Pipes1578 Posted January 31, 2023 Report Share Posted January 31, 2023 Hello everybody! I'm new to this forum. I just purchased my daughter her first car and it's a 2013 C-Max SEL energi. Just curious if anyone here has installed a battery tender to keep the 12volt battery charged when not in use. We live in the midwest and it gets COLD! All my other vehicles (non hybrid) have tenders on them to keep charged under cold weather. Has anyone installed one on your hybrid? Pro's and con's? I asked my local dealer and they did not seem concerned about it. Just would like some feedback if anyone has installed one yet? Thanks again! -PK Quote Link to comment Share on other sites More sharing options...
SnowStorm Posted February 2, 2023 Report Share Posted February 2, 2023 Do you plug it in at night to charge the main hybrid battery? If so, that might keep the 12V charged too (I don't have an Energi so don't know the answer). Otherwise, you should be able to connect the tender to the two posts under the hood (driver's side) where you jump-start if the 12V is dead. Quote Link to comment Share on other sites More sharing options...
cr08 Posted February 2, 2023 Report Share Posted February 2, 2023 Unless you have other battery drain issues, I wouldn't worry too much about the 12v battery and cold weather. Unlike traditional ICE only vehicles, these only use a comparatively tiny amount of juice from the 12v battery to start. It's just used long enough to get all the computer modules woken up and running. If the ICE needs to spin over, that is done by the HVB. And likewise just as a note since it trips some new owners up who aren't familiar with hybrid vehicles: No alternator in these. Instead there's a solid state DC-DC converter which takes power from the HVB and converts down to the 12+V for the 12v battery and auxillary systems. This is in full operation any time the vehicle is in Ready to Drive mode (the green vehicle indicator with the arros on the dash) whether the ICE is running or not. Also as @SnowStormpointed out, plugging in an Energi model via the EVSE also has limited capabilities to charge and top up the 12v battery. Under normal operation while the HVB is charging, it'll keep the 12v battery maintained since that's needed to operate the necessary modules during this process. Once the HVB is charged, the 12v battery will continue to charge until the vehicle is satisfied that it is topped up. Once this is complete it will completely shut down and the vehicle will go to sleep. It WILL NOT initiate additional charge cycles on its own unless you actively wake the vehicle by opening a door or unplugging/replugging the EVSE. If you do want to add a battery tender, there are a couple options available: 1) Some owners have added a 12v cigar lighter plug and utilized the socket in the cargo area. This is hot at all times and gives a fused, direct feed to the 12v battery. 2) Use the jump start terminals under the hood. You'll only be able to use the 'alligator clamp' style connections here. 3) You can dig in and attach leads to the 12v battery directly. You will want to make sure this is wired up AFTER the current sensors installed on the factory leads. This will allow the vehicle to be aware of the energy you are putting in and manage the battery accordingly. I have a thread where I detailed an inverter install and there are pictures showing where I wired it up which may be helpful: Quote Link to comment Share on other sites More sharing options...
Pipes1578 Posted February 22, 2023 Author Report Share Posted February 22, 2023 Thanks cr08! Very informative. I really appreciate your feedback. C-MaxA2 1 Quote Link to comment Share on other sites More sharing options...
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