Can anyone suggest a 3.7v high capacity battery?

[GPSToyz]

I'm working on a project where I need to deploy GPS devices in remote areas. Typical batteries only last a few days to a few weeks, depending on mode the device is in.

I need a battery that will remain charged for a year or longer under typical draw, if such a beast exists. Size is not important. I will be designing a custom enclosure and can accommodate most anything. I would prefer something flat, so say if it was an inch thick but 1 foot by 1 foot square, it would be better than if it looked like a car battery. I've searched the net to no avail.

Can anyone point me to a battery or company?

 

[ScottyUK]

Lithium thionyl chloride cells are great for long duration low drain applications. Lithium-sulphur dioxide have low self-discharge and handle higher power bursts.

What are your power requirements? Does this device have continuous drain, or periodically wake up from a sleep mode?


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If we learn from our mistakes I'm getting a great education!

 

[MacGyverS2000]

I need a battery that will remain charged for a year or longer under typical draw

A double-A battery will remain charged for several years under a constant current draw... that current draw just has to be very small. You need to define how much of a draw you require and at what voltage.

Dan - Owner

http://www.Hi-TecDesigns.com

 

[IRstuff]

Alkaline and button batteries can run for years, if the draw is sufficiently small. If we assume a 2-yr operating life, then the draw needs to be less than 140 uA per AA-equivalent battery.

TTFN

FAQ731-376

 

[GPSToyz]

The unit I am considering draws about 3.5mA continuous when in sleep mode. For about 1 minute in a 24 hour period it will wake up and do something (acquire satellite, send a GPRS packet over GSM radio, etc) which increases the current draw to 13 mA and then it's back to sleep again for 24 hours.

Even though battery size/configuration isn't a huge issue, the cost is. If I can use disposable batteries rather than rechargeable ones and save a ton of money that would be preferred. Thanks to everyone for your help.

 

[MacGyverS2000]

Well, you know the current draw you need and over what time period... calculate the total power draw and size a battery accordingly.

We're not talking a standard car battery here, though, as that'll be stone dead long before that year is up.

Dan - Owner

http://www.Hi-TecDesigns.com

 

[janiliewa]

I've never heard such a battery which could remain charged so long.Normal laptop battery likes this

http://www.atlaptopbattery.co.uk/compaq-presario-r3000-battery.html

just can last for about 3-4 hours.Any idea about it?

http://www.atlaptopbattery.co.uk

 

[IRstuff]

OK, so do the math:
[3.5mA*(24h-1min)+13mA*1min]*365 = 30Ah

for 30 days, it's 2.5Ah. A typical D-cell is rated at 15Ah, but the discharge curves show that at the discharges you are talking about, it's probably only good for about 1500 hrs:

http://www1.duracell.com/oem/Pdf/others/ATB-5.pdf

So, one simple alternative, given that alkaline batteries have very good shelf life, is to have a bank of such batteries and switch them in, after the previous one has lost too much capacity. So, something like a set of 7 D-cells, individually selectable, and switched out avery 1250 hrs would be a possible solution.

TTFN

FAQ731-376