Question? Thunder Power 3s 2250 Lipo

[econpatric]

Hey guys. Wondering about my lipos. I have two 3 month old lipo batteries both were bought at the same time. Both of the have 6-7 cycles. After each cycle (within an hour) they were set to 11.40v for storage. Yesterday I charged them both a .5c. One would not balance and hung at around 12.40v the charger timed out twice.

I am wondering if the battery is just acting up from being new and in storage for most of its life? or is there a bigger issue with one of the cells? How do I proceed?

 

[njswede]

How much out of balance is the cell? Timing out at 12.4V suggests it's 0.2V out of balance. That's not huge, so what I would do it just keep cycling it until you get it to balance. Chargers normally use a fairly primitive method to balance the cells. They simply discharge the cells with higher voltage until they come down to the voltage of the lowest voltage cell. The problem is that the discharge current used is very low, sometimes as low as 0.5A.

Keep trying, but if it hasn't gotten any better or gotten worse after, say, three more cycles, you probably have a problem with a cell. Thunder Power is a pretty reputable brand, so maybe they can help you...

 

[Steve_B]

IMHO it most likely says more about your charger than the battery.
I had (still have) a cheap Turnigy charger, which considering the price was ok, but it occasionally did exactly what you describe, it just took forever then ultimately failed to balance and top up a battery. Usually I just went and flown with the battery it would balance next time round.
I got myself an icharger 3010b earlier this year and have never since had a single battery fail to balance promptly, the batteries are the same, only the charger changed.

Steve

 

[econpatric]

Thanks for the input Steve. My charger is a Hitec X4 AC and is fairly new (about a year). I am surprised to think that it could be the charger. Hard to believe (and pisses me off to think) that I may need to look once again at a charger.

 

[Steve_B]

I doubt its faulty as such, just that some chargers seem to sometimes make a bit of a meal of balancing a battery. It's not usually a huge deal, just let the charger do it's best and providing the cells are reasonably close the pack is good to use.

Of course it could still be the battery, give it a cycle and see how it goes.

 

[econpatric]

Well, over the last week I did what NJSwede said and it seemed to work to bring the cell back up. However, starting out, this cell was a lot lower than I originally stated and now is closer to that 12.4v mark after 3 cycles. I used a battery alarm (set fairly high) and mainly flew circles so I knew when the cell was beginning to get low enough to cause issues.

With this being an issue on several batteries in the past, and after Steve_B's comments, I couldn't help but re-think my approach to charging with the Hitec X4 AC/DC Multi-Charger. When I bought the charger, I had thought that it would be nice to be able to charge 4 batteries at once, but with the new parallel charging boards a person could do that with a single port device and have way more power to throw at all of them. In addition, I have also been very disappointed with the charging performance on my 6s 5000mah batteries.

With the plan to buy a 3DHS 74" Edge, and having a couple of 60" planes and a 550 Heli, I needed to do something, as I will be using more of these larger batteries. After reading a few discussions on "the best chargers" I decided to go with the Power Lab 6 which I picked up last night from http://www.epbuddy.com/. I also decided to go with the Solid Hobby Power24 EC5 (http://www.solidhobby.com/) based on Doc Austins' 24+ Review. I PM'd Jeremy and he seems like an upstanding guy, he explained that this power supply was designed with the PowerLabs in mind. I had no hesitation about going with his product.

I'll upload some pictures of the units set up together as soon as they arrive.