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Jan 15, 2010, 10:08 PM
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Question

2 E-flite 7.4v Li-po battery's any help for them?


Hello;I have 2 E-flite 7.4v 800mAh Li-Po battery's in question with my Blade CX Heli.

I now have a Thunder AC6 Charger and a small voltage checker to check the voltage on the battery's

Battery #1 I balanced charged to 8.4v and 4.2v per cell charged ok.put in heli and seemed weak? I ran It about 4 foot high half to 3/4 throttle for about 5-6 min.If I tried to go any higher full throttle,red light on the cx,and seemed weak.so I set it down,checked the voltage and it read 3.82,3.85,7.68 total? Whats up with that? Seemed real weak.Can I do something with this to correct? Discharge with charger to 6.00v and recharge? Or is this battery Just no good anymore?

Same with the other battery.Can I do something with these,with the AC6 charger,or are they hopeless? I did not have this charger before,these battery's sat for a few months fully charged,before I smartened up and bought a decent charger/discharger, And the funniest thing is the guy at the hobbie shop said,don't worry about it,keep them fully charged,so I did.Now I have these 2 battery's like this.Is there any cure for these that I can do with this charger,or are they just junk?? Thankyou for any help with this.Dave
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Jan 15, 2010, 11:09 PM
Southern Pride
everydayflyer's Avatar
Just shows you that many hobby shop personal know very little about LiPolys. When you purchase them thaey are at 3.7 to 3.85 per cell not fully charged for a very good reason.

Looks like you need new batteries and there is not anthing that will help these.

Charles
Jan 16, 2010, 12:19 AM
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Quote:
Originally Posted by everydayflyer
Just shows you that many hobby shop personal know very little about LiPolys. When you purchase them thaey are at 3.7 to 3.85 per cell not fully charged for a very good reason.

Looks like you need new batteries and there is not anthing that will help these.

Charles
ya ok,this really tee's me off,and the guy I'm talking about owns the place.I bought 2 new 7.4v 2-cell 900mAh 25c battery's online and they where shipped at 3.8v per cell.So,the right way,is to charge them,use them,then when done,charge them or discharge them to a storage voltage of 3.8v balanced per cell.

what do I do with these 2? discharge them all the way and through them out?

Maybe I'll bring them to the guy that knows everything about these battery's at the hobby shop. He actually told me to take the word discharge out of my vocabulary,when I asked him about discharging to 3.8v per cell to store these battery's. He said this,and leave them fully charged.Now I have 2 bad battery's,and they don't give them away.
Jan 16, 2010, 08:24 AM
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ggcrandall1's Avatar
You could take them back to the LHS and explain the situation. But my bet is that he will give you some song and dance telling you that you are wrong. So it's probably a waste of time.

Discharge them to zero volts and chuck them.

Glen
Jan 16, 2010, 09:54 AM
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Quote:
Originally Posted by ggcrandall1
You could take them back to the LHS and explain the situation. But my bet is that he will give you some song and dance telling you that you are wrong. So it's probably a waste of time.

Discharge them to zero volts and chuck them.

Glen
ya he already told me I was wrong,that these battery's are good.I'd like to see him fly with these battery's..

can I discharge them to 0volts with the AC6 charger,any chance of swelling or any problems like that? they are not swollen at all now?
Jan 16, 2010, 02:55 PM
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Carlyle Harper's Avatar
Could the brushed motors in the cx heli be the culprit? They don't last forever and when on the brink of failure they start drawing more current making you think you have a dead battery.
Jan 16, 2010, 08:07 PM
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Quote:
Originally Posted by Carlyle Harper
Could the brushed motors in the cx heli be the culprit? They don't last forever and when on the brink of failure they start drawing more current making you think you have a dead battery.
I don't think so,I'll have to charge one of my new battery's to see if that's the case or not.Will let you know.Thankyou
Jan 17, 2010, 02:58 AM
Registered User
I was thinking something along the same lines. Sounds like the batteries are fine, but can't provide the current needed by the heli.

What does the red light mean on the Cx? On my Honeybee, it just means I'm at full throttle, not that the battery is low.

Flying for 5-6 minutes, landing, and finding your cells at 3.7-3.8 is expected. I'm not sure what you think the problem is.

In any case, I hope you get this sorted out. I bought an used battery for my heli, and I don't think it can provide the current needed. The heli just seems to "lag," like there is a delay in throttle response. Not as snappy.

Good luck!
Colin


Quote:
Originally Posted by Carlyle Harper
Could the brushed motors in the cx heli be the culprit? They don't last forever and when on the brink of failure they start drawing more current making you think you have a dead battery.
Jan 17, 2010, 09:43 AM
Registered User
Thread OP
Quote:
Originally Posted by ColinB
I was thinking something along the same lines. Sounds like the batteries are fine, but can't provide the current needed by the heli.

What does the red light mean on the Cx? On my Honeybee, it just means I'm at full throttle, not that the battery is low.

Flying for 5-6 minutes, landing, and finding your cells at 3.7-3.8 is expected. I'm not sure what you think the problem is.

In any case, I hope you get this sorted out. I bought an used battery for my heli, and I don't think it can provide the current needed. The heli just seems to "lag," like there is a delay in throttle response. Not as snappy.

Good luck!
Colin
I fully charged these 2 battery's with the AC6 Charger,and battery 1 was 4.2v-4.2v-8.40v with a charge capacity of 00698
the second battery fully charged was 4.20v-4.20v-8.40v with a charge capacity of 00785.? Do these battery's look good to you?

I Discharged them to 6.00v,and then recharged them to the readings above.What do you think? I don't see any swelling,etc.Yet they seem weak in the heli.
Jan 17, 2010, 09:57 AM
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ggcrandall1's Avatar
Quote:
Originally Posted by Lordgalla
I fully charged these 2 battery's with the AC6 Charger,and battery 1 was 4.2v-4.2v-8.40v with a charge capacity of 00698
the second battery fully charged was 4.20v-4.20v-8.40v with a charge capacity of 00785.? Do these battery's look good to you?

I Discharged them to 6.00v,and then recharged them to the readings above.What do you think? I don't see any swelling,etc.Yet they seem weak in the heli.
Do you have a watt meter? If so use it to determine how much current you are pulling at full throttle. There might be a clue there.

Glen
Jan 19, 2010, 11:30 PM
Registered User
Thread OP
Quote:
Originally Posted by ggcrandall1
Do you have a watt meter? If so use it to determine how much current you are pulling at full throttle. There might be a clue there.

Glen
I Discharged them both to 3v per cell 6v total,and re charged them a few times,cycled them like this a few times,and then balance charged them with my AC6 charger,to 4.2-4.2-8.4v,they seem fine now,flew them 4-5 times,and then discharged them in storage mode.I guess there ok now.From now on I use this charger,and put them in storage mode,when I'm done flying.Thankyou all for your help.I learned a lesson,not to keep these battery's fully charged,when stored for months.I am really happy with this AC6 charger for these battery's.


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