Want to add a battery, out of space, moving batts

[corn18]

I am thinking about moving my two SOK batts from the basement to under the front bed. We don't use that space for anything and it has better HVAC than the basement. And (this is the best part) there is room for adding more batteries. This is what I am thinking:


The batts would go to a Lynx with 2ga wire protected by 175A megafuses. Out to the 400A class T and then 6 ft to the existing Lynx.

The install will be easy as the 4/0 will just drop into the basement and run 6 ft to the existing install.

Whadya think?

 

[corn18]

Oooh, the bonus to adding a third battery is I can install my BT BMS's I had bought for my existing two SOK's. I had bought non BT batteries and wanted BT to monitor cell voltages. So I ordered two BT BMS's and installed them. Found out they could only do 125A discharge where the non BT are 170A. With only two batteries, I needed 325A for my MPII so the BT BMS's were out. With three batts, I can re-install the BT BMS's and order a new one with a BT BMS.

 

[justinm001]

You mean 2/0 gauge (00), and not 2 gauge right? 2 gauge is like 100a. Other than that seems great.

 

[corn18]

Yup 2/0

 

[corn18]

SOK 206 on order. Out of stock until 30 Apr. Gonna move the two I have now and put the BT BMS's in. I can live with 250A max until the 3rd battery arrives. So excited!

 

[corn18]

Moved the smart shunt to the batts so I could hook up the temp sensor. That allows me to mount the 600A cutoff directly to the other Lynx.

 

[chrisski]

IMO, your batteries and solar are not big enough to power your air conditioner, so the move you're describing won't matter for cooling. Heating will be fine in the master bedroom provided the heating is propane. Electric heat has the same power as the electric air conditioner.

In another post I described having to fill my roof of my fifth wheel with AC and put just about as many panels on the ground to produce enough electricity to power a single 15k BTU unit. With that I can air condition the master bedroom, or the rest of the RV, but not both. I also put reflectrix on my windows in the main part, block the 14 X 14 vents with the foam pads from the RV store, more reflectrix insulating the skylights, and reflectrix insulating the 2" gaps on the top and bottom of the RV bathroom and master bedroom doors.

Your one mulitplus II will power 1, but not both ACs that you have in that fifth wheel. If you put the batteries under the couch in main cabin, that could work, but how may kWh of batteries will you have? Takes about 1700 watts to power the 15 kBTU from the inverter with conversion losses and once outside temps are above 85, the AC will not shut off. I have 13 kWh of batteries.

 

[corn18]

I'm not trying to run the A/C for long periods.

I added the two solar panels because I could without running more wires or buying another MPPT. And they were on sale. Now both 100/50 MPPT's are maxed out. So I'm done with that. 1600W of solar.

I am adding a battery because I want to be able to use the BT BMS's. I had to buy the battery and another Lynx. Have all the wire. 8405 kWh of batteries.

Both of those are completely stupid reasons that have nothing to do with accomplishing anything useful. I need professional help.

 

[chrisski]

I'm not trying to run the A/C for long periods.

I added the two solar panels because I could without running more wires or buying another MPPT. And they were on sale. Now both 100/50 MPPT's are maxed out. So I'm done with that. 1600W of solar.

I am adding a battery because I want to be able to use the BT BMS's. I had to buy the battery and another Lynx. Have all the wire. 8405 kWh of batteries.

Both of those are completely stupid reasons that have nothing to do with accomplishing anything useful. I need professional help.

I think you have things just the way you want them.

 

[corn18]

I think you have things just the way you want them.

Went camping two weeks ago and never plugged into the 50A post. Need to justify this ridiculous system.

 

[chrisski]

Went camping two weeks ago and never plugged into the 50A post. Need to justify this ridiculous system.

To me that is exactly what you want. No reason to justify if you're happy.

