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Old Feb 23, 2012, 05:37 AM
bobepine's Avatar
Joined Jun 2011
7,660 Posts
Help!
Need Help Charging NiMH batteries with B6AC Charger

Hello,

I use a B6AC balanced charger to recharge the batteries for my Devo 8 transmitter. The Devo 8 uses 4 batteries. They are 1.2 volts each for a total of 4.8 volts which is the recommended voltage for the Devo 8.

The batteries are essentially just like AA batteries but they are NiMH rechargeable batteries. They are 2000mAh each (1.2v).

I'm not sure how to get the optimum charge with my B6AC charger. I also find the batteries charge faster than they should be, although I'm not sure. 1 or 2 hours is usually enough to charge them. The B6AC stops automatically when the batteries are full charge. By then the batteries are VERY warm, like borderline HOT.

And now here's the problem. When I plug the batteries to the Devo 8, the battery meter on the transmitter shows that the batteries are not fully charged. I'm missing one bar to have a full gauge.

The batteries are new, by the way. I just bought them. I use the stock plug on the 4 battery tray and hook it up to the charger and charge the 4 batteries at once that way.

Any help you can provide to help me better understand why I can't seem to fully charge these batteries would be very appreciated.

Thank you!
Chris
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Old Feb 23, 2012, 06:22 AM
Air, Ground & Water
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Canada, ON, Rockland
Joined Aug 2008
23,795 Posts
If you can't use the radio's charging method for 10-12 hours then OK to use your main battery charger.
Just remember that the SLOWER you charge your TX battery the better it is.

I charge my 2000mah AA cells at 200mah or 400mah.

Don't know your radio but its normal for some to not show full bar when using rechargeable batteries if that radio can take regular non-rechargeable AA cells.

Numbers are much more important then a Bar graph.

5.5-5.6 volt fully charge is good.

If you are charging your cells and they are getting warm border line hot then you are over charging them and thats NOT GOOD.
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Old Feb 23, 2012, 09:15 AM
PGR
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United States, CA, Costa Mesa
Joined Jun 2004
7,908 Posts
Some basic rules for charging NiMH packs with a delta-V charging algorithm (peak detect charger) are:
  • Don't use a NiCd charge cycle for NiMH packs!
  • Don't charge at less than 0.3C. If you charge below that rate the charger may not reliably detect the delta peak.
  • Don't charge at more than 0.5C unless you don't care how long your battery packs last.
  • Set the charger for a 4mV or 5mV delta (the peak detect or delta peak setting). 4mV is best but ypu can increase that to 5mV if you have false peaks and the charger shuts down prematurely.
I have 2000mAh Eneloop packs in my transmitters and I charge them "in transmitter" at a 0.8A rate with a 4mV per cell delta setting. The packs will be warm at the end of the charge cycle but not hot.

Pete
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Old Feb 23, 2012, 11:47 PM
bobepine's Avatar
Joined Jun 2011
7,660 Posts
Thanks very much guys. This is exactly the information I needed. I looked high and low online but couldn't find any information specific to my "problem." I will try charging them as per the above pointers and I'll let you know if it works for me.

Thanks again!

Chris
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Old Mar 02, 2012, 08:42 AM
bobepine's Avatar
Joined Jun 2011
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Just a brief update, I followed the info you guys posted and I now get full bars on the transmitter after I finish charging and the batteries are not nearly as hot. Just warm. Problem solved!

Thank you, gentlemen.

Chris
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Old Mar 18, 2012, 04:10 PM
Registered User
Joined Sep 2011
45 Posts
Quote:
Originally Posted by PGR View Post
Some basic rules for charging NiMH packs with a delta-V charging algorithm (peak detect charger) are:
  • Don't use a NiCd charge cycle for NiMH packs!
  • Don't charge at less than 0.3C. If you charge below that rate the charger may not reliably detect the delta peak.
  • Don't charge at more than 0.5C unless you don't care how long your battery packs last.
  • Set the charger for a 4mV or 5mV delta (the peak detect or delta peak setting). 4mV is best but ypu can increase that to 5mV if you have false peaks and the charger shuts down prematurely.
I have 2000mAh Eneloop packs in my transmitters and I charge them "in transmitter" at a 0.8A rate with a 4mV per cell delta setting. The packs will be warm at the end of the charge cycle but not hot.

Pete
I have multiple TX charging connectors, with somewhat different dimensions. They work on Futaba, but not on Walkera. It seems the inner diameter is too large and there is no contact with the pin (male) in the transmitter. Any suggestions on where to find one that fits? It looks like the plug that goes into Lipo balance charger (from the power supply) that came with the helicopter, might fit, but I'd prefer to be able to charge the transmitter and batteries at the same time.

Thanks,
Sven

Update, I found a plug, so disregard. Sven
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Last edited by helisb; Mar 19, 2012 at 10:37 PM.
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Old Mar 19, 2012, 10:45 PM
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Joined Sep 2011
45 Posts
Built in charger?

Quote:
Originally Posted by freechip View Post
If you can't use the radio's charging method for 10-12 hours then OK to use your main battery charger.
Just remember that the SLOWER you charge your TX battery the better it is.

I charge my 2000mah AA cells at 200mah or 400mah.

Don't know your radio but its normal for some to not show full bar when using rechargeable batteries if that radio can take regular non-rechargeable AA cells.

Numbers are much more important then a Bar graph.

5.5-5.6 volt fully charge is good.

If you are charging your cells and they are getting warm border line hot then you are over charging them and thats NOT GOOD.
Does anyone know if there is built in charging circuitry in the Devo 8, so NiMh batteries can be charged through the CHG connector with a 8-12 V, 200 mA power source (per the label next to the connector) or should a NiMh charger be used?

Thanks,
Sven
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Old Jun 16, 2012, 04:13 AM
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Joined Jun 2012
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I do not see how you will get a full battery meter using rechargeable with the Devo 8.

I have the Devo 8s and with rechargeable don't get a full battery meter on the transmitter.
reason being using 4 1.5 batteries your getting 6 volts, so a full meter will show.

With rechargeable batteries, your almost a whole volt down, so 4.8 volts-5.2. My Energizer rechargeable are charging to 1.39 volts, so no way will I get a full battery reading on my transmitter.

makes sense your not going to get full bars and no need to worry, as you do get the choice to use either, but with alkaline or Lithium 1.5 batteries your going to get full bars.

I would think if your getting full bar readings on rechargeable batteries on the Devo, your battery meter on the transmitter maybe not accurate.

Just my thoughts.
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Old Jun 16, 2012, 04:19 AM
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Quote:
Originally Posted by helisb View Post
Does anyone know if there is built in charging circuitry in the Devo 8, so NiMh batteries can be charged through the CHG connector with a 8-12 V, 200 mA power source (per the label next to the connector) or should a NiMh charger be used?

Thanks,
Sven
I am using a 12 volt 500 mAh power supply, which belongs to my Jump Starter, it charges up the Jump Starter, and works well with my Devo 8s, just plug it into the CHG plug and works well, saves having to pull the batteries out to charge it up.
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