RV 24v almost ready, I hope!

[gr8pix]

Here is my close to final draft of the months long learning experience. I added a second 24V battery in parallel and hope my fusing is correct from the batteries to the Lynx. Should I be fusing each battery at the positive terminal as well or fusing each battery with it's own class T? Please let me know if there is anything that needs attention.





I couldn't have gotten this far without the help of this forum and the amazing dedicated people helping each other out. Thank you MisterSandals, sunshine_eggo, pvgirl just to name a few!

 

[upnorthandpersonal]

Should I be fusing each battery at the positive terminal as well or fusing each battery with it's own class T?

Personally, I would. Every battery in parallel should have its own fuse. If something goes wrong in one of them, and this creates a short or low resistance path, the other battery will dump its energy in there as well - so for this reason, add a fuse to each battery.

 

[chrisski]

A couple comments.

1) You have two 70 amp inverter wired in parallel with 4 AWG wire, rated for 70 amps. Could be 140 amps going through this.
-Also, I have one of those 70 amp Orions and it moves my slide outs in and out and levels my 12 K RV with no issues. I am puzzled at how many cranking amps it delivers. I’m not sure two will deliver enough to start a generator.
-I have 2 AWG wire into mine, and that really is the max that will fit with a crimped lug. Two lugs won’t stack on top and be secured, so this may effect your wiring.

2) I have two 24 volt batteries, each with their own class T fuse, and an additional class T fuse after they’re combined. Those class T fuses and holders are huge at 6”, so fitting three takes up some space. Battery busbars what you have as distribution blocks and two class T fuses took up as much space as a single battery, half as tall.

3) Your bus bar your mini ANL fuses sit in, is it rated for what three SCCs could push? I only ask because it looks like a Blue Sea product that is rated for a 24 volt system, but only to 50 amps.

4) I prefer 4/0 after the batteries are combined for a 24 volt system. This is what I have for my 3 kW inverter. It’s got to do with low voltage inverter pulling higher current at 20 volts to meet the same wattage. I think the Victron may be a 2.4 kw inverter, And if so 2/0 would be fine.

 

[Checkthisout]

Here is my close to final draft of the months long learning experience. I added a second 24V battery in parallel and hope my fusing is correct from the batteries to the Lynx. Should I be fusing each battery at the positive terminal as well or fusing each battery with it's own class T? Please let me know if there is anything that needs attention.

View attachment 183494



I couldn't have gotten this far without the help of this forum and the amazing dedicated people helping each other out. Thank you MisterSandals, sunshine_eggo, pvgirl just to name a few!

Go with 48 Volts.

 

[chrisski]

Go with 48 Volts.

I do disagree with the 48 volts for RV builds.

Mostly because there are plenty of 12 volt accessories available, and a few 24 volt accessories available, but almost no 48 VDC accessories. What 24 volts will get you that 12 volts won’t is fast charging, and perhaps a 24 VDC fridge. Less loss on the wire that is probably already installed.

If there were 48 VDC accessories easily available like LED lights or USB Quick Charge, I’d be all for it.

 

[Checkthisout]

I do disagree with the 48 volts for RV builds.

Mostly because there are plenty of 12 volt accessories available, and a few 24 volt accessories available, but almost no 48 VDC accessories. What 24 volts will get you that 12 volts won’t is fast charging, and perhaps a 24 VDC fridge. Less loss on the wire that is probably already installed.

If there were 48 VDC accessories easily available like LED lights or USB Quick Charge, I’d be all for it.

What voltage is the chassis?

The widest variety of neato ? RV stuff is 12 volts.

I would run 48 Volts then just use a step-down transformer to run the DC stuff.

On my cabin I went 24 volt because I found a very cheap multiplus 24 volt.

48 is easier, especially if you plan to DIY batteries. Less BMS to buy, less charge controllers and you could just throw a single 48/5000 Quattro in there.

