How is a lithium battery pack wired?

  • 4 Replies
  • 293 Views

0 Members and 1 Guest are viewing this topic.

Offline bitclueless

  • Newbie
  • 0
    • View Profile
How is a lithium battery pack wired?
« on: 10/02/2017 09:32:30 »
hi all
i have a serious problem with my lithium battery pack that only contains 2x 3.7V =  7.4V.
it has 3 connection points, +, - and a center conection poin with no marking.
i charged it with after market that only used the + and - points of contact.
the battery charged but it wont work on my device.
i checked with multi meter and used it to light up lights and moters but simply wont work on my device. the device definaterly works because i use it with the other battery i have left.
what could be the problem.
any help would be greatly appreciated.
« Last Edit: 10/02/2017 10:26:18 by chris »

Offline Redwun

  • First timers
  • *
  • 4
    • View Profile
Re: How is a lithium battery pack wired?
« Reply #1 on: 21/03/2017 02:17:14 »
what type of battery pictures ?
what device ?

Offline chris

  • Neilep Level Member
  • ******
  • 5447
  • The Naked Scientist
    • View Profile
    • The Naked Scientists
Re: How is a lithium battery pack wired?
« Reply #2 on: 21/03/2017 19:27:55 »
Yes, how did you charge it?

Lithium cells require a bit more technology to charge and discharge them than a straightforward pair of crocodile clips. The electrode voltages are carefully controlled, particularly towards discharge, to prevent irreversible damage. The third terminal is used for this monitoring.
I never forget a face, but in your case I'll make an exception - Groucho Marx

Offline evan_au

  • Neilep Level Member
  • ******
  • 4348
    • View Profile
Re: How is a lithium battery pack wired?
« Reply #3 on: 21/03/2017 20:14:32 »
Some of them have a chip in the battery pack to record the state of charge; to prevent the battery pack going completely flat and prevent overcharging (with potential meltdown).

If this chip is not powered up during charging, then it can't record the newly added charge, and the device using the battery pack will think it is still flat.

Offline Redwun

  • First timers
  • *
  • 4
    • View Profile
Re: How is a lithium battery pack wired?
« Reply #4 on: 21/03/2017 21:01:40 »
correct there is some circuitry in most of these lipo batts . Use a meter to check the 3rd pin charge it momentarily on both . i have had luck with the iphone battery and some others this way,  it can be tricky you may have to trick it charge for a bit while its connected to device. depends on device and battery. on mine i didnt care because i needed it charged . Iphones stink but i needed to power up to make a call so i opened case and located batt since charge port was broken (4s) and i used a 5v usb like 100ma wall charger for the 3.7v batt i have a bin of random charger / ac to dc and etc. what are you charging. try to charge both pos +pins at same time for few seconds 15-20  , jump from the pos to the other pos pin and see if that helps . no guarantee and use lower miliamp charger . wear safety glasses when charging just in case.  worked for me for about moth i had 2 wires hanging out of cellphone iphone 4s both pos and the metal case was the gnd. i used 2 alligator clips hooked to a standard usb cord i cut off end red green black n white i just used red and black . got my phone to charge and power up for several weeks but slowly got worse but it did work.  i have charged a cellphone with a few AA batteries and some foil gum wrappers just to say i did it .have video somewhere maybe i posted it on youtube not sure 


Cheers !
Robert


here is the rig i used back in november still laying on table in the corner upgraded to samsung S7 active.

-some times a momentary jumper to two points will trick it may have to be charging in device , worth a try. dont brick it haaaa
« Last Edit: 22/03/2017 10:40:48 by evan_au »