Charger for self made Li-Ion battery pack?

[troller_cpf]

Hey there folks!
I want to make a Li-Ion battery pack for a mod that I'm doing on a spotlight.
I will put 8 Trustfire 18650 batteries in a 4s2p configuration, so to obtain a total of 14,8V and 4,8Ah. It will be used to power a 35W hid ballast...

question is: how can I recharge this battery pack without disassembling it every time? Can I take a normal 12V charger (with the suitable current capacity of course), cut the terminal, peel the two wires and just connect them to the two ends of my battery pack?

Thanks!

 

[Mr Happy]

question is: how can I recharge this battery pack without disassembling it every time? Can I take a normal 12V charger (with the suitable current capacity of course), cut the terminal, peel the two wires and just connect them to the two ends of my battery pack?

What do you mean by "normal 12 V charger"? Do you mean a 12 V SLA charger? In which case the answer is "Good God, No!!"

First of all, 4s Li-ion will give you 16.8 V when fully charged. Will your HID ballast work OK with that?

Secondly, are you trying to burn your house down or something? Trying to assemble and use a lithium ion pack when you don't know how to charge it is playing with fire, literally.

Please read up on lithium ion safety. There is a whole sub-forum on that general topic above ^.

Of course, from your user name you are trolling so I apologize for feeding the troll. But other readers might find this informative.

 

[The Dane]

No!
Lixx cells have a life of their own and given time will become different in capacity.
Thus 1 link in the chain will run low before the others and that "problem" will progress until the cell dies.

What you need is a RC Hobby charger with ballancing capacity, like this one:

hotlinked image removed
http://www.dealextreme.com/details.dx/sku.15225

 

[ubetit]

You'll need an balancing lipo charger. This isn't one you should mess around with without help if you don't know what you are doing. That pack will have a lot of power.

 

[TranceAddict]

you will need to know how to connect the balancing lead for the pack.


for a complete list of chargers, visit
http://www.progressiverc.com/index.php?option=com_content&view=article&id=13&Itemid=18

Schulze is highly preferable, Hyperion is a good buy too.

 

[ubetit]

Schulze is highly preferable, Hyperion is a good buy too.

Excellent chargers but overkill unless you are a heavy E-flier. A Turnigy Accucell 8 should work just fine.

 

[troller_cpf]

what about this?
http://www.batteryspace.com/smartcharger05afor148vli-ionpolymerrechargeablebatterypack.aspx

thanks!

 

[JBorneu]

what about this?
http://www.batteryspace.com/smartcharger05afor148vli-ionpolymerrechargeablebatterypack.aspx

thanks!

No. It does not have a balancer built in and it has not enough power. Li-ion cells should be charged around 0.5-0.7 C for best performance so a 4.8 Ah batterypack should be charged with a charger which can supply a current of 3 - 3.5 A minimum at 14.8 volts.

Edit: Read up on balancers and li-ion battery packs. Maybe you'd be better off using a commercial RC battery pack which has balancing connectors built in it. Then you could devise a connection in the housing of the light you're building to connect it to a hobby charger (but make sure it can be sealed waterproof to prevent shorts).