MGM controller do I go for amperage or cell count??

I've seen quite a few posts lately by newer guys asking questions about motor and battery choices. They are asking a lot of pertinent questions, but are passing over what has already been tried and proven.

I am far from being the resident pro on brushless conversions, but I have built about 8 of them so far, and have learned a few things from others and through trial and error.

I don't think that anyone would disagree with me when I say that there is sort of a formula for a successful truck conversion. 30,000 rpms is a good target to aim for with your motor and battery combo. There are also other considerations to keep in mind, like weight. Adding voltage is usually a good thing, but not at the expense of adding significant weight to your vehicle. A monster truck that handles like a boat is no fun to drive.

A couple of combos that come to mind that make winning setups in trucks are:

1. a Neu 1515/1y on 14.8v works very well and stays cool

2. a Neu 1515/2.5d on 14.8 or 18.5v also works very well and is very flexible

As for the A123 cells, I like them, but they do have their drawbacks. They are large and heavy and are limited in the amount of current that they can deliver in 1P configuration. I tried a pack of 5S1P A123 and although it ran OK, it really lacked the punch that I was hoping to get. For 5S, I think that a 2P configuration would really be needed. What I don't know is how much voltage you would have to run before the current demands are such that a 1P configuration would suffice.

You also have to keep in mind that the benefits of the added voltage will also diminish as more cells are added due to weight. The A123s weigh 70 grams each and are the size of a C cell battery.

If you just want to stick with A123s, I'd look into going with either a 5S2P or maybe even a 6S2P setup and get a motor that will get you around 30K rpms on your voltage.

Just keep in mind too that whatever voltage you do get, you'll need to charge it.

What I've said above is just my general opinion for off road trucks for extended running. Setups for specific purposes would probably deviate. I'm getting ready to start running a 1515/1.5d on 5S lipo for drag racing. Not very practical for off roading or extended running, but it's gonna haul butt.