Balance charging HOW?

[John Wagg]

When I charge a LiPo the charge lead and balance leads have obviously to be connected. After a while, on automatic fast charge, the charge starts dropping quite low but in this situation how do the cells balance out or don't they ?

Or do I have to do a specific balance procedure. ?

My charger shows total or individual voltages. What would be an acceptable variation between cells.

Currently just using 2s battery and Accucell S60 charger.

Cheers. John.

 

P.S edit - Just realised there is a "balance" selection on my charger. 

 

Edited By John Wagg on 14/08/2020 20:33:25

Edited By John Wagg on 14/08/2020 20:57:54

[Martin Harris - Moderator]

Most (if not all) chargers discharge the higher voltage cells via the balance leads when they reach full voltage while the other cell(s) catch up.

[John Wagg]

Posted by Martin Harris on 14/08/2020 20:42:32:

Most (if not all) chargers discharge the higher voltage cells via the balance leads when they reach full voltage while the other cell(s) catch up.

That sounds logical.

Thanks very much. John.

[Denis Watkins]

Your Accucell charger balances for you John to 4.2v and can go a little higher

If your charger shows 3 decimal places, then the 2 cells should be close to 4.2 but seldom identical

Edited By Denis Watkins on 14/08/2020 21:04:11

[Frank Skilbeck]

Posted by Martin Harris on 14/08/2020 20:42:32:

Most (if not all) chargers discharge the higher voltage cells via the balance leads when they reach full voltage while the other cell(s) catch up.

Not quite, what they have is a resistor in parallel with each cell, during charging this can be switched on to divert a small amount of the charge current around the high voltage cell allowing the others to catch up. This current is typically 80 to 100 ma.

[John Wagg]

Posted by Frank Skilbeck on 15/08/2020 08:00:57:

Posted by Martin Harris on 14/08/2020 20:42:32:

Most (if not all) chargers discharge the higher voltage cells via the balance leads when they reach full voltage while the other cell(s) catch up.

Not quite, what they have is a resistor in parallel with each cell, during charging this can be switched on to divert a small amount of the charge current around the high voltage cell allowing the others to catch up. This current is typically 80 to 100 ma.

Hope it doesn't sound to daft a question but I presume these resistors are in the charger and not on the battery cells ?

Only asking in case I ever make up my own battery packs. ?

Cheers.

[Peter Christy]

Posted by John Wagg on 15/08/2020 09:20:45:

Hope it doesn't sound to daft a question but I presume these resistors are in the charger and not on the battery cells ?

Only asking in case I ever make up my own battery packs. ?

Cheers.

Yes indeed! (There are no daft questions, only daft answers!)

Just to add to some of the above comments: As pointed out by Frank above, most chargers only allow a relatively small by-pass current (compared to the capacity of the pack), which means it can take a long time to balance a pack.

You can get "stand-alone" balancers which will discharge the high voltage cells at a much higher rate. These were quite popular in the days (not that long ago!) when chargers did not incorporate a balance port.

If your battery is a long way out of balance (I have one that I now use to power my starter!), you can reduce the charging time quite a bit by pre-balancing it with one of these balancers.

--

Pete

 

Edited By Peter Christy on 15/08/2020 09:39:55

[Dickw]

Posted by Peter Christy on 15/08/2020 09:39:01:.........................

Just to add to some of the above comments: As pointed out by Frank above, most chargers only allow a relatively small by-pass current (compared to the capacity of the pack), which means it can take a long time to balance a pack.

..................................................

Agreed, most chargers targeted at the RC/model fraternity only offer small balance currents and therefore take a long time to balance, but it is possible to get higher balance currents from more generalised charger offerings. The Chargery range of chargers balance at up to 1.3 amps according to their blurb - not actually measured it, but it seems to balance very rapidly on my 50010. It also balances right through the charge cycle from beginning to end.

Dick

[Engine Doctor]

If you have one cell thats a fair bit out of balance then you can charge the single cell on its own to bring it up a bit. Just set the charger to 1s and follow the following link . One thing i would say to change on the link is to fit a normal servo lead with plug to the charge lead with the signal wire and pin removed . This will plug nicely into the balance lead sockets

Edited By Engine Doctor on 15/08/2020 11:42:03

[John Wagg]

Thank you all for the replies and links.

A little bit more of understanding and thanks again.

John