Pure Solar vs. Solar+Alternator

[arctictraveller]

Originally Posted by carringb

Depends on your driving vs parking time. New vans have 500 amps of Alternator output, so that’s 6,000 watts.

That seems a bit high to me. Anyway, I'd go for both as solar output can be all over the map depending on the weather, location, shading etc. In winter, the sun is not as strong, and can be lower on the horizon in addition to the snow on the panel. A broom may not be able to remove all the snow and ice that has frozen to the panel, with the result being partial shading. A small amount of shading can reduce the panel output significantly. In Alaska and the Pacific North West, my three 100w panels are not really enough to keep my two 6vdc golf cart batteries fully charged despite only running a small refer, a couple LED's and the propane heater at night. The cost to run a wire from the alternator shouldn't be too much, and to save money you could use a simple disconnect switch until you saved up for a better, automatic system. My system uses a starter solenoid energized by an ignition on source, so anytime the engine is running all batteries are combined and when the engine is off, they are separated. It's not the best, but the solenoid can be had for around $30 or less.

[carringb]

Originally Posted by arctictraveller

That seems a bit high to me.

Ford transit now has dual 250 amp alts from the factory, with a 250 amp lug off the smart junction box for secondary battery system charging, which allows that system to still integrate with smart charging (mild regen basically, once you hit about 80% charge) and auto start stop.

https://media.ford.com/content/dam/f...Tech_Specs.pdf

[AndrewInSeattle]

Originally Posted by Kibo

Wowza, that low?! Great point though, latitude/location matters.

Well, obviously it varies greatly, but most of the prime camping sites near us -- even on the coast -- are in heavy forest, so you get filtered sunlight at best. We may park out in the open in winter, and sometimes get into the double-digits of amperage on a sunny day around noon, but that's rare and doesn't last long!

[Twoxentrix]

Brp - some great points being contributed here & many variables we all must contend with which we have little control over...other than hoping for the best. Have you considered supplementing your power supply utilizing a portable generator for those instances when all else doesn't work in your favor???

[JohnandMandi]

We have one 255W 37V panel, a Blue Sea Systems ACR, and one 200 amp/hr AGM battery. That setup has served us well for over 5 years of living in the van full time. We may replace our house battery battery with 2, haven’t decided yet. What we like about the ACR is that it is 2-way. When either the solar or the alternator is maintaining at or over 13v the banks are connected to top off all batteries. We do have the remote switch for the few times we don’t want the banks connected. Doing over we’d still have both. There were times of inclement weather or excessive heat where we crammed in the shade that reduced our solar input well below acceptable. Supply runs or repositioning got us back to 100%.

[Scalf77]

You can have both. Bogart Engineering states their SC2030 can also be used as a DC to DC charger. So with a little extra work you can have solar and alternator charging. Throw in their TM2030 battery monitor and you have a pretty nice system for a small battery bank.



just need to size that relay accordingly.

-greg

[BCam]

Renogy also has a combination solar controller/DC-DC charger. It's more expensive, but it's an MPPT controller:

https://www.renogy.com/dcc50s-12v-50...ger-with-mppt/

[Kibo]

I'm pretty happy with the Kisae DC-DC, but one feature of the Renogy caught my eye:

• Trickle charges the starting battery via solar panels if the service battery is fully charged.

That would be a cool feature to have! That said, I don't think it would work with my Lithium BMS and I think I would still prefer the Kisae due to the display.