GENS Ace lipo battery
 

i finally received my 3300 4s gens ace lipo and the cells are all screwed up, first of all the packs voltage was 15.12 which from past experience is really low, i have 2 IMAX B6 chargers and the first charge i did the cells read:4.19 4.17 4.19 4.18, this was strange to me but i figured its a new battery so ill cycle it maybe it will straighten out. I discharged it and charged it up again at 3.0 amps, it read this time 4.20 4.18 4.17 4.18, this to me is garbage because even the turnigy batteries i have ordered balance out correctly from day 1, Anyone have any of their own feedback about their experience with Gens Ace lipo packs?

RE: GENS Ace lipo battery
 

Welllllll … let me throw this thought/idea out for a wishful(wouldn't it be nice) 2012 perfect world. Let’s assume that your IMAX charger has the brain power to somehow calculate how much each cell's voltage should be charged during GEN Ace’s initial conditioning period. Let’s even take a big leap and assume the telepathy between the IMAX B6 and GENS Ace is able to actually~for make believe REAL determine the ideal top-end charged voltage for each cell during it’s first few cycles of conditioning … sooooo that at the LVC (whether 3.0v or 3.2v per cell) each of the four cells will have near identical discharge voltages that are within 0.05 volts of each other.

If you noticed the combined top-end voltage both times for the 4 cells was 16.73 volts. Thanks to the TLC telepathy between your brainy GENS Ace and your IMAX B6 your new 4S LiPo with its initial conditioning fill-up of 16.73v rather than 16.8 volts is to be envied. Also, what’s the problem with a storage/shipping voltage of 15.12v(3.78 volts per cell) for your new GENS Ace 4S 16.8v 3300mAh LiPo. Isn't 10.8v(3.6v per cell) a suitable charge when storing a 3S LiPo.

In order to accomplish this looking ahead equalized discharge feat(each cell within 0.05v of each other) at LVC, each cell’s top-end charged voltage can’t be exactly equal at 4.1825v per cell (16.73/4), but rather must be 4.20v, 4.18v, 4.17v and 4.18v. Each of the GEN Ace’s four 3300mAh cells were matched as close as any LiPo QC manufacturers zero tolerance benchmark. NASA can afford/expect GENS Ace to custom build a 4S LiPo with perfectly matched cells in nearly every way, but do you really need to carry aboard a near perfect $5000 4S LiPo in your toy plane.

Instead of berating your new GENS Ace perhaps you should be congratulating it … just my 2 cents:eek:

RE: GENS Ace lipo battery
 

My few packs have been shipped at perfect storage value and were/are balanced nearly perfectly. I've never balanced them. Why not just balance them to perfection and then they will be done?

RE: GENS Ace lipo battery
 

When someone like yourself is blessed with good fortune and common sense, then the prevailing thinking seems to be that you only need to balance charge every 5 or so discharge cycles ... the reason ... it takes a little longer to balance charge even a fairly good LiPo, but then what's a couple more minutes. Again, even an expensive LiPo balancer can't heal or renew a LiPo that has accidently been misused or abused. At least even an Astro Blinky or an inexpensive balance charger helps prevent the more rapid deterioration of a misused/abused LiPo, allowing the pilot to get the most cycle life even though that life isn't as energetic.

There is only so much even an expensive balancer can accomplish. No balancer can improve the original condition of a LiPo pack when it comes to trying to perfectly upgrade/match each cell's mAh capacity, IR, or whatever that is inherent at the time of manufacture.

_________________

Here's one NASA geek's suggestion for a GENS Ace LiPo benchmark by which to compare every other LiPo brand and pack size.

During the initial conditioning set LVC at 3.2 volts per cell(12.8v for 4S). A couple minutes after LVC check to see how much difference there is in voltage between the highest and lowest cell voltage. The closer the voltages the better matched are the pack's individual cells.

After 15 minutes write down the resting bounce back recovery voltages of each cell. Ideally they should be within 0.01 volts of each other with no more than 0.02 volts difference between the highest cell and lowest cell. Then after 30 minutes from LVC again record the resting voltages of each cell.

This record will then become your GENS Ace benchmark for getting a pretty good idea when comparing the initial qualilty of any LiPo pack whether 2S,3S or 4S.

RE: GENS Ace lipo battery
 

The answer to an imbalanced pack is always the same, balance the pack. No amount of cycling or other "tricks" will help it out. A cheap balancer, cheap balance charger, a cheap non-balance charger can be used to do this job.

Out of balance cells do not mean that the cells are garbage, we are only talking about the charge level here. Make them all 4.2 volts (or as close as you can read them) ;)


Your NASA persons first suggestion is great for determining cell capacity match and should be done as late as possible rather than asap after the discharge. 1 hr is usually sufficient for even the worst case scenario , for good packs 10-30 minutes is usually adequate. Comparing an asap check then a 1 hr check will speak of the IR's of the cells as related to each other and the actual IR of the cells.

There's equipment available that allows the user to see this info on screen in real time or view graphs.

RE: GENS Ace lipo battery
 

The problem here is the definition of a balanced pack. Just because 3, 10 or 100 imbalanced LiPo packs are charged to 4.2 resting volts per cell is no indication that the packs are now "balanced." BUT, if that is your definition of a "balanced pack" then me thinks its a tongue-in-cheek over-simplified definition. I think you even KNOW that there is more to a balanced pack than just 4.2 fully charged resting volts. I doubt that is the accepted industry standard for defining a "balanced" LiPo pack. But if it is then YEH, YEH for the ABCL (AmericanBalancingChargingLobby) ;)

As you are well aware IR is one important factor in the changing condition/aging of a LiPo pack or the mAh capacity difference between cells of a cheap bargain LiPo having inferior quality or imbalanced cell capacity. So, one way to determine the condition and any imbalance between cells (whether due to IR, mAh capacity, etc.) is to check the bounce back recovery voltages of each cell either just before LVC bench testing or within a couple minutes after LVC. It serves little purpose to wait one hour as the floating series voltages will tend to mask any imbalance.

Lithium battery chemistry is unique. For example you if check the resting voltage of say AA Eveready Lithiums that have depleted capacity the voltage needle indicator will still go high into the green supposedly indicating that the AAs are good to go. But put them into your little Canon digital camera and you probably can't take more than one picture before you see "replace batteries."

RE: GENS Ace lipo battery
 

Yep, that's the simplest most meaningful definition I can give.

I like to keep the other things separate. Varying cell's IR and/or capacity. Unfortunately we can't do much about these 2 things on any given pack.

Some of my "best" cells are terribly "matched" at least that's what I choose to define this condition where the voltage is grossly different when discharged.

If we consider the OP pack , then I'd bet money that the acq pack is of high quality , low IR , mismatched capacity, possibly mismatched IR. I would bet money that the only fix for this pack is to balance it by my definition.

We can talk about the other stuff as well, but I won't have a lot to say about it. The cell's IR all add up when using and charging the packs. If one cell's IR is very high then it's voltage simply sags during high rate discharge and droops UP during high rate charge. The capacity difference determines the final resting voltages at either end as well (with the smallest cell limiting the useable capacity)

My worst pack is probably not worth mentioning for a capacity difference of 1% or less. I've not checked it , but is not significant to me.

RE: GENS Ace lipo battery
 

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RE: GENS Ace lipo battery
 

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