RV Solar, charging and battery upgrade plan

[justinm001]

The wire I was planning on using is from Amazon seller recommeded by Will in his solar builds. Windynation. Shows its 105 rated.

2/0 Gauge 2/0 AWG 5 Feet Red + 5 Feet Black Welding Battery Pure Copper Flexible Cable + 10pcs of 3/8" Tinned Copper Cable Lug Terminal Connectors + 3 Feet Black Heat Shrink Tubing https://a.co/d/btTPjNm

I'm not seeing the temp rating for the cable on the listing, can you screenshot it maybe I'm missing it. The one temp rating 125c looks to be for the shrink wrap.

Also 105c is very hot I don't like any of my wiring to be warm under normal conditions. When the wires are hot then it'll heat the bays then cause all kinds of issues.

 

[ThrottleAbuse]

My gut tells me to take this slow. Just install the LiFePO4 and see how that does for you. You don't need to change anything to plop LiFePO4 into an FLA system. It won't be optimized, but it won't make blue smoke, either. Once you have some data, then start looking at optimizing it.

I am in no rush. I know I cant just drop in my batteries. I need to at minimum disable my automerge and add the DC to DC charger. If I dont the batteries have the ability to pull 100% of its capacity for hours on end. Adding the bus bars and fusing to them will be helpful if I add anything in the future.

Am I thinking correctly that I could simply just install the batteries and new DC to DC charger and simply use all the current wiring and just run the current wiring from the RV systems already installed to the positive and negative terminals skipping adding the bus bars. Then I only need to be concerned with the parallel wiring connecting the two new batteries. Since they have a BMS rated for 300A I only need 2/0 for this short of a length. In my original layout I was going to use the 4/0 to the bus bars so I knew I would have extra to sue to connect the batteries in parallel. Should I worry about a fuse between the two batteries? Do I rate that fuse at 125% of the BMS then?

 

[ThrottleAbuse]

I'm not seeing the temp rating for the cable on the listing, can you screenshot it maybe I'm missing it. The one temp rating 125c looks to be for the shrink wrap.

Also 105c is very hot I don't like any of my wiring to be warm under normal conditions. When the wires are hot then it'll heat the bays then cause all kinds of issues.

4/0 Gauge Pure Copper Ultra Flexible Welding & Battery Cable

WindyNation's 4/0 gauge welding and battery cable is a highly flexible industrial-grade electrical cable. A high strand cable count combined with a soft, pliable EPDM insulation results in a flexible cable every time. Our cable is resistant to tears, cuts, abrasion, water moisture, and oil-based...

www.windynation.com

Shows in the pic that its rated up to 105C. I dont mind going conservative and putting in larger wire when it comes to safety.

 

[justinm001]

I am in no rush. I know I cant just drop in my batteries. I need to at minimum disable my automerge and add the DC to DC charger. If I dont the batteries have the ability to pull 100% of its capacity for hours on end. Adding the bus bars and fusing to them will be helpful if I add anything in the future.

Am I thinking correctly that I could simply just install the batteries and new DC to DC charger and simply use all the current wiring and just run the current wiring from the RV systems already installed to the positive and negative terminals skipping adding the bus bars. Then I only need to be concerned with the parallel wiring connecting the two new batteries. Since they have a BMS rated for 300A I only need 2/0 for this short of a length. In my original layout I was going to use the 4/0 to the bus bars so I knew I would have extra to sue to connect the batteries in parallel. Should I worry about a fuse between the two batteries? Do I rate that fuse at 125% of the BMS then?

You should use 4/0 and if you're wanting a ton of power from the batteries you should run the 4/0 equal lengths to the bus bar or load.

4/0 is rated 260a at 90c. They have insulation that can handle hotter wires and more amps but trying to pull 600a from 4/0 is crazy, especially if you're connecting 2 batteries together then all 600a would be at that battery terminal.

Fuse needs to be under the wire ampacity limit. Fuses protect the wiring

 

[HarryN]

Hi @ThrottleAbuse

What @HarryN & @corn18 wrote are important.

I might of missed it, but on the alternator side, I did not see what juice you can expect ?

I prefer the Kisae 1250 or now the 12100 as the max amps can be “user controlled / programmed”.


