Mike Reyher
I made a personal discovery camping this weekend and found nothing searching the group on this so here goes. We were camping off grid in overcast conditions and it rained a good part of the time.
We have 400W of solar with a small system to run our fridge, Internet, CPAP with a 100AH Battleborn battery (since upgraded) . We never needed to but always thought we could just charge at idle if we ran short on power and this time that's what we decided we needed to do. So we started the 2020 Transit and I checked and saw 14.1 v input to the charger and putting out around 25A (Renogy DCC50S). After about 15 min the input voltage dropped below 13v and the charger stopped charging. I shut the motor off and started again. Again, 15 min and and then the voltage drop. When we got back home I saw an unrelated post on the Transit Forum about cancelling the start/stop also stops Smart Regenerative Charging (SRC) and keeps the voltage above 14v. So I ran an experiment here at the house, cut the solar input and drained the battery to 61%. I then started the van and cancelled the start/stop with the button on the dash and watched the system. Sure enough, I was getting near 50A (solar shut off) via the alternator and the voltage and charging held at those high levels and topped off the battery in about an hour as you can see below. So, if you want to charge at idle, cancel the start/stop and it will also cancel SRC.
Found in the 2020 BEMM
To be clear, at the campsite the house battery got down to 48% Saturday morning as shown below. Note that the times you see the starter battery at zero is when CCP2 is disconnected by the BCM. I am considering switching to CCP1 as I have never seen a full 50 amps output from the charger so it will not exceed the 60A capacity of the CCP1 battery connection.
And here you can see my attempt to charge at idle without cancelling start/stop.
And here is the point where we drove home (in the rain) for a couple of hours and it charges normally. Solar was connected limiting alternator charging but it got to a full. charge. Th regular little up/downs in voltage and current at rest is the fridge cycling on/off.
