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Dustbuster voltage change

Hi,

I am meant to be revising so have decided to repair a dustbuster
instead.
It is a 7.2v model and the transformer to charge it is knacked. Thus, I
was thinking of running it of a 9.6v AA nicad pack for which I have a
charger with a nice plug that would make life easy.

I have fitted the pack and the suction is great, motor doesnt seem to
get too hot and all would be well... but the batteries get absolutely
scortching!

How can I stop this happening? Do I need to put a resistor in to limit
current flow (but that would reduce suction I assume?) or can I run two
packs in parellel (current drawn will be the same - get 2x battery
life and the heat divided between the two packs).

Other option would be to use another battery type - an ideas? NiMH?
Lead-acid?

I know buying another one would be easier, but I'd rather experiment ;)

Cheers
squelch41
 
J

James Sweet

Jan 1, 1970
0
Hi,

I am meant to be revising so have decided to repair a dustbuster
instead.
It is a 7.2v model and the transformer to charge it is knacked. Thus, I
was thinking of running it of a 9.6v AA nicad pack for which I have a
charger with a nice plug that would make life easy.

I have fitted the pack and the suction is great, motor doesnt seem to
get too hot and all would be well... but the batteries get absolutely
scortching!

How can I stop this happening? Do I need to put a resistor in to limit
current flow (but that would reduce suction I assume?) or can I run two
packs in parellel (current drawn will be the same - get 2x battery
life and the heat divided between the two packs).


The batteries get hot because you're drawing a lot of power from them, what
you need is higher capacity (A-Hr) cells or put multiple battery packs in
parallel.
 
D

Dave Plowman (News)

Jan 1, 1970
0
The batteries get hot because you're drawing a lot of power from them,
what you need is higher capacity (A-Hr) cells or put multiple battery
packs in parallel.

Not a good idea to parallel Ni-Cads - etc. They tend to self discharge
even quicker. Use larger capacity cells in series.
 
I put 2 sets in parellel but it ended up drawing 10A as opposed to the
5A it was drawing from the single pack. The original batts are sub-c
cells - presumably their additional amp-hour rating would enable them
to run cool enough? Also, I suppose as it was a 7.2V, less current was
drawn?
 
J

James Sweet

Jan 1, 1970
0
I put 2 sets in parellel but it ended up drawing 10A as opposed to the
5A it was drawing from the single pack. The original batts are sub-c
cells - presumably their additional amp-hour rating would enable them
to run cool enough? Also, I suppose as it was a 7.2V, less current was
drawn?

Yes as you increase the voltage the motor will draw more current as well,
and in return you get a dramatic increase in horsepower.
 
Actually, having just looked, lead acid batteries seem to be in
multiples of 6v which isnt really suitable.

Would NiMH batteries be more suitable as they can provide more mAhs but
I'd imagine they'd get just as hot especially as they have a higher
internal resistance dont they?

Thanks
 
J

James Sweet

Jan 1, 1970
0
Actually, having just looked, lead acid batteries seem to be in
multiples of 6v which isnt really suitable.

Would NiMH batteries be more suitable as they can provide more mAhs but
I'd imagine they'd get just as hot especially as they have a higher
internal resistance dont they?


Yes, usually these things use NiCd's, I would think NiMH would be fine with
intermittant use though.
 
M

Mike

Jan 1, 1970
0
James Sweet said:
Yes as you increase the voltage the motor will draw more current as well,
and in return you get a dramatic increase in horsepower.

.... and a dramatic increase in smoke output (but only temporarily).
 
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