Troubleshooting

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Here are some common troubleshooting procedures. I'll try to expand this and add more videos. If you need more help, the best thing to do is post in the Ryobi 48V Mowers Subreddit. Alternatively, you can post in the Ryobi 48v Riding Mowers Facebook Group.

Mower Won't Turn On

This is one where many people aren't sure where to begin, but once you understand how everything is connected, it suddenly seems a lot less complicated. This video walks you through each step. You will need a multimeter, but, if you haven't used one before, don't worry, the video will do a quick tutorial.

The video uses an RM480, but the procedure is the same for all models. If you want to follow along with the wiring diagram, you can find it in the Document Library.

Load Testing Batteries

Battery voltage drops when put under a load. The bigger the load, the bigger the drop. Normally this is a small drop, but, with failing batteries, the drop can be much bigger. Loose connections can also behave this way, reading normal at rest, but dropping significantly 

If you suspect you have a battery issue and the voltage reads normally at rest, the next step is to load test the batteries. Bench testing is the most accurate, but testing them in the mower is often easier and tells us what we need to know.

Batteries in Mower

To do this test you'll need a multimeter and banana plug test leads.

1. Fully charge the batteries.

2. Plug the black banana plug test lead into the multimeter's common port and then plug it into the bottom right pin on the charge port. 

3. Plug the red banana plug test lead into the multimeter's V port and then plug it into the bottom left pin on the charge port.

4. You should now see the battery voltage. Fully charged lead acid batteries should be at least 52V. LiFePO4 should be at least 53V. If you are getting near zero, then you likely have a bad charge port. If your voltage is lower than 52, either your battery is not fully charged or has some other issue.

5. Leave the multimeter plugged in. Sit on the mower with the multimeter in your lap.

6. Turn on the mower blades for 5 minutes and monitor for voltage drop. If the voltage drops below 49V, then the batteries failed the load test.

Bench Testing

I'll start by saying, you can often have batteries load tested at auto parts stores for free. You do have to take them there and wait, but if you don't have or want to buy a load tester, it's a good option.

Also, the in-mower test is more useful for determining if your batteries are at fault for mower issues. This test is more useful for determining if the batteries are still usable for other purposes or resale.

You'll need a load tester. These procedures are based on the Konnwei KW208 when checking the stock batteries, but will be similar for other models.

1. Fully charge the battery. A good 12V battey lead acid should have a voltage above 13V.

2. Connect the clamps to the battery, Red to the Positive terminal, Black to the Negative terminal. It's best to clamp directly to the terminal if you can. If not, put a bolt into the terminal and tighten it.

3. On the tester, select Check.

4. On the tester, select Out-of-Vehicle.

5. On the tester, select AGM Flat Plate.

6. On the tester, select CA. This stands for Cranking Amps.

7. On the tester, use the default value of 400A. None of the stock batteries publish their CA or CCA ratings. That's because these types of batteries are not intended for starting engines. 400A is a good approximation for all the stock sizes.

8. Give the tester a few seconds to run. It will report a pass/fail result. While this is generally accurate, I think the best indicator is the is the internal resistance, labeled as "R" in the results. For the stock 100Ah battery, this should be around 5 mΩ, and less than 7 mΩ for the 75Ah batteries. Typically, double the spec is considered bad, so anything over 10 mΩ would be a failure. Sometimes batteries with slightly higher resistance can still be used for low amperage applications. A completely failed battery might have a resistance in the 100's of mΩ range.

Blades Turn Off After 5 Seconds

The blade controllers work together so if one blade isn't spinning, all the blades will turn off.

1. Make sure the mower is completely powered off. I'm paranoid, so I will disconnect the battery or blade motor connectors before going near the blades. Once you're sure it's safe, rotate each blade manually a complete revolution and make sure it isn't binding on anything. Grass clumps, sticks, string, or bent in metal can all prevent blades from spinning. Reconnect any disconnected connectors when finished.

2. If you're still experiencing the problem, lay your phone down on the ground to record a video of the mower blades. It may be easier if you raise the deck. You are looking to see which blade isn't turning on, so set your phone to record, sit on the mower, and start the blades. Wait for them to stop and review the video.

3. For the blade that isn't turning, check the motor connector. These connectors can become loose and the pins can also get pushed back. Make sure the connection is good and retest.

4. If you're still having a problem, swap the motor connectors so that the motors are connected to different controllers than before and record another video of the blades. If the same blade isn't spinning, it's likely you have a bad motor. If the blade that isn't spinning followed the connector, it's likely you have a bad blade motor controller. Follow the connector back to determine which controller is bad. You can differentiate between the master and slave controllers based on the number of connections. All controllers have connections to power, a blade motor, and the other controller(s). The master will have another connector with multiple wires connecting it to the drive motor controller and control panel.

Once you've narrowed down the issue, you can use the part lists in the Document Library to find the part number for the replacement part and the Parts page for information on ordering parts.