IMAX B6 Not Balancing?

[Punx0r]

I feel like I'm missing something here...

I bought a little Imax B6 to cycle and balance my lipo packs before building up the batteries to go on the bike.

I've got the charger set to LiIo mode to terminate at 4.1 VPC rather than 4.2

The trouble is, using balance charge mode, it doesn't seem to balance?

What am I supposed to see happening? I've just taken a pack off the charger and there's 0.12V difference between highest and lowest cell (highest being 4.18V). This can't be right...

Thanks,
Ant

 

[dogman dan]

Did it finish balancing, or just stop when it timed out. If it's really off, it can take a really long long time to complete balancing.

No garantee it's all that accurate either, it's a cheap charger. It could just be your jst connector is wonky as well. Verify your pack status with a regular voltmeter, or at least a different tool, such as a cellog 8.

When I have a really off balance cell I want to balance, I set the charger to 1 amp, 1s. Then I attach an adapter, that connects the battery main output to two leads with bare male jst connector prongs on them. Using a voltmeter to verify, I attach the two leads to the correct slots on the female jst balance plug on the battery. Turn on the charger, and the single cell will charge to full voltage. At that point, other cells may need a small adjustment, and the regular balancing cycle can work ok. It just takes too long, if you have a really out of balance pack to just use the balance charge setting on a cheap charger.

 

[Punx0r]

Yeah, it finished its program. The voltage steadily climbs to 24.60V, then current gradually ramps down to zero. I assumed this was the balancing stage.

The charger doesn't display cell voltages AFAIK, I measured it with a cheap cell checker, which I previously checked with a DVM.

I'll try balancing the remaining packs and see if there's any pattern in disbalance - to see if the reader or charger is missreporting a particular channel.

 

[adrian_sm]

This might be a dumb question...... but ....Do you have the balance lead connected as well as the power leads?

 

[gorach]

A genuine imaxb6 will tell you the individual cell voltages if when balance charging you use the scroll key. This scrolls between the pack charge data and cell charge data.
Watch out for the cheaper copies , mine went upin smoke 2nd charge.

 

[wesnewell]

See page 17 of manual. You have to use the Lipo Balance mode to charge if you want to balance charge. It is not the default mode.

 

[Punx0r]

Yes, balance lead connected

Good tip on the scroll key - I can now see the cell voltages

What's not the default mode? I have LiXX charge, discharge, balance, storage and fast charge. I'm using LiIo balance.

 

[dogman dan]

And it beeped at you that it was finished? or that it finished because it timed out?

Part of the balancing cycle is that the charger shuts off amps going in, while it discharges the highest cells for awhile. Then it will try again to finish. It can do this for hours if you have a stubborn cell that won't charge. One cell with much higher capacity can take forever.

You should be able to watch this happening on the display once you have the individual cell voltage showing. You should see the highest cells get discharged a small bit, over and over while the low voltage cells just keep slowly climbing.

 

[Punx0r]

I've just tried another pack and it does seem I didn't give it long enough, and it timed out rather than finishing. The pack just done took about 4 hours to balance deltaV after actual charging was 0.1V.

It finished showing all cells at 4.08V (24.6V pack total).

I checked this with a DMM, but just want to check I'm doing it right: DO neighbouring pins on the balance plug indicate one cell? I noticed that using the black pin as a common negative and working along the plug adds each cell in series.

Anyway, working in pairs I get 4.08V on each cell, except measuring between black and the first colour, which gives me 4.18V.

My cheapy cell reader is clearly not accurate, reading 4.06 - 4.10V for the "rest" and 4.18V for the black-neighbour combo.

I appreciate this is a noob question, but I want to be sure I'm measuring things correctly...

Thanks,
Ant

 

[d8veh]

I find that it does a good job of balancing when not fully charged, but once one of the cells has reached the maximum, it doesn't seem to figure out what it has to do and so takes a very long time to balance.

 

[Punx0r]

That's interesting, because I found balance didn't really change until the charger hit full (24.6v) voltage, then the slower cells started catching up and the higher ones dropped a tad.

 

[dogman dan]

Sounds like you are getting it figured out. adjacent pins correspond to one cell in the pack. Using a pair of bare jst male prongs, you cand connect to just one cell, and using 1 amp setting, charge just that cell bringing that one low cell up much faster. You put one jst prong on each main charging output wire.

Correct, no balancing will happen till one cell reaches end of charge, then the charger starts discharging that cell, and may cut input to all cells till the high cell or cells gets low enough to resume charging at a low amp rate.

It may take a looong time, particularly for large packs, or for packs paralelled into huge packs. You can adjust the time out setting longer.

Accuracy is not garanteed, not with your charger, nor with items like cellogs. Even your dvm may be off a tad, but at least with that, it's off the same amount with each cell you measure.

the jst plugs are notorious, a bit of resistance on one cells contacts will throw the balancing readings seen on the charger display waaaaaay off.

All part of why I call balanced to .05v close enough. I'll actually balance a cell if it's off .1v. If it's getting out of balance every cycle, trash can.

 

[Punx0r]

Thanks 8)