It's a good idea to have a speed controller which will either slow down or even stop the motors if the battery voltage gets low. However – and not a lot of people know this – you don't have to buy MTroniks at forty quid a throw. Save yourself thirty quid for a pair and try two of these FR40 units **LINK**

I've recently bought one for use with LiPo packs and I'm very impressed with what it will do. I used to manufacture speed controllers so I think I know a bit about them. Check out the specs for yourself. Mike is also a straight bloke to deal with.

Suit yourself; no purchase is compulsory.

Dave M

Howard,

I have a 1:24 scale Elco PT boat which was somewhat overweight and went down the route you proposed. I replaced two 9.6V, 2600 mAh NiMh batteries with a single 11.1 volt 6100 mAh LiPo. It reduced the overall weight by about 500 grm and the higher voltage improved the top speed of the boat.

In order to reduce the risk of over discharging the LiPo battery I fitted a battery checker/alarm as a cheaper alternatve to changing the ESCs. There are several types available but I used this one, **LINK** which cost about £10. It provides an audible warning when the battery voltage drops below a presettable level.

The model has two Mtroniks 25 amp speed controllers but I dont use the BEC supplies from them, the receiver has a separate 4.8 volt battery.  I have only been running the set up for about a month but it seems to work fine so far.

Gareth

Edited By Gareth Jones on 18/09/2013 12:55:10