mookaloid
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| posted on 19/1/10 at 12:13 AM |
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daft phone battery question
I have just opened up a battery pack and it contains 5 aaa NiMH batteries connected in series to give 6V like this:
 
Description
if I want to increase the capacity of this pack can I just add some more batteries in parallel like this?
 
Ideally I think I would need 10 batteries and have them in series (in parallel pairs) but I only have room in the case for 8
is anything wrong with the second pic or am I being stupid?
Cheers
Mark
"That thing you're thinking - it wont be that."
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blakep82
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| posted on 19/1/10 at 12:26 AM |
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i think you'd get 7.5v out of it if you do it that way (6v from the original pack, and 1.5 from the new ones)
batteries in serial add up the voltage (but not capacity)
batteries in parallel add up the capacity (but not voltage)
again, i 'think'
been a good few years since i was at school now 
edit, whats the voltage of each aaa type battery? isn't it supposed to be 1.5v each? the 5 of them should give 7.5v then?
or are they actually 1.2v?
edit again, i've well confused myself not...
have a look at this
http://www.nyc-arecs.org/Connecting_Batteries_and_Chargers_in_Series_and_Parallel.pdf
[Edited on 19/1/10 by blakep82]
________________________
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splitrivet
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| posted on 19/1/10 at 12:36 AM |
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Just use a higher capacity battery, thats what we do.
Cheers,
Bob
I used to be a Werewolf but I'm alright nowwoooooooooooooo
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mookaloid
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| posted on 19/1/10 at 12:37 AM |
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The NiMH cells are 1.2V each 
Had a look at the link - but it doesn't really describe the situation.
there's probably something wrong with it - but while it looks wrong I don't know if it really is wrong.
"That thing you're thinking - it wont be that."
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mookaloid
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| posted on 19/1/10 at 12:38 AM |
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quote:
Originally posted by splitrivet
Just use a higher capacity battery, thats what we do.
Cheers,
Bob
I was going to do that too! 
"That thing you're thinking - it wont be that."
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blakep82
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| posted on 19/1/10 at 12:39 AM |
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you're right, the link doesn't explain it, but it does show its more complicated than it looks
best case, i think it'll give 7.2v
[Edited on 19/1/10 by blakep82]
________________________
IVA manual link http://www.businesslink.gov.uk/bdotg/action/detail?type=RESOURCES&itemId=1081997083
don't write OT on a new thread title, you're creating the topic, everything you write is very much ON topic!
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splitrivet
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| posted on 19/1/10 at 12:43 AM |
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If tou want the batteries to last longer between charges operation wise its Ma capacity you want not voltage.
Cheers,
Bob
I used to be a Werewolf but I'm alright nowwoooooooooooooo
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blakep82
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| posted on 19/1/10 at 12:49 AM |
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quote:
Originally posted by splitrivet
If tou want the batteries to last longer between charges operation wise its Ma capacity you want not voltage.
Cheers,
Bob
yep, but what i'm saying is by adding the batteries as shown above, he'll also end up increasing the voltage, which might cause a lot of
problems
________________________
IVA manual link http://www.businesslink.gov.uk/bdotg/action/detail?type=RESOURCES&itemId=1081997083
don't write OT on a new thread title, you're creating the topic, everything you write is very much ON topic!
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RickRick
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| posted on 19/1/10 at 07:44 AM |
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i think what that will do is keep the voltage the same, and have say 4 cells with 1000mah each(the 4 on the left of the sketch) and effectivly one
cell(4 cells on the right hand side together) with 4000mah.
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mookaloid
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| posted on 19/1/10 at 08:14 AM |
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quote:
Originally posted by RickRick
i think what that will do is keep the voltage the same, and have say 4 cells with 1000mah each(the 4 on the left of the sketch) and effectivly one
cell(4 cells on the right hand side together) with 4000mah.
That's what I was thinking
"That thing you're thinking - it wont be that."
