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Battery problem?..

Old 08-10-2014, 02:37 PM
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time bandit
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Default Battery problem?..

I purchased some DBY 1800mah 30C lipos from HURC recently. I have one pack that measures across the three cells as follows: 4.20/4.14/4.10 This is at full charge this morning. Is this pack going kaput? Balance charging at 1.8 amps. They had to send me another pack right off the bat because one cell would only go to 4.10 and the others went to 4.20. Starting to think this brand isn't as good as the guy at HURC said they were. I hope I'm wrong.
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Old 08-10-2014, 03:23 PM
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You are measuring them how?
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Old 08-10-2014, 03:32 PM
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Balance charging on a Thunder AC6 at 1.8 amps. Then checking the individual cells through the charger to see how the cells are balancing.
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Old 08-10-2014, 03:45 PM
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You need to validate that the charger readout is OK with a DVM. If you have one of those little field cell checkers they aren't that accurate either.

Measure 1&2, 2&3, 3&4 wires at the balance tap. That will give each individual cell.
DO NOT TOUCH THE PROBES TOGETHER - SHORT! BAD!!!
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Old 08-10-2014, 04:15 PM
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How do I know which is which on the balance tap? Which end is number 1? All of my other brands of battery packs come up to full charge.
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Old 08-10-2014, 05:37 PM
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Red DVM probe on the red wire, black on the adjacent wire. Usually there is a small exposed opening on the back of the tap you can use.
Then move both over one space so now the red is where the black probe was. Then move again. Black should now be on the outside end black wire and red next to it on the inside.

But, if other batteries come out OK, that makes these suspect.
Now, if you have over discharged, stored charged, over-taxed, or other wise 'abused' these batteries then that's your problem.

You can charge up the low cells by making up a small 2-prong 'plug' and charge each individual cell. Cells are the same as the way you measured them individually.
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Old 08-10-2014, 05:44 PM
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Thanks for the info. I will give it a shot.
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Old 08-10-2014, 11:03 PM
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It could be a bad battery though on the other hand if the cells started out poorly balanced many lower rated chargers don't have enough drain current to bring them back into balance in one charge cycle.

If you give them a cycle or two only running down to half discharged them balance charging again you may find they balance up ok (or use a charger with greater balance drain current or a stand alone battery balancer).
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Old 08-11-2014, 01:24 AM
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A shorter way to say that is 'what is the battery history'?
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Old 08-11-2014, 01:56 AM
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Originally Posted by flydiver View Post
A shorter way to say that is 'what is the battery history'?
I got them in March from HURC. They had to send me another one because of a bad cell. The packs in question have about 10 flights on them. I have some different brand packs that are several years old. My friend gave them to me and they charge up perfectly. I'm not mad at HURC. I just think they got a bad run of these particular battery packs.
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Old 08-11-2014, 02:04 AM
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OK, not available for warranty.
How do they WORK?
(IMO that voltage discrepency is not necessarily a big deal as long as they work OK, are not puffed, come down no more than warm, and have never been crashed)

Do you keep them charged all the time?
Do you fly to LVC?
How hot it is around there?
How do you store them?

There are lots and lots of ways YOU can screw up a battery.
And, you can also get lame ones.

Battery roulette is just that sometimes.
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Old 08-11-2014, 02:13 AM
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Originally Posted by flydiver View Post
OK, not available for warranty.
How do they WORK?
(IMO that voltage discrepency is not necessarily a big deal as long as they work OK, are not puffed, come down no more than warm, and have never been crashed)

Do you keep them charged all the time?
Do you fly to LVC?
How hot it is around there?
How do you store them?

There are lots and lots of ways YOU can screw up a battery.
And, you can also get lame ones.

Battery roulette is just that sometimes.
If i did not use battery's after a crash, i would have no battery's
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