I need an idea how to keep my SKM53 GPS powered so my TTFF will be minimal

I am making a GPS tracker for my car that is plugged into the 12V outlet with a USB adapter. Problem is that my car won't power the 12V socket without the key. So everytime I start the car, it takes the GPS about 40 seconds to get a fix when the car is not moving. If I start driving, it can take several minutes to get a fix.

How can I keep the SKM53 GPS module alive with a very small battery that will only power the module itself and not the Arduino? I also want to make the Arduino charge the battery once it's powered.

Or am I looking at it wrong and I should just power that arduino with a battery? How much power does it consume?

Ideas are welcomed :)

Is it possible to keep saving the current position to the EEPROM and on powerup, send the last location to the GPS and Expedite its TTFF (time to first fix)?

The datasheet for the SKM53 says it includes a battery backup. Apparently, from your experience, that's not correct.

The datasheet for the Mediatek 3329 chip that the SKM53 is based on shows that there is an input for a battery backup (2.0 to 4.3V).

I've never seen a GPS chip that would allow the calculated GPS coordinates be used as an input to improve the TTFF.

I haven't seen that in the datasheet until you mentioned it... that can explain a few things... If I go back to the car after up to an hour, TTFF is very quick, but over an hour, I guess the battery dies and TTFF is long again. I guess that even in a new unit the battery won't last more than a couple of hours...

So I'll go back to my first question: how can I make a small, rechargeable backup battery?

I think you may be in trouble. As there’s no external VBACK-style pin you can only provide the full 5v to VCC, trouble is the module may decide to stay active and consume 45mA all the time.

Is there a shutdown/standby command?

It sounds like their BB is not very good, maybe email them to get more info.

EDIT: I notice that they have a sleep/standby row in the “Power consumption” section of the parameters table, but the value is TBD. That implies you can somehow set it to sleep mode though.


I got an answer from the manufacturer:

The backup battery in SKM53 is sufficient.But the satellite ephemeris is a time limit. The satellite ephemeris is invalid after an hour,the SKM53 will cold start.