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  • Thanks everybody for the questions and the input I really feel comfortable now knowing that what I had thought was the correct answer is actually the right answer. I need a confirmation from some people that were more knowledgeable than myself. I really want to thank ampster for walking me through a bit more detailed calculations, and walking me through the thought process. Now hopefully I won't have the Hindenburg, lol.

    Comment


    • Aaron,

      I have a few random comments from someone who lives full time in an RV with a big inverter and a battery:

      The 120V induction cooking elements are underwhelming if you are used to a regular induction or gas element at home. Think 1500W versus 4500W. Still, they work okay if you are patient. They are about 25% more efficient, which is nice but probably not an energy budget game-changer for most people.

      You say you are heating with a woodstove and maybe some small electric space units. A well-insulated modern 45-foot RV with double-paned glass windows will require something on the order of 3kW average power, continuously, to hold 66F internally with an outside nighttime temperature of 38F. (In reality with sunshine the load is weighted to the nighttime, of course.) So you are going to need a nice pile of wood and maybe some blankets for your adventure, if you are not willing to burn propane, diesel, or gasoline for heat.

      You mention electric water heating. Water can be heated at 400degF-gallons per 1kWh with a heater delivering 100% efficiency. Those small heaters typically are often sized for 1500W so they can be run on a typical 15A 120V residential circuit. Plan for about 1kWh per conservative, camping-style shower.

      If your bus basement is reasonably insulated, and especially if you place your water heater in it, you may not ever need to run an electric blanket to keep your batteries from going below 32F. They have a huge thermal mass and will prefer to stay close to the mean internal temperature of the basement rather than swinging much.

      Conversely, we know that maintaining lithium chemistries at temperatures exceeding 100F is deleterious to their health (regardless of other variables like SOC which also impact lifetime). It could be difficult to keep them cool when parked or underway on warm days on hot asphalt. This should be a real design consideration for you.

      You describe being able to fit about 3kW of PV on your roof. You should expect something like 18kWh of energy from that setup on good days. The panels will derate as they warm up, and you won't get perfect tracking, and you'll not always be at the equator. You should expect you could have a whole week with effectively 0kWh. What will be your plan in these cases?

      Camping in the sun is great in milder weather. When it's truly hot, the energy you get from the panels won't offset all the passive heating you'll receive in your rig. Just moving air with fans will help some, but your rig will still heat up. You and your family need to be comfortable living in that reality, or you should consider moving to the shade like the rest of us. But then, of course, you can't harvest any PV energy! What would your plan be in this case?

      You say you arrived at an 8kVA (inverters are typical in VA, not W) by summing the worst-case scenario for consumption. On the one hand, I suggest you revisit that with more care and caution, and see if you really need that large a system. It is unlikely you would have all the loads simultaneously. Moreover, any big quality inverter has substantial headroom and can absorb peaks above the rated continuous power for a short while.

      On the other hand, most inverters are rated in a perfect 75F environment, and you may not be able to maintain that with only fans in an enclosed space on warm days. So, oversizing may still be a good idea.

      While I'm a strong believer that you should have the freedom to make your own choices and live with the consequences, I encourage you to think very carefully about using cobalt-chemistry lithium batteries in a mobile living environment. If you have any children or animals who might inhabit your space, they may not have the same ability to exit quickly in the event of a runaway. Egress in general is often a compromise in RVs. There is a reason most boaters and many of us RVers elect to use iron phosphate (LiFePO4) cells despite their higher cost, lower densities, and bigger hassle factors. Be sure you have fully assessed that tradeoff and are comfortable with the additional risk before you proceed with a large system.

      Good luck!
      ​​
      Last edited by nebster; 02-19-2019, 01:20 AM.

      Comment


      • AaronTSchultz ,
        Nebster makes some good points about using the more volatile NCA or NMC chemistry. However if I remember correctly you addressed the fire issue by locating the batteries below the steel floor. Your idea of a roll out tray with a big Anderson connector could be enhanced. In one scenerio you could disable the stops on the sliders and have the rollout tray eject which would also disconnect the Anderson connector. That would give you more time to escape the RV.
        Actually if properly managed one can significantly reduce the fire risk in Tesla batteries. Statistically more people are killed by gasoline fires in cars than battery fires in Teslas. I would more concerned about bears when you are boondocking.
        Have you thought about putting bars on the windows to keep the bears out?LOL

        Somewhere did I see you reference Jason's awesome almost off grid system with multiple stacked Radians? When Jason first proposed that in early 2015 on the Tesla Motors Club forum I was sceptical. After a month or two after I saw how thoroughly he was going about his project I was inspired. I bought a Radian and initially connected it to some LFP batteries that I had from a VW conversion project. I had an elaborate set of Anderson's that would allow me to run the inverter on 48v or disconnect the inverter and drive the car on 96v. I ultimately rented that home and sold the Radian when I bought my home in Sonoma.

