12v? 24v? 36...48v????

Boon Docker wrote:

2oldman wrote:

Grit dog wrote:
This is becoming laughable. Talking 2/0 and 4/0 cables. Lol. U think he’s using the batteries to start his diesel truck 20 ft away or what?

I don't know why you're hurling insults. He's loading up on a lot of power. Have you never read the manuals for large inverters and see what cables they recommend?

Typical response. :R

Me or him?

Doesn’t matter if he has 100 batteries. He only has a 30A service.
Nowhere did the OP say he was going to install a 20kw inverter to power his own private microwave tower from his campsite.
And I’ll repeat for those hard of reading. It’s a 30A camper.
Oh and, now I’m making suppositions, but I’m supposing he wants the large reserve cap to be able to not have to fire up the genny in the backcountry. Which with 1000a or whatever he said and too much solar on the roof will accomplish spectacularly all in the 12v realm.
No 2, 3 or 4/0 needed either to pull max cap on a 30a camper thru an inverter if he’s really wanting to run his air conditioner 24/7 off of batteries….which would be a poor choice anyway albeit totally possible.
Maybe he’s upgrading the panel in the camper and also putting in an 11cf resi fridge, a chest freezer for flash freezing that early archery elk, whole, lol and enough 120v lights on the camper to p!ss you guys off from 2 counties over….
But he didn’t say that, or even allude to pulling huge loads that would be clearly advantageous to up the DC voltage significantly….. and then step it back down for ALL the DC loads in the camper.

Feel free to tell me what I’m missing here. But you can’t use silly things like cordless tools are more than 12v and he’s buying a lot of batteries….

What’s next?
The SIO2 or some other unobtanium batteries speech?
It’s a camper, not a NASA space station!

pianotuna wrote:

Cptnvideo wrote:
True, Don. But all DC components in a RV are 12 VDC to start with.

So power all the 12 volt loads from the converter, and power the converter from the inverter.

Or get a 40 amp output (on the 12 volt side) 48 volt dc to 12 volt dc box. Renogy makes one for under 200

It I were going Li, I'd consider this unit (or something similar):

48V 230Ah 11.7Kwh LiFePO4 Server Rack Battery

SKU: OP48V230 $3,300.00

https://www.opsolarbattery.com//product-page/48V200AH?utm_campaign=08da4453-007b-4130-b9b1-bac79ecfc523&utm_source=so&utm_medium=mail&cid=1987e189-3977-48cd-883e-0f8c4cdf22b7

And it gets better….only 3300 bucks? Where do I sign up for this deal? Lol
What the heck are you smokin up there?

This thread is like all the ones where “you should buy a Tesla, it’ll save the earth, save you money and rub yer ballz all at the same time…”. While driving your 2003 Honda accord with faded headlights, a whiskey dent and an oil leak… preaching the words of Lord EV!
Hahahaha

I mean EVs are more than 12v, so it makes sense, right?

afidel wrote:
Personally I'd run the 12V stepdown converter into a 12V battery, either lithium or SLA. That way peak loads for the slide motors and compressor motor get taken up by the 12V battery and the 12V converter can just top that off. I know there are folks that team a couple of 12V stepdowns together to supply the loads, but it has to be much more stressful on the components in them than if there was a decent pool of ampacity there. Since you aren't actually using it for storage capacity a 50Ah 100A LiFePO4 would work great and they're like $160.

The big advantage of 48V is you can use a much cheaper MPPT controller since they're basically priced on output amps and 48V is 4x lower amps for the same watts. Wiring costs are also much lower since you get to drop down to wire gauges which are commonly available instead of double 0 or triple 0 cables.

but thats like I said, keep the battery side all 12 volt and use a MPPT charger (more expensive by the way not cheeper) and stack the panels to 24v. you could probably spend a little more and get one that will handle a 48 volt input, but I don't know if it would be worth it for most people in a rv setting. the one problem you do run into with a all series run is shading.. in a home system where you have solar out in the open it isnt an issue, but for a lot of camping it is. I guess you would have to look at the price increase to a 48v input MPPT VS the upgraded wire size for the 24V setup. wiring is going to be an issue anyway you look at it with the size he wants to run so it will have to be resized.

edit, I did look at my brand and a MPPT charge that wil handle a 48V input is only 160.00 more canadian (one size biger) so it will be tight as to which way is cheeper, but I would go that way myself four 24V panels in a 48V series / parallel set up get the smaller wire size and you get some protection from shading.

pianotuna wrote:

Cptnvideo wrote:
True, Don. But all DC components in a RV are 12 VDC to start with.

