4@12v = 24v

Hi,

Three 24 volt batteries would require equal length jumpers to a buss bar.

I've actually found two at a Walmart Complex called Harbor Landing. But I'm chicken to plug in. I may try it, if and when I wear out my welcome at Churches I tune for, and friends. I did check them for power and they are both live.

BFL13 wrote:
PT have you found all the live receptacles around town yet? We have one on a pole at park near our place-I guess for Xmas tree lights the city does. The homeless guys in their strange RVs that keep moving from place to place in town discovered it and sometimes one will plug in at night. :)

smkettner wrote:
In order to properly balance six batteries you will need a bus bar.

X2

BFL13 wrote:
Still true that it would be better to have the DC DC converter closer to the 12v panel, so the longer set of wires (the input) would be 24v instead of 12v? (for voltage drop)

You don't necessarily have to worry about voltage drop on the input side of the DC DC converter. As long as it falls within the specs. I'd like to go the 24V route but would need a DC DC converter, 24V inverter and 24V converter (or 24V inverter/charger). Maybe in the next rig.

DryCamper11 wrote:
I'm assuming one advantage of 24 volts is reduced inverter current draw. My inverter is only 1200 watts and still draws 100 amps. Is that the main reason to go with higher voltages, or does the availability of higher voltage solar play into the decision?

In my case, both played a role.

Reduced current draw means smaller wire, which is much easier to work with. My previous 12v- T605 setup had 4/0 to the inverter with #1 interconnects. The interconnects could handle the high-current of something like a MW for a minute, maybe, then things would start to heat up. I did not want to wrestle with bigger interconnect wire, so I decided to up things to 24v.

As for the solar, my pre-wired 5er had #10 from the roof to basement, which wasn't going to cut it for 6 panels in parallel. My Outback controller handles up to 150vdc input and charges 12,24,36, 48 and 60v battery banks. Ya hoo.

The little DC converter is a neat little device (around $100) which keeps my house voltage at 12.5.. all the time.

Salvo wrote:
Charge controllers are current limited. A 12V battery system may limit solar to 300W. The same controller in a 24V system is limited to 600W, while a 36V system is limited to 900W.

Yessir.

BFL13 wrote:
You could make it all 48v instead of 24v too if you were starting from scratch.

Yeah, 4 12s in series would be sweet. From much of my reading about batteries, it's better to have them all in series.

pianotuna wrote:
Hi BFL13,

He already has a 24 to 12 converter--and a 24 volt inverter. I think he should stick at 24 volts for those reasons.

Agree. Sorry I wasn't more clear. I did say if from scratch.

I guess the main motivation is for solar as Salvo mentioned, but I keep looking at this remote power idea but put the Dc to Dc in the RV with no battery. EG could keep all the batts in the truck and when using the RV as a cabin, just do the heavy work (equalizing etc) on the batteries at home between visits to the "cabin" and have solar do what it can.

PT have you found all the live receptacles around town yet? We have one on a pole at park near our place-I guess for Xmas tree lights the city does. The homeless guys in their strange RVs that keep moving from place to place in town discovered it and sometimes one will plug in at night. :)

Hi BFL13,

He already has a 24 to 12 converter--and a 24 volt inverter. I think he should stick at 24 volts for those reasons.

Charge controllers are current limited. A 12V battery system may limit solar to 300W. The same controller in a 24V system is limited to 600W, while a 36V system is limited to 900W.

Sal

BFL13 wrote:
You could make it all 48v instead of 24v too if you were starting from scratch.

I'm assuming one advantage of 24 volts is reduced inverter current draw. My inverter is only 1200 watts and still draws 100 amps. Is that the main reason to go with higher voltages, or does the availability of higher voltage solar play into the decision? Given that you need 12 volts anyway for many RV devices, which means a DC to DC converter is needed, I wonder about the various pros and cons, cost, etc.

Does anyone want to comment? Or provide a link? Are there other advantages to 24V or higher? (If this is too much OT, just let me know. I don't mean to hijack the thread, but it looked like it had dealt with the main topic and was now drifting a bit anyway. I'm just curious about this higher voltage option.)
Thanks.

Very neat. One of the issues with the "remote power supply wagon" parked somewhere near the RV so you can just plug your shore power into its inverter (where the RV has no battery and you don't want to run the converter to make 12v) is that it would be too far to also run DC wires to the remote wagon.

At least with the Dc Dc method, you could have that in the Rv and the DC input wires for it from the wagon would be at 24v so they could be thinner wires.

You could make it all 48v instead of 24v too if you were starting from scratch.

BFL13 wrote:
so anything using the frame as neg path works?

Would it also work to just go from the DC DC output neg to frame and have just the pos wire?

The DC DC converter has 24v input, so it would go on the same batt posts as the inverter?

Still true that it would be better to have the DC DC converter closer to the 12v panel, so the longer set of wires (the input) would be 24v instead of 12v?

I guess so.. I don't know what is frame grounded and what isn't.

Don't know.

It is connected to the inverter terminals. And about 1' from them..it's the blue thing. It's infinitely variable from 12.0 to around 13.0. I keep it at around 12.5.

Ok so the DC DC converter has two output wires to the 12v DC panel, which is frame grounded, so anything using the frame as neg path works? Would it also work to just go from the DC DC output neg to frame and have just the pos wire?

The DC DC converter has 24v input, so it would go on the same batt posts as the inverter? (Mex would make busses there so there is only one wire per batt post)

Still true that it would be better to have the DC DC converter closer to the 12v panel, so the longer set of wires (the input) would be 24v instead of 12v? (for voltage drop)