Docs: IC2 is INA180A3IDBVR which has inadequate voltage range

Mon, 01 Jan 0001 00:00:00 +0000

Due to sourcing error, IC2 that was installed on the boards (INA180A3IDBVR) has a lower voltage rating than the original part. The voltage rating is 26V, but the mower needs 30V for the fully charged battery. That’s why some IC2 break after some time.

Symptoms:

mower stops charging
mower status topic reports 10A charging current, makes no sense with 2A fuses
IC2 breaks (black residue on the PCB)

Determining if you are affected

INA180A3IDBVR has marking 1A9D. If you see that - you are affected.
The good chip TSC101CILT is marked 0106.

Wrong INA180A3IDBVR

Good TSC101CILT

Solutions

First, for many people, it’s just working. So if your mower worked for a couple of weeks, it might survive. In that case you don’t have to take any action. If your robot does not charge anymore, there are two options: Fixing the hardware or ignoring the error in software.

I recommend replacing the IC to fix this issue.

Option 1

Replace IC2 with TSC101CILT (DigiKey 497-6947-1-ND, Mouser 511-TSC101CILT, TME TSC101CILT or other major distributor).

The process is pretty simple to do with a normal soldering iron.
Disconnect all modules and power from the mainboard before starting the replacement.

For replacement, follow these steps:

For desoldering the IC, use a blob of solder to cover all pins of the IC. Heat it up and remove the part.
Then clean the pads using desoldering wick.
Add solder to one pad, position the part with one leg into the pad and let cool.
Solder remaining legs, the part will not move anymore.

Option 2: Disable the safety check in firmware.

The current sense IC prevents the charger from applying excessive current to the battery. This is one of three safety checks in the charging circuit:

Fuse in the charging path
IC2 to measure the current and shut down charging, if excessive current occurs
Battery management system inside the battery to protect the battery.

If you feel that you don’t need the safety check and don’t want to switch the IC, you can disable the check in the firmware. We advise to do the hardware replacement instead.
As always: Do this at your own risk.

To do that, update your firmware, hard-coding charge current to -1A: Replace

        status_message.charging_current =
                (float) analogRead(PIN_ANALOG_CHARGE_CURRENT) * (3.3f / 4096.0f) / (CURRENT_SENSE_GAIN * R_SHUNT);

with

        status_message.charging_current = -1.0

For mainstream kit versions, we prepared this already.
Just update your OM_HARDWARE_VERSION in /boot/openmower/mower_config.txt to use the firmware without charging current control.

Existing Version	Change to
0_13_X	0_13_X_IGNORE_CHARGING_CURRENT
0_12_X	0_12_X_IGNORE_CHARGING_CURRENT
0_11_X_WT901	0_11_X_IGNORE_CHARGING_CURRENT
0_10_X_WT901	0_10_X_IGNORE_CHARGING_CURRENT
0_9_X_WT901	0_9_X_IGNORE_CHARGING_CURRENT

Docs: Outdated firmware in the kit

Mon, 01 Jan 0001 00:00:00 +0000

Pico firmware shipped with the kit was outdated.

Symptoms:

mower driving in circles, or showing an incorrect direction on the map

Solution:

update the firmware

Docs: Rain sensor cable is female, but male is needed

Mon, 01 Jan 0001 00:00:00 +0000

This was a production error, but can be easily mitigated with a couple of pins from the pin header.

OpenMower v1 Documentation – Known Issues

Docs: IC2 is INA180A3IDBVR which has inadequate voltage range

Determining if you are affected

Solutions

Option 1

Option 2: Disable the safety check in firmware.

Docs: Outdated firmware in the kit

Docs: Rain sensor cable is female, but male is needed