 

[gr8pix]

Personally, I would. Every battery in parallel should have its own fuse. If something goes wrong in one of them, and this creates a short or low resistance path, the other battery will dump its energy in there as well - so for this reason, add a fuse to each battery.

Thank you, that has always been my gut feeling on this. I was contemplating going with a couple of Marine Rated 225A MRBF's on the POS terminals and then after the distribution block and before the disconnect go with a 225A class T. The more I've been researching I'm quite surprised at the number of people that run parallel setups without fusing the positive terminals, especially on these lower priced Chinese batteries.

 

[upnorthandpersonal]

Thank you, that has always been my gut feeling on this. I was contemplating going with a couple of Marine Rated 225A MRBF's on the POS terminals and then after the distribution block and before the disconnect go with a 225A class T. The more I've been researching I'm quite surprised at the number of people that run parallel setups without fusing the positive terminals, especially on these lower priced Chinese batteries.

I made this drawing for JK, because before that they did not recommend running the BMSes in parallel with multiple batteries.

JK 4S 200A BMS

If parallel battery packs are required, the same voltage can reduce the chance of failure, But it's hard to achieve, Or add a discharge diode in each battery pack, which is the way we are currently considering How is the same voltage hard to achieve? 90% of the charge curve is at the same...

diysolarforum.com

 

[gr8pix]

A couple comments.

1) You have two 70 amp inverter wired in parallel with 4 AWG wire, rated for 70 amps. Could be 140 amps going through this.

Originally I had both Orion's wired to one slot on my Lynx Distributor and it was suggested to me to give them a dedicated slot and fuse each accordingly. I may size the wire down to 6 AWG , I could probably get away with 8 AWG on the 24V input side but will need the 4 AWG on the 12V output.

-Also, I have one of those 70 amp Orions and it moves my slide outs in and out and levels my 12 K RV with no issues.

Do you have a class A? if so I could use some info on wiring this in to the 12V DC side. Is it as simple as just disconnecting the charger/converter and inverter and replacing the Orion output to the DC Distribution

I am puzzled at how many cranking amps it delivers. I’m not sure two will deliver enough to start a generator.
-I have 2 AWG wire into mine, and that really is the max that will fit with a crimped lug. Two lugs won’t stack on top and be secured, so this may effect your wiring.

I sure hope it doesn't, I may have to use another bus bar if need be.

2) I have two 24 volt batteries, each with their own class T fuse, and an additional class T fuse after they’re combined. Those class T fuses and holders are huge at 6”, so fitting three takes up some space. Battery busbars what you have as distribution blocks and two class T fuses took up as much space as a single battery, half as tall.

This is the one I'm using for the batteries, it seems to be of good quality and marine rated https://www.amazon.com/Tocas-Power-Distribution-Busbar-Copper/dp/B0B7WQ98NX

3) Your bus bar your mini ANL fuses sit in, is it rated for what three SCCs could push? I only ask because it looks like a Blue Sea product that is rated for a 24 volt system, but only to 50 amps.

I'm going to look into this, thanks for bringing to my attention.

4) I prefer 4/0 after the batteries are combined for a 24 volt system.

The wire sizing relative to the power draw of the Multiplus II and not the combined max discharge of the batteries. ie: 3000W / 20V cutoff / .85 efficiency = 176A I think I'm already oversized.

This is what I have for my 3 kW inverter. It’s got to do with low voltage inverter pulling higher current at 20 volts to meet the same wattage. I think the Victron may be a 2.4 kw inverter, And if so 2/0 would be fine.

 

[chrisski]

Do you have a class A? if so I could use some info on wiring this in to the 12V DC side. Is it as simple as just disconnecting the charger/converter and inverter and replacing the Orion output to the DC Distribution

I do not have a class A. I have a fifth wheel.

I wired my 12 volt converter directly into where the battery cables for the 12 volt battery used to be.

If I placed mine to the DC distribution panel with the fuses, that is located past a couple of circuits and would have bypassed a couple of circuits and possibly left the positive live where the battery used to be.