0
\$\begingroup\$

Please advise me as to whether or not a current limiting circuit such as this one :

http://www.next.gr/circuits/Variable-Adjustable-Current-Limiter-Circuit-l23013.html

would be the ideal choice for my goal of charging 2 parallel lithium ion batteries with a string of super caps.

My circuit :

1). 7.2 vmax, 210 F super cap string >>

2). Boost convert to 8.4 volts output with a max of 5 A ouput when lithium ion batteries are at a minimum charge of 6.5 volts(i measures the output current with the battery load at 6.5 volt charge level >>

3) current limiter, limit current tfrom 5 A to maximum battery charge rate of 2.4 A ( one battery max charge rate is 1.2 A but I have two in parallel for a 2.4 A charge rate)

4). Load: (2) 8.4 Vmax lithium ion batteries in parallel.

Any advice would be appreciated. I would like to do this efficiently and without the use of resistive current limiting.

Thank you,

Tom

\$\endgroup\$
3
  • 1
    \$\begingroup\$ that one you linked to is resistive, isn't it? If you want to limit current efficiently, then you'll need a switch-mode current source. \$\endgroup\$
    – Neil_UK
    Feb 12, 2017 at 19:29
  • \$\begingroup\$ He's already has a voltage source in the circuit so a current source wouldn't make any sense. tw168 is looking for current limiting, not a current source. \$\endgroup\$
    – Kevin Brant
    Feb 12, 2017 at 19:36
  • \$\begingroup\$ I'm not sure if a current source would work in this case since the capacitors are my voltage source for this circuit. I would like to drop the current at the output of the boost converter from 5 A to a maximum of 2.4 A with minimal power loss. Would a current limiter be appropriate or are there better methods? \$\endgroup\$
    – tw168
    Feb 12, 2017 at 20:34

1 Answer 1

Reset to default
1
\$\begingroup\$

The circuit you show is effectively a resistive limiter, which you say you do not want.

You need a switching charger like the LTC1513 which will do what you want:

enter image description here

This won't quite meet you 2.4 A charge current requirement in the form shown above, but you could boost the current capability of the switch to meet the need.
The pulse current from your supercaps will go up as the voltage drops of course, so you may end up needing 10-15 A switch capability.

\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Not the answer you're looking for? Browse other questions tagged or ask your own question.