        Comment


        • Originally posted by AaronTSchultz View Post
          ..... I also have 4 individual BMS, 1 for each battery with a new circuit board that was attached at the re-seller 057Tech.com ...........
          I did finally look into this and those are just monitoring devices. They don't offer any alarm or user setpoints.
          Since the individual cells are fused there is less likelihood that a group of parallel cells will go significantly out of balance with the other groups. In my prior setups of 3 or as many as 12 cells in parallel I have felt the need for some safety cutoff if a group goes above or below safe levels. That may be less of an issue with the Tesla modules which have 74 cells in parallel.

          There is a much more expensive solution from Jack Rickard (evtv.net) for $1300 but one would have to evaluate the cost effectiveness of that level of control. It is ironic to me that Jack, who spent the first 5 years of his show bashing BMSs and is now producing and selling them.

          As I posted above, Jason, the owner of 057Tech.com, was my inspiration for my first hybrid inverter installation.
          Last edited by Ampster; 02-26-2019, 02:28 PM.

          Comment


          • I think it's pretty clear here what is happening. There are overly cautious moderators.. Who have been the GOD of the internet and have no doubt acquired knowledge, but are treating themselves as the end all be all of knowledge. They are instead of being helpful and asking posters to really address and emphasize the dangers, are just shutting down anybody that disagrees with their opinions. A very dictator approach. This is fine when you want to continue to be the top of the mountain instead of advancing knowledge. I do have a couple questions for the moderators that are concerned and shutting everything down.

            1. How many tesla vehicles have exploded without an accident?
            2. Of those that have exploded without accident, how many were over charged, or used too extremely in the vehicles. How many have exploded with light use between tolerances?
            3. Personally how many tesla + solar installs do you know of that have exploded and become dangerous?
            4. If a tesla car is 10x less likely to catch on fire compared to a gasoline combustion engine, are you also advocating everybody buy a tesla in order to save their family from the death trap of a normal car that will burn their family alive? Because if anything... let's be consistent.

            I say this in good humor as someone trying to understand this field And I can say it is extremely frustrating for you to just be shutting down information. It leaves me, who is the 1% and does my own electrical / building/ plumbing/ everything, to not be able to access both sides of the debate and instead just sees the moderators acting as a tyrannical dictator who shuts down any differing opinions.

            Something to think about. Advancing knowledge and understanding of ideas never caters to the bottom 99%. They drive forward with debate of the 1% who either make mistakes, or don't, and their discoveries trickle down to the 99%. If you really think anybody in the 99% is seeking out this discussion board to actually install these into anything... I believe you have a huge misconception of your demographic.
            Last edited by AaronTSchultz; 04-29-2019, 10:21 AM.

            Comment


            • No one mentions the submariners that died in WW2 from chlorine gas poisoning when submarine batteries got flooded with saltwater.
              A good metric about automobile fires is the number of fires per miles driven. In the case of Tesla's there have been 5 fires for every billion miles driven. In the case of ICE cars there have been 40 fires per billion miles driven. In the case of a Tesla battery being used in a stationary application as was the point of this thread it is unlikely that the battery would be stressed like in a car provided the user uses common sense.
              Last edited by Ampster; 04-29-2019, 12:57 PM.

              Comment


              • Originally posted by AaronTSchultz View Post
                I think it's pretty clear here what is happening. There are overly cautious moderators.. Who have been the GOD of the internet and have no doubt acquired knowledge, but are treating themselves as the end all be all of knowledge. They are instead of being helpful and asking posters to really address and emphasize the dangers, are just shutting down anybody that disagrees with their opinions. A very dictator approach. This is fine when you want to continue to be the top of the mountain instead of advancing knowledge. I do have a couple questions for the moderators that are concerned and shutting everything down.

                1. How many tesla vehicles have exploded without an accident?
                2. Of those that have exploded without accident, how many were over charged, or used too extremely in the vehicles. How many have exploded with light use between tolerances?
                3. Personally how many tesla + solar installs do you know of that have exploded and become dangerous?
                4. If a tesla car is 10x less likely to catch on fire compared to a gasoline combustion engine, are you also advocating everybody buy a tesla in order to save their family from the death trap of a normal car that will burn their family alive? Because if anything... let's be consistent.

                I say this in good humor as someone trying to understand this field And I can say it is extremely frustrating for you to just be shutting down information. It leaves me, who is the 1% and does my own electrical / building/ plumbing/ everything, to not be able to access both sides of the debate and instead just sees the moderators acting as a tyrannical dictator who shuts down any differing opinions.

