Lithium Battery Charging

[Tubamanandy]

I`m wanting to make up a small battery pack (4 x 3.7V 4000mAh lithium batteries) purely to run a front LED light.

Can anyone tell me what voltage/amperage I should charge the pack at and, more important, where I can get a suitable charger (ideally variable voltage so I could make up a bigger pack at a later date) ?

I'm not very good with electrics

 

[Alan Quay]

One of these:

http://pages.ebay.com/link/?nav=item.view&id=190818527250&alt=web

...and some JST connectors for balancing....

 

[Gringo]

I use Lithium ion & Lithium polymer cells and any suitable charger will control the charging cycle.
Something like this dose a lot more than you need but I'm sure you'll find a use for it in the future
http://www.hobbyking.com/hobbyking/store/__49452__IMAX_B6_AC_Charger_Discharger_1_6_Cells_GENUINE_with_UK_plug_UK_Warehouse_.html

 

[Tubamanandy]

How would I best wire up the 4 x 3.7V batteries ? I'm not sure because of the balancing side of things - do I just connect them in Series and charge at eg. 17V ? Really need to know charging voltage and amps

 

[Deleted member 4366]

Unless you already have the stuff, it's not worth it. Don't forget that you need to look after low voltage control as well, which means a lipo alarm and/or a permanently installed voltmeter.

You can get the whole lot: light, batteries with BMS and charger for £13, so no point in doing a self-build.

http://www.ebay.co.uk/itm/CREE-XM-L-T6-SSC-LED-3-Mode-Bike-Head-Light-Lamp-Torch-P7-4x18650-Charger-B0261-/261433308258?pt=UK_SportGoods_CyclAcces_RL&hash=item3cdea3b462

 

[Tubamanandy]

Already had the stuff in the garage and would like to use it - any ideas how to wire it up and charge it ?

 

[Deleted member 4366]

What have you got exactly?

 

[Gringo]

Unless you already have a dedicated lipo charger D8veh is correct, it's easier & cheaper to buy off the shelf.
The only way to charge lithium cells is with a lithium charger, no other charger will do.

 

[Tubamanandy]

Got 4 x 3.7V 4000Mah lithium batteries that I would like to utilise

 

[Deleted member 4366]

You need a lipo balance charger to charge them, or a 18650 cell charger. It depends whether you want to use them in series or parallel. What format do you want to use them?

In use, you mustn't let then go below 3.0v. If you have enough capacity for 2 hrs and you only ever use them for one hour, it shouldn't be a problem, otherwise you need to know when to switch off. They're not like other batteries that you can run flat.

Assuming that you want to use them in a 2S2P configuration from 8.4v to 6v, you'd need a 2S balance charger, a voltmeter or lipo alarm, a 2S balance connector and power leads with power connector that you can connect to your charger.

BTW. If they're 18650s , they won't be 4000mah. They'll be about 1300mah.

 

[Gringo]

Lithium-ion or lithium-polymer and do you have a charger with a lithium battery setting.
Do you intend wiring them in parallel to get 3.7v X 16000mah or series to get 14.8v X 4000mah
Do they look anything like this