anyone run 2s n 3s series together?
 

i have a friend whos going to run a caster truggy with 2s & 3s series to get 5s. I told him its not a good idea.

either get 2000kv with 4s

or 1350kv with 6s

the weight of 2 batts is different also. Any advise on this?

Its fine... Nothing wrong with 5s just has to make sure batteries are of same type and age...

Putting the 2s on motor side would probably balance the truck

Yeah, as long as the packs are the same age and spec he will be fine. I like 5s for buggies, good mix of power and less amp draw than 4s.

Nothing wrong with using 2s and 3s together. That was my main battery setup for about a year, until they decided to bring in a 4s limit where I race.
The 3s pack will only be ~100 - 150 grams heavier, so just put in on the lighter side of the car and the balance should be pretty good.

Agreed. After all, putting any combintation in series is no different than how lipos are wired internally. You could put a 1s pack in series with a 4s pack if you wanted. As long as the series packs are charged/balanced and used together, and have the same amount and type of use, it does not matter in the slightest.

I'm thinking of using 2 x 2S packs I've been given, in series also.

Do they need to be connected in series when charged/balanced and treated basically as a 4S pack, or should they be OK to charge/balance seperately as a 2S each? Which is better?

Doesn't really matter as long as they are both charged the same amount. However, charging seperately requires two chargers/balancers, or double the time if using a single charger.

I run a 2s and 3s in my Savage Flux, all good!