Energi dead 12V battery after storage - need advice

[BobRay]

My 2016 C-MAX Energi was stored outside in the sun (plugged in) for six months in Florida. The 12V battery was dead as a doornail.  It didn't seem to take a charge so I replaced it.

 

I think the battery was original, so at five years it was probably due anyway, but it's possible that the storage killed it. I have to store the car again each summer and could used some advice. It won't be driven at all for six months.

 

First, a couple of questions:

 

1. When the Energi is plugged in, does that charge the 12V battery?

2. Is the cooling fan that runs during charging powered by the 12V battery?

3. Does that fan ever run when the car is not plugged in?

4. Is there a way to prevent the HV battery from charging beyond 80%?

5. Ditto for the 12V battery

 

Now for the advice.  My thought for the HV battery is to leave the car plugged in, but put a timer on the cord so it only charges at night and only for a limited time each night. 

 

For the 12V battery, the car has a charge control in the engine compartment from when I towed it behind my RV it takes 12V input.  I think it helps prevent overcharging, so I'm thinking about connecting the output of an 8-amp charger to input of the charge control unit, and also putting the 8-amp  charger on the same timer. 

 

Does that sound reasonable?  IF so, what do you think I should set the timer at for the best battery health?

 

Thanks for any help!

 

 

[cr08]

1) Yes. When plugged in it will maintain the 12v battery up to a point. Part of the charging procedure is once the HVB is finished charging, it'll continue to top off the 12v battery until it is deemed full. However I do believe once this has happened, it stops monitoring until something else 'wakes up' the vehicle like Go Times, remote starting, opening a door, etc.. Sitting over summer it'll probably just charge once during the initial HVB charge cycle and then stop there.

2) From a technical standpoint, yes. However during this time the EVSE is maintaining the 12v battery charge. This cooling fan is for the actual internal charging system for the HVB.

3) The particular cooling fan you hear while charging only runs during that time. It does not run while unplugged or when the vehicle is being driven. As noted above, it is just for the charging system. Additionally, the actual cooling fans for the battery do not operate normally during charging. They only operate while the vehicle is being driven (as requested by the vehicle programming). There's ways to trick it to run during charging (Namely you plug it in while the vehicle is still running and then shut it off. The cooling fan will continue to operate as needed while the charge cycle is active. It is my understanding once the charge cycle ends, all of this resets so the battery cooling fan will not run on a subsequent charge cycle. I'm not 100% on this though.)

4) Not that I am aware of short of just manually monitoring and managing it yourself. Supposedly with the 4G modem upgrades and the move to the FordPass app instead of MyFordMobile adds a charge level restriction setting, but it is unconfirmed if it actually works for the C-Max since MFM never had that feature and the vehicle may not be programmed to take advantage of it.

5) Same. However the vehicle has intelligent battery monitoring and management for the 12v battery so it's not going to overcharge/cook the 12v battery being plugged in a lot.

 

If the charge controller acts as a battery maintainer, you could easily work with that. With outboard chargers, I'd worry about ensuring they are designed to maintain the battery and not just act as a simple charger/jump starter. Worst case, you can buy an actual battery maintainer almost anywhere that will be more than sufficient for this purpose.

Edited December 30, 2021 by cr08

[cr08]

Ultimately if it is being parked over the summer, what I'd do is charge the HVB up to about 50% to 80%, no higher. You'll need to monitor and do this manually as I noted above. Unplug and leave it when it reaches this point. Then hook up a battery maintainer to the 12v battery and leave it be. Should be no need to set it on a timer unless you want to for energy consumption reasons. The 12v battery is going to be a bit more resilient and a proper battery maintainer is going to keep it in an optimal state and are designed to be run consistently for long term storage.