[pct-l] Bleeding off Lithium Batteries

[jeff.singewald at comcast.net]

Interesting.  I have a GPS that I have been using for 3 months and I have totally got the geocache bug so it is on nearly every day.  I use Lithium batteries on my Garmin and have no problem.  There is a setup option to specify what type of batteries I am using.  It is always set to Lithium.  Never had to bleed my batteries.

Elevator

-------------- Original message -------------- 
From: stewjohns at comcast.net 

> I bought some new Lithium batteries for my Garmin GPS the other day, and when I 
> put them in, 
> and turned on the unit, it came on for a few seconds and then the display faded 
> out and the unit 
> turned off. The problem is that Lithium batteries come out of the box with a 
> voltage of 1.8v, while 
> the equivalent alkaline battery has an out of the box voltage of 1.6v. The 
> extra voltage of the 
> Lithium, triggers the over voltage circuit in the GPS, and it shuts it off. The 
> solution is to bleed off some of this voltage by running it through some other 
> device for a bit. 
> 
> Being a curious electronic technician, I wanted to quantify this a bit and find 
> out how much you 
> need to bleed off before you can use them in the GPS. I pulled out my fluke 
> multi-meter and measured the out of the box starting voltage of both alkaline 
> and lithium batteries. 
> Alkaline = 1.6V 
> Lithium = 1.8 V 
> 
> I then installed the New Lithium batteries in the GPS to verify that they would 
> not work. 
> Then after confirming that they wouldn't, I installed them in a mini-mag 
> flashlight. My plan was 
> to run the flashlight for 1 minute, measure the voltage of the battery, and than 
> install them back in 
> the GPS to see if they worked. I intended to repeat this at 1 minute intervals 
> until I could get 
> them to work in the GPS. My experiment lasted only 1 minute of data, as after 1 
> minute in 
> the flashlight, the Lithiums worked fine. Measured voltage after the 1 minute 
> bleed off---1.72V. 
> It doesn't take much bleed off to get them to work. 
> 
> If you are a GPS user, and want to take 
> advantage of the extra life that Lithium batteries provide, I would suggest you 
> test your spares 
> before you head out to the trail-head, and bleed them off a little if necessary. 
> I suppose you could 
> rig something in the field if you had to, but why not be prepared ahead of time. 
> 
> The GPS unit tested was a Garmin map 60CSX. The Batteries tested were Energizer 
> Lithium AA, 
> and Duracell alkaline AA. 
> 
> Doc Holiday 
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