Charging NIMH using NICD settings?

[quasar54]

Hello everyone,

I have a CEF80 that can charge both NIMH and NICD - there is a switch to specify the type of battery being charged. My question is whether charging my eneloops in it with NICD settings would cause issues; e.g. is the end-of-charge termination signal for NIMH different from NICD?

I ask because in NIMH mode, the charger uses 0.85A for AAA batteries, which is higher than 1C (i.e. bad thing, my batteries are 800mAH)! If switched to NICD mode, it charges at 0.425A which is said to be a good rate.

Here's a picture of the specs FYI:

Thanks!

 

[Mr Happy]

In principle it would probably be OK. However I have a charger with very similar specifications and when I switch it to the NiCd setting there is a timer cut-out that operates after 1h 25m. This means the batteries do not end up fully charged.

In actual fact, I don't think there is any need to worry about the 0.85 A charge rate, especially when charging Eneloops. They will accept that charge rate fine.

 

[quasar54]

Hello Mr Happy,

Thanks for poking my thread! :poke:

:grin2:

In principle it would probably be OK. However I have a charger with very similar specifications and when I switch it to the NiCd setting there is a timer cut-out that operates after 1h 25m. This means the batteries do not end up fully charged.

Heh actually I've used it in the NICD mode too by accident before but didn't watch for the length of charge. Thanks for this great information - did you actually time it to check out how it charged the batteries?!? :wow: I'll try timing my own to see if there is a timer to interrupt the charge in NICD mode in that case...

In actual fact, I don't think there is any need to worry about the 0.85 A charge rate, especially when charging Eneloops. They will accept that charge rate fine.

I didn't know that - seeing that you're one of this forum's knowledgeable posters - could you give me some background on the why, just out of curiosity? I thought that in principle charging at >1C was always bad. Also, I also have some non-eneloop AAA batteries - I suppose this could kill them...


By the way, regarding the original question, so there's no difference in the end-of-charge termination signal between NICD/NIMH? According to this excellent page I found, there seems to be none:
http://www.angelfire.com/electronic/hayles/charge1.html

Cheers,

David

 

[Mr Happy]

Heh actually I've used it in the NICD mode too by accident before but didn't watch for the length of charge. Thanks for this great information - did you actually time it to check out how it charged the batteries?!? :wow: I'll try timing my own to see if there is a timer to interrupt the charge in NICD mode in that case...

Most good chargers ought to have a backup timer as a safety feature -- then if by any chance it misses the end of charge it will cut out before a meltdown happens.

I thought that in principle charging at >1C was always bad. Also, I also have some non-eneloop AAA batteries - I suppose this could kill them...

The guideline is to charge between 0.5C and 1C when using - ∆V termination, but this is only a guideline. If you go a little outside this range it does not mean anything bad will necessarily happen. NiMH cells are pretty robust in general.

By the way, regarding the original question, so there's no difference in the end-of-charge termination signal between NICD/NIMH? According to this excellent page I found, there seems to be none:
http://www.angelfire.com/electronic/hayles/charge1.html

There is a difference with older chargers. Dedicated NiCd chargers may expect a larger - ∆V signal and are likely to be harmful to NiMH cells. However, when a charger is modern enough to charge both NiMH and NiCd then most likely the NiCd mode will use the more sensitive NiMH settings and will be safe to use either way.