wamba2000 Posted January 24, 2013 Report Share Posted January 24, 2013 (edited) Sorry if any of you have had battery problems. I have read about access to the 12 volt ( low voltage) battery. I have pulled the rear hatch cover off, but can find not rubber access panel or way to get to the battery short of removal of several screws. Has anyone posted a picture of how to access the 12v battery if it needs to be replaced or serviced? I have read through most of the threads but may have missed it. Thanks in advance. Edited January 25, 2013 by wamba2000 Quote Link to comment Share on other sites More sharing options...
valkraider Posted January 25, 2013 Report Share Posted January 25, 2013 I think you have to remove screws and take off the back plastic pieces to actually remove or replace the 12v battery. Quote Link to comment Share on other sites More sharing options...
PWBarrett Posted January 25, 2013 Report Share Posted January 25, 2013 Lift the hatch in the cargo area. Remove the rubber pad in the bottom. Remove the plastic panel under that.Here's how much of it is visible at that point:(I haven't looked into how many screws you'd have to take out after that.) Quote Link to comment Share on other sites More sharing options...
Tom Posted January 30, 2013 Report Share Posted January 30, 2013 So if you need roadside assistance for a jump start, where do the cables get attached? Quote Link to comment Share on other sites More sharing options...
zhackwyatt Posted January 30, 2013 Report Share Posted January 30, 2013 (edited) So if you need roadside assistance for a jump start, where do the cables get attached?There are posts under the hood in the front of the car for jumping. Edited January 30, 2013 by zhackwyatt Quote Link to comment Share on other sites More sharing options...
valkraider Posted January 30, 2013 Report Share Posted January 30, 2013 Also, this car barely needs "jumping". It's more like a small hop. You can actually provide enough juice to wake the electronics with just the 12v adapters in the car itself... Quote Link to comment Share on other sites More sharing options...
Tom Posted January 30, 2013 Report Share Posted January 30, 2013 Thanks Quote Link to comment Share on other sites More sharing options...
roninsd Posted January 31, 2013 Report Share Posted January 31, 2013 Check out p. 255 in the manual. Quote Link to comment Share on other sites More sharing options...
DaveofDurham Posted January 31, 2013 Report Share Posted January 31, 2013 Also, this car barely needs "jumping". It's more like a small hop. You can actually provide enough juice to wake the electronics with just the 12v adapters in the car itself...Are you saying that if the 12 volt battery is depleted to the point where you can't start the car and the hybrid battery has power that you could make a connection from the 12v adapter in the car to the under the hood terminals for the 12 volt battery and use power from the hybrid battery routed through the 12 v adapter in the car to jump the 12 battery? Quote Link to comment Share on other sites More sharing options...
MikeB Posted January 31, 2013 Report Share Posted January 31, 2013 Dave, I think you just violated a law of physics or something there.... I've got a set of jumper cables that go from the 12v adapter in one car to a 12v adapter in another, they don't provide much current but will charge one battery off another. Since the C-Max doesn't need much power to boot the computer, this type of adapter is probably sufficient, rather than a heavy-duty set of jumper cables that most cars would use. Quote Link to comment Share on other sites More sharing options...
DaveofDurham Posted January 31, 2013 Report Share Posted January 31, 2013 (edited) Dave, I think you just violated a law of physics or something there.... I've got a set of jumper cables that go from the 12v adapter in one car to a 12v adapter in another, they don't provide much current but will charge one battery off another. Since the C-Max doesn't need much power to boot the computer, this type of adapter is probably sufficient, rather than a heavy-duty set of jumper cables that most cars would use. I don't think the laws of physics are a problem here. In valkraider's message, it said " You can actually provide enough juice to wake the electronics with just the 12v adapters in the car itself..." If the 12v battery is dead and the hybrid battery has power, and if the hybrid battery is the source of power (and I do not know if it is) for the 12v outlet and other accessories, then in theory you could get energy from the hybrid battery through the 12v outlet to the 12v battery to give the 12v battery a jump, Here's what I can't figure out. I don't think the 12v outlet is hot (energized) when the car is totally off. The car needs to either be started or put in accessory mode to energize the 12v outlet. The car can't be started if the 12v battery is dead (that's the problem we are trying to overcome). In order to turn the car on you without trying to start it (get car in accessory mode) you need to press the start button without your foot on the brake or turn the key to accessory position, but if the 12v battery is dead I don't know if accessories will be energized when you press the start button without your foot on the brake or turn the key to accessory position. I defer to someone who knows more about how these aspects of the C-Max function or someone who Edited January 31, 2013 by DaveofDurham Quote Link to comment Share on other sites More sharing options...
