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Thread: Correct charge rate for Imedion 2400 NIMH

  1. #1

    Default Correct charge rate for Imedion 2400 NIMH

    Ok I know I have asked before on the correct charge rate for my Imedion 2400mah cells. I have a BC-900 and BC-700 charger. I really think my BC-900 is not working correctly when charging cells at 1000mah. For example I was charging at 1000mah in cells 2,3, & 4. The cells got a little warm and voltage was at 1.49 and capacity was reading 2100mah and a little over 2 hours time. Now what concerns me is the temperature of the cells on the charger, I manually pulled them and the charger did not show full. So based on that I don't feel like stepping up the charge rate to say 1500mah would be any better? Also for those that have these batts and eneloop batts in terms of life cycle what is the difference in charging say at 200mah vs say 1500mah? My main concern is the wonder if the charger is overcharging my batts? I though 1.45 meant that the cell was full, anything over this is possible overcharge? I am correct on this? Can anyone shed some light on this please.

    Thanks,
    Joey

  2. #2

    Default Re: Correct charge rate for Imedion 2400 NIMH

    Quote Originally Posted by Flatshovel View Post
    Ok I know I have asked before on the correct charge rate for my Imedion 2400mah cells. I have a BC-900 and BC-700 charger. I really think my BC-900 is not working correctly when charging cells at 1000mah. For example I was charging at 1000mah in cells 2,3, & 4. The cells got a little warm and voltage was at 1.49 and capacity was reading 2100mah and a little over 2 hours time. Now what concerns me is the temperature of the cells on the charger, I manually pulled them and the charger did not show full. So based on that I don't feel like stepping up the charge rate to say 1500mah would be any better? Also for those that have these batts and eneloop batts in terms of life cycle what is the difference in charging say at 200mah vs say 1500mah? My main concern is the wonder if the charger is overcharging my batts? I though 1.45 meant that the cell was full, anything over this is possible overcharge? I am correct on this? Can anyone shed some light on this please.

    Thanks,
    Joey
    Powerex, the maker of that Imedions, recommend a charging rate of .5C and discharging rate of .25C for your Imedion 2400mah AAs.

    I have tried those rates in my C9000, and in the charging mode, they do get warm, even on the hot side, on the last few minutes of

    charging process. No temperature concerns in the discharge mode.

    I also have an iCharger 106B+ hobby charger. I have tried those same charging and discharging rates as suggested by Powerex,

    on my Imedion 2400s. They never get warm, even on my 18650s.. I would say that most of the heat on the cell comes from

    the heat generated by the charger and on the confines of the cradle itself.

    It does go up to 1.48V (and the warming up in the C9000) just before the "done" goes up.

  3. #3
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    Default Re: Correct charge rate for Imedion 2400 NIMH

    Quote Originally Posted by Flatshovel View Post
    Ok I know I have asked before on the correct charge rate for my Imedion 2400mah cells. I have a BC-900 and BC-700 charger. I really think my BC-900 is not working correctly when charging cells at 1000mah. For example I was charging at 1000mah in cells 2,3, & 4. The cells got a little warm and voltage was at 1.49 and capacity was reading 2100mah and a little over 2 hours time. Now what concerns me is the temperature of the cells on the charger, I manually pulled them and the charger did not show full. So based on that I don't feel like stepping up the charge rate to say 1500mah would be any better? Also for those that have these batts and eneloop batts in terms of life cycle what is the difference in charging say at 200mah vs say 1500mah? My main concern is the wonder if the charger is overcharging my batts? I though 1.45 meant that the cell was full, anything over this is possible overcharge? I am correct on this? Can anyone shed some light on this please.

    Thanks,
    Joey
    You can't measure the mAh capacity on a charge cycle as the charger has to put more in than the batteries actual capacity ... The only way to get an accurate battery capacity is to do a discharge test ... So , ideally you should charge to full , then discharge , then recharge ... The discharge capacity is the correct one.

