Battery Charger for 3 rechargable AA in series.

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idriswilliams

Member
Hi,

Does any-one know of a suitable charger that will do three rechargable AAs in series? For our Scout Lamps we are using old Oldham headsets (LED inserts)  with rechargable AA in various battery boxes (mostly petzl zooms) It would make life a lot easier when charging to be able to do this through the headsets (using the old lead acid charging rack fittings). It would also enable us to use better battery boxes more water resistant and not fiddleable with prying young fingers!

Idris Williams
 
bograt

bograt

Well-known member
So, effectively you are looking for a 4volt charger that will fit onto a multi-clip headlamp board?
 
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idriswilliams

Member
bograt said:
So, effectively you are looking for a 4volt charger that will fit onto a multi-clip headlamp board?
Click to expand...

Thanks for your reply. Yes but there is no reason why it could not be wired directly into an individual Oldhams head connector. Of course if it would do several of these that would be a bnus.

Idris Williams 
 
I

idriswilliams

Member
Wayland Smith said:
Something like an IMAX B6AC will do what you want (probably.)

http://www.amazon.co.uk/s/ref=nb_sb_ss_i_2_9?url=search-alias%3Daps&field-keywords=imax+b6ac+charger&sprefix=imax+b6ac%2Caps%2C352
Other suppliers are available.
Click to expand...

Hi Thaks for your reply, the batteries we are using Energizer from tesco (or other supermarkets) are labeled Nickle metal hydride. these are presumably the NiH that your links sugests with charge 1-15 of. would that have to be say 5 sets of three batteries. Each 3 being wired in series but the 5 banks of 3 wired in parallel? Or have I got the wrong end of the stick?

Idris Williams 
 
bograt

bograt

Well-known member
I use a standard battery charger set at 6v with an in-line variable resistor to lower the voltage, I suspect the 5v line of a reclaimed computer PSU would work just as well.
 
royfellows

royfellows

Well-known member
Idris, am I correct in thinking that what you wish to construct is a multi bay rack charger?

If so each bay would need to have its own individual PCB with whole being fed by an appropriate transformer/rectifier set up preferably protected by RCD and the DC/Low voltage side covered by a line fuse.

 
Wayland Smith

Wayland Smith

Active member
The IMAX charger will (in theory) detect the No of cells in series, adjust charging voltage and cut off at full charge.
HOWEVER

If the cells are not very close, or one is faulty they you can get charging problems.
As Roy says the ideal way to do this is an individual controlled circuit to each cell.

Also (to be honest) the IMAX charger is widely copied by our Chinese friends.
Mine works fine, but best to be safe and never leave it un-attended, especially with Lithium cells.
 
I

idriswilliams

Member
royfellows said:
Idris, am I correct in thinking that what you wish to construct is a multi bay rack charger?

If so each bay would need to have its own individual PCB with whole being fed by an appropriate transformer/rectifier set up preferably protected by RCD and the DC/Low voltage side covered by a line fuse.
Click to expand...

Hi,
Thanks for your reply. My initial thoughts were of a single charger of the built into a 3 pin plug type which had the right output voltage for 3 AA rechargables which I could cnnect to an Oldhams plug in & twist head connector. However, if it were able to drive a bank of these that would be a bonus.
I am afraid my knowledge of things electrical only goes as far as a first year Civil Engineering course with a  series of lectures in which it was mentioned that they thought these new-fangled transistors might one day amount to something. PCB & RCD are jargon words that mean nothing to me! RCB I understand as I use one for power tools outside. Can you explain please?

Idris Williams
 
P

peterk

Member
If you don't need a fast charge then maybe someone can confirm that NiMH battery packs (or is it a single cell?)  can be trickle charged with a current equal or less than the capacity/10 for  days with no effect on the capacity or life of the cells e.g. 2000mAh capacity would charge from flat with 200mA constant current in 15 hrs.  Also constant current charger circuit would need few components??
 
royfellows

royfellows

Well-known member
peterk said:
If you don't need a fast charge then maybe someone can confirm that NiMH battery packs (or is it a single cell?)  can be trickle charged with a current equal or less than the capacity/10 for  days with no effect on the capacity or life of the cells e.g. 2000mAh capacity would charge from flat with 200mA constant current in 15 hrs.  Also constant current charger circuit would need few components??
Click to expand...

Check this out

https://en.wikipedia.org/wiki/Nickel%E2%80%93metal_hydride_battery

There will be more stuff on the web on other sites.
For what its worth I think that NiMH is poor choice compared with LiIon.
 
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