House electrical change to Tesla Battery modules

[Joe Camper]

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I know you've got cloth awnings on the bus but I couldn't help myself when you mentioned putting a solar panel on an awning. This little hundred-dollar panel from Amazon charges to 8D gel batteries. It's the only charged source I use and it more than keeps those two batteries charged up for me for what little I need I have a small residential fridge and a little TV at night that I watch 3 or 4 hours and what I use by night this panel replaces by day and I could go indefinitely I just don't understand why solar is it more prevalent with the buses. I've mentioned it before they have solar fabric somebody needs to make the whole top side of the awning one big solar panel with solar fabric.

When you guys are boondocking on inverter it's really not necessary to leave the inverters constant on it's also beneficial if you turn them off because they're using voltage just idling whether there's a load on them or not. Usually it's the refrigerator that quite possibly could be the only constant load that you need to keep going if the weather is fair. So get to know your fridge see how long it takes for the compressor to cycle off and do some testing and run the inverter 4 an hour every three or four hours and when it's running make sure that the thermostat on the fridge is set all the way over to cold so it runs the whole time. huge battery Banks you guys got in them buses only God knows how long you could go with some solar panels if you didn't run the inverters constant on when boondocking. Coordinate your other loads with the runtime for the fridge and then just turn it on for the intermittent loads when you need them andthen turn them back off. How dare I even suggest this for Prevo. We should get together and have an Enduro camping contest let's go out to Quartzsite and see who can hang out the longest on the provisions that you carry out there with you wouldn't that be fun.

Great thread Fred have fun testing and playing around.

[freds]

Hi Joe

I am definitely putting my system together with boondocking and places like Quartzsite in mind.

I agree with you about the inverter being a major draw while it is idling.

One target for the Raspberry Pi automation is an automatic sleep mode; if it detects that the cell phone's for occupants are not attached to the local wify (occupants present) and there is not a load (something cooking in instant pot) on the inverter for thirty minutes.

You would have to do that contest based on available solar levels, power consumed; with detriments for generator runs, etc.

Of course if I duplicate my home PC setup with multiple monitors and no solar input I can easily burn through my battery bank in a day.

PS. Another update that I am making to my humble home on wheels is to change the refrigerator over to a DC compressor.

[Anthem]

Hey Freds, enjoyed reading your writeup of what you did. I almost went the Tesla S battery route as well. I didnt want to deal with a slightly non-standard voltage with that pack, as I think its using cells which sit at 3.7 instead of the more normal 3.2v x 4 cells that LiFePo4 cells work at. Glad you took it on, and hopefully it gives you good working margins. . .

I'm on my second lifepo4 install. This time using almost all Victron equipment as I love their bluetooth, victron connect, and vrm portal. Their inverters are awesome and I have a pair of them in split phase. Debating putting in an autotransformer to balance the inverters, but so far not too many problems with the split phase (outside of 30amp service).

The Victron controllers give you good manageabilty. They also now interface with some MFD devices in the marine world. So you can convert to NMEA2K and do some things on that front. The RV network and open marine one just hasnt taken off as much as NMEA2K still works.

Interesting choice on Pi. Its probably the cheapest and most flexible. Arduino might work better for battery bms type of work, but you have that covered. I had those same choices, but currently working off a PLC controller that does what I need to do. You may also want to look in to that, but it is a bit more costly than Pi, but the number of modules and things they have prebuilt is pretty extensive(proximity sensors, motion, etc). IFM makes some great mobile PLCs with CanNet network built in and all using CoDeSys development platforms. But again, pricy.

Anyhow, totally cool. Love to hear more as you progress. I'm also debating solar panels since there is so much real estate, but have to tackle a bunch of other projects up there.

[Gil_J]

Ed,

Be careful going to a split-phase setup. The new NEC allows campgrounds to be wired with 3 phase power. So, your nominal 240V just went down to a nominal 208V.

How are you going to use an autoformer to balance the loads? Are you considering 2 autoformers, one per phase? In that case you could achieve a near balance in voltage, but I'm not following how you'll achieve load balancing.

You are dead on when it comes to advancements and acceptance MMEA-2000 compared to RV-C. RV-C was born at the downturn of the RV industry, so few wanted to invest in it. Frankly, NMEA-2K is far more robust and has widespread support. RV-C should simply die in favor of NMEA-2k.

Great info!

[Anthem]

Gil yeah, I saw that. Probably on a post you made in some other. . I dont think we need to worry about 208 but the 104 vs 120 since technically the 50amp plug is two phase 120/240. But yes, its an issue. I have the victron Autoformer to balance the inverter outputs. . But I havent installed it as my powertech generator doesnt seem to care that L1 is more loaded than L2. .

Now, back to the input issue. yeah, that had me concerned as well. I have the Hughes Autoformer that will boost it 11% which will take it to an acceptable level. They claim it will keep the 2nd phase in-phase and the Victron in split phase will work without an issue. Have not tested as I havent installed it just yet.. . Lots of transformers to consider. But yes, the issue is there. But 104 might just be as problematic on an input as the split phase. The split phase to me - seems to be a bigger issue if I have to dogbone adapter to 30amp service as thats single phase and the Victron units in split phase - will only power one side when there is not a split phase input. Not too big an issue since the L2 side will just be inverted from the battery as L1 powers L1 through the inverter - which in turn is charging the battery back to whatever L2 is drawing (whew). Not ideal, but then again 30amp service isnt ideal. .

