BC-6 Balance charging 2 packs at once

[theglennster]

I thought I would like to share my new method of charging 2- 3cell T-Rex packs with one Bantam BC6 charger basically halving the charging time.:YeaBaby:

The BC6 is capable of charging 6 cells at once and has a built in cell balancer although normally you only charge one battery at once using this method it treats the Lipos's as a 6 cell pack and balances them. Here's how I did it:-

1. Make up a serial (Y shaped ?) charging lead I use Deans on my batteries so it ended up looking like this. Note the polarity in the picture.

http://www.helifreak.com/attachment.php?attachmentid=24809&stc=1&d=1187727581

2. Buy a Thunderpower Balance adapter TP6P4PE (not essential but a nicer way to do it) You can cheat by plugging one of the lipos balance taps into the 6 pin socket but offset it next to the 4pin (this is important or you will get an error)

http://www.helifreak.com/attachment.php?attachmentid=24810&stc=1&d=1187727659


3. Connect the batteries up as the photo taking note of the polarity. ENSURE the positive charge feed is on the positive balance feed. I can not stress this highly enough or you WILL short your batteries or damage the charger.

http://www.helifreak.com/attachment.php?attachmentid=24811&stc=1&d=1187727814

4. Set the Bamtam to charge 6 cell at whatever rate appropriate for your Lipo's and feel smug that you have two packs charged in the time it normally takes to do one.

There are other ways of doing this it can be done in parallel instead an treating it as a 3cell but I tried this option and it works for me.

Please Note you are doing this at your own risk if you don't pay attention to the polarity you can cause damage as you are basically shorting out your Lipos. (Dont ask me how I know this :oops:)

YOU HAVE BEEN WARNED

Many thanks to all the Freaks who helped me out with this little project unfortunately my original post was lost in the big 3 day time warp recently so I cant name them all but you know who you are.:thumbup:

Cheers
Glenn

[Big Fil]

Cool! Are you charging at 2.1 amps? How far off are the voltages of the batteries when you begin charging? I would think if they were not close it'd take a long time to balance.

[theglennster]

Hi BigFil
I'm going to have to do a bit of experimenting with charge rates as I've only just finished the setup I suppose I should time a single pack charge and compare it with a dual pack and see the results perhaps doing 2 in the same time as one pack is a bit abitious :dontknow

I agree I also certainly wouldnt like to charge an almost full pack and an empty one the balancer would be working overtime and would probably take an eternety to charge. I did notice it seemed to take longer to top it up at the end it took a while with all the cells bouncing between 4.19 & 4.2v only time will tell.

I'll post some results after I have played with this arrangement for a while. But so far its looking good.:YeaBaby:

[Big Fil]

Cool, keep me posted on what you find. I've got a BC-8 and would like to be able to do this. Then between two chargers I could charge 3 packs at a time.:Bang

Now if I could only find a single charger that would charge 3 600 batts and 3 450 batts at the same time i'd be in heaven.

[aaron07]

I've got a similar set-up. My 3S 2170 charged in series are almost charged by 50mins, then it takes about 70mins to balance 0.1amp. 120mins for full balance charge (4.2each cell) every time.

[Big Fil]

So then you aren't really gaining any time by charging both at once other than the convinience of not having to switch packs when one is done.

[Steel Butcher]

It's best just to use "Fast charge", it will charge both in under an hour, and it still balance charges. You just lose the last percent or so.

If both packs are close in voltage I have found that the balance charge is still one hour.

[Steel Butcher]

3. Connect the batteries up as the photo taking note of the polarity. ENSURE the positive charge feed is on the positive balance feed. I can not stress this highly enough or you WILL short your batteries or damage the charger.


Glennster:

What you should do is put a piece of reflective tape on the 6S balance lead, and another piece on the positive main lead. This way, the two cables are paired up to the same battery and you are unlikely to hook them up wrong.

I have been charging this way for months with the BC-6, works well.

You can see my set up on the old gallery, hard to see but they are marked with green reflective tape:
http://oldsite.helifreak.com/album_showpage.php?pic_id=17000

[theglennster]

Just a bit of feedback now I've tested this setup

Using this method for charging two equally discharged packs is definitely the way to go :thumbup: the only problem I can see is the larger the difference in balance between the two packs the greater the knock on effect in balancing time.

2 fully discharged Lipos (down to 11v) will take 90 mins to charge using the normal balance method but as Steel Butcher has pointed out you can really reduce this using the FAST charge setting. I am charging the Lipos at 2.1amp. You can really see towards the end of the charge the batteries are full but it juggles around balancing at 0.1a with the last 0.1v between the cells for a good 20 mins you can pull the plug before this point or use fast charging to miss out this bit.

For an experiment I did a bit of playing around to try and see if you put a fully charged pack with a flat one how long would it take to charge ? and I got to 12 hrs and gave up :rolling. This is obviously the downside to this method of charging you wont do any harm but it will probably take a day to charge the 1 flat lipo.

Anybody with a Bantam BC-6 or BC-8 I would say go for it this is an easy way of getting your lipos twice as fast just be careful of the polarity when plugging em in. Buy the Thunderpower adapter if you want to do it cleanly or put the 4 pin plug into the 6pin socket it all works.

Cheers
Glenn

[pilotjosh]

If you charge 2 3s packs at the same time, can you still tell how many mah you put into each pack? Or does the BC6 only tell you total put into BOTH packs combined?

[kgfly]

Since the packs are connected in series the same charge current flows through both (apart from the current dumped by the balancer) so (approximately) the same mAh goes into both. The greater the imbalance within or between packs, the harder the balancer will work and the more of the reported mAh will above the actual recharge.

If you chose instead to charge 2 x 3s packs in parallel then the total reported mAh must be divided by two to estimate the recharge into each pack.

[kamtsa]

So then you aren't really gaining any time by charging both at once other than the convinience of not having to switch packs when one is done.

Some company is coming with an automatic LIPO charger/switcher and they ask recently for suggestions for product names (don't remember the details).

Kam

[Bunter]

Hi

Thanks Glenn, but what is the green board between the lipo on the right and the TP adaptor?

Thanks

Bill

[BFashions]

There is also this https://www.unitedhobbies.com/UNITEDHOBBIES/store/uh_viewItem.asp?idProduct=2156
which means you don't have to make your own deans connector loop...

I am going to give this method a go with that lead, however I have a BC6 Align balance board, http://www.wattsuprc.com.au/ProductPhoto/EAC124/EAC124_1.jpg

So to charge the 2nd pack, I can plug it into the 4s connector, do I justify it to the left or to the right in that balance board?