Converting an Ambrogio L210 to GPS RTK

tgcoder

Member
I started working on converting my L210 to use RTK. I already have several other mowers, including an L32, 4.00 Elite, and 4.36 Elite. I don't like them mostly due to the track they make around their mowing areas. I purchased the L210 used, so that I could use it as a test machine to convert to RTK. So far I have built a station to transmit the error correction data and placed it central to the property. I have 6.5 acres of land and about 5 acres is mowable. I have also built a device that I used to plot GPS data every 12" around my test area, which encompasses about .46 acres. It plots the latitude and longitude into a file which I will use to control the test mower.

Now, I am starting on modifying the mower itself. As I am building all of the circuits myself, my first problem is to devise a charger circuit for the mower. It contains a 26v lithium battery. I was wondering if anyone had a circuit source I could copy. The charging station seems to only supply a source for the power. The charging circuit appears to be on the robot's mother board. Can anyone help?
 

Fürst Ruprecht

Well-known member
If you use lithium cells you need a charge manager that controls the charge current. therefore, ready-made, encapsulated chargers are often used. an alternative are the battery management systems, which regulate the charging current and charge all cells evenly. they can be used with a suitable DC voltage source. The "Ardumower" perimeter transmitter uses a suitable lithium charger and switches between perimeter wire and charging mode.
 

tgcoder

Member
The mower has a single 25.2 volt battery. I was able to find the specs on a similar battery made by a different manufacturer. However, I'm sure the specs are the same for both batteries. Using that info, I can design a charging circuit for it if needed. My problem is that I'm not sure if the motherboard on the current mower contains a charger or just battery monitoring cirduit so that it can determine when to return to the charging station. I would think that the charging station knows how to charge the battery, but I'm not sure about that yet. Thanks for your reply.
 

Bernard

Well-known member
Staff member
The mower has a single 25.2 volt battery. I was able to find the specs on a similar battery made by a different manufacturer. However, I'm sure the specs are the same for both batteries. Using that info, I can design a charging circuit for it if needed. My problem is that I'm not sure if the motherboard on the current mower contains a charger or just battery monitoring cirduit so that it can determine when to return to the charging station. I would think that the charging station knows how to charge the battery, but I'm not sure about that yet. Thanks for your reply.
On mower :
Power PCB read in real time the Bat voltage and the charging sense using INA226
On Sender :
Esp32 also read the charging sense using INA3221

Software charging manage the bat voltage by this way.
On mower:
A low voltage (23V for example) tell mower it's time to return to charging station.
When mower is in charge a low charging sense (0.2Amp for example) can stop the charging process ,or a duration limit (5 hour in hard code).
It's a good process for lead Acid ,but for a perfect Li-Ion charging process it's better to use a true li-ion charger with variable sense connected to sender.
On sender:
When mower touch the charging contact signal wire is stop and charger is use to fill the mower battery.

Wiki for software:

sample of li-ion 7S charger (7*4.2V=29.4V at full charge) . your 25.2V is the nominal value of the battery (7*3.6V=25.2V)
 

tgcoder

Member
Thanks for the reply. For some reason, I never considered replacing the charger in the charging station. Your selection would seem to work perfectly, and the cost is very reasonable too.
 

tgcoder

Member
If anyone is interested, I used a UMLIFE Three-Phase DC Brushless Motor Controller that I got from Amazon to test with my L210 in order to control the motors. It worked nicely with a potentiometer and using PCM. The wiring connection I used was:
Motor
MA - Black
MB - Red
MC - Brown

For the Hall Sensor wiring:

5v - Red
Ha - Green
Hb - Yellow
Hc - Blue
Gnd - Black

For PCM, use the control input for the PCM signal and ground to ground. Make sure the onboard pot is set to minimum or fully counter clockwise.
 

SefanH

Well-known member
Thats the X11H driver i use too.
If there is not enough space in the mower, a smaller driver (X12H) is presented here by Bernard.
 

tgcoder

Member
I've got plenty of room for a 210mm x 100mm board, which will easily fit three of them plus all of my other parts.
 
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