I am just starting to look at your schematic, but note the amperage difference for the inverter vs the rest of the equipment. I might consider splitting the wiring paths from the battery bank into ( 1 Inverter ) & ( 2 Everything Else );

View attachment 207246

With that inverter “out of the way” you might be able to utilize something like a “Safety Hub 150” for both pos / neg bus & fuse block ;

View attachment 207247


View attachment 207248


Are you intending on using 600 amps out of your Epoch Bank? I’m all for planning for future additions / use, but if you look at what your needs are now & what they might become “load calculations” I think it best to be realistic for “now” & “future”.


You didn’t list the RV Loads, but other than the inverter your amps are;

30
125 ( which I understand you are pondering a reduction here ? ) AC2DC charger
50
?? RV Loads


What amps do you expect to be pulling out with the inverter ?

I am going to suggest a slight alternative to what @RV8R posted.

For the 12 volt loads, start at the bus bar with shortish wire and run it to a breaker, perhaps 50 amps.

Then run your 8 or 6 awg wire to a fuse block near your 12 volt loads. This will protect the wire for these smaller loads from the power in the main bus bar.

I like to do a couple of these for loads in various locations so that there is a healthy wire carrying the power the bulk of the distance, but just short runs to the final power end use.

Since the fuse blocks can handle 30 amps, in theory you could just attach the solar to a fuse block instead of the main bus bar. The fuse block might be one of the heavier duty ones like @RV8R suggested as well.

 

[HarryN]

I am in no rush. I know I cant just drop in my batteries. I need to at minimum disable my automerge and add the DC to DC charger. If I dont the batteries have the ability to pull 100% of its capacity for hours on end. Adding the bus bars and fusing to them will be helpful if I add anything in the future.

Am I thinking correctly that I could simply just install the batteries and new DC to DC charger and simply use all the current wiring and just run the current wiring from the RV systems already installed to the positive and negative terminals skipping adding the bus bars. Then I only need to be concerned with the parallel wiring connecting the two new batteries. Since they have a BMS rated for 300A I only need 2/0 for this short of a length. In my original layout I was going to use the 4/0 to the bus bars so I knew I would have extra to sue to connect the batteries in parallel. Should I worry about a fuse between the two batteries? Do I rate that fuse at 125% of the BMS then?

With Li batteries and a built in BMS, I would still put a breaker in between each battery and the bus bar.

There are a couple of reasons.

- If / when the BMS trips, the way that they are re-set is to disconnect it from all other sources of power. Flipping a breaker on / off is so much easier than getting out the tools.

It also is not so easy to tell if they have tripped, so sometimes flipping them on / off can just be reassurance that it is not tripped. This also can replace the need for a fuse in that location.

- When you have a battery based power system with this much "umph", you will want an easy way to turn power off for different sections to work on it and do minor edits.

 

[ThrottleAbuse]

You should use 4/0 and if you're wanting a ton of power from the batteries you should run the 4/0 equal lengths to the bus bar or load.

4/0 is rated 260a at 90c. They have insulation that can handle hotter wires and more amps but trying to pull 600a from 4/0 is crazy, especially if you're connecting 2 batteries together then all 600a would be at that battery terminal.

Fuse needs to be under the wire ampacity limit. Fuses protect the wiring

I dont think I will need to be pulling 600A from the batteries. I just know they are capable of producing that due to the BMS specs. I think the largest single item draw is my Magnum invertor which the specs say can pull 400ADC. I know the 12V system in the RV can pull some at the same time. I would guess its not a very large draw. It would stand to reason that all the wiring coming from the RV to the batteries is all rated correctly and fused safely from the manufacturer. I am not adding any additional draw sources and only adding charging. The Renogy DC to DC MPPT manuel gives me good guidance on specing fusing and wiring there.

Tell me if I have this correct. The 4/0 wiring between the two batteries would be rated for 440A. The max potential draw would 300A due to the BMS. So I wouldnt need a fuse between the batteries. Also since the RV wiring and fuses should be already specced correctely for the items installed I can simply connect all those items directly to the batteries terminal and not need to worry about fusing to bus bars or wiring to bus bars.

If I wanted to be cautious I could for example add a Class T fuse between the two batteries rated at 400A to protect the individual batteries in case something happens catastrophically to one of the batteries. Since max potenital out of the working battery would be 300A so 125% of 300 is 375A. Or is this just a waste of money on a fuse that isnt required?

