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Author Topic: Making two battery packs out of one  (Read 2221 times)

sinjon

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Making two battery packs out of one
« on: September 18, 2008, 02:22:59 pm »

I have a 9.6V battery, eight cells, two rows of four made up in one package.
Put it in front of the motor - the bows go down, one side of the motor - I get a list.
I would like to split it into two packages of four cells each (4.8V) so that I can have one each side of the motor.
Is this something I can do myself ? if so how,  please.

Colin
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Martin [Admin]

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andrewh

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Re: Making two battery packs out of one
« Reply #2 on: September 18, 2008, 03:23:41 pm »

sinjon

that's a yes, so long as you can solder reliably

I'm assuming that the pack is two sticks of cells, probably shrink-wrapped together with pos and neg coming off that same end.

cut off the heatshrink - it has to go.  BE VERY CAREFUL if the cells are bare metal not to lay it down on anything metallic - even a pin!
The sticks may be bonded together  - usually with hot melt glue.  Take no nonsense - separate them

There will be a link at the end opposite to the leads and plug - probably welded on-stainless strip.  Cut this in the middle using strong scissors/shears

Now is a good time to protect the two lines of cells using (preferably heat-shrink) but failing that cardboard tube (good enough for B&D) or wrap with tape

Now you are going to fit a replacement link where you cut
The ideal link is silicone  insulated wire but there are lots of options including knitted braid, or even household solid electrical cable 2.5 mm2 or larger (this will eventually break from vibration)

Clean the old (cut)  strap within an inch of its life - scrape, sand with wet and dry, degreease with meths, cellulose thinners or better still acetone.

Note: is is FAR better to solder to the strip metal connector than to solder to the battery end itself
Note 2;  all soldering to batteries (of any sort) needs to be short and sweet (to avoid overheating the contents of the battery)

so you need:
 a good flux (I use an acid plumbers flux, and WASH IT OFF) but there are nickel fluxes made for the job
A Hot Iron - I used 15W for years but 25W or bigger is normally advised
Good solder

Tin the wire ends of the joiner wire
Tin the nice clean joiner strip ends
Solder the joiner wire to the cut bits of the strip (quickly, hotly and neatly)
cool off - wash off flux if its an acid type, remove with meths if its a resin type

insulate the soldered ends  - heat shrink or Insulating tape

viola - a spaced pack!

Sorry if your grandmother already knows how to suck eggs ;D
Did I mention clean and quick?
andrew
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sinjon

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Re: Making two battery packs out of one
« Reply #3 on: September 18, 2008, 04:03:57 pm »

Thanks Martin,

And thanks Andrew,
I have spent a large part of the day trying to find a company to do this for me.
Followed your instructions, and there we are already to be soldered, and my iron is a 25W, it may be simple if you know what you are doing, but I hadn't a clue.
A little bonus on route, it is a very snug fit in a plastic Steradent tube and its the same length, never throw any thing away.

Thanks again
Colin
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andrewh

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Re: Making two battery packs out of one
« Reply #4 on: September 18, 2008, 04:37:12 pm »

Sinjon

Hope it keeps goiing well
25W is quite enough - keep the iron clean (scrape with knife blade, dip in flux and tin well)
It will solder well to the welded tabs  - they are much lighter and absorb less heat

I see you are in Bury StE
At the moment I am travelling a lot to Bedford and area
Would be happy to lend moral support - or do it with you  - are you in a hurry?
andrew
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sinjon

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Re: Making two battery packs out of one
« Reply #5 on: September 19, 2008, 09:28:17 am »

Thanks Andrew, It was just so easy - all soldered up and sitting in newly painted tubes.
A smear of mastic around the ends, and they are better than new.
If you are around BSE by all means pop in for a cup or a glass.

Regards
Colin
 
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Colin
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