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[TheOldMan]

I need to find a light weight battery,  I am running 2 x 380, 7.2v brushed motors,  viper marine 15 esc, but all the 7.2 Ni-Mh battery's are to heavy.
What can I do?,  I need a lightweight  battery with the umph.
Chris

[grasshopper]

Are you only looking at NimH cells or have you looked at LiPo batteries?
They latter tend to be much lighter than the former.


Oops, just read your OP....definitely check LiPo batteries out!

[TheOldMan]

Thanks grasshopper,  can I just change to LiPo ,would I have to change anything else.
Chris

[Netleyned]

Does your charger charge Lipos?
If no a new charger will be needed.


Ned

[tigertiger]

Not cheap, but some of Japanese motorbikes use 12v Lipo batteries and have done for a few years. These are most common on the grey imports. You may be able to get these batteries through Fowler's of Bristol who do mail order. http://www.fowlers.co.uk/parts/from_fowlers_web.shtml
They would I think be able to do back orders from Japan.

[Netleyned]

Why would The Old Man need Motorbike Batteries?[size=78%]. [/size]

He is trying to save weight and his motors are
7.2V 380's.


Ned

[grasshopper]

Shouldn't have to, a 2s pack will give you 7.4 v, they will only supply what the two motors require in current. Only advisory would be to see if your ESC has a LiPo compatible voltage cutoff. If not then a low voltage warning buzzer or voltage cutoff would be cheap enough to buy.
Lipos don't like being over-discharged (forgotten the exact figure)


A LiPo charger will be necessary too...


I used to use a lot of NiCd / NimH batteries both ready made and often used to solder up my own packs for boats and RC buggies and now Short Course trucks. Never had an issue with LiPo, apart from them being too light for my old vintage Grasshopper weighs too little for the increase in power, even when using 5000mAh cells in a hard case !


If there's anything compact/light you might need bringing over I'm in Cyprus next May!

[essex2visuvesi]

http://www.hobbyking.com/hobbyking/store/__933__300__Cars_Parts-Batteries.html


Any of the 2S packs on here should work, there's even some that are shaped like the traditional stick packs.
Also hobby King show the weight of each pack as well

[TheOldMan]

Shouldn't have to, a 2s pack will give you 7.4 v, they will only supply what the two motors require in current. Only advisory would be to see if your ESC has a LiPo compatible voltage cutoff. If not then a low voltage warning buzzer or voltage cutoff would be cheap enough to buy.
Lipos don't like being over-discharged (forgotten the exact figure)


A LiPo charger will be necessary too...


I used to use a lot of NiCd / NimH batteries both ready made and often used to solder up my own packs for boats and RC buggies and now Short Course trucks. Never had an issue with LiPo, apart from them being too light for my old vintage Grasshopper weighs too little for the increase in power, even when using 5000mAh cells in a hard case !


If there's anything compact/light you might need bringing over I'm in Cyprus next May!

Thanks Grasshopper,  for your kind offer , I will send you a pm latter.

[Netleyned]

What hull are you putting this lot in?
If it's one of the small plastic models
380's are a tad fast.
If you are after scale speed 385's are a
much better motor for slow speed torque
and run time.


Ned

[w3bby]

I'd go with the LiFePO packs instead of LiPo. Safer chemistry but only having 3.3 volts/cell instead of 3.6 of LiPo. You still need a charger capable of charging them.