    On my C9000 , I charged to full and then removed and replaced the cells a couple of times and got a reading of 8mAh then 1mAh ... I only did this the once , just to see if the charger would cut off before the batteries were overcharged ... I'm happy that the C9000 is working well.
    .

  4. #4
    Flashaholic* ChrisGarrett's Avatar
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    Default Re: Correct charge rate for Imedion 2400 NIMH

    I have 8 Imedion 2400s and I figure that they're actually 2250 mAh cells, so on my BC-700, I'll charge them at 700mA, for ~.3c and on my C-9000 I'll go a bit higher...maybe .5c.

    Chris
    Convoy: S2, M1, M2, Fenix: P1D, PD32, HL30, ET: D25C Ti, SF: 6P, ZL: SC-600, Klarus: P2A, Jetbeam: BA-20, Icon: Rogue 1, L3: L10, Xeno: E03, ShiningBeam: I-Mini, Olight: i3s, SWM: D40A, M11R, V11R, Maglite: 6Ds, MMs, Solitaires, LaCrosse BC-700, Maha C-9000, XTAR VP2, MP1S, WP2 II, NiteCore i4, v2.

  5. #5

    Default Re: Correct charge rate for Imedion 2400 NIMH

    Ok I have another question, what is the difference of the life span of the battery's charging at 0.5c vs 0.1c? Also I think the heat I am feeling on the battery's when charging is coming from the charger due to the limited space between the battery's. I was thinking about making a adapter to fit in the slots of the charger and attach this to a homemade battery holder to charge the battery's to see if the heat is coming from the charger or battery's. Does this sound like it will work and is a good idea?

    Thanks,
    Joey

  6. #6

    Default Re: Correct charge rate for Imedion 2400 NIMH

    From Maha/Powerex's (manufacturer of Imedions) C9000 manual,

    "Charging at a rate below 0.33C and above 1.0C is not recommended.

    Charging too slow may prevent the charger from terminating correctly.
    Charging too fast may damage the battery.

    Typically speaking, slower charging rate will yield better battery
    performance but requires longer time. Faster charging rate may not
    charge as fully and battery temperature can be higher."

  7. #7
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    Default Re: Correct charge rate for Imedion 2400 NIMH

    Quote Originally Posted by Flatshovel View Post
    I was thinking about making a adapter to fit in the slots of the charger and attach this to a homemade battery holder to charge the battery's to see if the heat is coming from the charger or battery's. Does this sound like it will work and is a good idea?
    It might be okay for a test if you keep an eye on it but I wouldn't do it on a regular basis ... the batteries will not be in contact with the temperature sensors, defeating the overheat detection.

    I have Imedion 2400s and charge them on a Maha C9000 at the default 1000 mA; they get warm but not hot.

  8. #8
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    Default Re: Correct charge rate for Imedion 2400 NIMH

    Quote Originally Posted by DreadHunter View Post
    From Maha/Powerex's (manufacturer of Imedions) C9000 manual,

    "Charging at a rate below 0.33C and above 1.0C is not recommended.

    Charging too slow may prevent the charger from terminating correctly.
    Charging too fast may damage the battery.

    Typically speaking, slower charging rate will yield better battery
    performance but requires longer time. Faster charging rate may not
    charge as fully and battery temperature can be higher."
    The C9000 has the best of both methods ... Charges at 1000mA using CC/CV then switches to 100mA for two hours to get the last few percent of charge in ... Then it drops to 10mA (forever) till you take the batteries out.

    With Eneloop AA's , I just put the batteries in and after a few seconds the C9000 starts up at 1000mA (actually between 991mA and 998mA) and when the "DONE" comes up I just leave for at least two hours ... It is nice that you get a "time taken" display for the CC/CV part of the charge , and a voltage readout ... When the C9000 drops to the 10mA , you can see the cell voltage drop slightly by about one millivolt.

    Charging has never been easier for AA's.

    AAA's are different in that I drop the charge current to 400mA and when "DONE" is displayed , I only leave them an hour before taking them off.
    .

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