Parkflying taken to new levels with Polymer batts. New Voltage regulators. - RC Groups
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Apr 05, 2003, 03:55 AM
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LESLIEx317537's Avatar

Parkflying taken to new levels with Polymer batts. New Voltage regulators.

I donno if this was mentioned here before or if I should be posting this in the battery forum, but I thought some people would like to know.

Kokam has a new line of products coming out.

I always wanted to be able to use my 7.4 volt Kokams in my Nitro RC car and truck and now I can with the voltage regulator which will regulate the voltage to 5 volts.

Also if they make one for 3 cell apps, I can then run a voltage regulator on my Moth and run 3s packs on the IPS motor and tune it down to say ~8 volts. It also has a onboard LED battery level indicator. More lights flying in the sky at night.

Glad to see that parkflying and RC has been and is further going to be taken to new levels.
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Apr 05, 2003, 05:22 AM
Professional idiot
Probably the wrong place especially as all?/most parkflyers use BEC to save weight and therefore don't bother with seperate RX battery packs.

I'm not sure there would be much of a market for an 8v limiter especially for 3 cell packs. Don't fotget the voltage on a 2 cell pack when charged is 8.4v. You can accomplish the same thing with ATV(lighter) or good throttle management.

Devices like this will see Lipo get a wider market which can only be good.


So as not to confuse things. They don't appear to be Kokam products but FMA products.
Apr 05, 2003, 10:37 AM
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LESLIEx317537's Avatar
I meant use the 3s for a Moth.

For example you hook up a 11 volt batt and it goes out as 8 volts. No speperate Rx.

I was just giving a example of Rx usage for my RC cars.

But for someone who only has 3s packs and owns a moth would like to have that small voltage limiter that weighs very little to power his moth with 3s and not put of 11 volts to fry the poor IPS.

Also run a 3s on a A10 and limit the voltage to 8 volts, to preserve those edfs.

You can also set ATV on the Tx, but this seems safer.
Apr 05, 2003, 12:37 PM
Stress Be Gone
GBR2's Avatar
I'm not sure what you are thinking about voltage regulators is correct. I found only 2 listed on the FMA site. Their function is to supply 5 volts to the flight system at a greater current level than most BEC's built into speed controls. I didn't see anything that said 8v.

A voltage regulator that would regulate a 3 or 4 cell lithium voltage output to 8v would have to sustain whatever current draw was called for by the motor/speed control. There would be a lot of heat generated in the regulator by dropping the voltage and passing all that current. Heat means lost power to the motor system.

The best way at the moment to use a 3 cell pack would be to prop smaller/less pitch, so that the total watts the system draws is approximately the same as with a 2 cell pack. Watts is watts.
Apr 05, 2003, 01:13 PM
Professional idiot
GBR2 - He didn't suggest there was one yet but that one would be nice. I hadn't thought about the power aspect, going to get warm pumping 10A through one of these things. That's why the average BEC is only 1A. Have you seen the size weight of the ultimate BEC and that's not even close.

Leslie - Another approach if you only have three cell packs is to make the pack from single cells. My new packs are done this way to overcome the balancing problem inherant with Lipo series packs. It also means I can have 1, 2 or 3 series packs depending on the application.

I think you are also probably fairly unique in having 3 cell packs and wanting to downgrade them to being effectively 2 cell packs. You've got a lot of wasted weight in that extra cell.

Apr 05, 2003, 01:20 PM
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LESLIEx317537's Avatar
Yeah, proabbly better for my Nitro RC car apps rather than planes.

But that's what I was looking for.
Apr 05, 2003, 10:41 PM
Rob H
Flyfan's Avatar
I don't have any lithiums yet - still studying threads and learning.

I'm using GWS geared300s and also dd400 and GWS geared 400s and it seemed to me that 2 cells would not be enough and 3 cells would be too much. (I've burnt a few 300's out, now testing the 'reverse the motor in the gearbox' idea)

So I also was thinking that a voltage regulator would be a good thing. Is there any other way of just drawing off the volts you need without making heat and wasting energy ?