battery charging question

[koenejet]

I have a blade nano cpx and a blade cx2. I got the nano used with 10 batteries. I bought an adaptor cable that would let me connect 3 of the nano batteries together and charge them from the cx2 charger. Now, I noticed that I get greatly reduced time on the nano batteries before they kick out. The motor basicly shuts off for a few seconds, and then back on. So here is the question. And I think I know the answer, I'm just afraid I'm right and would like another opinion. The nano chager puts out .3 amps, and the cx2 charger puts out .65 amps. I read that you are not supposed to charge more than 1C. I never thought about it when I started using the cx2 charger for the nano batts, but I was charging more than 1C (right?). So, now the question (finally), could I have damaged the batteries by charging more than 1C, and that's why they don't last any more than a couple of minuetes?
Thanks for any help.
(after a charge the voltage is good though, and when the motor cuts of the voltage is around 3.4 to 3.7v. Don't know if this info helps or not, but just in case.)

[Russell Harding]

Stock nano batts are good to 3C.

Do you store them charged? I've noticed on nano batteries that even a week at full charge is very bad.

[koenejet]

storage is random, as far as if they are charged or not. Since I got them used, I don't know how old they are, nor do I know how long they should last under normal use.

[koenejet]

could someone let me know if my math and understanding of C rating/charge is correct.
If my nano batts are 150 mAh, and the charger is putting out .65 amp, then doesn't that mean that I am charging it at about 4C?
If that's the case, then how badly am I damaging the batts if they are able to charge at 3C?
Thanks again,

And, I don't know if it matters, but with the setup I'm using, I'm charging 3 at the same time, so I don't know if that is .65 amp to each battery, or .65 amp divided between the 3. Which if it is, then there shouldn't be a problem. Correct?

[Russell Harding]

If the charger is set to .65A, it will be split between the batteries, for ~.22A each.

[Zor1]

Originally Posted by Code3Medic

If the charger is set to .65A, it will be split between the batteries, for ~.22A each.

For a charger to be set at 0.65 amps it has to be a constant current charger.

If the batteries are in parallel the current in each branch depends on the internal resistance of each battery. It is not necessarily equal.

I believe that the stock charger is rated at the 0.3 amp but that is not necessarily the charging current.

Zor1

[Pfloyd]

IIRC the CX2 batts are 7,4 volts, not 3,7v,

[JonJet]

Pfloyd is correct...unless your adapter cable splits the charge voltage, your batteries are being charged at double voltage of 7.4v - not 3.7v as they should be

If that is the case, your nano batteries are toast

Edit: And this thread is over 2 months old - oops

[koenejet]

yes, but the charger is a parallel charger, it charges each cell to 3.7. I bought an adapter on ebay to connect the 3 nano batts to the parallel connector.

The charger that came with the CX2 can do either 2S or 3S.

[JonJet]

Originally Posted by koenejet

yes, but the charger is a parallel charger, it charges each cell to 3.7. I bought an adapter on ebay to connect the 3 nano batts to the parallel connector.

The charger that came with the CX2 can do either 2S or 3S.

Then I would think it might be okay, but not ideal...

.65 amps would give each battery .22, but if they are not equal it might cause a rapid 3 or 4C condition on the lowest battery

[JonJet]

Re-read your first post...

You are below LVC at 3.4 - 3.7v, ideally you want to charge to 4.2 and fly 80%, or to 3.8

If you've done this a few times, the batteries are probably senior citizens

[koenejet]

I think (or know actually) that my problem was that I was leaving them either fully charged or discharged between flying. Sometimes that would be several days or weeks. I got new batteries and the thing flies great now. And now I leave them at 3.7V between flights.

Thanks all for the inputs.

[JonJet]

Originally Posted by koenejet

I think (or know actually) that my problem was that I was leaving them either fully charged or discharged between flying. Sometimes that would be several days or weeks. I got new batteries and the thing flies great now. And now I leave them at 3.7V between flights.

Thanks all for the inputs.

Make it 3.8v minimum and you'll be good to go

It wasn't the time left full or discharged, it was the LVC condition that damaged them