GPS Battery

[Rich]

Thanks for sharing this info on replacing the OEM charge type battery with a 2032.

I've known this is an issue for a while, but never took the time to look into it. I also noticed that 3DR documented the battery design with the Rev B GPS release.

Unless someone is flying every day, your OEM battery will be discharged and you will have to wait for a cold gps start each time.

I always wondered if the Solo firmware could send the time to the gps to give it a sudo warm start, but I haven't done more than wonder.

I may consider doing the cr2032 battery mod as often I don't fly for weeks at a time.

I know we shouldn't complain about the Solo, but this part of its design makes absolutely no sense at all.

 

[pyrate]

Now that people are speaking freely, the rev A board had LOTS of design issues
They went with it anyway to get it to market

I should note, that the shield took care of most of the issues.
but the battery one is a great find.

 

[RichWest]

Color me impressed... Just flew my bird and it was ready to FLY within 35 seconds with 8 sats and hdop of 2.0. Same location as Sunday's flight, but even so still a huge improvement overall. I got to a max of 12 sats in flight above the tree line.

Without a doubt best mod ever, well maybe not best ever, but pretty stinking great! Thanks again @cynfab !!!!!

 

[JoelNewman]

Nice work Rich.

This might explain a weird thing I saw in one of my flight logs, where the GPS Time flat-lined for the first minute or so, then suddenly corrected itself and started increasing normally once it had picked up satellites.

GPS time is in blue, number of satellites in orange.

Solo had not been powered on for 74 hours.



FYI it looks like it started at the correct time before it flat-lined, but calculating back showed that it was actually about 20 seconds out at the start.

 

[Rich]

Yes, this is a case of the gps rtc time not being set until it picks up the first satellite so I can an start the clock running at the right time and date.

I hate that rechargeable battery in the gps design. Mine is always dead as I don't fly daily.

I hope anyone designing new GPS modules will take this type of user into account. Not all of us fly every day or week. This is why a battery on the GPS can help by keeping the RTC running.

Constantly having a rechargeable battery over discharged is not normally good for it.

 

[Frank Foster]

WOW! just stumbled upon this thread, and it is some GREAT information. Thank you so much, and I agree, it has to be the best GPS mod yet! I can't hardly wait to get into my Solo's and do the mod! Also explains why my older M6 3DR GPS units seem to work even better than the Mro M8's. I have one of the older square 3DR GPS units on my Y6, (3D Robotics GPS Module For Pixhawk And APM 2.6 | eBay) and it shows sats inside my mobile home, while the Mro's and other M8's I've tried, NEVER pick up anything until I go outside. I would think the Mro's batteries would have a charge, as they should be fairly new, but who knows? I'll do some measurements.

 

[Frank Foster]

I just measured the voltage of a brand new Mro M8 GPS battery. Had to do it while it is connected to the GPS, as it appears to be soldered/welded in. Got 2.7 volts

 

[cynfab]

Frank, How long had your mRo sat unpowered? I haven't done any extensive tests with the M8N as to power consumption, but my mro has not been installed in a Solo yet, I got it October ant its battery measures 2.44V today. So It could be that the M8N has a much lower current draw while unpowered than the NEO-7N, which is possible since the 8030 chip is of newer design than the 7020 in the 7N. The other thing it could be is that the batteries used in the Rev A GPS were crap. Or maybe a bit of both.
IMHO the M8N is a much better choice, hands down. 3DR's claim that the 7N was as good or better is BS.

 

[Frank Foster]

My Mro came in the mail a couple maybe 3 weeks ago. I have one installed, and 2 still in the box. Did you notice the battery is not easily replaceable? I want to try the 2032 battery swap.

 

[cynfab]

Based on what I've seen with my Mro, you should not need the CR2032 mod. Be it better parts that Jordi used or less standby current from the M8N, the result is that the battery is not drained as rapidly. Mine has lasted since October without being powered on.
Measure the battery voltage. Add some data to what little we know about how the Mro battery fares over time.

 

[Frank Foster]

2.7 volts