I will list the way it is desired to work in real life camping based on what I have arbitrarily picked as what I think the "best practices" for real world use. Probably nobody will fully agree with them, but most everybody also has different ideas about what is best for lithium in general, including the upfitters and manufacturers so that is expected.
* The system is wired with the alternators parallel and controlled by one Wakespeed remote regulator.
* The manual, remote switched, Blue Sea separator is still in the system, but it has moved from the firewall to right next to the lithium pack in the rear. The Wakespeed voltage sense wire is at the separator on the cable from the alternators so the sense wire will control the voltage when the lithium bank is disconnected, but still be accurate when charging the lithium pack.
* The plan is to operated the lithium bank mid range as much of the time as we can. Roughly 40-70% SOC or so. We would only charge to 90-95% if we were going to not be driving for a long time, like a week, but tanks will be full way before that so not likely to happen.
* With the lithium bank out of the charging circuit while driving, which will probably be 80% of the time, we can manually switch charge voltage by a switch on the dash to activate the feature input on the Wakespeed. With lithium we will be at 13.7-13.8v in absorption and when just the lead acid is in the system we can move that up to maybe 14.1v to top off the starting battery. Turning off the feature input switch allows it to go to float which will be about 13.2v.
* We can start the van with lithium pack in or out of the charging system so when we don't need charging we just leave the separator open and use the van normally and drive away. If we have somehow killed the starting battery the separator can be closed to start the engine and then disconnected right away.
* Staying midrange in SOC does not have to be a very accurate process as it really doesn't matter where it is in the range when we stop charging. A quick look at the battery monitor to see how many AH we are down and using time will be plenty close, as we found out on our test trip even with less than stellar voltage amperage holding of the Charles regulator. The charging amps are controlled to setting by the Wakespeed looking at battery amps, not total, so it will hold that charge amp rate no matter how many loads are on or the engine is using more going up a mountain. This will make predicting charge time super easy. We are going to be set 120 amps but will use the Wakespeed feature of "shaping" the charge rate at different rpm ranges to reduce that at idle and off idle to improve the loading of the engine and serpentine belt at those speed. It will also reduce heat gain under the hood at low speeds and idle and also run the alternators cooler. Steady on highway will will average very close to 120ah per hour charging and in town probably in 80-100ah per hour range, I think. Our test trip showed the charge efficiency to be very close to 100% in the midrange charging so getting a recalibration of the battery monitor will rarely be needed, I think. I will probably have different control in the shore charger to use it to go the probably 90% SOC and have the monitor set to reset as full at that point.
* Using power as we want without saving any intentionally (new concept for us) but not using the AC on batteries, we found we used in the 60-70ah per day on the test trip. It was cooler so we had the propane furnace running almost every night on that trip and it used maybe 8-10ah overnight and with the occasional daytime run in the morning. We have much more capacity than we could get by with so it will likely make life really easy on the road and probably eliminate shore power almost all the time unless we need AC. We never plugged in on the 30 day test trip without issue at all and were in places normally about 3 days but at the end of the trip we didn't charge for 6 days so we would be 40-50% for overwinter storage.
Questions and comments are welcome as the whole lithium thing is still evolving and the fact that retrofitting into older lead acid battery systems makes it all a lot more difficult for everyone to determine what to, especially with very contradictory information coming out of the sellers and manufacturers of drop in style lithium batteries. Ours are considered drop ins and we are running them on the internal BMS systems in them. They are 12, 206ah, SOK plastic case batteries. There are 3 in parallel for 618ah.
I still need to get the time delay relay in and that put back together and make the guarding around the batteries as they are in the storage under the bed so might get knocked on once in a while.
I am putting together the pix that I have and getting them sized and named, but will need to take a bunch more and will start getting them posted as time allows.
We are looking forward to spring so we do a bit setting tweaking before we do a 3 week spring trip.
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