Life battery

[john stones 1 - Moderator]

Whats it mean 4S1P and 4S2P ?

[Frank Skilbeck]

4S1P means 4 cells in series, 4S2P means two sets of 4 cells (in series) in parallel.

S= number of cells in series

P= number of parallel trains

So 4S1P is 4 cells total, 4S2P is 8 cells in total (2 x 4).

[Martin Harris - Moderator]

4 cells in series and 2 packs of 4 cells in series paralleled together (same voltage, twice the capacity).

[john stones 1 - Moderator]

Thanks fellas, not my strong suit lecktrickery, which pack would be best for a starter battery ?

[Martin Harris - Moderator]

As they are the same capacity and C rating, I'd go for the 4S1P as there is less chance of in-life failure. I use retired LiPos that have got to the point where they don't give good flight performance - they are effectively free* - but use a 3S unless you have a 12 - 24V capable starter...

*Should appeal to a Yorkshireman?

Edited By Martin Harris on 07/11/2017 16:34:57

[Frank Skilbeck]

I use both a 4s LiFe (A123 cells in my case) and old 3s lipos to drive my electric starter, either would work great, might be worth asking if any of your fellow electric fliers has got any 3s lipos that they aren't using, something like a 3s 2200+ mah would be good for the job, or the 4s1p you identifed earlier would do the job, just remember to set your charger for LiFe cells when charging it.

[john stones 1 - Moderator]

Starter will be o.k on 4s life rated to 15v, me being thick skinned and never having had a lipo go pear shaped on me, I'd sooner have a life fastened to starter whilst I'm using it..just in case. I've some tired 3s Lipo's if you want them though. thanks Martin.

[Don Fry]

Being a hooligan, I habitually use a 4S lipo with a common or garden cheap starter, 12v.

On a small sample, accepted, but it hasn't broken in three years of use continual use, nothing over 38cc, and I note, it uses little power, because the increased oooomph goes to low current use when the back emf kicks in?

[Martin Harris - Moderator]

I use a 2650 mAh 6S lipo rewired to 5S (long story involving some wrong info from HK, yet another electric dead stick, some smoke and a warranty claim) to power my Just Engine geared starter, a great bit of kit which would probably start a Merlin with a bigger rubber cone...sorry, my Mum's told me a million times to stop exaggerating...but it hasn't baulked at anything I've tried it on. Although the motor is rated to 24V, my experience is that it isn't the same case for the switch, so 18.5V nominal is ideal. I probably charge it 3 times a year.

Edited By Martin Harris on 07/11/2017 18:09:39

[Steve Hargreaves - Moderator]

A 3S Lipo will easily power a starter John....I have a very old & tired 3S 2200mAh on my ancient Sullivan starter & this spins up to a 15cc 2 stroke with ease...certainly much, much better than the 7Ah SLA battery I used to use...