Where Can I Find the Right Specs for a Battery Pack for Laser Tag Vests?

AI Thread Summary
The discussion focuses on building a custom battery pack for laser tag vests, highlighting the specifications of using 6 NiMh 3800mAh 1.2V batteries wired in series. A key component mentioned is a small resistor, which is likely a thermistor used to monitor battery temperature during charging. Participants emphasize the importance of safe charging practices, recommending a trickle charge method over quick charging to avoid risks. There is also a suggestion to check electronic supply stores for compatible thermistors and battery packs. Overall, the conversation underscores the need for careful consideration of battery specifications and safety when creating custom packs.
ztekneq
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I work at a local entertainment venue and wanted to experiment by building my own pack for current laser tag vests. The manuf charge us a FORTUNE!

So the specs are 6 NiMh 3800mah 1.2V 4/3 Panasonic 370a's wired in a block series

there is a small resistor (i think) on the lead but I cannot make out what its specs are..this is where i need some help. What do you guys think it might be?
 
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It's unlikely to be a resistor that would just waste heat, it's more likely to be a fuse which is a good idea if you are strapping the batteries to your body.
 
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k

quite possible... looked like it might have had bands like a resistor though...

its not on the lead to the connector so to say.. there is a wire (small) soldered to the first positive cap in the series drops down next to the battery and is then connected to the middle lead of the three lead series

http://www.tekneq-design.com/battery.jpg
 

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In that case it's probably a thermistor to monitor temperature of the battery while charging.
A common way to charge NiCd/NiMH is to turn up the charging current until it starts to get hot and then back off a little.
If you aren't worrried about charging speed it is better/safer to just charge for 10-12 hours at 10% of the battery capacity.
 
is there any specifications that one would need to replace such a part?
 
You would need to know it's cold resistance which you can measure with a meter, you could estimate the temperature coefficent by putting in warm water and then measuring it's resistance again.
But like I said, it's easier/safer to just trickle charge the batteries, quick charging home made battery packs is a bit dangerous to the battery and you!
 
It is exactly a thermistor! I am actually duplicating an existing pack. What would be the downfalls of hooking in the wrong thermistor? I have an existing intelligent charger that is being used as well. Is there anyway to estimate what thermistor should be used?
 
You might want to try some electonic supply houses.
For instance, Radio Shack sell a 6 cell nicad pack for RC cars with charger for about $20.
They also sell connector adaptors.
 

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