I’m doing a 100 mile + ride this weekend which will be the longest time I’ve run my 820 for (by a long way). I’ve got a 2,600mAh battery pack that can be taped under the stem to give extra juice if/when the main battery dies.

I’ll be using navigation but also probably the “battery save” feature which keeps the screen off except for when turns etc are coming up.

What sort of battery life should I expect before needing backup power?

I had mine running for 13 hours for the Mallorca 312.

GLONASS turned off, GPS only.
Backlight always off.
Tones off.
Wifi off.
Bluetooth off.

Had about 15-20% battery left at the end.

Sounds better than I was expecting!

Was that with navigation running or only recording?

I had a map route showing, but no turn by turn nav – I never use it anyway, it annoys me, so I just follow the line on the map. I can’t see the nav function using much more power.

As above, turn off as many feature as you can (bluetooth etc), turn off the backlight, or both turn down the brightness and also the length it displays for. Finally, only have the map displaying when you actually need it, e.g. in towns and villages when you actually need to see where you are going. The rest of the time, don’t view the map as it ‘moving’ and constantly updating uses up loads of battery.

This is all from my experience, but no doubt others will disagree 😀

That’s pretty much the plan GingerOne – combined with “battery saver” mode which keeps the display totally off unless there’s a turn coming up.

Tried it last night- apart from crash g twice within the first 3 miles (grrrr) it worked just fine. Only issue with battery saver mode seems to be that you have to check it every now and then to check it’s not just silently crashed.

Just plug your powerpack in at the start of the ride no need to worry about battery saving mode then. I get about 24hrs from a 5000 mah pack backlight on half brightness and mapping on’ normally Finnish a 600 km Audax with about 50 percent battery left

Cheers Rob – that’s pretty much the info I’m looking for.

So – 2,600 mAh pack plugged in from the start – mapping on, backlight, bluetooth, wifi, glonass off, beeps on – that sounds like it should do just fine from what I’m hearing – thanks !

I was a bit surprised to find my 820 ran out of juice on a 5.5 hour ride at the weekend! I assumed it’d be good for 10 hours or so.

I’ve also got a 100 mile ride in a couple of weeks – I really want to have the display on the whole time in order to pace myself with my fancy new power meter.

Will turning off Wifi + blue tooth and not using the turn by turn nav, likely stretch out the battery to 6 – 7 hours?