 

[justinm001]

I dont think I will need to be pulling 600A from the batteries. I just know they are capable of producing that due to the BMS specs. I think the largest single item draw is my Magnum invertor which the specs say can pull 400ADC. I know the 12V system in the RV can pull some at the same time. I would guess its not a very large draw. It would stand to reason that all the wiring coming from the RV to the batteries is all rated correctly and fused safely from the manufacturer. I am not adding any additional draw sources and only adding charging. The Renogy DC to DC MPPT manuel gives me good guidance on specing fusing and wiring there.

Tell me if I have this correct. The 4/0 wiring between the two batteries would be rated for 440A. The max potential draw would 300A due to the BMS. So I wouldnt need a fuse between the batteries. Also since the RV wiring and fuses should be already specced correctely for the items installed I can simply connect all those items directly to the batteries terminal and not need to worry about fusing to bus bars or wiring to bus bars.

If I wanted to be cautious I could for example add a Class T fuse between the two batteries rated at 400A to protect the individual batteries in case something happens catastrophically to one of the batteries. Since max potenital out of the working battery would be 300A so 125% of 300 is 375A. Or is this just a waste of money on a fuse that isnt required?

I wouldn't push over 260a unless I had to because that's the rating at 60c. Regardless of what the wire jacket is rated for.

The wire isn't just a single device but all loads combined and in either direction. So if you're maxing out the inverter at 400a plus 100a random 12v loads that's 500a.

If you ran 4/0 from each battery at the same length to a buss like a Lynx 1000 then fused each there at 260a that would be ideal. You'd have 510a and all loads would be split evenly between the 4/0. Keeping things nice and cool.

I even do this with my 48v system but since 100a I just connect the 2 batteries together

 

[corn18]

Ok, that's a quarter million dollar rig, so let's do this right. You are putting WalMart equipment into a Ferarri.

Get a Victron Lynx distributor for your bussing needs. Don't bother with those buss bars and fuses all over the place.

Connect the batteries in parallel with 4/0 wire.

Connect the batteries to a 400A type T fuse.

Connect the type T fuse to the positive Lynx terminal with 4/0 wire.

Connect the inverter to the Lynx and use a 400A mega fuse in the distributor.

Replace the Magnum inverter with a Victron MPII 3000 120x2.

Basically, just install my system. That coach deserves the best.

 

[justinm001]

Ok, that's a quarter million dollar rig, so let's do this right. You are putting WalMart equipment into a Ferarri.

Get a Victron Lynx distributor for your bussing needs. Don't bother with those buss bars and fuses all over the place.

Connect the batteries in parallel with 4/0 wire.

Connect the batteries to a 400A type T fuse.

Connect the type T fuse to the positive Lynx terminal with 4/0 wire.

Connect the inverter to the Lynx and use a 400A mega fuse in the distributor.

Replace the Magnum inverter with a Victron MPII 3000 120x2.

Basically, just install my system. That coach deserves the best.

View attachment 207377

I agree. Which t fuse did you use on your rig? Also how'd you get the smartshunt to the lynx, just drilled out the hole?

I think imma get a 2nd lynx for my 12v side and clean it up a bit.

 

[corn18]

I got the Blue Sea type T fuse holder:

https://www.amazon.com/gp/product/B001VJ03LA/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1

And bought this 400A type T fuse (these can be hard to find sometimes)

https://www.amazon.com/gp/product/B0015357RW/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

I did drill out the Lynx to attach it directly to the smart shunt. I also needed a longer bolt to attach the battery grounds. It amazed me how all of it all lined up and I didn't need more 4/0 cables to attach things. Really short 4/0 cables are almost as stiff as a bolt.

 

[ThrottleAbuse]

Ok, that's a quarter million dollar rig, so let's do this right. You are putting WalMart equipment into a Ferarri.

Get a Victron Lynx distributor for your bussing needs. Don't bother with those buss bars and fuses all over the place.

Connect the batteries in parallel with 4/0 wire.

Connect the batteries to a 400A type T fuse.

Connect the type T fuse to the positive Lynx terminal with 4/0 wire.

Connect the inverter to the Lynx and use a 400A mega fuse in the distributor.

Replace the Magnum inverter with a Victron MPII 3000 120x2.

Basically, just install my system. That coach deserves the best.

View attachment 207377

Haha. I wasnt trying to put crap in it. I have never even seen the lynx stuff. Checking them out I should get the Lynx Type C Powerin and a Lynx Distributor. Should I use a 300A class T fuse on each battery in lead to the Lynx? I will finally get to head over to the RV tomorrow to check whats actually in it as far as battery connection equipment. I really appreciate you all for taking the time to help me plan this.

