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View Full Version : BC8 takes ages to balance


c.penhallurick
04-14-2008, 04:36 PM
Hi.

If someone has already asked this, sorry.

When Im balancing my Flightpower Evo 25 4900mah lipos I often find that the BC8 can take up to two hours or more to balance. The cell counts are bobbing between 4.19 and 4.2v. The amp input is down to 0.1 or even zero. I set the balance at 1C/4.9A. My lipos are fairly new and I never run them very low. After a flight they still remain fairly balanced. This doesnt happen on any particular lipo either. I have five of these lipos for my 600 and it could happen to any of them.
It also happens with my 2500 6s packs and my 2170 3s packs.

I often get a time out before the balancing has finished.

I have even started the balance again after a time out and sometimes it just keeps going.

The wierd thing is that sometimes the packs balance fairly quickly.

Please advise?

RC Accessory
04-14-2008, 08:20 PM
Hi.

If someone has already asked this, sorry.

When Im balancing my Flightpower Evo 25 4900mah lipos I often find that the BC8 can take up to two hours or more to balance. The cell counts are bobbing between 4.19 and 4.2v. The amp input is down to 0.1 or even zero. I set the balance at 1C/4.9A. My lipos are fairly new and I never run them very low. After a flight they still remain fairly balanced. This doesnt happen on any particular lipo either. I have five of these lipos for my 600 and it could happen to any of them.
It also happens with my 2500 6s packs and my 2170 3s packs.

I often get a time out before the balancing has finished.

I have even started the balance again after a time out and sometimes it just keeps going.

The wierd thing is that sometimes the packs balance fairly quickly.

Please advise?

What you are describing is your packs have a resistance issue one of the cells. If you monitor the individual cells, you'll see one of the cells drop in voltage when the charge rate drops to 0. The charger will try again to maintain the voltage of the cells.

If this is happening on all your packs, then I would suggest you get the charger looked at by Bantam through your dealer.

c.penhallurick
05-09-2008, 04:24 PM
So anyway.......

Since my last post I have been having various chats with Evan via PM.

Ive been going up the wall with this problem.
Ive put seperate posts on other forums to find if others are having the same problems. One or two people are. Even got to the point where I have ordered a V Balancer to use in conjunction with my BC8 on its normal charge cycle. Really frustrated!!

However...
My last PM from Evan was that he now thinks that the balance board/connector may be a bit moody, so I ordered another one. You wouldnt think that much could realy go wrong with these boards as thet are just a pile of connectors.

Put the new board on today. Flew a few lipos(hard). Put them on a balance charge with the new board. F**!k me! Flightpower 4900mah 25c 6s fully charges and balanced in just over 65mins at 1C. Roughly the same for two others.

Two pieces of advice....
Listen to Evan.
Before you do anything else try a new board.

Evan, a big thanks I would never have just tried a new board unless you had said.
Thanks. Thanks. Thanks!

RC Accessory
05-09-2008, 04:42 PM
So anyway.......

Since my last post I have been having various chats with Evan via PM.

Ive been going up the wall with this problem.
Ive put seperate posts on other forums to find if others are having the same problems. One or two people are. Even got to the point where I have ordered a V Balancer to use in conjunction with my BC8 on its normal charge cycle. Really frustrated!!

However...
My last PM from Evan was that he now thinks that the balance board/connector may be a bit moody, so I ordered another one. You wouldnt think that much could realy go wrong with these boards as thet are just a pile of connectors.

Put the new board on today. Flew a few lipos(hard). Put them on a balance charge with the new board. F**!k me! Flightpower 4900mah 25c 6s fully charges and balanced in just over 65mins at 1C. Roughly the same for two others.

Two pieces of advice....
Listen to Evan.
Before you do anything else try a new board.

Evan, a big thanks I would never have just tried a new board unless you had said.
Thanks. Thanks. Thanks!

Thanks for the Kudo's! :lol:

My guess would be that the old board had an issue on the traces which caused the increased resistance that I described. The only explanation that I have is that the one pack does have increase in resistance over the others, plus the increased resistance on the board, hence the problem.

