Mamba Max on 4s A123 cells?
 

Evening all,

Can anyone confirm if the Mamba Max ESC is happy running on a 4s A123 pack? I want to run that sized pack (with a ~3000kV, possibly lower motor) on my E Jato conversion.

Cheers
Andy

The MM runs 4s lipo just fine with the BEC disabled, so 4s A123 would be even better.

It should run it just fine, but disable the BEC (either unplug the red wire from the Rx wire or get a short servo wire extender and remove the wire from that so you don't have to mod the MM). Once you do this you'll need an external BEC such as the CC BEC, Mike sells a few different BECs.

The internal BEC should would on 4s A123 as the voltage isn't much higher than 12 cells NiMH but the farther over 5 volts (at least, I think it's a 5v BEC) you get, the hotter the BEC will get and on 4s A123 you could possibly burn up the internal BEC.

I've run 5S A123 on it with the external BEC & a fan. No problem, don't forget to cut the red wire.

I use my Mamba max combo 5700Kv with 4s A123 ZERO problem I use internal BEC without fan....

Really, the internal BEC should be disabled for anything over 2s lipo or 7-8 NiMH cells. I did a test with just 3s a while back and a small 250mA load (1.5w of wasted power) caused the MM BEC to heat up a lot and quickly. Servos can pull quite a bit more than 250mA depending on application.

That said, by the time you buy a MM and a decent external BEC, you are right about at the price point of a MMM. Unless space is a premium, you might be better off with the MMM, especially since CC said the MM is technically only designed for 3s or 12 NiMH cells and running any higher may void the warranty.

That's true, and if you buy a MMM you can run more voltage with a lower KV motor (more efficient setup) and still have a warranty. I don't think the MMM is too big though, considering what it can do.

http://i140.photobucket.com/albums/r...y/DSCN1734.jpg

I ran 4s A123 with the internal bec, a fan and 4800 medusa motor with no issues. Before that I ran 6S A123 with the external bec and fan.

On the MM? If so, did you feel the BEC circuit? I guarantee it would have been hot hot hot. It probably ran fine, but do you realize the BEC circuit is on the same PCB as the brains circuit, and that PCB is totally enclosed with no cooling except where the heat can make its way through the traces and then to the heatsink? I personally would not want all that heat next to logic circuits, but that's just me. Excessive heat is a component killer, or at least shortens component life.

I understand what you are saying. Latest encounter was in the CRT.5 of mine. With the foam tires it runs like mad till the pack dumps. With those big Imex tires it will thermal within 5 or so minutes. You can only imagine the ampdraw. Timing is set on high and punch on 80 or so. Start power on low.

I understand that heat shortens component life, but by how much? From 3000 hours to 1500 hours or less? If I get a few years out of them, I'll be happy. By then there will be better products out.

i run 5s lipo on many MM in a truggy with a neu 1515 1y 2200kv . never had a failure , touch wood

I've been running 4s A123 on 3 mamba max's, two sidewinders, a sidewinder micro and a mamba micro pro all using internal bec, never had a failure or excessive temps.

In fact, I originally tried using a bec, and I think the voltage dip of a123 cells was causing the V input of the bec to drop below its threshold and the Rx was resetting, caused me to have a few accidents. I tried nearly everything - originally i thought it was glitching due to placement of wires etc, but I quickly discovered that wasn't the problem, I tried running ferrite rings and adding capacitors to the power lead side and the Rx power in side (i first tried low capacitance to no avail, and cranked up the capacitance till it was rediculous, still with no fix).

I ended up removing all the caps and ext. BEC and it works flawlessly. Go figure haha.

Anyway, point is, go for it! all the esc's are rated to 12 cell nimh, and ive seen my nimh cells peak at 1.45V, so thats 17.4V input it should be rated for (at least), which is between 4 and 5 fully charged A123 cells. (3.7-3.8vpc)

Hi Folks,

Thanks for the input :) I'm planning on running an external BEC anyway (a Castle one if I can find any in stock here in the UK!), mainly because I am aware of heat build up issues, as many people have mentioned.

Regarding the MMM, then I'm going to buying one of them too. It is destined for a 1/8th truggy conversion, but I can't decide between the HongNor X2, or the RC8T. I always prefer to run high voltage, low kV setups where possible, it's a habit from messing around with powered gliders. You can get the same input power, but need smaller and lighter components that don't need to be sized to handle massive current draws.

Cheers
Andy