Ford C-Max 12V Battery Replacement Including HV Disconnection 

Thanks for the SuperThanks! I really appreciate it.

Glad you enjoyed it! Wish there was a voting process on RU-vid myself...

😂😂😂

Ignorant can be fixed. Stupid maybe not.

Wow, I’m glad it was so easy!

Hey, so glad this was helpful to you! Have a good one.

Glad you were able to get it done. Definitely worth it to remove the high voltage connection to make access easier.💪

Hey Martin, thanks for the comments! Did you get this done on your C-Max?

Thanks for the comments and suggestions for the ODB Adaptor you used. Is this the same one: geni.us/OBDlink_EX

@@DansWay Correct. This is the exact one I bought.

@@winsorro thanks for the confirmation!

Glad it was so helpful!

Thanks for the feedback!

I wonder if the 12 volt jack in the back of the vehicle couldn't be used as a sort of a jump start port. I know it's not going to handle the amperage needed to jumpstart from zero but it could perhaps be used to give a charge over 15 to 30 minutes to the 12 volt battery sufficient to start the car. (I know it doesn't actually directly start the engine.) I was thinking one of those handheld lithium jump start packs would be handy.

Since your battery is working fine and it's cumbersome to replace, I'd wait until it is necessary and then use this awesome video as a guide. You will start to see warning signs of the battery weakening well before you are in dire circumstances. If you are concerned about being unable to start, you could get a small portable NOCO lithium battery pack to easily jump the C-Max using the grey negative post and red capped positive terminal, right side under the hood (or also jump anyone else in need you come across). You could also get a NOCO battery maintainer, which can top off your charge via the same remote battery posts and might buy you some time until one of your battery cells just gives out being able to hold a charge.

I have one of those large socket sets that has both normal and deep sockets. Looks like they are available using Amazon prime: amzn.to/482aV2f

I actually used an extension bar to get it removed ... but after turning it forever, realized the nut on the bottom was frozen. It ended up snapping the bolt when I applied a vice grip on the nut to stop it spinning!

Thanks for the comment!

Thanks for the compliment! I worked hard to try to make the steps clear enough to follow for everyone.

I appreciate the comments!

Hey there, so I don't have a specific battery recommendation. I went to my local parts shop and put in the best battery they offered. I would suggest an AGM battery due to the fact that they don't have the same spillable acid inside. for the manual reset process, I didn't do it myself because I wanted to do it with my ODB scanner to see things actually changing. I would strongly suggest owning a scanner. For the cost it lets you see what is going on and diagnose all of your vehicles before you take them to the shop (if at all...)

Wow, I haven’t heard of that problem before. Let us know how it goes, and what the fix was.

Although others have said otherwise I believe the reset for the battery is just a fancy timer to tell you when to get a new battery. This is probably because it's so inconvenient to have a dead battery in one of these cars. But I don't think it has anything to do with the charging correctly or not that just doesn't make any sense. I and many others have replaced our 12 volt batteries and didn't reset and there are no consequences practically speaking.

You are exactly right, an AGM battery would be much better for this location. In the video I did show the re-installation of the breather tube at 13:38. My replacement battery had holes on both sides, so I had to cap the one closest to the bumper.

Thank you very much! Have you done this yet?

thank you for that comment - my family just bought a 2014 C-Max Hybrid and I'm suspecting we'll need to replace the battery at some time. Really grateful for this video and the community of commenters!

Wow, Rudy, you slammed through that change! Did you remove the HV connection as well?

@@DansWay Yes, sir. I did everything you did. Since you went through the discovery process, I did not have to. I did use an electric ratchet that sped up the removal of parts. I made sure not to over-torque.

@@rudeman80 Awesome! Thanks for your input. Glad to know this can be done quickly once the process is understood...

Thanks for your comments! Once I got this installed (and replaced the faulty water pump that was running randomly when the car was off), all the errors I was getting on the car went away so I haven't thought about it again since. Let me know if you found an AGM that would work in this form factor as that would be preferred for many reasons.

Not sure how to do that easily. Removing the panels only takes a few minutes with the right T30 bit. Just give it a try and you can have it out in less than 10 minutes.

Thanks! Did you get this done on your C-Max?

I just didn't like the way the power connector was all scratched up by Ford's service department replacing it in the past so I researched what it takes to remove it. You don't have to for sure... Just less likely to smack it when removing the battery, and you don't have to stand the battery on end to get it out with the conector removed.

I'd pull the plug from the old battery to put it on the new one myself. The fumes around it will be acidic, so whatever you suff in there needs to be plastic for sure.

@@DansWay Aha, of course! Thank you! Now that I'm in that far I see that the old battery has such a plug. Some folks were talking about duct tape, didn't sound optimal.

I just manually connect to the wifi signal from the ODB adaptor before opening the app. Let me know if that work for you.