But i havent come across the 204 problem just yet. . . . but I know its there.

[Gil_J]

Just so you know. The 3 phase power should have no effect on the 120V single phase. It's 120/208V because the phase difference is 120 degrees instead of 180 degrees of split phase.

Generators definitely prefer balanced power between the legs. Because of this Vantare use to have all 120V appliances and had there generators configured for 120V.

I'm still not certain how a transformer is going to balance leg loads. I'll have to look at the Victron transformer you referenced.

[Anthem]

Oh sorry - yeah, 3 phase 208. Sorry, threw me off with the 204. lol. but if its split phase 208, what will happen with the split phase configured Victron is the same as if there was only one leg operational. The other one would fail to sync (unless I configured on the fly from 2P at 180degres to 3P at 120 degrees. But even if it failed to sync, it would take 120 on one leg in to one inverter and the other would continue to invert off the battery while the first one supplied loads on L1 and charged what was being removed from L2.

The other option is parallel. But you would have to split the inverters up in to completely independent units for this to work. As parallel requires the two to be in identical phase. The advantage for all of this is to keep one monitoring system. The displays can read a split phase or parallel system but it cannot read two systems. So unless I wanted to double all the front end displays and controllers (which is how the previous Heart Interface was) - then you have to go split or parallel. Some have gotten around the problem by autotransforming on the front end - which would take two legs and create its own 120/240 output(but this doesnt work for 3 phase 120 degree out of phase - well at least I dont know if it does or not). . So lots of ways to skin the beast, but unfortunately not all of them are perfect - as each has advantages and disadvantages.

The victron autotransformer takes two legs and because neutral isnt passed - it balances the output legs - up to 32amp differential.. PDF documentation here https://www.victronenergy.com/upload...nd-100A-EN.pdf

And agree with you. NMEA2k is so much further along than Silverleaf's implementation or RV-C. Even signalK is better.. . I seriously thought about running NMEA2k but it would have been overkill on an older bus. but I've done my boat completely in n2K. I think I might have 20+ maretron nmea2k devices on the network there reading DC amp,volts, AC amps,volts from various sources. Of course you need/want more information on a boat than in a motorhome. . .

[freds]

I think the Victron inverters with the power boost feature will automatically adjust for the difference.

With my Tesla when I first got it; I had to charge at a hotel (unplugged a dryer) and with their wiring the voltage was at 198 volts, took 14 hours to charge the car instead of the expected eight.

I had arrived bone dry with 3 miles of range remaining!!! This was when their super charger network was first being built and had large gaps in the coverage.

[freds]

First sort of sunny day with a single panel hooked up to the bus:



Look at the last four days of production as that was days that a solar panel was actually hooked up and not simulating them with an external power supply (29V).

My panels are 72 Cell LG High Efficiency 375W Mono Solar Panels and I purchased ten of them used for $1,500. Thinking that I might be able to get anywhere between 7-9 panels installed on the roof.

The graphs show the last four days with a single panel propped up against the side of the bus. The first day was late afternoon hookup, after returning the bus to the storage yard.

Today's production was about an 18% increase in charge level on my Tesla Battery modules and the maximum production was 344 watts on the 375 watt panel.

In working on my automation's, definitely going to have to have a scenario for using excess solar production for when the bus is unoccupied.

[freds]

Hey Freds, enjoyed reading your writeup of what you did. I almost went the Tesla S battery route as well. I didnt want to deal with a slightly non-standard voltage with that pack, as I think its using cells which sit at 3.7 instead of the more normal 3.2v x 4 cells that LiFePo4 cells work at. Glad you took it on, and hopefully it gives you good working margins. . .

I'm on my second lifepo4 install. This time using almost all Victron equipment as I love their bluetooth, victron connect, and vrm portal. Their inverters are awesome and I have a pair of them in split phase. Debating putting in an autotransformer to balance the inverters, but so far not too many problems with the split phase (outside of 30amp service).

The Victron controllers give you good manageabilty. They also now interface with some MFD devices in the marine world. So you can convert to NMEA2K and do some things on that front. The RV network and open marine one just hasnt taken off as much as NMEA2K still works.

Interesting choice on Pi. Its probably the cheapest and most flexible. Arduino might work better for battery bms type of work, but you have that covered. I had those same choices, but currently working off a PLC controller that does what I need to do. You may also want to look in to that, but it is a bit more costly than Pi, but the number of modules and things they have prebuilt is pretty extensive(proximity sensors, motion, etc). IFM makes some great mobile PLCs with CanNet network built in and all using CoDeSys development platforms. But again, pricy.

Anyhow, totally cool. Love to hear more as you progress. I'm also debating solar panels since there is so much real estate, but have to tackle a bunch of other projects up there.

Yes in using Tesla Battery modules they have different chemistry and are fully discharged at 19 volts, most inexpensive inverters where originally designed for lead acid battery's and turn off at 22 volts; which wastes a signification portion of the storage capacity.

I have been noodling away on how to handle 30 AMP 120 volt service and I would think just activate one inverter/charger to charge at the 120V level and have a manual switch to active that second.

I.E. If driveway surfing only draw 15 amps on 120, if plugged into 30 amp service enable an additional 15 amp draw.