help with lipos

[chriser0]

lately ive been thinking about lipos for my supervee 27. ive always had nimh and kinda afraid of lipos. what the risk of them exploding.

[Fluid]

I believe the OP wanted a serious answer. There is no need to fear modern LiPos as long as you treat them correctly. Five years ago LiPo technology (and charger tech) were not nearly as good as today, the risk of fire is far far less today! I will admit when I started using LiPos several years ago I was worried that I would damage them or cause a fire. But after 4+ years I have never burned up a LiPo, while I had blown up several NiMH cells. A few basic but vital rules to follow if you want to avoid problems:

- Use ONLY a LiPo-specific charger. Not a nickel cell charger!!!
- Do not charge packs unattended
- Never over-discharge a LiPo below 3.0 volts
- Do not let LiPos get hotter than 160*F. 140*F is a better maximum
- Keep LiPos balanced, cells in a pack should not be more than 0.02 volts apart
- Store LiPos with 50%-60% charge (~3.8 volts)
- Never puncture a LiPo cell
- If a pack gets wet, remove the shrink (carefully, see above) and dry thoroughly

If you follow these rules (and others supplied by the battery maker) you will have no problems and will enjoy the higher performance and run time of LiPo batteries.

*Note: it is my experience that you should buy the best LiPos you can afford. While cheap packs are attractive and work for many folks, there is risk of getting poor cells which just won't charge. Too, some cheap packs are not labelled correctly and will overheat if you are not careful. If you will be running RTR setups then the less expensive packs may work fine, but if you want to pull over 120 amps you are better off with higher quality cells.



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[chriser0]

i was thinking of the grim racer yellow lipo packs. (running them in a stock Super vee 27. lipo shutoff from kinetic)

[Fluid]

Those should work great for you use! Now get a good LiPo charger and a small balancer and you're good to go for years of LiPo fun.


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[chriser0]

what is a balancer. any ideas on a cheep charger and balancer. whats the deference from 2 s and 4 s.

[kookie_guy]

what is a balancer. any ideas on a cheep charger and balancer. whats the deference from 2 s and 4 s.

you want your cells in a lipo pack to be the same voltage. A balancer hooks up to the balance plug on a lipo battery, and makes sure they are all being topped up evenly. 2s means there are 2 cells, 4s means there are 4 cells. Each cell is 3.7volts. So a 2s lipo battery is 7.4volts, 4s is 14.8volts. With a supervee, you can do one of the following....

1) 2x 2s packs in series, which will give you 4s
2) 1x 4s pack
3) 2x 4s packs in parallel, which will theoretically double your run time, but always check your motor/esc temps when running for extended periods of time.

Since you are just starting out, option 1 is the best for you. Also, when buying packs, the typical capacity we tend to buy is 5000mah. As for the C rating, if you can get 40C, then get 40C. Basically that means the 5000mah pack can safely put out 200A. You will never get near that in a supervee, but if you ever upgrade your system, your packs will be able to handle the higher demand.

Can't help with a cheap charger/balancer. I've always relied on my hyperion duo charger, which has built in balancers. Not the cheapest by any means, but personally, I feel they are the best.