Forum: General Topics

Hi Natilla,

Battery life can be quite variable, depending on how intensely you're using TMJ. With my W910i I can easily get 4-5 hours use from a full charge, and rarely has the phone completely run out of power. A friend has a K800i and has similar, or longer life if anything (though I guess I'm generally using it a bit more heavily than most anyhow!). As you noted, the battery does have to power quite a few functions, so the more these can be minimised the better:-

- Backlight. This possibly has the biggest effect on battery life. I'd only recommend using the Menu/Display/Backlight On function for short periods, or if the phone is on external power (eg car cigarette lighter, etc). Reducing its brightness in the phones Display Settings will also help. When the display goes black TMJ completely stops drawing anything on screen, so this has an added benefit for battery life.

- Bluetooth. On the whole this should be a relatively low drain on battery power, and I would imagine is far better than using a phone with built-in GPS, as these can really sap the power (not to mention the better signal that external GPS devices seem to achieve). Some phones have a bluetooth Powersave option, though I've not tested this see if it has any effect on mine.

- GPRS/3G. I keep 3G turned off as I've heard that this can be a bigger drain on power than a basic GPRS connection. I guess the actual drain will vary a lot anyhow - if you're out in the country with poor reception then the drain will be higher too. If you're trying to conserve battery power as much as possible, then you might only want to use Menu/Web/Enable Upload for short periods at a time - it will then upload the current track in bursts, but when you get home it should still all be stored correctly on the website.

I've not done any scientific tests but the Text page (screen [1]) requires the least rendering effort, so may slightly improve battery life. Also note that Menu/Display/High Frequency Screen Updates draws each page 5 times per second instead of the default once per second, so should also be used sparingly...

Anyone else have any comments on battery life on other phone models?

Cheers,
Stephen

Anyone else have any comments on battery life on other phone models?

My phone is a SE W810. I used it yesterday for six and a half hours, the phone just dropped slightly off the green battery indicator. I find the battery life to be remarkable.

I've set the phone up for continues backlight, so I can study the map while I'm walking / cycling. When I've finished I press the shortcut button which then allows the backlight to turn off and save power. I press the shortcut button again and select TMJ again to get the program back. I guess this might help conserve a bit of power.


Thanks again for such a brilliant killer application.

Sure, should be fairly easy to add - I'll put it in the next version...

Cheers,
Stephen

Sorry, forgot to mention. I don't send the track to the internet live.

Using my Blackberry Curve 8320, I can easily spend a day bicycle riding and geocaching, maybe 6-8 hours or more. But I need to start with a full charge and I'll be drained (the Blackberry battery, that is) by the end, particularly if I use the screen a lot for finding caches. My bluetooth GPS puck would probably go for 2 days; the phone is by far the limiting factor. I use live tracking and occasionally use the screen depending on what I'm doing.

As others have noted, battery life is going to depend on:
• Screen on-time and brightness - Less of both will extend battery life, and this is the biggest factor in normal usage.
• Radio usage - Obviously turning off the radio will extend life, but disables the phone. My BB has a wi-fi radio, and obviously this should be turned off. The bluetooth radio must use some power but I haven't been able to tell that it's very significant. I think most phones manage radio power and reduce it when you're near a tower. So the phone uses maximum radio power when it's looking for coverage. This can cut battery life in half or worse if you're outside of cell service range. So turning off the cell radio (and thus all TMJ web access) when you're in a remote area would save a lot of power.
• Charging - It's easy to build yourself a 5V USB charger - mine uses an old Altoids tin - and this will power both my GPS puck and the blackberry off a standard 12V accessory plug, ie. a car's cigarette lighter. Even a few minutes on the charger can give a big boost of service time. If you have access to any power source, I suggest considering this.

Hi Paul,

I would definitely suggest trying the extended transmit time. Although J2ME/TMJ doesn't have any direct control over the connection timeout, I've found on my W910 that the connection does shutdown after a minute or so. Once this happens TMJ should sit quietly until the next transmit time, so setting this to every 10 minutes (or even longer) should minimise connection usage.

However, as Wayne says, phones do need to constantly check where their nearest transmitter is (for receiving calls, etc), so if you're cycling through very remote areas then the phone will potentially use more energy to 'talk' to the distant transmitters. Not a lot that you can do about that though. :-(

One thing I would suggest (though it might be too late if you're already on the road/in a tent!) is that a bluetooth GPS device would probably extend the phones battery life a fair bit. You'd obviously need a way of charging this as well, but the phone should last longer, maybe enough for a full days cycle...

Good luck anyhow!

Cheers,
Stephen