valkraider Posted January 31, 2013 Report Share Posted January 31, 2013 I mean there are jump start devices which plug in to the 12v adapter. There is another thread here where people have posted links to the devices. I'll have to look for the thread. I believe the 12v connector in the cargo area and the one in the console cubby are always hot, so juice should be able to flow in to the 12v system just as it flows out of the 12v system via those outlets. I'll look for the thread... Quote Link to comment Share on other sites More sharing options...
salman Posted January 31, 2013 Report Share Posted January 31, 2013 The 12 volt battery is 12 volts. The LiOn is high voltage. The power in 12 volt outlets in the car is 12 volts and comes from the 12 volt battery and, when the car is running, from a step down converter that converts high voltage from the LiOn battery down to 12 volts. When the car is off, any current in the 12 volt outlets is from the 12 volt battery and the connection to the step down converter is off. Here is what can possibly be done, apparently tested by some posters: A 12 volt battery booster can be plugged into a 12 volt outlet rather than connected to the jumping posts for the 12 volt battery (posts are under the front hood, battery is in back under the cargo area). The booster sends power through the 12 volt outlet to the 12 volt battery, and all that is needed usually is a quick flash to start the car. pomtrey 1 Quote Link to comment Share on other sites More sharing options...
valkraider Posted January 31, 2013 Report Share Posted January 31, 2013 Here is where we discussed these sorts of devices: http://fordcmaxhybridforum.com/index.php?/topic/361-battery-dead/page-7 Quote Link to comment Share on other sites More sharing options...
pomtrey Posted January 31, 2013 Report Share Posted January 31, 2013 The 12 volt battery is 12 volts. The LiOn is high voltage. The power in 12 volt outlets in the car is 12 volts and comes from the 12 volt battery and, when the car is running, from a step down converter that converts high voltage from the LiOn battery down to 12 volts. When the car is off, any current in the 12 volt outlets is from the 12 volt battery and the connection to the step down converter is off. Here is what can possibly be done, apparently tested by some posters: A 12 volt battery booster can be plugged into a 12 volt outlet rather than connected to the jumping posts for the 12 volt battery (posts are under the front hood, battery is in back under the cargo area). The booster sends power through the 12 volt outlet to the 12 volt battery, and all that is needed usually is a quick flash to start the car. i like that answer! after our car suffered a dead battery for the second time, we bought a jump-starter (by peak, 600 amps) which we haven't needed to use, gratefully. but if i am alone and ever needed to jump the battery, i would so rather plug it into the 12 volt outlet than work with the jumper cables. i am assuming that the jump starter is the same as the battery booster yr referring to, or at least can be used in the same way. hopefully, it will NEVER be an issue again. that is my dream. Quote Link to comment Share on other sites More sharing options...
salman Posted February 1, 2013 Report Share Posted February 1, 2013 Pomfrey Please call Ford (both your dealer's service department & Ford's Customer Care line) and let them know you have had dead batteries twice, if you have not already done so. As you can see from the dead battery threads there are many of us who have had the same problem and we are trying to get Ford to figure out the cause and correct the problem. They are more likely to put their engineering teams on it to the extent they face the fact it is not just an isolated problem effecting only a couple of cars. Quote Link to comment Share on other sites More sharing options...
Paul Murray Posted January 30, 2014 Report Share Posted January 30, 2014 Check out p. 255 in the manual.pg 255 in my manual is "wheels and tires". Mine is pg 189, jump starting your vehicle. Quote Link to comment Share on other sites More sharing options...
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