 

[corn18]

Haha. I wasnt trying to put crap in it. I have never even seen the lynx stuff. Checking them out I should get the Lynx Type C Powerin and a Lynx Distributor. Should I use a 300A class T fuse on each battery in lead to the Lynx? I will finally get to head over to the RV tomorrow to check whats actually in it as far as battery connection equipment. I really appreciate you all for taking the time to help me plan this.

Depends on how long the wires are to the Lynx. I didn't put fuses on each battery because I used 4/0 wire everywhere and each BMS can only put out 155A. My single 400A on the Lynx input protects all the 4/0 battery wires.

Your max output is 300A and 4/0 wire can handle that just fine. My MPII at full load pulls 328A, so 4/0 works great and the 400A type T keeps everything safe.

 

[justinm001]

Haha. I wasnt trying to put crap in it. I have never even seen the lynx stuff. Checking them out I should get the Lynx Type C Powerin and a Lynx Distributor. Should I use a 300A class T fuse on each battery in lead to the Lynx? I will finally get to head over to the RV tomorrow to check whats actually in it as far as battery connection equipment. I really appreciate you all for taking the time to help me plan this.

The only difference between a power in and distributor is the distributor has lights and a board but you can't use so doesn't matter.

The best setup would be to have each battery wired up to a powerin then the lynx shunt then the lynx distributor. The powerin gives a fuse for each battery, the shunt has a fuse for all combined then each load has its fuse on the distributor. All lynx is 1000a so if you had 4 each 250a batteries that would be ideal.

The lynx doesn't have Bluetooth like the smartshunt and is like 3x the price. I have them both.

 

[ThrottleAbuse]

So I got a chance to check everything out in the RV right now. Currently my 4x 6V 230Ah batteries are 2S2P and have a 600A fuse on positive and negative 3/0 wiring that is about 10ft in total lenght 5ft each. It seems the factory fused the 3/0 for 600A?

I am going to get a Lynx Class T and will be able to run 4/0 about 1.5 ft to the Lynx and will use 300A fuses for each battery. From the Lynx to the RV loan will be about 2ft of 4/0. I will be able to hook the Renogy 50 DC to DC right to the Lynx.
As far as the Solar panels I am planning 4x Richsolar 200W 24V panels. I did this intial drawing for Richsolar 4x 200W 12V. Is there any benefit or negative to using the 12V over the 24V panels? The 24V are about $30 less each right now? Since they will be flat the likely will never produce a full 800W. I will use 10awg wiring to a MC4 Y connector then run 8 awg wire to the solar controller with a 30A breaker in line.

 

[ThrottleAbuse]

Another update if anyone is still following along. The Lynx Class T power in wont be availabe in the US until June. Timing wont work for me so I ordered a Lynx Distributor. I will run individual 4/0 Wire from each battery to a 600A rated blue sea battery disconnect then through a blue sea class T fuse and holder rated at 400A. This should keep the max available from the Lynx to the RVs current setup below the 440 ampacity for 4/0 wire. I will have a short run from Lynx to the RV. I will also be able to connect the new Renogy 50A dc to dc mppt to the Lynx.

As for the solar panels I think I screwed up. On a whim I ordered 4x Rich Solar 250W panels. The specs for them and the controller are this.





I was going to run them 2S2P but that will be pushing the limits of the controllers 50V max. I would be at a Voc of 45.6V. Initially I thought no problem but then I realized at -20 C I would be at something like 52V Voc. I had done all the calcs based on the 200W 24V panels but realistically those would have been pushing the limits as their Voc is 45.4V at 25 C. Or am I overthinking this and there is a very low chance that panels mounted flat on my roof will ever see max Voc readings? With my current solar setup that is a 525W array I think the highest I have seen is it producing about 19V and 260W.

So now I am trying to decide the best plan of action. Do I run the panels in a 4P configuration? Tell me if I have this wrong. Isc in 4P would be 54.8A. 8awg wire would be roughly 25ft to controller and under the ampacity of 55A for 8 awg wire. Is this safe? Finding MC4 connectors rated for that many amps seems to be a challenge. Most 2to1 or 4to1 are rated for 20A or 30A. Most I found was a 2to1 rated at 40A.

