Re: Li-Po setups

#25498
ph2t
Participant
  • Posts: 2088

Klims, don’t listen to betty. If the guy drove it would ba a VW and would never leave 2nd gear, lol…..

You can go as fast as you want to but there are limits to what is feasible when you have a 1:28 scale car runnign along at 50-60kph on the ground. lol….

Suspension is a big thing. It can just be too fast to dampen well.

Grip is also an issue. You need some really nice soft n sticky foams to get that power to the ground and keep it there.

As for the two ebay links I would stay away from the JDR li-ion since they won’t give you the punch you need for the hot motor you will run to get the speed you want. I’ve run li-ions before and they will dump power very quickly. You can try the li-polys in that other link mate and see how you go. If you were to do that though just by the free standing cells at http://www.atomicmods.com and fit them to your mr-02.

that’s what I did with my polyquests….see the attached pic.

Quote:
i know this isnt really a lipo question, but if i had a 6 cell setup with 4.8v running to the pcb and 7.2 running to the turbo would this work? i figure its the same as having a voltage reg on the turbo isnt it?

That won’t work. The reason why is that the mosfet gate voltages don’t fully alternate between GND (0v) and Vcc (4.8v for 4 cell nimh). Whilst I won’t go into the full details, you will find that both the p-chan mosfets on your turbo will always be on. When you apply throttle you will create a short circuit along one path of the h-bridge and blow the turbo.

Found this out myself during the course of my nelly turbo development. I know it’s a shit to read but if you do get the chance read my nelly development thread. I go over this very problem is overwritten detail. lol…..

Quote:
so anyway i was talking to the electronics guy at work who tells me that it is possible to run a load of 7.2v with a 5v gate voltage, however it does require some circuitry. i’ve been trying to figure something out using a configuration like this one (does’t seem to be up), but to adapt it to 4 input signals. what it does is use transistors and some pull up resistors to trigger the gate. i’ve been told that the right combination of resistors can make it happen, but i’d need to do some circuit analysis.
Has anyone tried to do something like this? is it a waste of time trying to get it to work?

Yes it should work. You need to use pull up AND pull down circuitry on the pchan AND nchan mosfets respectively. Then drive the spider from the 4 inputs as usual. I use MOSFET drivers on my nelly deluxe to achieve a similar (but more effective) result. (MOSFET drivers are suited to turning on MOSFET really well, really fast, really hard!)

good luck dude……