I am in an area that I can go boondocking. I can either drive 30 minutes from my house and get to state trust land and park and camp where I want, but in a city of 6 million people, in that state trust land I do have neighbors 100 or 200 yards away. Or I can go 90 minutes to BLM land and have no neighbor for a mile. Its also nice knowing I have this in my bugout kit. This year I started thinking about getting land up north and bringing setting it up the first year and living out of it getting the land ready with a septic system and well and building a structure on it the next.

I have a pretty big system and I'm sure some would say ridiculous. I know I've heard one guy drive by and tell his passenger that about my ground mount. I got a kick out of it.

I honestly think I get as much "Utility and happiness" out of this system that people get out of their toys. I don't have a swimming pool or side by sides and I don't take exotic vacations, so I do my RV build. Other people's priorities are elsewhere.

 

[corn18]

Maybe this is a better (i.e. easier) option. I have room in the basement for a 3rd SOK. It would be a 3 ft run to the existing system. I can leave the existing system in place (yeah!).

Now what to do with that 3 ft run?

1. Use 2/0 cable and make them all 3 ft. 150A MRBF on each battery.

2. Use 2/0 cable on the 2 closest batteries. Use 4/0 on the 3 ft run. The 2/0 1 ft cable has a resistance of 0.0000795. The 4/0 3 ft cable has a resistance of 0.00015. So twice the resistance.

I'm leaning towards #1 cause it's easy to do and I have the cable.

Bussing the 3 batts is a concern. Easy to add another wire to the A+B switch. Not sure I like 3 cables on the smart shunt. I'll have to see if there is room for two buss bars. No room for a Lynx.

 

[corn18]

Ahh geez, the Lynx distributor just arrived. It is so beautiful, I have to use it. Even made the LED hack cable last night and it works. Gonna stick with the original plan to put the batts under the bed.

 

[SoggyShoes]

@corn18 or you could figure out the length of the longest battery cables you would need for under the bed and change out the cables of the existing batteries to match that.
Then you can have even more batteries and let the addiction continue longer!

 

[corn18]

@corn18 or you could figure out the length of the longest battery cables you would need for under the bed and change out the cables of the existing batteries to match that.
Then you can have even more batteries and let the addiction continue longer!

I have room for about 16 batteries under the bed.

 

[HarryN]

Ahh geez, the Lynx distributor just arrived. It is so beautiful, I have to use it. Even made the LED hack cable last night and it works. Gonna stick with the original plan to put the batts under the bed.

It is pretty, but it doesn't really provide a good way to disconnect the batteries to re-set the BMS or working on the system without using tools on a hot system. That is why I don't like them.

 

[corn18]

This is what I dry fit yesterday. Everything works as expected. Love having all the space to work vs the super compact install.

What's the best way to secure the batts under the bed?

 

[corn18]

Got the install done. No big issues. I like it. Only issue I have is that the Lynx has an extra slot for another battery. That is gonna cost me $650 for another battery. I did size the 2/0 battery cables long enough so I could add a 4th battery and have them all equal length.

Have only load tested to 1800W. That's all I ever use anyway. Once the third battery is in, I'll load test it to max.

 

[SoggyShoes]

Got the install done. No big issues. I like it. Only issue I have is that the Lynx has an extra slot for another battery. That is gonna cost me $650 for another battery. I did size the 2/0 battery cables long enough so I could add a 4th battery and have them all equal length.

Have only load tested to 1800W. That's all I ever use anyway. Once the third battery is in, I'll load test it to max.

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I am glad I am not the only one that the Lynx having a spot for another battery means you must now get another battery! Of course this is the obvious conclusion!

It is awesome to be on a site where the way I think is normal.

 

[wiseacre]

I am glad I am not the only one that the Lynx having a spot for another battery means you must now get another battery! Of course this is the obvious conclusion!

It is awesome to be on a site where the way I think is normal.

That only leads to my problem, all spots are filled and now I need another Lynx and then another 4 batteries
..leading to another Lynx and another 4 batteries
..and on and on and on
..please make it stop