would running multiple batteries in parallel reduce overheating / damage of each battery

Question

I have a cooler rated at 12V, 160mA, and a set of two 9V alkaline batteries rated at 100mA.

Would connecting it to the 2 batteries in parallel present any risks?

It's been a while since my studies so... correct me if any off the following assumptions is wrong:

The fact that the batteries are only 9V should only impact the resulting speed of the cooler, no other damage anywhere.
Connecting the cooler to a single battery will most likely make it overheat / burst into flames.
Connecting the cooler to the 2 batteries added in parallel should make it spin slower, but it is safe (no damage on any components).
Adding 2 1.5V batteries in series to each of the 9V batteries, then adding the resulting circuit in parallel and connecting the cooler should be both safe and allow the fan to get to max speed.

For all you disclose about the cooler, it may not operate at all at 7.5...9.6 V. Then again it may, for a Peltier cooler, 160 mA sounds pretty low. How long does it need to run? What makes you consider alkaline cells, stacks of 6 instead of stacks of 8 (12 V nom.)? — greybeard, Commented Jul 10, 2023 at 14:31
connecting 2 batteries in parallel would result in the batteries charging each other because of their voltage not being 100% the same — Christianidis Vasilis, Commented Jul 10, 2023 at 14:35
It needs to run for about 1h or so. Tomorrow I plan to buy and actual ac/dc converter. But right now is so hot in here I am about to take my skin off :D. — zozo, Commented Jul 10, 2023 at 14:36

hacktastical · Accepted Answer · 2023-07-10 16:23:51Z

1

Yes, the fan will run slower, otherwise nothing will burn up.
No, the 9V alkaline battery has enough internal resistance that will limit the current to a non-hazardous level. It may heat a little but it’s not going to blow up.
Yes. Again, with the limited current a 9V battery can deliver, it’s not a hazard to connect them in parallel. You will get more run time that way. (I have a telescope with exactly this setup.)
If you’re going to that much trouble to make 12V, you’d be better off choosing more suitable batteries than 9V. 8 AA 1.5V in series would do ok.

answered Jul 10, 2023 at 14:38

hacktastical

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\$\begingroup\$ Tyvm. I just need to do with what I have for today until night comes and it gets colder outside without blowing up anything :D. Tomorrow when the shops open will implement a real solution (I'm thinking of an adjustable 220V AC -> 3-12V DC adjustable coverter (to be able to regulate the speed from the voltage)). A PCW controller is not worth the cost for what I need. \$\endgroup\$
– zozo
Commented Jul 10, 2023 at 14:41
\$\begingroup\$ Since you talk about the "speed" of the cooler then is the cooler actually a fan? \$\endgroup\$
– Audioguru
Commented Jul 10, 2023 at 17:46
\$\begingroup\$ Well... is a cooler since it gets cool air from a different room. But you can think of it as a fan. Solution... kind of worked... gave me 0.5 Celsius difference from before. But I need more :(. \$\endgroup\$
– zozo
Commented Jul 11, 2023 at 10:12

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