Battery help please

[working_it _out]

Hi i have a 5D Mag and was wondering if i could put 4 stacks of AA 6 high ( 24 in total ) to give a voltage of 7.2v with spacers to hold all the batterys and stop them turning and copper plates at the top and botom to complete the circuit ,, dont know if i am on the right track or not any help would be nice , and could i charge it in the Mag ( save taking them out ) with a plug in the end cap it is an older mag and they fit in the tube.

Thanks not sure if this is in the right spot or not but any help greatly appreciated

working it out

 

[DM51]

Welcome to CPF, working_it_out :)

We have a Batteries sub-forum where your question would fit best, so I'll move it there now.

 

[working_it _out]

thankyou !

 

[45/70]

Hi work. Your idea is reasonable. The dimensions are correct etc, but one thing you may have a problem with is, although the inside of a M@g battery tube is anodized, it's still possible to have a short circuit with your copper spacers. I've had problems with this. The anodizing inside the tube is very thin. I doubt there's room, but if you could roll up some paper, or thin plastic to line the tube with, that may take care of the problem.

Also, there would be 48 contact areas involved, just with the cells. That could very likely be a problem, unless you have a means to ensure that all contacts are solid. With 24 cells, that may turn out to be a real nightmare.

As for charging them in the light, that really wouldn't be possible as NiMH/NiCd cells cannot be charged in parallel (ie. the groups of 4). Speaking of which, I would be very careful not to over discharge the "pack", so as to avoid reverse charging of weaker cells. If this happened with this setup, you'd initially be reverse charging 4 at a time. :eek:

So anyway, in theory, it should work. If you try this, let us know if it works out. :)

Dave

 

[arek98]

Hello and welcome

24 cells in one pack that’s a LOT of them.
You will need to align them well and then secure. Look at FM battery holders . They are too short for you and configured for 4AA per 1D length but it will give you an idea how really good battery holder looks (including charging port).

What are you trying to achieve? Do you need 7.2V specifically or you just trying to put as much capacity in you light as possible?

If you need 7.2V but can sacrifice Ah then you could use 6 C cells and sleeve (cheap one may be made using 1” schedule 40 PVC pipe).

If you can use 6V then get 5 D cells, just not the ones they sell in stores with capacity of AA. Look here.

If you be buying NiMh cells (any size) look at LSD cells (Low Self Discharge). They have slightly smaller capacity but keep charge much longer than regular ones if light is not used. AA size, Eneloops are best. C & D size – Accuevolution on linked above pages are good.

 

[working_it _out]

Thanks very much for your replys

the copper washers would only be on the top and bottom the AA cells would be end to end, think 4 columns joined at the top and bottom and i am just trying to put as much capacity in the light as possible and use the NiMh AAs that i all ready have, maybe i am better off just getting a new charger and some NiMh D cells, what would be better do you think but i will drop 1.2v.
and it looks like it will be much better to take them all out to charge.

thanks again for your help

SLOWLY

working it out

 

[mdocod]

Fitting 4 AA cells abreast in a stock mag is usually pretty tricky. Some brands and capacities fit, many don't. It's best to have the body bored out, and best to use some sort of battery adapter to get all of the cells in alignment. The problem with this, is that a battery adapter adds length, so space must be sacrificed for the parts involved.

Here's an example of some 4-abreast adapters for mags, these are designed for use in mag bodies that have been at least quad-bored:

Eric

 

[working_it _out]

Ok thanks guys i may have to think this over a bit more