This is the primary reason by battery companies keep the balance taps so very short. When I hear about these issues with any charger, I also inquire to see if a lipo extension is also being used. Longer wire, increased resistance.

Glad that it all worked out for you!:clappp

c.penhallurick
05-09-2008, 04:52 PM
A friend also told me to cut the tabs/clips off the lipo connectors so that the connectors slide in and out of the board recepticles easily without too much movement to the joints on the connector board. I imagine this would help as the tabs clip on quite tightly and sometimes are a pain to undo. Ive done this and its much easier.

Thanks again.

RC Accessory
05-09-2008, 04:57 PM
A friend also told me to cut the tabs/clips off the lipo connectors so that the connectors slide in and out of the board recepticles easily without too much movement to the joints on the connector board. I imagine this would help as the tabs clip on quite tightly and sometimes are a pain to undo. Ive done this and its much easier.

Thanks again.

That is a great point. Some of the taps fit the sockets so tightly, that I can see it being very possible to weaken the connection to the pcb.

The new Bantam EAC boards have the sockets further apart making it easier to get your hands on to the tap to release it from the socket.

Here is a pic of the new EAC129 board for the BC-6 series chargers.

http://www.bantamtek.com/image/Accessory/EAC129.jpg

c.penhallurick
05-13-2008, 04:11 PM
Evan.

My problem came back yesterday. However I found that the first lipo I charge always balances fine.

When the first had finished I was pressing stop, connecting another lipo and away to go. Thats when I was seeing the problem.

This is what I have found....
If I completely turn of the charger, connect the lipobefore I turn back on and balance then they seem to all balance in one hour or so. They dont seem to be left hanging like before.

I hope that I have explaned this well enough.
What is the reason for this or is it the way that it shoud be done?
Regards.

RC Accessory
05-13-2008, 04:58 PM
Evan.

My problem came back yesterday. However I found that the first lipo I charge always balances fine.

When the first had finished I was pressing stop, connecting another lipo and away to go. Thats when I was seeing the problem.

This is what I have found....
If I completely turn of the charger, connect the lipobefore I turn back on and balance then they seem to all balance in one hour or so. They dont seem to be left hanging like before.

I hope that I have explaned this well enough.
What is the reason for this or is it the way that it shoud be done?
Regards.

I'm thinking of what I do myself....

After the charge is complete, I just take the battery off the charger. When I reconnected, I clear the screen then connect the battery, the proceed to charge. I cannot imagine that the order would make a difference.

Play with it more and see if you can repeat the issue consistantly.

c.penhallurick
05-13-2008, 05:10 PM
Yeah. Its wierd.
Three of my lipos were left hanging yesterday. I did them again today, turning off and on between each and they all balanced straight away.

I flew one lipo tonight. one that always takes the longest to balance (if ever) plugged it all in, turned on then started. Balanced in 67 mins or so.

Im flying tomorrow after work, see what happens then with the off and on approach.
Why cant life be simple?
You must be fed up of me by now!

zguy
07-25-2008, 12:53 PM
My BC-8 still has this issue on all packs, including brand new ones. It charges to 0.0A, but will not shut off until 120min time-out.

Has there been a conclusion as to what the cause and fix may be?

If it is the adapter board, then should this be covered under warranty?
Thanks!

RC Accessory
07-25-2008, 12:59 PM
My BC-8 still has this issue on all packs, including brand new ones. It charges to 0.0A, but will not shut off until 120min time-out.

Has there been a conclusion as to what the cause and fix may be?

If it is the adapter board, then should this be covered under warranty?
Thanks!

Have you replaced the connection board? If you have and the problem persists, contact your dealer.

zguy
07-25-2008, 01:14 PM
Hi Evan,

You are my dealer ;) and we've spoken a few times this year regarding this issue.
I have not tried a new adapter board as per our last discussion you believed the problem was aging batteries and not the charging equipment.
Now the problem is still happening with brand new packs.

