Re: 48 volt all-electric coach plans
Reply #3 –
Yes, I think once you have an AGM battery bank for the 12V House, then a separate Lithium 48V bank for the 110V distribution in the bus is the way to go. But, unfortunately, the pricing on Lithium with built in BMS at this time, July 2021, is twice that of a good quality AGM. So, for now, I think Firefly OASIS Group 31 AGMs is a better bang for the buck, at least for me.
As some of you know, I'm also investigating a 48V system for the 110V part of the house. I'm taking a slightly different approach.
1 - I have already purchased 8 of the Firefly OASIS Group 31 AGM batteries to put into the battery compartment where the bus had 3 8D Gel House batteries. Those used to be charged by a Xantrex Prosine 2.5. The Xantrex is coming out. In its place, a Victron Multiplus II 12/3000/120-50 2x 120V will be installed. That setup will be a 928 AH 12V battery bank dedicated exclusively to the 12V distribution of the bus. I don't plan to take the OASIS batteries below 30% SOC.
Note: But, for now, I will be using those batteries temporarily, along with the Multiplus for both 12V and 110V for the bus.
2 - In the future, I plan a separate battery bank for the 110V. That will be managed by a Quattro 48/10000/140-100/100 120V. That bank would ideally be 4 of the Battleborn BBGC3 in series for a total 270 AH at 48V. The reason for the BBGC3 is because of their convenient form factor. Four of those and the Quattro will fit nicely and take less than 2' in the back of one of the compartments in the bus. The relative low weight of lithiums per AH compared to Lead Acid is also nice. I don't plan to take the Lithiums below 20% SOC.
Update (7/1/2021): So, all of the above with the BBGC3 would be ideal, but price is a constraint. So, the Firefly OASIS will be used for the 48V and 12V banks.
- My plans are to keep the Propane/Electric refrigerator and propane stove. I already have Aquahot for heating.
- Since propane will satisfactorily take care of refrigeration and cooking and the Aquahot takes care of heating, the 110V battery bank will easily take care of supporting 1 of the 15000 BTU AC while driving.
- The 140 amps of charging from the Quattro will work great with the 270 AH lithiums. That is because the 10 KW generator could bulk charge those batteries in less than 1.5 hours or so. Then solar could absorption charge for the rest of the day.
Note: But, because the BBGC3 are not currently in the budget ($2900 ea.), I shall wait for a sale on those to start on that project. If the OASIS were available in the form factor of the BBGC3, I could have used those instead. May be Battleborn would like to sponsor this project. 
Update (7/1/2021): I will use the Firefly OASIS for both banks.
3 - With the 1 Quattro in the bus and the Lithiums, I will then add another 48V battery bank at the homestead and another 48V Quattro and set them up in a split setup for home power backup. But, that is another future project.
4 - I also like Peter's idea of upgrading the alternator to 430 amp. That's another future project. I will trigger that project if I ever decide to buy a Hybrid or electric toad. In that case, I could have one or more BBGC3 installed in a box next to the Chassis batteries by the engine. Another appropriate inverter could sit back there. I could then pump alternator sourced juice into the electric toad while traveling to some destination. Alternatively, I could have the inverter in the back of the bus keeping the Multiplus and Quattro at the front of the bus charging the House banks, both 12V and 110V, by pumping 110V to them, at the loss of efficiency.
5 - Future solar for all battery banks.
The above setup would work great to provide AC while driving, while boondocking and also for charging an electric toad. I just need to keep reworking the budget!
Topic: 48 volt all-electric coach plans