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Help needed

siggy

Mar 3, 2012
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I have a small body cam powered by a 3.7V 1300mAh 4.4WH internal battery. The battery dies fairly quickly. So looking to piggyback a booster pack to supplement the internal battery. When used indoors this camera can be powered by a mains brick and lead. So my thoughts are to use a booster pack when not connecting to household power.

The problem I'm having (not having to “thunk” these problems in a millennium) is I can build a battery booster pack to deliver 4.2V at 1000 - 3000mAh* using 18650 batteries BUT... The internal battery should be recharged at 200mAh if I’m correct. I trying to figure out how to limit the current from the booster to 200mAh. So as to not overcharge and damage the battery

*depending on what I have available at the time.

I tried not limiting the output current but the internal battery got hot very quickly hence the need to limit.
 
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Harald Kapp

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How is the body cam's battery charged? Via USB as is common today? Then simply connect a power bank to the camera's USB port while outside.
 

siggy

Mar 3, 2012
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No via a DC jack. I tried using a USB to DC jack cable but found the USB wasn't tight enough and disconnected too many times. Maybe I could deconstruct the battery bank and fill in the USB holes and replace with a wire DC male jack?
 

Martaine2005

May 12, 2015
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What voltage is the DC power supply? ie - to the DC jack?
Create a battery supply with that voltage and use the DC jack for powering the camera.

Martin
 

Harald Kapp

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You'll have to find the right DC jack. They come in various diameters.
Leaving the body cam unharmed and creating a matching power adapter is imho your best option. Ths way you don't have to mess or interfere with the internal charging electronics of the camera.
 

Martaine2005

May 12, 2015
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You'll have to find the right DC jack. They come in various diameters.
Leaving the body cam unharmed and creating a matching power adapter is imho your best option. Ths way you don't have to mess or interfere with the internal charging electronics of the camera.
He already has one and powers it from mains indoors. He omitted the voltage required.

Martin
 

siggy

Mar 3, 2012
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You'll have to find the right DC jack. They come in various diameters.
Leaving the body cam unharmed and creating a matching power adapter is imho your best option. Ths way you don't have to mess or interfere with the internal charging electronics of the camera.

He already has one and powers it from mains indoors. He omitted the voltage required.

So you say to make the external battery match the internal maybe with a little higher voltage >Say battery pack 4.2V with 1300mAh batteries?

By the way, the initial post says the Camera "is powered by a 3.7V 1300mAh 4.4WH internal battery"

What I want is to create a power bank that is 3.7V to 4.2V that can say provide a charging current 200mAh* or a supply of 1300mAh* for say 4 hours so that when the battery bank is exhausted the internal battery can either just run for a period then stop or survive long enough to have an additional battery bank be installed.

*I have batteries that are 18650 3.7V 3000 mAh which would need to be limited "fuse" or something else?


[Mod edited - quotes added] for clarity]
 
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siggy

Mar 3, 2012
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PS I have the right size DC jack for the battery bank output to the camera. I just need to limit the current to either 200mAh or 1300mAh trying not to kill the internal battery.
 
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