12v alternator: is 24v system worthwhile?

[MrBond]

Given that my main source of power is the 120a 12v alternator on my camper van, is it worth going to a 24v system? It seems step up converters have high losses, negating any benefits. I boondock, so rarely plug in but am interested in using EV chargers.

I am looking at a comprehensive upgrade for the 1993 B350 camper so that I can add ac for my service dog and I. My 3 way fridge also died so that's part of the mix. Most of my lighting and USB outlets are better on 24v, with just some fans on 12. Expecting to replace the 200ah of lead acid with 400ah at 24v,.and around 600w of solar.

I'll detail more once I figure this first step, as have been going round in circles. I'd originally planned 48v but 12v alternator charging is a nightmare.

Thanks!

 

[S Davis]

Given that my main source of power is the 120a 12v alternator on my camper van, is it worth going to a 24v system? It seems step up converters have high losses, negating any benefits. I boondock, so rarely plug in but am interested in using EV chargers.

I am looking at a comprehensive upgrade for the 1993 B350 camper so that I can add ac for my service dog and I. My 3 way fridge also died so that's part of the mix. Most of my lighting and USB outlets are better on 24v, with just some fans on 12. Expecting to replace the 200ah of lead acid with 400ah at 24v,.and around 600w of solar.

I'll detail more once I figure this first step, as have been going round in circles. I'd originally planned 48v but 12v alternator charging is a nightmare.

Thanks!

I would stick with 12v and get a dc/dc charger. I have 560ah @ 12v on my work truck and charge at 50 amps with a Redarc 50 amp dc/dc. The Redarc has solar input, I don’t use it so don’t know how well it works. Probably a 30 amp model would work.

 

[justinm001]

If you're switching from lead acid then you'll want a DC DC converter or multiple. Doesn't really matter is 12/12 or 24/12 or even 48/12 I believe efficiency is the same. Also efficiency doesn't matter much, 1hp makes like 900w so even if 80% efficient you're only burning 1.2hp vs 1hp. You can typically get a larger alternator cheap if that's an issue

 

[chrisski]

Given that my main source of power is the 120a 12v alternator on my camper van, is it worth going to a 24v system?

Probably not.

If you're consistently running 1000 watts for hours on end then yes. If you go up to 2000 watts for several minutes, then yes.

upgrading to 24 volts is only good if you are going to be pushing huge amounts of amps.

 

[MrThisIsME]

You running the fridge off propane I assume?
As mentioned efficiency would be somewhat the same. but the upfront cost will bite you as you will need to buy a 24vdc-to 12vdc convertor as well if you change voltage. Which would be a good enough argument to stay at 12v for a low AH system.
Either way you would need a battery charger to charge off the alternator. 12v and 24v are readily avail, but to find a 12v to 48v charger on the cheap, not going to happen. Only a few avail and the cheapest is like $800.

FYI charge time coming off a 12v alternator would be the same for a 12v, 24v, 48v system. Power is power.

 

[MrBond]

Many thanks everyone.

The fridge used to run on propane, but I've never found them that good in high temperatures. Prefer a compressor design for that. I'll be keeping propane for heat and cooking.

Back to 12v then! First job will be upgrade the puny wiring from the starter battery to the back. Surprised it never got hot.

 

[RV8R]

I will throw this out there fir your consideration;

If your van’s alternator has the capacity & you are sticking with 12v, you could consider an inverter run by the alternator then 120vac to where your batteries are to a 120vac to 12vdc charger. 120vac wiring can “go long” runs with say 12 gauge wire ,,, the length ( van length ) for a 120vac icircuit is almost not a consideration for 12vac.

Or

I like the Kisae 1250 as a DC2DC charger because it is very user programable & you can limit the current from 5amps to 50amps in 5amp increments. Nit sure what your 120amp alternator can spare for the house batteries .

DMT1250 – Kisae Technology Inc

https://www.kisaepower.com/wp-content/uploads/2020/04/AbsoCharger_Manual_DMT12V_24V-Series_Rev-D_190612_Print.pdf

There are some extremely efficient 12vdc fridges out there. TF130 is pretty good.

 

[time2roll]

2000w inverter will easily run a small air conditioner. I would stick with 12 volts.
Be careful with the DC-DC chargers as the input amps can easily be 50% greater than the output amps. I would be closer to 20 amp rated output with a stock 120a alternator.

May need a utility connection or a generator in that TX summer heat.

 

[S Davis]

I ran 1/0 DLO to the dc/dc charger, there is very little voltage drop it pulls about 52 amps and charges about 49 amps.

I ran from the aux battery with a 125amp fuse and then into a 125amp breaker and to the rear of the truck. I wrapped the DLO in spiral wrap under the truck for extra protection.

 

[S Davis]

The charge lines run up through the floor in the back of my crew cab to the charger, that feeds a 600amp buss bar where my two 280ah batteries and 12/3000 Victron inverter tie into.

I also have a 1/0 charge line going to the truck bed with a lift gate plug for 12v power in my commercial cap.

 

[Vigo]

I would stick with 12v as long as you can get an inverter that will power your loads. With 400ah of lifepo4 you could support some huge loads as long as the batteries are near the inverter and the wiring between them is large enough.

I have a 12v system with a 5kw MSW inverter and 460ah of lifepo4 in my RV and i have never once considered moving to 24 or 48v. Too easy to just keep paralleling batteries in or moving them around etc. The flexibility is worth a lot to me.