Mod to Scott Henion Charger

[arx_n_sparx]

Hi All:

I wanted to use this charger for both charging up a 3s pack, and also to use it for parallel charging on the same pack for cell balancing. With this mod, all you need is one more trim pot, one resistor, and a double pole double throw (DPDT) switch. For those of you unfamiliar with this charger, here's Scotts' website. http://www.shdesigns.org/lionchg.html Please refer to it or Scott for questions.

Basically, I've just redrawn it a bit, and took out the circuit between points A,B, and C (they were added back in, don't worry), and tied it into the DPDT switch. Added cost was minimal.

Brad

P.S. A big thank you goes out to Scott for creating and posting this circuit free of charge!

[SteveC68]

I know this thread is pretty old, but since there is only a single post I figured it wouldn't be that much of a stretch to read 2 posts.

Here is my mod to Scott's wonderful lipo charger. I combined Scott's version 2 and version 3 and came up with a charger that will charge 4S and 5S at different rates. I've built his version 3 and it works great.

Steve

edit:changed D1 to 1N5400 type.
edit: 1ohm resistors are 1watt all other (unless noted) are 1/4watt

[Dan Baldwin]

The 1N4001 (D1) is a 1 amp rated diode, but in your circuit it could have over 2 amps through it. You really should have a higher current diode.

Dan

[SteveC68]

Good catch Dan. How about a 1N5400?

http://www.mouser.com/Search/ProductDetail.aspx?qs=7w0fSgRKp901K0LFFrfx%2fg%3d% 3d

Steve

[Dan Baldwin]

Yup, that should be fine.

You may find that you can't get good calibration on both cell counts because you only have one pot. You set one, and the other is a little off. I would put a separate pot in series with each fixed value resistor so that when you switch cell counts you switch in a different fixed resistor in series with a pot.


Dan

[tashunka]

Hi Steve,
do you think 25v are enough as input for 4 cells?
thanks in advance

Stefano

PS. Sorry for my bad english

[Chippie]

Stefano,

Yes more than enough...All you need is to ensure that there is sufficient input voltage to ensure the regulator doesnt drop out...Too much voltage and you increase the package dissipation( it becomes hot! )

[tashunka]

Thanks Chippie !!
:-)

[tashunka]

Has someone the pcb for this version?
thanks in advance

[tashunka]

Hi SteveC68,
i'm looking for your modified version charger's PCB; in the similar threads links there are some of Schott's version 3 but no one of your version!
Have you some?
thanks in advance