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Grimsdale
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| posted on 19/1/10 at 08:16 AM |
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you want two arrangements like your first picture, then join the +ve together and then the two -ve leads together. That will give the correct voltage
and twice the capacity.
[Edited on 19/1/10 by Grimsdale]
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Mr Whippy
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| posted on 19/1/10 at 08:36 AM |
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quote:
Originally posted by Grimsdale
you want two arrangements like your first picture, then join the +ve together and then the two -ve leads together. That will give the correct voltage
and twice the capacity.
Yip, easiest of the lot. Just buy two normal packs solder the same coloured wires coming out the ends together, no need to solder onto the cells
Fame is when your old car is plastered all over the internet
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Liam
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| posted on 19/1/10 at 10:22 AM |
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First proposed arrangement wouldn't have raised the voltage as there are still 5 series cells from - to +. But it wouldn't increase
capacity either as you've only parallelised one element of the series array - sort of like this...
+
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-
The capacity would still be limited by when the non parallelised cells run out - i.e. the same time as before! As said above you need to parallelise
the whole series array with another one, like this...
+
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-
Or just buy higher capacity cells and stick with the original number.
Liam
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BenB
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| posted on 19/1/10 at 12:34 PM |
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The original suggestion is a bad idea.
You'll effectively have a number of cells in series but where one has a much bigger capacity than the others.
The "single" cells will drain down first and then get reverse charged by the cells in parralel.
As already said just get two packs and piggy back them in parallel.
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mookaloid
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| posted on 19/1/10 at 12:41 PM |
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quote:
Originally posted by BenB
The original suggestion is a bad idea.
You'll effectively have a number of cells in series but where one has a much bigger capacity than the others.
The "single" cells will drain down first and then get reverse charged by the cells in parralel.
As already said just get two packs and piggy back them in parallel.
Ah that makes sense, only problem is that would take 10 cells and I only have space for 8 - I'll just to use 5 high capacity ones then.
Thanks for the input guys
"That thing you're thinking - it wont be that."
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Ninehigh
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| posted on 19/1/10 at 07:32 PM |
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Hang on a minute how old's your phone to have aaa batteries in it? It'd probably be cheaper to get a new phone rather than do this messing
about...
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Liam
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| posted on 19/1/10 at 09:00 PM |
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quote:
Originally posted by Ninehigh
Hang on a minute how old's your phone to have aaa batteries in it? It'd probably be cheaper to get a new phone rather than do this messing
about...
Did wonder, but then assumed we must be talking a cordless house phone or something. Unless he's one of those people who use an ancient old
brick mobile for retro cool factor .
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mookaloid
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| posted on 19/1/10 at 10:38 PM |
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quote:
Originally posted by Liam
quote:
Originally posted by Ninehigh
Hang on a minute how old's your phone to have aaa batteries in it? It'd probably be cheaper to get a new phone rather than do this messing
about...
Did wonder, but then assumed we must be talking a cordless house phone or something. Unless he's one of those people who use an ancient old
brick mobile for retro cool factor .
Retro Brick  
and actually the AAA's are a substitute for the original rectangular ones but they just fit in the case
"That thing you're thinking - it wont be that."
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Ninehigh
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| posted on 19/1/10 at 11:52 PM |
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In which case could you just replace them with rechargeable ones and solder them up to a "rig"?
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mookaloid
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| posted on 20/1/10 at 12:27 PM |
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quote:
Originally posted by Ninehigh
In which case could you just replace them with rechargeable ones and solder them up to a "rig"?
yep
"That thing you're thinking - it wont be that."
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Liam
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| posted on 20/1/10 at 01:26 PM |
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What you really want is the phone wired to a utility belt full of big battery packs. That's true portability.
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Ninehigh
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| posted on 20/1/10 at 08:02 PM |
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quote:
Originally posted by Liam
What you really want is the phone wired to a utility belt full of big battery packs. That's true portability.
And it would be very retro!
We had aaa batteries in our cordless phone, and when they started lasting about 20 minutes we replaced them with normal ones, and it didn't
work...
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