Use 24v Batteries to run 12v System... Possible?

[furyous68]

Sorry for the long post....

Hi everyone. I am new here. I am an RV greenhorn... don't even own one yet. But, we're in the market & the biggest thing I want out of it is to be as self-sufficient as possible. The very first thing I will be doing (besides checking over the engine, trans, rearend, and general health of the coach) is updating the charging system with a solar system. I do not want to run the generator unless absolutely necessary. I HATE when other campers run their generators for 12 hours out of the day, & I refuse to be one of them.

I'm looking at a 12v/24v solar system w/ a 60A MPPT controller. I know I could use 1 or 2 12v AGM batteries. BUT... I'm really interested in seeing if it's possible to run the RV's 12v system off of 1 or 2 24v batteries. If so, I could use 1 or 2 smaller batteries & due to you only needing to pull 1/2 the amps @ 24v's. I assume you would need a step-down converter between the 24v batteries & the 12v converter in the coach... right?

Somebody school me!

[theoldwizard1]

time2roll wrote:

theoldwizard1 wrote:
Achieving proper multi-step charging will be the BIGGEST problem to solve !

Done:

http://www.bestconverter.com/DLS-Series-24-Volt_c_145.html

Some of the NOCO chargers will do 24V, but they are $$$ !

[2oldman]

jplante4 wrote:
There was nothing in the OP's OP that mentioned tent camper.

2nd post.. his reply to you.

[jplante4]

drsteve wrote:
You seem to be saying that because the OP is a tent camper rather than an RV owner, he's not supposed to have an opinion on generator use? That if he owned an RV his attitude would NOT be judgmental and prejudicial?

There was nothing in the OP's OP that mentioned tent camper.

[drsteve]

jplante4 wrote:
I didn't see any reference to LOUD generators. That debate has raged here several times and usually results in a closed thread.

I would remind all the generator haters that there are several reasons to run a generator. Just ask anyone who uses a CPAP how they get by of solar only. Don't get me started on the Keurig users. When someone who doesn't own an RV writes " I HATE when other campers run their generators for 12 hours out of the day, & I refuse to be one of them.", that's judgmental and prejudicial.

You seem to be saying that because the OP is a tent camper rather than an RV owner, he's not supposed to have an opinion on generator use? That if he owned an RV his attitude would NOT be judgmental and prejudicial?

[time2roll]

theoldwizard1 wrote:
Achieving proper multi-step charging will be the BIGGEST problem to solve !

Done:

http://www.bestconverter.com/DLS-Series-24-Volt_c_145.html

[2oldman]

jplante4 wrote:
When someone who doesn't own an RV writes " I HATE when other campers run their generators for 12 hours out of the day, & I refuse to be one of them.", that's judgmental and prejudicial.

Maybe so, but it's how most people I've dry camped with feel about it. If you have special power needs I think it behooves you to invest in enough batteries to get through the night. I really don't think that's a big imposition on ONE person who otherwise disturbs the entire campground.

[theoldwizard1]

MrWizard wrote:
...
but how will you charge the 24v bank, solar ? special charger from 120v ?

special add on 24v alternator for the engine ?

Achieving proper multi-step charging will be the BIGGEST problem to solve !

[furyous68]

pianotuna wrote:
Hi,

It would be best to get the RV before purchasing solar panels that may not fit.

As for power--make a wants vs needs list. For example I want to run an induction hob, but I NEED to run the furnace.

furyous68 wrote:
I was actually looking at a 600w system w/ monocrystalline cells & a 60A mppt controller. It's only 4 panels. When I get the RV, I'll see if I have room to put another 2 panels on top.

Was just browsing... not purchasing 😄 . As far as RV's go, I'm looking at models between 28' & 31'. I've looked at a couple 2006 Fleetwoods, a 2010 Thor, and a few Winnibegos. I really like the layouts of the Fleetwoods. They both had under 80,000 miles... but I'm always leary of buying something that old.

[jplante4]

I didn't see any reference to LOUD generators. That debate has raged here several times and usually results in a closed thread.

I would remind all the generator haters that there are several reasons to run a generator. Just ask anyone who uses a CPAP how they get by of solar only. Don't get me started on the Keurig users. When someone who doesn't own an RV writes " I HATE when other campers run their generators for 12 hours out of the day, & I refuse to be one of them.", that's judgmental and prejudicial.

[2oldman]

furyous68 wrote:
I think I read that you need to generate at least 35A from the panels to charge a 24v battery... is that right?

No, amperage only determines how long it takes. You must be pumping 28.8 volts into it, which means your solar must be something greater than that.

drsteve wrote:
I and most others would suggest that the inconsiderate dolts who run loud generators all day are the ones who don't belong.

Agree.

[drsteve]

jplante4 wrote:

However, if you're already passing judgment of how other people pursue their recreation, maybe this isn't the lifestyle for you.

I and most others would suggest that the inconsiderate dolts who run loud generators all day are the ones who don't belong.

[MrWizard]

the only thing that works better at 24v, is an inverter

your bank might be 24v, but unless you buy a purpose built 24v lithium battery, any other 24v system will be built using 6v batteries or 12v batteries

yes you can get a 24v to 12v converter, for the house systems

but how will you charge the 24v bank, solar ? special charger from 120v ?

special add on 24v alternator for the engine ?

[time2roll]

With 600 watts of panels and a 24v battery you only need 25 amp controller.
24v x 25a = 600w and you will very rarely if ever actually get 600 watts produced unless tilted perfectly at the sun at noon.

https://www.lithiumion-batteries.com/products/24-volt-lithium-batteries/24v-100ah- $2600

[pianotuna]

Hi,

It would be best to get the RV before purchasing solar panels that may not fit.

As for power--make a wants vs needs list. For example I want to run an induction hob, but I NEED to run the furnace.

furyous68 wrote:
I was actually looking at a 600w system w/ monocrystalline cells & a 60A mppt controller. It's only 4 panels. When I get the RV, I'll see if I have room to put another 2 panels on top.

[furyous68]

time2roll wrote:
To be independent you need more battery, not less. To get more from solar or from the dreaded generator consider a lithium battery. Going to be a bit extra up front but could be the last battery you buy.

Yes for a larger system going 24 or 48 volts will have an advantage. I assume you are thinking 800+ watts solar.

Yes you can get a DC/DC converter to power the 12v accessories. I recommend Victron.

I'm really interested in the LiIon batteries. Just don't have that kind of cash yet. But definitely will be saving up to switch over to a set of those at some point in time. 1 100Ah LiIon runs around $1500.

I was actually looking at a 600w system w/ monocrystalline cells & a 60A mppt controller. It's only 4 panels. When I get the RV, I'll see if I have room to put another 2 panels on top.I think I read that you need to generate at least 35A from the panels to charge a 24v battery... is that right?