Inverter/12volt-24 volt question

Yes, you'll need a DC-DC converter to get back to 12v. Victron makes good ones. And you'll need a 24v charger to do it right. PM me.

Properly connected (two sixes are wired differently than two twelves at the batteries) there will be no difference with any 12 volt appliances.

Your battery charging system ( converter and solar) will be for 12v. You would have to do each 12v battery one at a time with the converter. The PWM solar controller might be one of those that can do 24-24 or 12-12.

An MPPT controller has a buck converter so it can be used as the DC-DC with 24v input and put out 12v but has amps limits depending on its amps rating.

DIVE2XS wrote:
Hi,I have a tundra 24 inverter that I took out of my Freighter semi and am installing in my tt.
I am taking out 2 6volt batteries and repacing them with 2 12volt bateries.

The 2 12V batteries will not have much more run time than your current 2 6V batteries. Depending on your load, 4 6V batteries would be better and I will get they would live longer !

Unless you’re operating an electric motor (i.e. a reactive type load), I’m not seeing enough of a practical advantage - JMO…

3 tons

DIVE2XS wrote:
Hi,I have a tundra 24 inverter that I took out of my Freighter semi

If the tundra is modified sine wave, this is not worth the effort.

How many watts is the Tundra?

The battery bank will need some method of charging. Choices are solar, stand alone battery charger, 24 volt converter, or dc 12 to DC 24 device.

By the time all the necessary equipment is added, it may not be worth will using the Tundra.

Thanks for your responses. My original intent was to utilize what I already have to both keep the cost down and investigate a design a system for a future RV.
The Tundra is a 2000 watt inverter. Not sure but I think it is a modified wave.
My friend did all the wiring and set up for this system. He did so using the 2-6 volt Trojan batteries and it didn't work. I replaced all the electrical outlets on the 20 amp circuit thinking that I had a short. Didn't work.
I installed switches to isolate the inverter from the shore power.
You most likely saw in my signature the I have a 100 watt solar on my rig. I don't think that I used it maybe more than a few times. It doesn't put out enough energy with the 2 50 watt panels.
I would like to learn more on what I can do with my 2 6 volt batteries even if I have to get another inverter.
For the time being, I don't need the solar. I would like to be able to run 2 CPAP machines at night. I want to run the refrigerator while driving instead of using the propane. Most likely I could charge the batteries while driving from place to place.
Is a 2000 watt inverter large enough to run that 20 amp circuit?
Any ideas would be appreciated.
Thanks

DIVE2XS wrote:
Thanks for your responses. My original intent was to utilize what I already have to both keep the cost down and investigate a design a system for a future RV.
The Tundra is a 2000 watt inverter. Not sure but I think it is a modified wave.
My friend did all the wiring and set up for this system. He did so using the 2-6 volt Trojan batteries and it didn't work. I replaced all the electrical outlets on the 20 amp circuit thinking that I had a short. Didn't work.
I installed switches to isolate the inverter from the shore power.
You most likely saw in my signature the I have a 100 watt solar on my rig. I don't think that I used it maybe more than a few times. It doesn't put out enough energy with the 2 50 watt panels.
I would like to learn more on what I can do with my 2 6 volt batteries even if I have to get another inverter.
For the time being, I don't need the solar. I would like to be able to run 2 CPAP machines at night. I want to run the refrigerator while driving instead of using the propane. Most likely I could charge the batteries while driving from place to place.
Is a 2000 watt inverter large enough to run that 20 amp circuit?
Any ideas would be appreciated.
Thanks

Well, you’d have to do somewhat of a redesign just to be able to utilize the 24v inverter, so if it were me I’d simply stick with the two 6v batteries (in series to arrive at 12v) and get a decent pure sine wave inverter…A 2000w inverter could provide approximately 16 or so amps, so if wired into an existing circuit you’d want to avoid exceeding that amount (e.g. by avoiding simultaneous multiple large appliances…). I doubt your CPAC approaches that amount, but your refer may well (??)…One other thing to remember with 12v dc is to make sure your inverter cables are sized correctly for the particular load (AWG Gauge and round trip to inverter cable lengths) - this should not be assumed or overlooked…

3 tons

DIVE2XS wrote:
My friend did all the wiring and set up for this system. He did so using the 2-6 volt Trojan batteries and it didn't work.

No. It's tough to get 24v from 2 6v batteries...if that's what you mean.

Can you identify the tundra 24 you have from this web page?

https://www.tundrainverters.com/en/all-products/

What I'm seeking to know is if a 24 volt input or not?