Is there a way to increase voltage from 4.8 volts to around 7 volts? I race electric RC cars and I thinking is there a way to increase the voltage from the battery pack (4.8v)to the electonic speed controller with out adding another cell to the battery pack. Some kind of DC to DC converter. It would have to be small and light. Handle about 7 to 9 amps.
step up transformer? That would be my first guess, shouldnt need too many windings to take 4.8v to 7 so it shouldnt be heavy and it should handle 7 amps, though that does seem an awful lot for an rc car are you sure about the current?
You would also have to convert the DC to AC to use a transformer. There doesnt seem to be any DC/DC converters that will handle that sort of current the highest rated ones ive seen are 10W.
It may be possible to attach a transistor(darlington array) to supplement the output of the converter IC. The transistor, if selected correctly and with the proper heatsinking, will handle the extra current load through itself. Your efficiency and switching frequency may suffer but playing around with the values will yield the best results.
Xiachunyi, I'm a noob at this stuff. Where would I find the parts/schematics for something like that?
hey, i think you could use 3 diodes normal ones and connect it to the ground of the speed control and then to ground something like this (ground speed control)----->|-->|-->|---| where(-->|--) is a diode just like this link http://www.semis.demon.co.uk/Pics/ppwincct.bmp he used two diodes to bring the voltage to 13.4 down from 12 out of the voltage regulator (12 + 2*(0.7)) ~~ 13.4v yours (4.8 + 3*(0.7)) = 6.9 ~ 7v
This (pdf) may be a likely candidate for what you want. Scroll down to page 11 and you will find some information on using an external transistor to boost the available current. Page 14 contains the design equations you will need to use to get approximate values for your needed components. Since I assume you do not wish to mess around with SMT, here is a link to the DIP form of the chip: MC34163PG Make sure to adjust the size of the inductor and diode accordingly since you will be pulling all of your needed current through those components.
Thanks for the replys, but I think this one is over my head. I looked at the pdf and I don't understand enough of it. Thanks again
Sorry to hear that. One thing I must ask, are you sure about the amount of current you need from the battery pack is that much? How big is your battery?
The battery pack contain four cells. Each cell is 1.23 volts/4200 mah. These batteries have a discharge rate of 30 amps. The motor pulls about 8 amps from a dead stop. When the motor gets going I'm sure the amps drop a little.
Hmm, I tried searching around for a commercial solution but it seems that all the converters that can fill that kind specification require a higher input voltage. Not to mention they are expensive and a little hard to acquire.
i have no idea what amount of current these things can handle but i believe they are from disposable camera's and maybe you could redesign the circuit with bigger components to handle higher currents http://www.allelectronics.com/cgi-bin/item/DC-32/200/DC-DC_CONVERTER_.html
I think your drain will be increased greatly. Once your engine is up to speed it will be acceptable, but from dead stop, i think your batteries will drain much much quicker in comparison. What type do you race?
