Charger modification

[ENZO]

This is my first post. I've got a ZZ SE on the way, and I'm looking at modifying the controller/charger unit to run on alternate power sources. I'm going to solder some wires to the ones that connect the AAA battery compartment to the circuit board, and run the wires to a plug outside of the controller.

There are two power sources that I will have connected to the other plug that will connect to the one wired into the controller.

1) A six AA battery holder containing five 2500 mAh NiMH rechargeable cells and one dummy cell to complete the circuit. These are 1.2V cells, so 5x1.2 gives me 6V. I already have a good charger and AA NiMH cells, so I want to run these instead of disposable or rechargeable AAAs. Four rechargeable AAAs would only give me 4.8V anyway, so I don't think I'd be getting optimum performance.

2) An AC/DC converter with adjustable voltage. It can provide 6V, 6.5, or 7V with a maximum output of 2Amps.

So my question is, how do I provide the proper resistance to keep the internal cell of the car from drawing too much current? Do I need to solder a resistor into the circuit when I attach the auxiliary power source wires? If so, which resistor do I use to match the requirements of both the external power sources described above?

[Matic]

Adding a resistor wont help much, because battery has a variable inner-impedance (it rises while charging) so the current wouldnt stay constant. You can use LM317 as a constant curent regulator (for charging from NiCd or wall adapter).
I is really easy, all you need is lm317 and one resistor

http://linear1.org/gm/archives/00000147.php

And you can add a charging led parallel to the resistor....

[Guillaume C.]

What happen if we simply plug the 6V 2A in the controller?? Me too i search a way to stop buying battery and always have full charge but i'm not too good in electronic....

i have built stand alones for se's and normal zip zaps, for the zip zaps i highly recommend not using anything above 3v and for the zip zap se's i was plugging in 7.5 with no problems if you want to try 9 be my guest, i made a post along time ago about a part you can get from radio shack actually someone else had done it before me i beleive its rfnagel dont quote me on that but look around you will fiind the posts and it is the answer a simple mountable coaxial jack, i highly recommend it dont mess with soldered wires