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Cmax battery dead

57K views 12 replies 9 participants last post by  alexeyussda2051 
#1 ·
This is the third time the battery was dead in garage. Have not left anything on to drain battery. Had to charge battery. Took car to dealer and of coursee they found no electrical problem however problem still occurs?
 
#3 ·
Try to charge battery then disconnect it. See if its dead in the morning. Ive gotten bad batteries before. I heard most Auto zone batteries are made in china now.The price of one from the Ford dealers aren't that bad these days.
 
#8 ·
I'm wondering if it is just that the car doesn't need to start? With the C-max, it runs on both the engine and battery. If it has a full charge on the drive battery, the motor will not start right away. Does the green car icon come on after you turn the key? If so, it is ready to drive. It will not start the motor. It is only a problem if the icon does not come on and the motor does not start.
 
#9 ·
Get a small charger for insurance

We keep one of these in the car just in case.

ABN PowerAny 12000 mAh Multi-function Car Jump Starter and Personal Power Bank Battery Charger with LED Light for Laptops /Cell Phones
available at Amazon for about 70.00. Its small and holds a chargefor several years and can use to charge other things .
 
#10 ·
I know this is an old thread. Other forums have a lot of info on this problem. A lot of early C-Max's had this problem. And Ford had a tough time fixing it. It would appear that Ford never really found the root cause of the problem but they knew something was draining the battery. This is a complicated engine and drive train. Ford came up with multiple fixes. I think all 2015 and newer C-Max's had enough fixes built in that the problem ha stopped to be an issue. They do have updates for older C-Maxes that seem to work. One fix was to automatically turn off the radio 10 minutes after the ignition is turned off.
 
#11 · (Edited)
From what I have read on another C-MAX forum:
When you push the start button, you are not starting the ICE, just the electronics. The electronics will determine if the ICE needs to be started. If it does the HV battery will start it. What you are looking for is the "Ready to Drive" notice on the gauge.
If you get no indication that the electronics are ON or no READY TO DRIVE notice, it is most likely the 12V battery or connections. CAREFUL if you decide to check the HV connections.
If you can jump it to start, it should recharge the 12v from the HV. If it does not start the next time it is a further indication of a bad 12V. DO NOT buy some off brand, replace with a FORD battery. It all may depend on what year your C-MAX is.
 
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