Lipo

[Matt C]

Hey All,

Could someone give me the low down on lipos, which are the good ones, power, charging etc?

Thanks

Matt

[egneg]

I can't speak for others but I like the Elite-35C-5000's

http://www.cheapbatterypacks.com/main.asp?sid=1466610&pgid=showlipos&man=ELT&cat=E35

[Matt C]

thanks egneg

would i see an increase in performance?

so without sound too silly what do the numbers mean?

i know that my esc can handle 2 - 7 lipo and the motors can handle 2s to 4s?

help:)

[Matt C]

Also what does the c rates mean? If my esc can handle max 90 amps and 2-7 cells which packs should i be looking at ?

Prob reading this wrong but if i bought a pack that was 35c with a 175 amps continuous wouldnt that pop my esc and motor shortly after?

[egneg]

Most definitely ... they are like night and day over the others. The numbers have to do with output amps the higher the better because the batteries will last longer if they are not being pushed to their limits.

[Matt C]

so for a feigao 9l and 90a esc what would you recommend?

[egneg]

Depends on whether you are going for speed and a short run time or a longer run time with more weight.

[egneg]

Also what does the c rates mean? If my esc can handle max 90 amps and 2-7 cells which packs should i be looking at ?

Prob reading this wrong but if i bought a pack that was 35c with a 175 amps continuous wouldnt that pop my esc and motor shortly after?

The boat will not pull more amps than it requires so it all depends on your setup.

[Matt C]

Would probably be looking at more speed than run time. So if my motor pulls e.g 70 amps max this would be the amount pulled from the lipos even if they had 100+ amp drainage?

[Simon.O.]

Would probably be looking at more speed than run time. So if my motor pulls e.g 70 amps max this would be the amount pulled from the lipos even if they had 100+ amp drainage?

Your motor does not have a "max drainage" It can and will given the chance pull a lot more that 70A
What you need to do is spell out the setup that you have.
Motor, esc, prop(s) hull,

I have blown a few electric bits over the last few years and don't want to do it again.
I don't want to see you blow any !!

Give us the numbers of the bits that you have and I am sure the help will come.
I'll help.

[egneg]

Correct. For example if you have a120 volt 15 amp circuit in your house but all that is plugged in is a lamp with a 100 watt bulb it will only use 1.2 amps because that is all it requires. amps x volts = watts.

Simon is correct in that you will see spikes such as when you hit the throttle out of a turn or when the boat leaves and re-enters the water.

[Matt C]

Ok heres the info, the hull is a 41" cat, currently running two feigao 540 9l motors through two etti esc 90amp. Prop size is 51mm pitch 71. Thanks for your help with this.

[ED66677]

lot of guys in France use 4900mAh Rhino's from Hobbycity.com they perform very well for the money even when racing!
some other guys are also testing the Flightmax but let's wait and see!

[Matt C]

Ok still a bit confused.

my motors can handle 4s at most which i believe is 14.8 volts.

if i had two 7.4 which would both be 2s in series would there be any difference and if not why have smaller packs, i guess depends on space in the hull?

my esc can handle up to 7 cells max 30 volts so not too worried about that

So the bit where im getting confused is still the c number. My motor will pull 70ish amps at max and that you need to times the c number by the size of the pack to work out the discharge current.

This discharge current on a 25c 3700mah pack would be 92.5 amps. Now i've read this is better for the battery and you will get more cycles if the max current isnt used, but equally as simon.o has said motors are prone to pull more amp's and potentially pop.

How do i prevent this or if i missing the point please let me know?

[egneg]

What you need to worry about is the ESC. For example a Marine Turnigy 120A will handle a burst of 240 amps for a given length of time. As long as you do not exceed the burst rating in the allowed time everything will be Jake.