I don't think it should be an issue, just make sure the car is fully off, and been off for a while so it is only using the low-voltage battery at most.

Mine did this and just needed new spark plugs. I've never had a hybrid specific problem on my c-max just run of the mill gas car problems.

I'm having the same problem, John. Did you get it resolved.

The only time that happened to me I needed spark plugs. No lie most of the problems you have with a hybrid are going to be the same problems you have with any gasoline engine car.

Wow, great adaption. I love it! I actually got the datasheet for the connector itself and saw the exploded view. There were also some numbers on the connector that implied that the tabs needed to be pried up. I assume there is some official tool, but a simple screwdriver makes it move just fine... 👍

Yah, sounds like it could be time. You could put a charger on overnight to top it off and see if there is any difference after that.

Actually I did that one a few weeks ago: Easy Ford C-Max LED Headlight Replacement ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-MTSYAH0UG-8.html

I agree the turn signals are a pain in that you have to add ballast resistors. I’m doing that turn signal video now so hopefully that video will drop in two weeks.

Thanks for the comment. I haven't had a prblem with the interior panels myself. Are you saying that the clips don't stay engaged in the door even after being replaced? So strange... There are typically a whole series of clips around the perimiter (sides and bottom), then one or more screws that hold it tight to the door. Those screws should be keeping the panel around the door handle pulled tight against the metal structure of the door. Perhaps those are missing, or the part they screw into is missing/broken/cracked?

@@DansWay thank you for the insight. Dealership said clip where replaced. Don't believe them their lips are moving. Iam going to go and get the clip kit you used on battery video and do it myself. Can't make it any worse. Ty again.

​@@charlotteowens4644, let me know how that works out. Not sure those clips will be what you need unless they look right to you. Take a look at the design. Could it be more like this? amzn.to/3sqqK3H

Removing the battery doesn’t change any settings. It won’t work without the battery so it won’t know any better about the battery being removed.

The kiey is to connect to the Foreseal WiFi scanner using your wifi connection in settings on your phone. Once connected, then open the app and it should find it no problem.

Also, I had to “reset” the tailgate too. Had to close it manually then it would open and close. Unless because I didn’t reset battery life. But I had to do the windows too.

@@Dcris78interesting! I haven't heard of that one myself. Are you saying it wouldn't close automatically at all?

Aw man, what a pain. How’s your back? Any other tips you can suggest?

@@DansWay Back is fine. I'm just amazed Ford designed it like this. The only thing the 12V really needs to do is turn the HV relay on. They could have made it much smaller.

Got it, sorry about that problem you are having! The way to fix that problem is to open the driver door with the mechanical key, then pop the hood. From there, you can use jumper cables to apply power to the car using the red power tap located on the driver side of the car. That will power up the car computer and allow you to use the trunk hatch release/lift.

That is a great price from the dealer! The quote I have is $110 from Ford...

@@DansWay I'll take it. I don't move around as well anymore, and felt that the $40 was worth it for the time lol.

I got the same price from the ford dealer of $110-120.

@@BigKy-Mart Was this a ford dealer? It seems they are independent from ford, like some one local from an alley tire shop.

@@Luiblonc No, Buick/GMC store where I work. No discount on labor. A bit higher than the standard battery install fee of $30.

Hey Mike, Yah there are some phantom draw problems with some cars that tend to kill the 12V battery quickly. Do some google-searching and you will see lots of potential reasons. I found that my car's water pump was running continuously, or in strange 'waves' faster/slower even when the car was off. Replacing the water pump eliminated the battery problem for me. Definitely a DIY task if you are handy. Another possibility is the radio not shutting off. That is another one where twice in the past year I have had to pull out a fuse under the glovebox (F69 I believe) which basically reboots the entertainment computer. The computer is always running, and can crash or get stuck in a mode so it never enters power-down mode. The speakers will turn off (except for the dash mounted one for some reason), but it will also run down the battery.

My brother had problem with battery. Took over a month to get someone "certified " to troubleshoot. After scanning everything was ok. What was happening was key fobs were week. If hybrid can't sense the key fobs the engine won't let start. $10 to replace fob batteries fixed the problem.

You can hook up jumper cables or a jump pack under the hood to apply 12 to the system so you can pop the hood. Let me know if this helps.

@@DansWay Yeah, I ended up doing that before I read your message. Just kind of odd that, unlike most vehicles, the CMAX seems to have no manual method of opening the hatch from the inside. I looked through a bunch of forums about it. Anyway, thanks for the video on switching out the battery!

It's not easy TBH. Best method I have would be to measure the battery voltage over a period of hours to see if the voltage is going down over time. The first measurement shold be done after several hours since the last use of the battery as well, so you will need to open the hatch and leave it there for an hour or so before taking a first reading, then wait several hours for a second.

You can open the hood and apply power to the 12V system and battery with a battey charger or jumper cables. Once powered, you can pop the trunk.

