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Registered Member #51
Joined: Thu Feb 09 2006, 04:17AM
Location:
Posts: 263
For this years science fair project, I plan on testing standard batteries, and seeing if they will take a charge (I know this is possible). I plan on constructing at least 3 circuits for use in testing. I will build a circuit to discharge the batteries(1.5v cells), a constant current charger with an lm317 regulator, and a "pulse" charger.
My question is this: to build a pulse charger, could I use something as simple a 555 and a transistor/FET to discharge say a 4700uf cap at 1.5v into the battery? Or is something more complex needed to keep the cells from exploding?
Registered Member #63
Joined: Thu Feb 09 2006, 06:18AM
Location:
Posts: 1425
I worry about the cells getting hot and exploding...
maybe you'd consider making a charger for "rechargeable alkalines" or some of those other quasi-rechargeable technologies... be careful... use a current limiting resistor on that cap =)
Registered Member #51
Joined: Thu Feb 09 2006, 04:17AM
Location:
Posts: 263
Im really not too worried about the batteries exploding, as I'll be using a blast screen sort of thing. I'll also test the batteries in a regular charger where they are sure to explode. I'm just wondering if its possible to use a 555 ot build a simple charger.
Registered Member #175
Joined: Tue Feb 14 2006, 09:32PM
Location: Sudbury, ON
Posts: 111
What sort of "non-recharchable" batteries are you using? I'd suggest zinc-carbon, as these apparently offer a smaller chance of going boom, and a good chance of success for charge taking.
Registered Member #58
Joined: Thu Feb 09 2006, 05:40AM
Location: Tri-Cities, Washington, US
Posts: 317
This has been done by AfrotechMods, he just took some duracell batteries and recharged em, he said one time one "exploded" ( made a little hole in it and leaked out some acid he cleaned up with his finger ) hehe Link:
Registered Member #51
Joined: Thu Feb 09 2006, 04:17AM
Location:
Posts: 263
Thanks for that link mike. I love that site and totally forgot about that article. I will test alkaline batteries, as well as the cheep (carbon zinc) type.
Registered Member #162
Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140
At moderate charging currents, explosions can be prevented by having a thermal sensor stop the charging, since temperature rise comes before explosion. (usually) You could use one sensor/cutout for all experiments.
I found 'good' results only if very partial discharge is allowed before recharge.
Registered Member #111
Joined: Fri Feb 10 2006, 01:04AM
Location: Menasha,Wisconsin
Posts: 65
i dont know why, but sometimes when i have dead batteries, i put them in the sun for a few days. i dont uderstand how, but it seems like i actualy do get more juice out of them.
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Charging "nonrechargable" batteries