I have been living with this issue until a known fix was available. The charger is great, but it would be nice to have it alert when done and not waste time checking.

Thanks!

RC Accessory
07-25-2008, 01:21 PM
Hi Evan,

You are my dealer ;) and we've spoken a few times this year regarding this issue.
I have not tried a new adapter board as per our last discussion you believed the problem was aging batteries and not the charging equipment.
Now the problem is still happening with brand new packs.

I have been living with this issue until a known fix was available. The charger is great, but it would be nice to have it alert when done and not waste time checking.

Thanks!

Call me to discuss when you can. With screen names, sometimes I have no idea who you are! :)

c.penhallurick
08-10-2008, 03:18 PM
This realy is a strange issue that I hear more people experiencing.

Evan and I looked at many options that would correct it. Boards seemed to work for a very short time but things soon went back to where they were. I even had my BC8 replaced and again it was fine for a very short time before the issue was back.

The wierd thing is that if it is a lipo/resistance issue, how come the new charger worked perfectly on my before problematic lipos for a short while? If it is a lipo problem surely it would raise its ugly head on a new charger as well as the older one?

However.... These days I just use the charge mode for my packs but I still use the balance board. At the end of each cycle my packs/cells are balanced within 0.01 of eachother. Again this is strange because I' told that the balance feature doesn' work in nomal charge mode. Yet if you monitor the cells during this cyle there is up and down activity as in balance mode.

Anyway guys the main point is that now I just use the charge mode but still connecting to the balance board and im getting a full, balanced charge on a FP 4900mah 6s in 60-70 mins at 1C.

I still love the Bantam. Is so easy to use. If yer having the above issues just try what I'm doing as its working fine for me.

Christian.

RC Accessory
08-10-2008, 04:00 PM
Sounds like the problem again is the board. When these issues come up, so far 100% of the time it has been the board and most of the time it is the TP/FP boards. Since you and discussed your problem, I have found that the boards are getting abused due to the clip on the TP/FP balance taps. Appearently, if you do not fully release the tab then remove the tap out of the socket you put pressure on the socket which causes the problem.

I have suggested to people using the TP tap to remove the clip from the tap and this releases the stress on the socket when removing the tap.

c.penhallurick
08-10-2008, 04:41 PM
Hi Evan. How are you?

I have no taps on my packs, I removed them all before I had my new charger and board. I am also very careful when connecting and removing the balance plugs. To me, there must be something else? Maybe ita a bas connection between the charger and the board plug?That aside as I am not having a dig.

My main point (although the issue is a strange one) is that I am having great success just using the charge mode with the balance board and that others with the same issue should try it. For whatever reason I am having great success this way. I check the balance of the cells after each charge and they are all on target. If it works for others.. Cool!

Christian.

c.penhallurick
08-10-2008, 04:50 PM
I still have the old style board though. None of my LHS's in Britain have the new type yet. When they do I will of course try one.

cbdane
08-10-2008, 05:19 PM
I don't think that it has anything to do with the adapter boards. In my very humble opinion, there is a quirk with the BC-8. I'm saying this as a big BC-8 fan.

Here's my 2c. I was a very early adopter on the BC-8 and I have two of them that I have used for almost 2 years. I make my own very high quality Molex locking balancing leads using gold plated industrial connectors that I install myself. Here are a couple of photos of my setup. I use the same balancing connector on all of my packs ranging from 2s receiver packs all the way up to my 6s 5Ah packs.

When all of my batteries were brand-new, the balance charge feature worked great, adding only 10-15 minutes max to the charge cycle. However, once the packs had aged a bit (30 cycles or so), I began to see the "never ending" balance cycle problem. I simply switched to standard charge mode and never looked back. My theory is that you get balancing benefits in the standard charge mode, however, the balancing threshold is lower. Somehow, I think, the degree of match between the cells required in balancing mode is too high and cannot be attained, even with a quite healthy pack that has a little time on it. My experience is with 6 separate 5s 4900mAh LiPos from 3 different manufacturers (FP, TP, and Kong). When I look at the voltages on individual cells during and after charging, they look very well matched, even though I am not using the balancing feature.

