My 7 years old Roomba 4230 doesn’t power on anymore. The last time I tried to use it, several months ago, it just played the 4-note song after a few seconds in the cleaning process. I tried the battery rest procedure and the 72 hours charge, but it still played the 4-note song. At the time I didn’t have much spare time to troubleshoot the problem, so I just let my robot sit there for a few months (I disconnected the battery, though). Now I tried again and the robot doesn’t even turn on after a full 72 hours charge: I connect the charger directly to the robot and the Power button slowly blink red. It takes about 5-6 hours to turn green. Then I waited for 72 hours but as soon as I disconnect the charger, the power button turns off and there’s no way to turn it on again. The charger output is 22.5V while the battery reads 10.5V. Should I just replace the battery? Any other advice?
Julie,
thanks for your reply, I tried that but it didn’t work. Same result: robot doesn’t turn on after being charged; the new battery reads 7.7V! Is there anything else I can do to troubleshoot the problem. I also have a Dirt Dog but it looks like it uses a different battery/charger, so I’m not sure I can swap battery/charger with my 4230 to do some testing. Any other suggestions?
Thanks a lot for your help!
Julie,
thanks again for your support. Can I also use the dirt dog’s charger on the Discovery 4230? I’m trying to isolate the faulty component.
Julie,
thanks again for your invaluable help! This site rocks!
So, it appears that the culprit is my Discovery 4230’s fast charger. I have charged the new battery in the Dirt Dog with its slow charger, and the battery read 14.7V and the Discovery ran for more than one hour with the new battery. Then I charged the new battery in the Discovery using the Dirt Dog’s slow charger, and again the battery and the robot were fine. Is it possible that the Discovery’s fast charge is faulty, even though its output is 22V? I’m puzzled.
Thank you for this information. In this case, it does sound like the charging system inside the Discovery is defective. We would therefore suggest that you replace the robots motherboard. If you are comfortable with soldering, you may also replace U2 and U4 on the motherboard.
You’re correct. We unfortunately no longer sell the motherboard. The Discovery series robots has been discontinued for several years now and we have therefore discontinued many parts for this generation of robots.
In this case, we would suggest that you try a replacement battery. The Robot will not turn on with a battery that only reads 10.5V
Your robots charger is giving you the right output and therefore a new battery should resolve your issue unless your robot has a charging problem.
In this case, yes we would recommend testing the robot with your Dirt dog battery. Even if the battery is not the same color the Discovery 4230 and dirt dog batteries are interchangeable.
If your Roomba battery only measures 7.7V, it is normal that it will not turn on the robot. It should read at least 14V for you to be able to have the robot clean.
Certainly. They have the same type of plug and same voltage. One is probably a slow charger and the other a fast charger.
Thanks for your comment. It is appreciated.
Normally, when the charger reads 22V it does charge the robot fine. It is definitely strange that it does not charge with the fast charger. But, in this case now you know that both robots are fine and a new battery charger is much easier to replace.
Julie, thanks a lot for your help! I’ve checked the instructions about replacing U2 and U4 and it sounds something I can do on a spare afternoon 
BTW, I’ve searched your website for a replacement motherboard, but it looks like you don’t carry it. Can you confirm that?
Thanks again!
Julie,
it looks like that the chargers are both fine as they both can charge the new battery properly when the battery sits in the Dirt Dog. The 4230 also runs fine when the charged battery is moved from the Dirt Dog. Unfortunately, both chargers can’t charge the battery when it’s inside the 4230, so I assume my 4230 has a problem. Should I replace the whole motherboard? Is there anything else I can try? Is it even worth it?
Thanks again for all your help!