Or run 4P and a combiner box on the roof and then 6awg down to the controller. Speaking of combiner boxes is AM solar the only one out there? $100 for a pretty basic looking thing seems ridiculous. This is definitely a conservative approach.

Another option is 4P but run two sets of 8 awg wires from the roof down to the controller.

And the nuclear option which is looking like the #1 contender since my Renogy DC to DC MPPT hasnt shipped. Scrap it. Buy a Orion XS and a Victron 100/50 MPPT. The Orion wont ship till May. However, since the solar addition is already half baked I can install the MPPT and solar and be most of the way there. The only downside here is this system wont charge the starter batteries with the solar.

 

[justinm001]

I believe mrbf are just as good as class T. Many just use the normal power-in /distributor.

Scrap Renogy junk and get victron. The Orion XS is amazing and their mppts are so much better. Plus they connect to cerbogx so you can monitor remotely.

 

[Mercruiser]

I believe mrbf are just as good as class T. Many just use the normal power-in /distributor.

Scrap Renogy junk and get victron. The Orion XS is amazing and their mppts are so much better. Plus they connect to cerbogx so you can monitor remotely.

I bought a Buss MRBF to use with a new Victron Mutiplus II 12V. I put a 300A fuse in it and did some low current (60A) testing with the Victron as a source (charging) and load (inverting). I was surprised how warm the MRBF got. I kept tightening it, which is a little nerve racking since the fuse body is just plastic and is under a clamping force. That got the heat generation down, but its still the warmest part of the circuit, per my IR camera.

Looking at the very thin metal contact area on the top and bottom of the MRBF fuse body explains why it heats up. There just isn't much cross sectional area here. My theory is that the MRBF was designed for engine starting battery applications where you only crank the starter for a few seconds, or maybe 10 seconds max. It doesn't seem like the metal has anywhere near enough cross sectional area to be good for 300A continuous. I lost confidence in the MRBF as being suitable for use with an inverter that will have a continuous high-amperage load.

I decided to bite the bullet and get a Class-T. Wow, what a difference in the cross sectional area of the conductors. The Class-T has a lot of metal. I still use my MRBF for bench testing with a 50A fuse, so that I don't accidentally blow my expensive Class-T fuse if I hook up something wrong while testing.

On a related matter, my Victron Orion XS is being delivered today. I am looking forward to bench testing it and comparing it to my Victron 30A DC-DC.

 

[Mercruiser]

And the nuclear option which is looking like the #1 contender since my Renogy DC to DC MPPT hasnt shipped. Scrap it. Buy a Orion XS and a Victron 100/50 MPPT. The Orion wont ship till May. However, since the solar addition is already half baked I can install the MPPT and solar and be most of the way there. The only downside here is this system wont charge the starter batteries with the solar.

The Victron Orion XS has shipped. Mine arrives today.

 

[justinm001]

I bought a Buss MRBF to use with a new Victron Mutiplus II 12V. I put a 300A fuse in it and did some low current (60A) testing with the Victron as a source (charging) and load (inverting). I was surprised how warm the MRBF got. I kept tightening it, which is a little nerve racking since the fuse body is just plastic and is under a clamping force. That got the heat generation down, but its still the warmest part of the circuit, per my IR camera.

Looking at the very thin metal contact area on the top and bottom of the MRBF fuse body explains why it heats up. There just isn't much cross sectional area here. My theory is that the MRBF was designed for engine starting battery applications where you only crank the starter for a few seconds, or maybe 10 seconds max. It doesn't seem like the metal has anywhere near enough cross sectional area to be good for 300A continuous. I lost confidence in the MRBF as being suitable for use with an inverter that will have a continuous high-amperage load.

I decided to bite the bullet and get a Class-T. Wow, what a difference in the cross sectional area of the conductors. The Class-T has a lot of metal. I still use my MRBF for bench testing with a 50A fuse, so that I don't accidentally blow my expensive Class-T fuse if I hook up something wrong while testing.

On a related matter, my Victron Orion XS is being delivered today. I am looking forward to bench testing it and comparing it to my Victron 30A DC-DC.

Weird I just checked and ran my AC and dehumidifier off 12v power for about 10 minutes to check. Pulling about 200a total, 100a from each battery through the mrbf 200a fuses and all seem fine. The shunt was actually hotter than the mrbf as was the lynx1000a bar. I am using Amazon bojack mrbf fuses and the bars.