I have a new edge 800. I was looking at the genuine external battery packs but they are a quite pricey and seem low in terms of mAh.

would one of these work or would I end up with a broken Garmin?

http://www.amazon.co.uk/EasyAcc-Emergency-flashlight-Incredible-Blackberry/dp/B005JSG7GE/ref=pd_sim_sbs_ce_2

The voltage seems to be Ok at 5V the amps are higher (my garmin plug says 0.3A, this is 1A. I’m concerned about the lack of oercharge protection but also my lack of knowledge on batteries and chargers!

There is a generic AA garmin charger

http://www.amazon.co.uk/Portable-Emergency-Battery-Charge-Extender/dp/B0042892SM

and a specific garmin kit but that is £60. I thought the top one would also be useful for an ipod or phone on other trips.

Help appreciated. Thanks,

How long are you intending to ride for? the battery on my 705 is supposed to last 15 hours and I’ve never had any trouble.
There was quite a bit on the Garmin 705 forum about extended battery packs a while back and I seem to recall they where sensitive to how the USB plug was wired up (get it wrong and it thinks its connected to a PC).

I was hoping to do the coast to coast and if it all goes wrong and we hit trouble htat would be when I need my gps the most and whe it would be about to die.

Also, I was thinking about using it to record our journey on a multiday canoe trip and lending it to the wife to record a multi day horse riding trip. Not at all why I bought it but I was just looking into options in case it was easily doable for £25

Without appearing a total @rse that’s one reason I bought a Garmin which can take regular batteries, it’s used mostly for saling and on trips of a week at a time without ability to recharge so ability to put in fresh AA’s Is essential. As you say when you bought the unit this wasn’t a factor.

You can go some way in preserving the battery life by ensuring no backlighting, using simple display screens etc but if you really want to run for 2 days then you’ll need a recharge and getting the “approved” kit makes the most sense, you’ll kick yourself if you go budget and then it fails.

I googled this the other day so I could extend my Edge 800 battery life for a multi day trip. There are battery packs out there, but there needs to be a firmware update of the GPS for the unit to think it is connected to a battery, not a PC. The Edge is voltage sensitive (don’t go over 5V), but the current is not important. The 1A battery will just allow the GPS to work for longer (it is like Amp/hours for lights batteries).
I was then thinking about advertising on here to hire someone’s who has bought one, so if you ever think of buying one, consider renting it out (I am sure there are a few people who would hire one for £10/time for 24 hour events, multi day trips, etc).

I’ve just read a really long thread on the garmin site and the firmware issue is sorted. I can run mine while it is charging from the pc or charger so I don’t think an external battery will be an issue.

The battery is 1100mAh in the unit itself so I think I’ll take a punt on a suitable 5000mAh one and just test it over several days use (commuting, weekend rides etc. to see what life I get). I would have though 30-40 hours is possible. Voltages etc. all look to be good.

I thought about an AA one as I’ve used GPS about 10 years ago for trips lasting 5 weeks or more in some fairly remote bits of Canada. We used AA batteries. Lots of AA batteries! 99.5% of my riding is less than 7 hours for which this unit is ideal.

Do you know which pins on the GPS connector to wire the 5V and ground to? That was the other thing I wasn’t sure about…

here are some examples of people using it external packs for anyone reading this later on.

http://yacf.co.uk/forum/index.php?topic=50711.15