@@DansWay I wonder if there’s no energy, the trunk can’t be opened?

@@Narek1988Correct, there is no way that I'm aware of to release the latch without applying power to the 12V terminals under the hood to power the 'dead' 12v battery.

Wow, I have no idea what would be going on there. Were the keys working before? Does the alarm sound right away when connecting the battery?

@@DansWay The keys were working before all of this started. The car sat for a couple days while my husband was out of town. I went to use it and the fobs wouldn't let me in. I thought it was the batteries in the fobs. Replaced them without luck. When my husband got back, he did some trouble shooting and that's when he replaced the 12v battery. Recently, the car sat while we did some internet research on the alarm sounding and fobs not working. We went out today to at least try to figure out the alarm. He hooked the 12v battery back up and I was prepared to try a couple of the 'fixes' that I found online, but the alarm didn't start back up. Thank goodness! One thing down! We also tried to reset the battery monitoring system, but the flashes of the bright lights and then pressing the brake pedal didn't seem to work. I tried to program the intelligent keys, but the car doesn't detect either key. We are able to put the key in the 'slot' on the steering column and use that to start/turn off the car. But the remote doesn't work for the door locks or anything else. I replaced the batteries in both, but still no impact. I'll keep looking for a fix online in the hopes we don't have to take it to the dealer to get them reprogrammed. Thanks for your video on replacing the 12v battery ~ my husband looked at several and said your's was the best, and the closest to our 2016 c max hybrid.

@@user-vw2bt7cb7j Any update on the car?

@@DansWay Thanks for checking back. We haven't been able to reprogram the intelligent keys. Haven't found the right thing online. I think we'll have to take it to the dealer for help. Our 'resolve efforts' have been put on hold while we dig out of a couple major snow storms. Hopefully next week we can figure it out. Thanks again!

Hey the@@user-vw2bt7cb7j, whats the update on your car? Did you get it all worked out?

Wow, so strange. I would double check the high voltage connector that is over the battery if your removed it, and the high voltage battery disconnect behind the seat.

@@DansWay I've done that multiple times. Just had it towed to the dealership. 😭

So strange! So what happens when you press on the brake and press start? I've never seen this myself. Anyone else have any ideas?

@@DansWayfigured it out. It was the high voltage disconnect. I didn’t put it back correctly. I was tired and wasn’t fully aware. But once I double checked I realized I forgot to fully connect it.

Hey Bill, did you get this done on your C-Max as well?

Not sure why it didn't work for you. Were you on Android or Apple? I have this one as you can see in the video. Now I did upgrade to the 'pro' version but I don't believe that would be an issue with basic connection.

@@DansWay I’m not sure why either. I’m using the Apple iPhone version. Maybe FORScan Lite changed the coding in the latest version 1.5.16 since they changed the core. It does say on the App page that they no longer recommend ELM 327 adapters. Anyway I ordered the recommended VLinker FD BLE adapter which fortunately is not that much more at $45 and uses Bluetooth which will be much more convenient than the Wi-Fi connection. I’ll let you know if this works.

@@DansWay I got the vLinker FG+ adapter from Amazon (one of the recommended adapters on the Forscan Lite App) and was able to get it to connect to Forscan Lite and to reset the battery age. So I think the Foseal adaptor is no longer compatible with Forscan Lite. Also, I was able to confirm that the manual reset method (flashing highbeams & pressing brake) did not work for me either.

@@Blztrls Ok, I'll have to try using mine to see if it still works. I just used it last night on my daughter's Kia Soul no problem.

You're welcome, hope this was really helpful.

The next step is to use jumper cables connected under the front hood to the jump-start terminal on the driver side of the car. There is a red cap you remove that shows a metal tab you connect to for the + or positive connection to a jump-pack or other car. The negative connects anywhere on the metal frame of the car. This should power the car enough to open the rear hatch with the button on the center dashboard.

Oh man, I can only imagine the mechanics thoughts towards you seeing all that... Thanks for the laugh!🤣

@@DansWay The soft-handed, service writer only said the 12 volt battery was in the back hatch so I threw everything in the back seat 🤷‍♀️ My former rural life taught me to carry survival gear so hey 🤷‍♀️ You know what you don't know until you know it! I do know my hands were tougher than his mushy limp handshake. 💪 - signed, former 20-year ranch wife 🏇

I got a bunch of different problems when the battery was getting weak which is why I chose to replace it.

@@DansWay I going to buy one like that tomorrow and I wanted to know as much as possible information, I make a drive for 30min and looks like was ok. I'm now used worth hybrid vehicles ✋

Are you commenting on the backup camera?

@@DansWay yes, have the same camera, unfortunately no difference

I'm not aware of any memory-saver mechanism for this car. I don't recall even loosing my radio stations for example.

Good to know! Thanks for that 😃

Hey Bill, glad this was helpful. How did your installation go?

Thanks so much for the tip! I really appreciate it!