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Topic: DIY Battery Packs (Read 1 time) previous topic - next topic

Vinterwoo

I have an instrument I've made that is meant to be deployed in a watertight housing. It's made for long-term deployments, so in the past I've purchased large alkaline battery packs.

The packs are rosettes of D-cells that have been soldered together, and then wrapped with shrink wrap. The packs are quite expensive, for what turns out to be just a bunch of economy brand batteries wrapped up in tape.

Using other commercially bought instruments I was instructed to only use these particular brand of battery packs, or risk voiding my warranty. When I asked what was so special about these packs, I was told there was a small piece of electronics included in the wiring that kept the batteries from exploding/ melting/ shorting/ ect....


Now that I'm making my own instrument, I'd like to also make my own battery packs. I like the idea of using conductive glue as opposed to soldering the wires, but otherwise the project would be about 24 D cells wired up in a series/ parallel configuration to supply an output voltage of 6 volts.

Can anyone advise me of any pitfalls of making my own battery pack? Or what this "special" piece of electronics included in the commercially available pack might be?

And if I have to do anything out of the ordinary considering this battery back will be used in a small air-tight space for a period of about 2 weeks?

mrsummitville

Did  you take the battery pack apart and find a "special" electronic circuit?
Alkaline D-Cells?
Why not rechargeable batteries?

DrAzzy

Probably just a ptc fuse or similar.
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Vinterwoo

Did  you take the battery pack apart and find a "special" electronic circuit?
Alkaline D-Cells?
Why not rechargeable batteries?
No, I did not find anything special. Thus the mystery grew deeper for me

mrsummitville

No, I did not find anything special. Thus the mystery grew deeper for me
A direct short of a 4S6P Pack of D-Cells could generate, up to, 60 AMPS !
Short Circuit protection is not optional.

Vinterwoo

#5
Dec 03, 2015, 03:45 am Last Edit: Dec 03, 2015, 03:51 am by Vinterwoo
A direct short of a 4S6P Pack of D-Cells could generate, up to, 60 AMPS !
Short Circuit protection is not optional.

Good to know.

Can you recommend an appropriate short circuit protector for this kind of application?

And does it matter where in the wiring scheme I place the circuit protector?


Thanks!


zoomkat

Quote
I like the idea of using conductive glue as opposed to soldering the wires, but otherwise the project would be about 24 D cells wired up in a series/ parallel configuration to supply an output voltage of 6 volts.
Well, forget the glue idea. How much current will the batteries need to supply? How long do the batteries need to last? Youtube has videos of making battery packs. Why not just buy 6v batteries? Academy Sports has 6v sealed lead acid replacement batteries and chargers for electric deer feeders.
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MarkT

Did  you take the battery pack apart and find a "special" electronic circuit?
Alkaline D-Cells?
Why not rechargeable batteries?
Fairly obviously because this is for long-term deployment - most rechargables have short
self-discharge times compared to the shelf life of primary cells.
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

mrsummitville

Fairly obviously because this is for long-term deployment - most rechargables have short
self-discharge times compared to the shelf life of primary cells.
Li
Fairly obviously because this is for long-term deployment - most rechargables have short
self-discharge times compared to the shelf life of primary cells.
OK, then I think, Non-Rechargeable Lithium Batteries
have one of the longest Shelf-Life ratings, 10 Years or more.
One Non-Rechargable Lithium 3.6V vs two Alkaline 1.5v ?
The OP needs to weigh the Cost vs Shelf Life vs Energy Density, etc ...

keeper63

Or what this "special" piece of electronics included in the commercially available pack might be?
No, I did not find anything special. Thus the mystery grew deeper for me
This is what is known (in the sales industry) as "blowing smoke up your ***"

That special invisible piece (plus voiding the warranty) is what gives them the leverage to charge you a boatload for something that costs them little to make (or purchase).

Though I am surprised that on a pack of that size, that there weren't any inline fusible links in the wiring, or maybe thermal resets, or even a standard fuse. At any rate - when you build your pack, put something like that in place. It's cheap insurance.
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Vinterwoo

LiOK, then I think, Non-Rechargeable Lithium Batteries
have one of the longest Shelf-Life ratings, 10 Years or more.
One Non-Rechargable Lithium 3.6V vs two Alkaline 1.5v ?
The OP needs to weigh the Cost vs Shelf Life vs Energy Density, etc ...

This battery pack will be powering two small peristaltic pumps, so I've been advised to stick with alkaline batteries as opposed to using lithium. I'm assuming lithiums do not hold up as well when driving motors, and do better with smaller loads?

mrsummitville

This battery pack will be powering two small peristaltic pumps, so I've been advised to stick with alkaline batteries as opposed to using lithium. I'm assuming lithiums do not hold up as well when driving motors, and do better with smaller loads?

High Drain?
In the Battery Showdown report they stated, "... Lithium cells really shine under high drain ..."
Battery Showdown
Click on each Graph to zoom in.

DrAzzy

#12
Dec 03, 2015, 10:58 pm Last Edit: Dec 03, 2015, 10:58 pm by DrAzzy
There are a large number of different types of lithium battery....

Lithium coin cells use lithium manganese dioxide chemistry (typically), ~3v, and are good for long life, but not heavy loads.

Lithium thionyl chloride batteries are known for their incredibly long shelf life, and they are normally used to provide small loads for very long periods of time. Their handling of large loads however is poor.

Lithium AA-replacement batteries use lithium iron sulfide chemistry, ~1.5v, and apparently good at heavy loads (according to the link above)

And that's just the non-rechargable kinds...
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