Charge NiMh with Li-on charger?

[VegasF6]

I am looking for a very cheap solution to charge 3xC or D in series in a maglight with a charging jack. The cheapest I have found is the "smart charger" that is commonly found on battery junction and some other sights for about 26$ (the red one).

If I get a 1amp Li-on charger from DX and wire in the charging jack, could that do the job? I know it charges at 4.2V, but at least some them continue to trickle charge, which is normally a bad thing, but could be good in the case of NiMh?

Otherwise, any solution to charge strictly a 3.6V pack on the cheap? I had thought of the wall wart style chargers that come with some cordless screwdrivers, but that would take FOREVER.

 

[michelkenny]

I am looking for a very cheap solution to charge 3xC or D in series in a maglight with a charging jack. The cheapest I have found is the "smart charger" that is commonly found on battery junction and some other sights for about 26$ (the red one).

If I get a 1amp Li-on charger from DX and wire in the charging jack, could that do the job? I know it charges at 4.2V, but at least some them continue to trickle charge, which is normally a bad thing, but could be good in the case of NiMh?

Otherwise, any solution to charge strictly a 3.6V pack on the cheap? I had thought of the wall wart style chargers that come with some cordless screwdrivers, but that would take FOREVER.

Different chemistry, need a different charger. Unless you like batteries blowing up.

 

[mudman cj]

Don't try it. Charge termination sensing for Nimh is very different from Li-ion.

 

[mdocod]

It'd be one of those situations where it would sort of work, but not correctly, I don't think the NIMH cells would ever be topped off completely in this type of setup.

 

[VegasF6]

I am concerned mdocod is probably right, I am worried about them ever getting a full charge. As far as them blowing up or something, I highly doubt that would be a concern. The safety concerns (imho) would apply to charging li-on on a nimh charger, but nimh are inherently safer.

Actually, I am sure I saw a charger advertised to do both, but that doesn't mean it was a reputable claim.

It seems a li-on charger is a much simpler device than a delta-v or other smart charger. What I hypothesize will happen is the cells may not reach there full potential, but it would be closer to using a simple trickle charger.
Here is a simple explanation of how a lithium charger works, now if only it described how this differs from a nicad/nimh charger and what it would mean to me.
http://www.flyelectric.ukgateway.net/lithium.htm

This is a schematic I found on another forum on how to build one. It is just like a cc driver board for a led. But I don't fully understand how it works, or how I could modify it to shut off at a higher voltage. There are resistor values on the second page. Also this is for a DC input source, so there is the added problem of buying/building a transformer. I wonder if it needs to be a switch mode power supply, hmm my ignorance is showing again.
http://www.shdesigns.org/lionchg.html

Here is another dumb question, how exactly do I set up my meter to test a li-on charger to see if it has a sharp cut off at 4.2-4.3V, or continues to trickle charge?? I was going to set up a li-on battery and charge it through the amp setting on my DMM, but I am not sure if that is correct? So just connect the - side with a magnet and a wire, and the + side in series through my meter, acting like a shunt?