Hi guys
I have just started using A123 2 cell packs for Rx / servo power in a 50cc Gas model.
The problem I have is that when balance charging using a Hyperion EOS 610i Duo the packs only balance to .6 of a volt.
Can anyone tell me if this is normal with this type of cell.

I have been using A123's for about two years now and have never balanced any of my packs. I have 2, 3, and 4 cell packs. I check them occasionally and if they are off I do a deep discharge and charge them to 3.65v per cell. They always come back to within .1v per cell.

I have a bunch of 3 & 4 cells. After the first charging on my FMA Cell Pro 4 there is NEVER a difference.

Is your charger rated for LIFEPO4 cells ? Are you sure it is set correctly ?

If definately yes to all you have a bad cell. What else is possible ? Bad charger? or bad balancer setup ?

I read the specs.

At 270 bucks, it should sound a alarm that a cell is shot. Stop the charge.

Is this your first charge on the pack ? Did you build the pack? Check for a wiring error in everything. Pack & balancer cable.

Post back

You realize this charger is out of production ? I hope it is not a new purchase.

Rich

.6v is a long way from balanced!
.1v isn't balanced either but it is a long way from where you are. I have used the FMA charger(s) so balance hasn't been a problem.
Some others I've heard of have flattened the cells and then recharged and have obtained a condition that is close.

I've used them for quite some time but I cannot tell you the effects on life cycles or performance from the extended 'out of balance' condition.
So far, a little over two years, my balance comes out to "on the money" . That is using the 10S which I have had since they were announced. Prior to that I used the 4S (no longer available from FMA replaced by the more versatile 4 Multi.)

I WOULD be concerned by .6v out of balance if it were my set up.

Thanks for all the replies Guys.To answer some of the questions;
Yes the charger is rated for li-fe Po4
Yes it has been set correctly
I have 4 packs in total one pack seems to balance spot on the other 3 are .6v out.
So is it the charger or 3 bad cells in seperate packs purchased seperatley?
If I run a seperate balance program after the so called balance charge it does balance to within .01v but it does this by discharging the high cell.
Confusing eh.

Quote "If I run a seperate balance program after the so called balance charge it does balance to within .01v but it does this by discharging the high cell.
Confusing eh. "
Quote

Frankly no. That is how you balance.
Your chance of receiving many "faulty" cells' is close to zero. When there is but one per pack______I'll let you fill in the blank.

BTW Do you actually HAVE A123 or simply LiFePo4 ??? There is a world of difference.

My FMA does a immediate cell check and starts dragging down ALL the higher untill they are the same voltage as the weakest cell. THEN.....It will start to charge them all up.

If the SAME 3 are always out & the SAME 1 is always in.

The packs have been damaged in assembly or by you somehow during operation.
Post back as you have a very unusual problem.

The charge/discharge/charge/discharge cycle should continue throughout the balancing function.
To do otherwise assumes that one discharge cycle has equalized the cells.

That proves to be a poor bet.

The purpose here is to guard against the overcharge of the cell with the highest charge acceptance and the discharge/charge/discharge cycling is the method.

If the cell with the higher charge acceptance is routinely overcharged it will exhibit a short life expectancy.

Assuming (unlikely) that you had enough packs then you could segregate the cells and solder up new packs based upon their charge acceptance levels.
Interestingly enough those packs then made up of the cells with lower charge acceptance cell will through continued cycling exhibit a life / performance span very close to the others.

This "seeming miracle' is no miracle at all simply the result of proper and extensive balancing.
For most RCers this is simply not worth the trouble and is unjustified by the inherent savings.

Running a fleet of say 150 to 200 Golf Cars it is justified simply by the weight of numbers.

Thanks again for all the advise guys.
From what you are saying it seems to me it could be the way my charger handles the A123 cells (They are genuine A123 ) For all other types of cell Lipos Nims etc. at the end of the balanced charge they are balanced. I have never had to run a balancing program afterwards.I am still not shure what to do for the best do you think that running a balance program after charging is a safe bet?

I personally would prefer one that ran concurrently with the charging process.
My reason is to prevent ongoing overcharge of the cell(s) with the highest charge acceptance.

Since the cells are truly A123 I am less concerned as I feel in RC we are far more likely to replace them due to the 'time factor' than due to an actual degradation in performance.
1000 cycles with a 100% depth of discharge is a ___ L-O-N-G ____ time. That is "spec" for A123.

Chances are that you will phase them out around the three year mark regardless of the performance level indicated. Even though there may be plenty of cycles left, I expect to do the same.
RCr's are quite conditioned to the NiCad way of life and the penalty for trying for one cycle too many is simply too harsh to accept.
At three full years I consider "value received".

We still have not solved the 3 bad packs. Were the cells soldered on the ends ? If yes. They were probably overheated and vented a small amount of the capacity. There is / was a pressure relief valve built into the LIFEPO4 cells at 1 end. I think I would take the chance of more damage to the bad packs and put the GOOD cells together into 2 good cell packs.

Were the cells soldered?

I had the packs made up by Robotbirds here in the Uk.

Send the 3 bad packs back, for 3 good ones. No other way.
You deserve perfect packs for perfect money paid.

My attitude in business dealings.

Post back on how it goes. Other "Kings Men" would like to know also.

Rich.........other side of the pond.

Perhaps you can point me to the part where "bad packs" has been addressed as all I see is improper balancing.

You are joking ?

Deadly serious.

He pays for 4 NEW packs and you would ARGUE with him that the 3 who can not chage up to full voltage are PERFECTLY good ?

Get a life Troll.

Not a Troll at all.

I simply spent 37 years in the battery business Engineering was but one (a smaller one) of the functions directed. At the time the Company was the largest in the free world (it shall remain nameless)____MY choice.

I detest making such background notes public. Your lack of understanding, followed by a pugnacious and precipitous remark, seems to leave little choice.

I view all of these forums as equals speaking to equals ____ most of us are RCr's and that is a bond which is close enough for me.
We all enjoy some aspect of the same hobby and that is all it takes for me to accept you______even though at this moment YOU are a bit of a trial for me.

Tell me, _____ what are your qualifications?????

I was in charge of getting ALL new factory designed rejects running. I never had time for engineers who could not right a honest error because of a oversized ego. I just went immediately over heads till the error was corrected at no charge.
We of course had no use of the equipment and lost money until the equipment ran. Sometimes a back charge was agreed to, as we lost a contract or customer.

We paid new prices. I expected new performance.

Rich

In other words you have none which is applicable to the subject being discussed.

Anger alone is far from reason. As a matter of fact it clouds reason.

Please forgive my lack of rising to your lofty self appointed standards.

Oh mightest of all Trolls. Spare my life & mental well being.

Thank you, your most highneeness.

No problem at all.

You've succeeded in ID'ing yourself in terms no one else could possibly use and still pass muster.
If you would choose to be less defensive the world might prove to be a nicer place than you currently think that it is______if not "the World" at least RCU.

You still on a high ?