So power all the 12 volt loads from the converter, and power the converter from the inverter.

Or get a 40 amp output (on the 12 volt side) 48 volt dc to 12 volt dc box. Renogy makes one for under 200

It I were going Li, I'd consider this unit (or something similar):

48V 230Ah 11.7Kwh LiFePO4 Server Rack Battery

SKU: OP48V230 $3,300.00

https://www.opsolarbattery.com//product-page/48V200AH?utm_campaign=08da4453-007b-4130-b9b1-bac79ecfc523&utm_source=so&utm_medium=mail&cid=1987e189-3977-48cd-883e-0f8c4cdf22b7

why when there is no need for it? you got used server rack batteries for a screaming deal so you converted,, or for some reason you had it at 48V before you converted to server racks. if you would have went LiFePO4 you wouldnt have had the drooping issues that made you need a higher voltage ;)

StirCrazy SiO2 make lifepo4 look bad when truly large draws are needed. So why would I get a battery that has essentially a "limiter" (otherwise known as a BMS) on it at 1 C????

StirCrazy Serial panels with bypass diodes which all large panels have is more shade tolerant than parallel panels and this is especially true when there is shade like a A/C involved. It's a factor but not necessarily hugh.

I wanted a more efficient system but adding another panel may be a better price performance option.

For me 1500W solar systems "require" the larger 60/72 cell panels and MPPT. 12V panels for 1500W is certainly possible but last time I looked more panel cost and more panel square footage.

Since an RV is chock full of 12v appliances (btw, that work seamlessly!), there’s no practical advantage to a higher voltage system (excluding a solar PV MPPT config) and up-converting and down-converting UNLESS you are trying to power a high amperage motor at a considerable distance (something like an anchor winch at the far end of a boat…), whereby AWG wire gauge economy is paramount. Otherwise, it’s mostly about discussion points - Great for Coffee!!

3 tons

StirCrazy wrote:

afidel wrote:
Personally I'd run the 12V stepdown converter into a 12V battery, either lithium or SLA. That way peak loads for the slide motors and compressor motor get taken up by the 12V battery and the 12V converter can just top that off. I know there are folks that team a couple of 12V stepdowns together to supply the loads, but it has to be much more stressful on the components in them than if there was a decent pool of ampacity there. Since you aren't actually using it for storage capacity a 50Ah 100A LiFePO4 would work great and they're like $160.

The big advantage of 48V is you can use a much cheaper MPPT controller since they're basically priced on output amps and 48V is 4x lower amps for the same watts. Wiring costs are also much lower since you get to drop down to wire gauges which are commonly available instead of double 0 or triple 0 cables.

but thats like I said, keep the battery side all 12 volt and use a MPPT charger (more expensive by the way not cheeper) and stack the panels to 24v. you could probably spend a little more and get one that will handle a 48 volt input, but I don't know if it would be worth it for most people in a rv setting. the one problem you do run into with a all series run is shading.. in a home system where you have solar out in the open it isnt an issue, but for a lot of camping it is. I guess you would have to look at the price increase to a 48v input MPPT VS the upgraded wire size for the 24V setup. wiring is going to be an issue anyway you look at it with the size he wants to run so it will have to be resized.

edit, I did look at my brand and a MPPT charge that wil handle a 48V input is only 160.00 more canadian (one size biger) so it will be tight as to which way is cheeper, but I would go that way myself four 24V panels in a 48V series / parallel set up get the smaller wire size and you get some protection from shading.

What I was saying is that a 30A MPPT can put ~1,500W into a 48V system, to accomplish the same with a 12V battery system requires a 120A MPPT controller which are 3-4x the cost and several times the size and mass.

3 tons is correct. To add, 48 volt systems in a house make total sense. But not in a RV that comes equipped with 12 VDC components designed to run off 1 or 2 batteries.
The OP wants 1500 watts solar and 12 kwh batteries, which is similar to what I have. My 12 volt system has a grand total of 16 feet of 4-0 wire. So I don't see wire size/cost to be the issue as some on here do. And no 48-12 or 120-12 converter to overload or fail.