting to recover a pair of deep cycle lead acid batteries from my daughter's houseboat. Why don't they teach women to look after batteries as well as babies etc.!

Initially showing 2-3Volts eventually climbed up to 13.6V but only taking a charge of 2 amps. I plan to fully discharge at 4 amps (if I can find a suitable headlamp bulb) and then re-charge.

The engine battery shows full Volts but will not take a charge......

[rick.hughes6]

of a simpler circuit ... all I need is ability to charge 6 & 12 V batteries, non-deep cycle.

and cutter batteries. They now dead and dont respond to chargers. Would e.g. a

210 shot (like a defribulator) or similar do it? Or are the batt's dumpers?

You can supply a de-sulphiting pulse, it's not that high a voltage just enough to be above cell gassing limit.

[Grimly Curmudgeon]

Not worth taking the chance, imo. Lithium is a treacherous chemistry, ready to f*ck you up the arse with the slightest provocation after it's been annoyed enough. Iow, if the lithium cell has been under or over charged, bin it. Don't risk your house burning down or your hand been blown off.

[Mark]

You can buy a kit to make one

[Rick Hughes]