Battery charging problem / question

I've done some searching on this forum, and couldn't quite find my exact question answered, so if this has already been covered 3,000 times, please forqive!! I have 6 of the Venom 8.4v 4200 and or the 5000 batteries. The 4200 (2) had the same problem as just 1 of the 5000's is experiencing and that is from the discharged (6.20v-6.84v) my Onyx 240 will shut down @ 7.24 -7.28v
(394 ma to 201 ma) and take only 15.46 minutes to 4.01 minutes to charge. This has only happened on a total of 3 out of 6 batteries. The other 3 batteries charge up fully and work just fine. Venom to their credit has taken the 4200's back and replaced them, however without explanation. But what is going on with these? The questionable units do not "heat up" while charging (less than 80 deg). Any ideas people?
Gary

[QUOTE=gmcrump]I've done some searching on this forum, and couldn't quite find my exact question answered, so if this has already been covered 3,000 times, please forqive!! I have 6 of the Venom 8.4v 4200 and or the 5000 batteries. The 4200 (2) had the same problem as just 1 of the 5000's is experiencing and that is from the discharged (6.20v-6.84v) my Onyx 240 will shut down @ 7.24 -7.28v
(394 ma to 201 ma) and take only 15.46 minutes to 4.01 minutes to charge. This has only happened on a total of 3 out of 6 batteries. The other 3 batteries charge up fully and work just fine. Venom to their credit has taken the 4200's back and replaced them, however without explanation. But what is going on with these? The questionable units do not "heat up" while charging (less than 80 deg). Any ideas people?
Gary[/QUOTE]

could be a bad cell on one of does batterys, also what amp are you charging them on I also have the 240 and charge my venoms a 3 amps I have the 8.4 5000mah and havent had any problems with them are you having a problem with the 4200 or the 5000mah. now what do you mean by taken only 15.46 to 4.01 also your saying that the batteries only take 394 to 201 ma is that amount of time the batteries charge and the alarm goes off explain it better.

I gues you're discharging your batteries too deep.

I thought that explanation was simple enough to understand. It's not how I would have said it, but it was easy to work out.

I would say you have at least one bad cell in the packs. I have found the same sort of thing with my charger and my nimh from time to time. Generally when it happens it is because the cells have been sitting for a while (about 2 weeks) without use. When it happens I just restart the charge and hope for the best.

Or, if I have just used the batteries and it does that, then I usually have a bad cell. Are your batteries in a side by side configuration? Can you check the voltage of each cell individually with a multimeter? To avoid damaging a single cell in future, don't discharge them so much.

Also, another question, does the 240 onyx allow you to change the mv/cell peak detection? If so, or if not, what is the setting on? If you can change it, up the setting. I usually use 7 or 8 mv/cell and most of the time get a good charge on them.

[QUOTE=timie1]I thought that explanation was simple enough to understand. It's not how I would have said it, but it was easy to work out.

I would say you have at least one bad cell in the packs. I have found the same sort of thing with my charger and my nimh from time to time. Generally when it happens it is because the cells have been sitting for a while (about 2 weeks) without use. When it happens I just restart the charge and hope for the best.

Or, if I have just used the batteries and it does that, then I usually have a bad cell. Are your batteries in a side by side configuration? Can you check the voltage of each cell individually with a multimeter? To avoid damaging a single cell in future, don't discharge them so much.

Also, another question, does the 240 onyx allow you to change the mv/cell peak detection? If so, or if not, what is the setting on? If you can change it, up the setting. I usually use 7 or 8 mv/cell and most of the time get a good charge on them.[/QUOTE]

this is what I dont understand....and take only 15.46 minutes to 4.01 minutes to charge?

First off the reference to the 15.46 minutes is time to charge after they have been run. The 4.01 minutes was after I tried to restart the charge process. The MA is what the charger says the battery took during the period of the charge. In other words the charger is thinking the battery has "peaked" (I assume) and shuts down before it should. The battery voltage never seems to rise above 7.28 after being re-started. The Onyx 240 cannot be adjusted for voltage, only amperage. I use the recommended 3AMP setting.1.5, 3.0, and 5.0 Amps are available. I should mention the problems have been from (new) out of the box. Thanks you guys for your replies.
Gary

I stumbled across a sight that specialized in problems for RC planes, and e mailed a certain Red Scoffield. He replied that the problem is common with new batteries that have sat a long time as Timie1 had indicated. He suggested charging at C/10 for 14 hours, whatever that means. "they need a formulation cycle", he claims. So I will discharge it and charge it on my lowest setting and give it a try. Thanks to all for the suggestions.
Gary

[QUOTE=gmcrump]I stumbled across a sight that specialized in problems for RC planes, and e mailed a certain Red Scoffield. He replied that the problem is common with new batteries that have sat a long time as Timie1 had indicated. He suggested charging at C/10 for 14 hours, whatever that means. "they need a formulation cycle", he claims. So I will discharge it and charge it on my lowest setting and give it a try. Thanks to all for the suggestions.
Gary[/QUOTE]


yes give that a try and let us know good luck.

C/10 means C divided by 10.

For 5000mAh batteries, C is 5Ah, so...5Ah / 10 = 0.5Ah. This means to charge your batteries at 0.5Ah for 14 hours.

I received a reply to my question from Red, and he said the same thing! He and all of you, have been most helpful. Thanks again.