NiMH 1.2V charger

I've got the Eveready 15 minute charger. I roasts each battery individually.

Luhan

I always start here

martin

Roasts? Is this a good thing, or a bad thing?

I always thought that fast chargers don't charge as well as the slow chargers. Is this correct?

Michael

I suspect damage to some of the batteries. They seem to lose charge very quickly. I think a 1 hour charge (the 1 C rate) would be best. I have one of my own design but its about a 10 hour charge.

Luhan

Thanks... (Mouser doesn't carry an LTC4060??)

Michael

I'm in spain, so I don't use Mouser

martin

Are you really? Just yesterday my co-workers and I treated our contractor (who is leaving) to lunch of his choice: he chose a Basque restaurant. (It was in Chino somewhere, east of Los Angeles.) Very interesting.

Unfortunately, I had a cold, and couldn't really taste anything. I just had the soup.

Michael

Yep, but the wiring shop I (ab)use, in the UK gets samples from the local Linear office, they are quite helpful, and

so you can purchase online, but I havent used that, I'm still a Luddite when it means giving my financial info over the Tubes. The Spanish around here,generally refuse to use credit/debit cards, very much a cash economy, even buying my car was cash

martin

Yep, even here, when buying a car from an individual, s/he wants cash or a cashier's check. (Not even a personal check, from my ~limited~ experience.)

Buying from the car dealer is a little more accommodating. (Plus, the dealership wants to trap you into paying high interest rates on their preferred car loans. ;-)

Michael

chomp

Argh, this was a dealer.......cash,

BTW where are you? I assume somewhere in the US, since you said "mouser"

martin

I'm in Sacramento (California), but about twice a month have to fly into Ontario (near Los Angeles, not the one in Canada) for work.

Man, the turbulence on yesterday morning's flight to Ontario was the worst I've ever been in. Thought the plane was going to crash for sure. The plane was flying sideways...

Michael

Battery manufacturers seem to disagree with you. They recommend 1C fast chargers for NiMH.

Do they? Reference, please?

Here's what I found:

The issue is with proper charging termination. NiMH can be damaged without proper charging termination. At 0.1C, the temperature delta is

They don't really tell you why.

single 1.2V

batteries.

parallel

take care of

charger that

anywhere

battery

---------------- I always wanted to make a battery charger that ran off the USB . The USB would provide charging energy and a uC would monitor the battery.. Software would display charge info. I vaguely recall that one type of battery chemistry has a small short voltage plateau when charged by constant current..It's a signature of full charge..Software can catch this detail and take action.. But can't remember details. D

-----------------

Probably available at a better price, with a plug the right shape, and closer to you too.

Bye. Jasen

LOL! what I said about closer to you is definately right then... seing as I'm about 43S 172E and spain's around 40N 5W

give farnell.co.uk or maplin.co.uk a look.

Bye. Jasen

Not a plateau, but a spike. So for NiMH, you need to monitor the charging curve over time. Also, the spike is small and hard to detect. Temperature detection is more reliable. USB will not be able to supply enough current.

This will do a single cell:

----- +5 ----Vin|LM317|Vout---+ ----- | Adj [R] | | +----------+ | [NiMh] | Gnd ----------------------+

I = C/50 forever; I = C/10 for 14 hour rate. If using 14 hour rate, you could use a 24 hour appliance timer like Intermatic TN111C

R = 1.25/I

Ed