multi purpose charger plans

[mhmitchell]

I am looking to build a all purpose charger for NiMh, NiCad and at least two cells L-poly.

I would prefer one that does not use a PIC or any type controller since if I have to get an emulator and electronics to program the thing I might as well save my pennies for a commercial system.

It should also be capable of reasonably quick field charging.

Does anyone know of a tried and true charger schematic/plans that fits this description.

Thanks,
Mike

[simingx]

Why not just buy something like the Hobbico Quick Field Charger II? Easier and will probably end up cheaper than building your own....

[mhmitchell]

actually I have several hundred dollars wortth of electronic parts. My cost would be very low.

[Happy Hobit]

Hi Mike,

I would prefer one that does not use a PIC or any type controller since if I have to get an emulator and electronics to program the thing I might as well save my pennies for a commercial system.
I don’t do PIC’s, but I program AVR’s and it costs less than $10 to build a ‘Programmer’ and ‘Development board’ total. (including an ATTiny-15 microcontroller ($2.56)) Free Compilers and Assemblers, IDE, programming software and Program Simulators are all available. :)

If you go the AVR Freaks website ( http://www.avrfreaks.net/index.php ) there’s even an Appnote, AVR 450, ‘Battery Charger for SLA, NiCd, NiMH, and Li-Ion, batteries’ http://www.avrfreaks.net/Tools/showtools.php?ToolID=271


It should also be capable of reasonably quick field charging.
You didn’t say how many NiCad and NiMh cells you wanted to charge but it’s no problem charging a 2-cell Lithium battery pack from a 12 volt supply.


The chemistry, and how they’re charged, is totally different between NiMh / NiCad batteries and Lithium batteries. An analog charger that does both would require two different chargers in the one box. The only thing they would share is the DC supply

Here’s what you need for NiCad and NiMh batteries, http://www.maxim-ic.com/quick_view2...v_pk/1666/ln/en or this one, http://www.capable.ca/rcstuff/fastchg.htm .

And here’s a Lithium charger, http://www.rcgroups.com/forums/showthread.php?t=130567&highlight=lithium+charger


Doing a search in this group for ‘Lithium’ and ‘charger’ or ‘NiCad’ (or ‘NiMh’) and ‘charger’ gets results.


Jay

[Zlatko]

Mike,
If you want to tinker have a look at LM3647.
Thats the "brain chip" from National Semiconductors.
Does the lot Li-Ion, Li-Po, NiMH and NiCd
I got the Eval board before there were any Li-Po cells available ( 4 years ago ) and it still works great but there are lots of jumpers and settings.
Cheers and Good Luck

[mhmitchell]

thanks guys seems like I have some more researcg to do!

[Bruce Abbott]

I suggest you make two (or even three) chargers, one for each type of cell. That way there's less likelyhood of an unfortunate accident, and you might even be able to charge several batteries at once...

Here's my Nicad/NiMH charger which doesn't use any exotic chips:-

Simple Peak-detecting Nicad Charger (http://homepages.paradise.net.nz/bhabbott/charger.html)