This has been a very widespread complaint with the BC-8 (you'll see many reports in this and other forums) but as best that I can tell, skipping the balance mode doesn't seem to detract from charging performance. It is safe to say that I have over 1000 charge cycles between my two chargers and 3 electric helis (2 T-Rex 600's and a 450). Please don't read this as a criticism. I've sold many BC-8's (so to speak, by recommendation) and I still don't hesitate to recommend them.

http://www.helifreak.com/attachment.php?attachmentid=17225&d=1174362099

http://www.helifreak.com/attachment.php?attachmentid=17224&d=1174362114

http://www.helifreak.com/attachment.php?attachmentid=17223&d=1174362130

c.penhallurick
08-11-2008, 01:31 PM
Thanks for your comments cbdane.
I agree that it must be some quirk with the charger. As I said above, I am now also using the standard charge mode and am having no problems at all.
Even though I have this quirk thing I still love my Bantam and would also recommend them to anyone. And fair doos to Evan his efforts, help and service are top notch.

RC Accessory
08-11-2008, 01:44 PM
Thanks for the kind words and I appreciate the passion for the chargers as I have the same. I hear what you guys are saying, but I'm not convinced yet. This will be one of the topics I bring up with Bantam when I have my annual meeting with them. Actually it will be brought up before the meeting.

One of the reasons I am not convinced it being the charger is that nearly all of these type of issues have been when the TP tap is used. Only 1 has been an Align style and none have been Polyquest or Kokam. Personally, all my packs use the Kokam or Align taps so I have not seen my charger/adapters/batteries experience this at all.

I do ask the customer most of the time to send me back the questionable adapter and I test them out. Most cases I do get it to act up, but not always on the first or 2nd try. When I can't get it to act up, I can only assume that it was either the charger or battery, but you never know.

Big Fil
10-05-2008, 05:30 PM
I've been having the large balancing times with my BC8 for some time as well with new or old batteries. Hadn't thought much about it though until recently the numbers started jumping around erratically and noticed it let one of my cells go up to 4.24v. I like others here have been a supporter of Bantam but it does appear that there is an issue with the BC-8 since so many of us seem to be seeing the same issue. I haven't tried the non-balance mode at this point but quite frankly i'm quite hesitant to even use the charger after finding it let a cell get past 4.2v.

One other issue I noticed was I did have a balance lead pull out of my 6th cell on one but didn't notice it until at a friends house and 2 of his TP chargers and a Hyperion charger would not charge the battery. When I put it on my BC-8 it charged it but if you scroll to the next screen, which I don't always do it did not read the 6th cell. In this case the other chargers seemed to have better protection in place to catch somehting wrong with the battery.

RC Accessory
10-05-2008, 06:13 PM
If the voltage of any cell reads above 4.20 such as you describe the charger needs to be checked out.

Big Fil
10-05-2008, 09:22 PM
Evan, how do I go about returning this to have it checked out. I purchased this from GrandRC but it's been over a year since I purchased it so i'm not sure if they would get involved. Fortunately my father let me borrow one of his TP chargers for the time being so at least i'm not grounded. I currently have it banging away on the one battery that got way out of whack and checked a few others and they seem to be OK. Looks like I caught the issue fairly quickly so hopefully no harm was done.

RC Accessory
10-06-2008, 03:51 AM
Evan, how do I go about returning this to have it checked out. I purchased this from GrandRC but it's been over a year since I purchased it so i'm not sure if they would get involved. Fortunately my father let me borrow one of his TP chargers for the time being so at least i'm not grounded. I currently have it banging away on the one battery that got way out of whack and checked a few others and they seem to be OK. Looks like I caught the issue fairly quickly so hopefully no harm was done.

They should as your dealer. If they won't support you, then contact me privately.