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Small Cabin Forum / Off Topic / 3.7 volt radio battery
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paulz
Member
# Posted: 7 Jan 2020 19:19 - Edited by: paulz
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I have a small portable, rechargeable radio I use outside at my cabin. About the size of a deck of cards. Goes dead after a couple of hours. 3.7v battery, like a cell phone. I also have a bigger 3.7 v battery out of a portable TV that died that I could tape to the radio. But the radio battery has 3 brass connectors, the TV battery has red and black wires only.

Can I use it, either by itself of connected with the radio battery?

paulz
Member
# Posted: 7 Jan 2020 19:38
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Forgot to mention, the radio recharges off a USB port.

ICC
Member
# Posted: 7 Jan 2020 19:43 - Edited by: ICC
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The third contact point is usually for temperature sensing. The charger can slow the charge if the battery gets too hot.

How would you charge the battery from the TV?

paulz
Member
# Posted: 7 Jan 2020 22:42
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Hmm, glad you mentioned that. TV had a 9v wall wort. Which got me thinking, how would that do with a 3.7 battery. So I just had another look at it, looks like it says 3.7x2.
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0107201938_HDR.jpg


ICC
Member
# Posted: 7 Jan 2020 23:04 - Edited by: ICC
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Quoting: paulz
it says 3.7x2


So that may mean 3.7 volts x 2 = 7.4 volts as in serially connected. It strikes me as an odd labeling.... makes me wonder why they don't state 7.4 volts???? Do you have a multimeter? Measure the voltage.

3.7 x 2 could also mean connected in parallel. ??? Anyhow, measure the battery volts. It may very well be that connecting that to the radio would not be good.

If the radio has a USB port how about trying a power bank plugged into the radio with a few elastic bands holding them together?

paulz
Member
# Posted: 7 Jan 2020 23:45
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7.9 volts. Good thing I didn't start farting around with it. Power bank, good idea. Don't have one of those things yet.

Thanks ICC!

Brettny
Member
# Posted: 10 Jan 2020 08:44
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18650 battery are about 3.7 volts. What are the dimentions of that pack and what is the battery make up? No car? Lithium?

Usually if you search for a battery pack voltage the size you want will come up. There's many dif shapes and sizes but usually voltage matches a size baring an oddball one off pack.

Most of the lithium stuff in portable battery packs are going to be 18650 battery. Most of the cordless hand tools, vacuum, laptops and I'm sure there's a lot more.

ICC
Member
# Posted: 10 Jan 2020 10:53 - Edited by: ICC
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There are an almost endless variety of sizes of lithium-based cells or batteries that are rated at 3.6 or 3.7 volts. They come in both flat cells like the ones used in most smartphones and cylindrical shapes in a wide array of diameters and lengths. There is no standard size. The 18650 is the most common cylindrical cell. The rated voltage is normally 3.6 or 3.7 volts. The capacity can vary from only a 100 mAh to thousands of mAh and the cells can deliver much higher amperage than the alkaline cells we are very familiar with.

If one is going to mess about with lithium cells one should also be aware that a short circuit can result in a fire involving the cell itself. I do use them in many projects and have never had any dangerous situations arise, but bad things do happen especially if one is not careful and knowledgable about the potential dangers.

It is possible the cell in the radio is wearing out. A replacement could rectify that issue. Or perhaps the cell is simply too small a capacity for the current use.

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