battery which tells you when power is running low? (li-ion)

I’ve recently bought this.

http://www.ebay.com/itm/12V-Portable-12000mAh-Li-ion-Super-Rechargeable-Battery-Pack-Portable-for-CCTV-/181146307799?pt=US_Rechargeable_Batteries&hash=item2a2d294cd7

While it works, theres no way to know when the battery is running low.Is there anything similar on ebay,etc. which makes a noise or flashes a light when power is low?
Thanks.

There are lipowarners or lipo alarms available for RC stuff, maybe you can use one of theses but normally they use the balance plug which your linked pack doesn’t has.
You could definitely use a cheap voltmeter as an indicator, but these have quiescent current.

Thank you very much for your reply.

I guess it wont work then.

You mean it will drain power even when the device is off?
Sorry I don’t know much about electronics.

Yes if you would plug one of the cheap voltmeters with a 7segment display on the pack it would consume a bit of power.

You could use a voltmeter, a male and female plug and a switch. Solder the bits together and voila. Switch it off when not needed or simply unplug it and forget about the switch. Not sure if that is what you are searching.


I just did a quick search on eBay for lipowarners and the descriptions say that every cell gets monitored and not the total voltage. That makes sense because sometimes one of the cells has a bit lower capacitance so it gets discharged faster.
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There is some protection build in. There has to be a charging circuit built in too, because these packs gets charged with a normal power supply…

So there is no safety reason and the voltmeter solution may worka as a indicator.

I had these items in mind:

Or

http://www.ebay.com/itm/DC-Connector-Power-Jack-Adapter-Plug-Male-Female-2-1x5-5mm-CCTV-1-2-5-10-20-50-/221068033657?pt=US_Lighting_Parts_and_Accessories&var=&hash=item3378ae7e79

If you think that would be what you want you can search the cheapest options.

I thought in such a voltmeter:

http://www.ebay.com/itm/DC-3-3V-17V-Green-LED-Panel-Meter-Mini-Lithium-Battery-Digital-Voltmeter-/121254788559?pt=LH_DefaultDomain_0&hash=item1c3b593dcf