dei 520t battery, can it be changed out?

Trying to rig a backup battery for a GPS tracking unit. Was told to get the 520t which I did. Unit only has .7Ah of reserve/backup power.

I've never done it - however there's not really any reason you couldn't, provided the 520T's battery is 12V (I've never metered one and I know an alarm will typically run on lower voltage, hence the caution). 

I'd suggest the first thing you should do is measure the current draw from your GPS unit if you haven't yet - it may be low enough that it's not worth the trouble of the battery swap.

Thanks for you comment.

I did measure the voltage of the 520 right out of the package and it was 12.1 volts. So that is okay. I then use my GPS unit's 'current draw' figure and determined in my application the 520 would only last 2 hours.

My view is that it would really be stupid to be only backed up for 2 hours. After that the GPS would stop transmitting and I will have nothing. A 2.8 Ah battery would give me about 9 hours of backup. Well worth the cost of $20.

Has anybody used the larger battery..?