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Controlling battery heat?

memurphy

Feb 16, 2023
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I have an project where I am lighting up 3 6v 0.3 amp small lights from a double 9v battery pack wired in series. Although it works fine, the batteries are getting hot very quickly. I’m new at hobby electronics and have read several article in this simple wiring but no mentions of the controlling the heat. I thought the electricity flow would not cause this intense build up of heat and I’m not sure what to do to prevent it. Any pointers to something that will help me understand what’s happening with this simple circuit and preventing the battery heat build up would be appreciated.

Cheers,
Ed
 

Bluejets

Oct 5, 2014
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If you are referring to the 9v smoke alarm batteries, they are low current devices only.

2 x 9V in series is 18v.............how many of these 3.6v 300mA lights are you running and how are they connected?
 

Martaine2005

May 12, 2015
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3 x 6V lamps @ 300mA
Or 3.6V lamps @ 300mA?
What batteries are you using?
Either way, 900mA (almost an Amp) is a lot for a 9V battery and won’t last long at all. It’s rapidly being drained and will get hot.

Martin
 
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memurphy

Feb 16, 2023
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Thank you both for the replies and info. I am (obviously) missing the knowledge I sorely need. I attached a picture of the setup. There was a switch between the battery and lights but I removed it while figuring this out. I think I understand and in my simplistic terms, the 3 lights are pulling the power out of the batteries so fast it'll be dead quickly and it will heat up in the process. Anything you can share about balancing the setup so that the batteries last longer and stay a safe temperature would be appreciated (even if just a pointer to a tutorial.) I recognize that part of my problem is that I haven't been able to grasp the math that I've seen on the sites I've been looking at and hence missing something important.
 

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bertus

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Nov 8, 2019
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Hello,

You have put the lamps parallel.
That way 3 X the current is taken.
Put the lamps in series and try again.
What is the allowed lamp voltage?

Bertus
 

memurphy

Feb 16, 2023
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Hello,

You have put the lamps parallel.
That way 3 X the current is taken.
Put the lamps in series and try again.
What is the allowed lamp voltage?

Bertus
Thank you. I reconfigured the wiring and the batteries warm up a little but not nearly what it was. The lamp voltage is 3.8 (I originally said 6, but I had forgotten I replaced the 6v with 3.8v.)
 

memurphy

Feb 16, 2023
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PP3 batteries are no good for your application. If you must, use C or D cells. They will last much longer.

Martin
Thank you for the recommendation Martin. I am seeing that the batteries charge dropping quickly so great point that I will try out.
 

memurphy

Feb 16, 2023
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Replace the incandescent bulbs with high efficiency LEDs. LEDs will require series resistors to limit current.
Thanks Alec_t. I had not even thought to look for LED E10s to try this out. This set up is actually meant to mimic the wire up in a friend's advent pyramid (example pic attached if you're mildy interested in what those are) which were incandescent so that what i focused on. But you're right, highly efficient LEDs would be better and most likely last longer. I'll try them out!
 

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daviio

Mar 2, 2023
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I have an project where I am lighting up 3 6v 0.3 amp small lights from a double 9v battery pack wired in series. Although it works fine, the batteries are getting hot very quickly. I’m new at hobby electronics and have read several article in this simple wiring but no mentions of the controlling the heat. I thought the electricity flow would not cause this intense build up of heat and I’m not sure what to do to prevent it. Any pointers to something that will help me understand what’s happening with this simple circuit and preventing the battery heat build up would be appreciated.

Cheers,
Ed
if you are really worried about the battery heat control then I will tell you about a hack. In this way, you can easily control your battery heat. this is a Free BeagleBone Guide for Beginners and advanced people.
 

Bluejets

Oct 5, 2014
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if you are really worried about the battery heat control then I will tell you about a hack. In this way, you can easily control your battery heat. this is a Free BeagleBone Guide for Beginners and advanced people.
And the list goes on and on....... o_Oo_Oo_O
 

Harald Kapp

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@Bluejets : just in case you wonder: I deleted the posts by daviio as totally unrelated to the topic and not giving new information.
 

memurphy

Feb 16, 2023
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One last follow up with the outcome. I switched to a 6 D Cell battery pack and that worked out OK. It did last for a good while but not really long enough (in my opinion to supply the advent pyramid which I would expect to be lit for long stretches during Christmas. So in the end ((and because I learned a lot here) I got a power adapter supply with a barrel connector that had the same output, soldered a female connector onto the pyramid wiring and it's working perfectly. Thanks again to everyone for the assist!
 
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