RC10Talk - The Net's Largest Vintage R/C Community

Hi All,

With out boring you all too much, I spent my youth racing (or trying to ) a Schumacher Bosscat/ProCat mongrel with lots of mods that I had cobbled together, eventually sold all in 96 and haven’t touched one since....things have quite clearly changed since then!

Seeing as I now - like most have the time on my hands I have just taken delivery of a topcat classic kit complete with the upgraded transmission.

Now I used to run various different motors back in the day and seem to remember a mix of trinity and reedy kit varying from 17.5 triples down to a 9turn which was utterly mental but drained the batteries within minutes! From what I remember the 12.5 double was what got used the most - still seriously quick though!

Have spent a few days now looking into and trying to get my head round brushless motors KV ratings ,compatibility with ESC’s and lipo batteries and it’s melting my brain!

Does anyone have any useful advice when it comes to picking the right setup please?

Thank you!

I would go sensored....they are smoother, a 17.5 is equivalent to a 27 turn back then, but batteries are much better now. 2s is your standard battery compared to your old 6 cell. I personally wouldnt go more than a 10.5 on 2s with that car. It might handle more but thats plenty. Get a 2s battery that fits your mounting dimensions, an esc/motor combo, and a lipo charger and your all set. If you have a decent 2.4 radio system you can always turn your throttle endpoint down until you see how the car handles the power. But calibrate esc at 100% first. As far as kv ratings, take the ,(kv of the motor) x (voltage) = rpm

Amazing - thank you, so I was actually thinking something like a 10.5t and roughly 5000kv?

I’m reading about the balance of torque vs rpm - would 5000kv be a good balance between the two - obviously I know gearing up / down can also adjust this balance.

Sensored motors will be listed by number of turns. Motors listed by kv ratings are generally sensorless. The kv ratings can be confusing at first. A kv rating is just a claimed rpm rating. 17.5t-10.5t sensored motor is what you should be looking at. One with adjustable endbell timing is a plus, but not necessary. 10.5t motor in a vintage car is a ton of power.
One mistake I made when making the switch to lipo batteries, was not learning about proper storage. A lipo charger that has a storage setting will make things much easier and save you money by keeping your expensive lipos in good shape.

Amazing- thanks for the advice!

I’m starting to get my head round it - just the lipo situation to sort now Did read about needing to store them at 50% charge.

Lipos should be balanced at around 3.8v per cell every time you're done using them. A decent charger will do this automatically with the storage setting. I use an Ultra Power 10 amp charger. They cost around $60. This style charger lets me monitor exactly whats going on while charging/discharging. It allows me to keep track of my batteries condition and once you get familiar with the functions, makes lipo maintenance trouble free. You really want to take all the guess work out of lipo batteries. If you don't take proper care of them, they can explode/burn your house down or at the very least, you'll ruin the batteries. Properly balanced and stored lipos last a long time. I have some batteries that i use for racing that are used 6-7 times, once or twice a week, and are still in good shape after over 2 years. It all sounds more complicated than it really is. A good charger makes it all happen with the push of a couple buttons.