how to charge lipos
 

Hi all im now to all this and have some bits on order - ive not used anything since the good old days of nicads so question is how to do charge and use lipo's in a safe way ? any cheap good recommended chargers? it all seems quiet complicated to me - any getting started guides anywere ?

You need three things.

Cells - Ideally BRCA legal
Lipo charger with balance leads
Lipo sack

I can recommend the UAC 50 by Core/Schumacher for a charger.

Once you have you cells of choice, if you post the MAH and the C rating then we can work out your maximum charge rate.

It's not difficult - in many ways they are easier to care for than the old round cells.

DO use a LiPo charger - I'm sure you will find many recommendations, I use Hyperion, but if you have a trusted local shop it might be worth buying something from them in case you need help in person. Don't use a NiCd/NiMH mode by mistake.

DO charge at 1C - this is the capacity rate, so for a 5000mAh pack it would be 5A. Some packs might advertise a higher charge rate but there really isn't any point.

DO use the balance leads every time - this will ensure that none of the individual cells in the pack get overcharged - it is such a quick job to plug them in it's crazy not to.

DO have a LiPo sack to hand - admittedly I don't usually use one but it is more peace of mind and some races will insist on it.

Also...

DON'T Discharge the pack below 3V per cell (6V for a 7.4V/2s pack). It will permanently damage them. Use the Low voltage cutoff in your ESC or buy a seperate cut-off or alarm for the car.

DON'T Cycle the pack unnecessarily. They don't need it.

DON'T Store the packs either fully discharged or fully charged. This can also damage them. I tend to just leave the pack alone after my last race of the day, for more peace of mind you can use the "store" mode that most decent chargers have.

And a little bit of LiPo jargon...

s means the number of cells in series - at 3.7V per cell - most 1/10th cars are running 2s/7.4V packs.

p means the number of cells parallel connected with each other - it's not usually published for car packs, but they are often 2s1p (just 2 cells connected in series) or 2s2p (2 sets of 2 cells connected in parallel, then connected in series).

4.2V The maximum voltage of a charged cell - so a 2s car pack will be fully charged at 8.4V.

CC/CV The way the chargers work. They start of with a constant current to bring the cells up to their maximum voltage, then maintain that voltage by slowly ramping down the charge current to nothing.

I think that covers most things!

LiPos are great. One of the best things to happen to the hobby. Basically, as long as you don't treat them like a d*ckhead, they will cause you no problems. Same for everything really!

Don't leave in the car connected (between meetings) even if the switch is off, I have seen slow discharged lipos become unrecoverable.

Remember that you can charge, use, charge all day, run on one battery just topping up if you like, no memory effect. (second battery as backup)

When you buy a charger get one with cables to suit the battery connections, special attention to the type of balance plugs.

Lots of power and lighter !!!!!!! how you going to cope :woot::woot:

I cant wait :) im going to get a uac50 charger, and there are a few 2nd hand lipo's in the for sale bit - ive just got to work out how to mount it in the cougar now , most at the club use saddle packs - all quite confusing lol i think i just need to get it all then read the instructions carefully !

I would buy new Lipos unless you can get them from a trusted source, just so you know the history. If they are swollen then there past there best.

If you go along to your local track then i'm sure someone will point you in the right direction.

oh really ? at the club i went along to everyone used SMC 5200mAh but i did not really want to spend that much money :(

The SMC's are awesome cells, I use/sell them, and have had them for one season now and they are as good as the day I got them, but yes they are £79.99 a per pack.

You could always get a cheaper pack to start with, and upgrade at a later date. To be honest to start with you will probably be better off with a low 'C' pack.

The only reason I say about cells is they have been known to "go up". I must stress that this is very rare, and is why I say buy from someone you know, or buy new.

thanks :) i think i actually met you on wends this week ! came down with Adam and Tom, i should be coming this week (finally got a car.. ) but still need lots of bits and bobs , best have a chat with you so you can sell me some bits :)

Cool, what car did you go for?

ended up getting a cheap 2nd hand cougar sv (just to get started - i will be getting a sv2 in a few months ! ) what are these batterys like ? they seem very good value !

http://www.hobbyking.com/hobbyking/s...Lipo_Pack.html

I've not used/seen them before, so I don't know to be honest. Are you looking to enter any regional events this year?

If you have everything apart from the lipo's I'll lend you a set for next weeks meeting if you like, and we can have a chat about it then.

nope i need Looooads of stuf , ive got an ESC , Motor, the car, and thats it.. so need transponder, battery, charger, tranny servo etc... very kind for the offer but think im prob a week or two away from getting all the bits i need. Im really on a budget - i only came along last week as it sounded fun and im hooked and want a go :) its been 15 years since ive had a go.. so i will need some practice! off topic i know now - but im a photographer can i bring my camera down for some action pictures ?

That'll be awsome if you could.

Cool will do will keep me busy anyway while i watch everyone else have fun :) its been so long since i did it i hate not knowing how to do stuf - so best get all my own kit and dive in ! lol