Ha, after all this i just found out that the 2020 express cutaways come with a 150amp alternator standard. That's still not enough for fast charging, but a small charger shouldn't be too much issue. I'll have to use a clamp meter and do some testing to confirm, especially since I'm planning to add a powered sub to the cab.
The 2020 express had an option for a 220amp alternator that's available on Amazon for $285. Swapping to the 220 alt, running a second power wire direct from the alt (so that vehicle electrical wiring doesn't need to be swapped) to a renogy 12/24 20 ($157 on amazon) and then using the remote on/off tied to a spare engine run/stop circuit in the fuse block seems to be the lowest cost option to get some reasonable amperage to the battery. Including wiring, fuses, and misc. cost ~$500 and deliver 720w max, 480w continuous.
For my 5.6kwh pack limited to 10-90% charging (4.5kwh effective) it'd take ~9 hours to fully charge, but this is just to supplement solar so that seems sufficient to me.
The only other reasonable option is the victron 12/24 10 ($69) on the current alt, but that might be pushing it a little bit close without doing some more vehicle level electrical testing. Specs for that unit say 20a max, 10a continuous. I'd have to add a relay tied to a spare engine on/off circuit. I'm pretty sure I could add the relay to the 24v side right? That'd drop me down from a 50a relay to a 30a, but I'd have to find one that switches on 12v with an output is rated for 24v. Might be easier to find a 50a rated normally open relay and switch everything on the 12v side. Total cost for this is probably ~$120-150 but only nets 240w continuous, 480w max. 18 hours for a full charge, basically just a trickle.
Last pie in the sky option is swapping to a custom high power alt (highest I'm seeing is 400amp for $480 https://www.phoenix-alternator.com/...ess-3500-Base-6.0L-V8-364CID-Alternator/3-GB/) and a wakespeed ($680) plus the required bits and bobs. Probably ~$1300 total cost and should give 125+ amps at idle assuming 100a as the max vehicle load. 1500w+ of continuous power at idle that could go as high as 180a at speed keeping a 70% alternator max current limit. 2,160w+ during highway driving sounds pretty nice tbh. You'd take a noticeable hit to fuel economy though, 0.2125 gal/hr on idle, and 0.306 gal/hr at speed. I get ~15mpg at 60mph driving without the truck built out yet, theoretically you'd take a 7.65% hit to fuel economy dropping down to ~13.85mpg.
The 2020 express had an option for a 220amp alternator that's available on Amazon for $285. Swapping to the 220 alt, running a second power wire direct from the alt (so that vehicle electrical wiring doesn't need to be swapped) to a renogy 12/24 20 ($157 on amazon) and then using the remote on/off tied to a spare engine run/stop circuit in the fuse block seems to be the lowest cost option to get some reasonable amperage to the battery. Including wiring, fuses, and misc. cost ~$500 and deliver 720w max, 480w continuous.
For my 5.6kwh pack limited to 10-90% charging (4.5kwh effective) it'd take ~9 hours to fully charge, but this is just to supplement solar so that seems sufficient to me.
The only other reasonable option is the victron 12/24 10 ($69) on the current alt, but that might be pushing it a little bit close without doing some more vehicle level electrical testing. Specs for that unit say 20a max, 10a continuous. I'd have to add a relay tied to a spare engine on/off circuit. I'm pretty sure I could add the relay to the 24v side right? That'd drop me down from a 50a relay to a 30a, but I'd have to find one that switches on 12v with an output is rated for 24v. Might be easier to find a 50a rated normally open relay and switch everything on the 12v side. Total cost for this is probably ~$120-150 but only nets 240w continuous, 480w max. 18 hours for a full charge, basically just a trickle.
Last pie in the sky option is swapping to a custom high power alt (highest I'm seeing is 400amp for $480 https://www.phoenix-alternator.com/...ess-3500-Base-6.0L-V8-364CID-Alternator/3-GB/) and a wakespeed ($680) plus the required bits and bobs. Probably ~$1300 total cost and should give 125+ amps at idle assuming 100a as the max vehicle load. 1500w+ of continuous power at idle that could go as high as 180a at speed keeping a 70% alternator max current limit. 2,160w+ during highway driving sounds pretty nice tbh. You'd take a noticeable hit to fuel economy though, 0.2125 gal/hr on idle, and 0.306 gal/hr at speed. I get ~15mpg at 60mph driving without the truck built out yet, theoretically you'd take a 7.65% hit to fuel economy dropping down to ~13.85mpg.
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