                Something to think about. Advancing knowledge and understanding of ideas never caters to the bottom 99%. They drive forward with debate of the 1% who either make mistakes, or don't, and their discoveries trickle down to the 99%. If you really think anybody in the 99% is seeking out this discussion board to actually install these into anything... I believe you have a huge misconception of your demographic.
                If you go back to the original post it has to do with used Tesla batteries wired for a home energy project. Not Tesla EV's, Powerwalls or other manufactured home storage systems. All of those have been engineered with charging and cooling systems that will help reduce the potential for a fire or worse.

                If you want to play engineer and try to experiment with a used EV battery then more power to you. I just want to make sure anyone that does try it will do the work as safely as possible. Electricity will kill even experienced people because they become complacent with the dangers. IMO playing with used EV batteries that are not a "designed system" opens the door to a danger even experienced people subject themselves to.

                So if you feel my posts are not reaching the bottom 99%, then think again. I have to make sure anyone that comes to this forum gets answers to their questions and are given safe instructions to use the Solar pv technology. If I have to be a little stern or abrupt in my posts then suck it up because you are not responsible for the people that come here. I have been tasked with helping and keeping them safe. You have not.

                Comment


                • Originally posted by AaronTSchultz View Post
                  This is fine when you want to continue to be the top of the mountain instead of advancing knowledge.
                  I don't speak for the others, but here's my take: The forum isn't for the few who are trying to advance the state of the art, it's for the majority who are looking for advice on proven methods. It's also run by a business that doesn't want to be sued. Besides deleting spam and issuing time-outs, moderators must filter what we think might be dangerous (to the poster or others following his lead) based on whatever experience and knowledge we have. It's a judgement call we need to make, and if some folks aren't happy, so be it. We hope you stay but if this forum doesn't suit your needs, there are plenty of others.

                  Comment


                  • Sun Eagle. Moderators comments especially earlier in the posts condemn the use of these systems, instead of simply offering the opposing view. By your reasoning nobody should ever attempt to do electric in the home because it could start a fire and or kill them. I believe a more productive approach would be "These systems should not be worked on without thorough understanding of the dangers and how to avoid them. However, if you are going to work on them, these are the steps needed to be as safe as possible". That way you are actually increasing knowledge instead of increasing fear. People that are going to do the Tesla batteries, are going to do them regardless of what you say, so why not help them in how to do it safely while providing information instead of giving them no information and having them go at it in the dark. That is assuming you feel you could be helpful in the topic.

                    I would also like to ask again, How many solar installations of these 2nd hand batteries are you aware of that exploded?
                    And again, since Gasoline cars are so dangerous with fires, comparatively, are you consistent with your fears, or is it that you just have become accustomed to one danger vs. the other?

                    Comment


                    • Ok. If you guys are so afraid of being sued... Couldn't you just put. "We disagree with what this person is saying" Instead of banning him because "you are tired of arguing with him". It seemed a little childish and it seemed like he was offering advice for someone who wanted to attempt this, while still addressing it's dangerous if you don't know what your doing... where as SunEagle just said... I don't like what your saying, so I'm taking my ball and going home. LOL.

                      Comment


                      • Originally posted by AaronTSchultz View Post
                        Sun Eagle. Moderators comments especially earlier in the posts condemn the use of these systems, instead of simply offering the opposing view. By your reasoning nobody should ever attempt to do electric in the home because it could start a fire and or kill them. I believe a more productive approach would be "These systems should not be worked on without thorough understanding of the dangers and how to avoid them. However, if you are going to work on them, these are the steps needed to be as safe as possible". That way you are actually increasing knowledge instead of increasing fear. People that are going to do the Tesla batteries, are going to do them regardless of what you say, so why not help them in how to do it safely while providing information instead of giving them no information and having them go at it in the dark. That is assuming you feel you could be helpful in the topic.

                        I would also like to ask again, How many solar installations of these 2nd hand batteries are you aware of that exploded?
                        And again, since Gasoline cars are so dangerous with fires, comparatively, are you consistent with your fears, or is it that you just have become accustomed to one danger vs. the other?
                        Maybe I can provide better information to those that want to risk a DIY solar energy system. Or maybe I need to be a little less friendly when it comes to telling people not to play with matches.

                        Each approach will help some people and turn off others. There is no good approach in teaching others what not to do and why. Just look at all of the colored fingers on those people that are told "wet paint do not touch".

                        As for how may used battery systems have exploded? I don't know the number. But I will tell you I know of about a dozen certified electricians that worked for POCO's or Industrial Plants that have been electrocuted while on the job. They knew what to do and what not to do yet they got comfortable with the job and lost their fear of the dangers and died.

                        As far as I am concerned, instilling fear of a danger keeps people safe. Telling them politely "not to do this or that" seems to have less of an effective outcome.
                        Last edited by SunEagle; 04-29-2019, 01:32 PM.

                        Comment


                        • Lastly, and I know you guys are probably discussing a ban on me. Your default to "We don't want to get sued" is a bit naive. Earlier in this post one of the moderators stated "I would use leaf batteries, they are safer and more configurable" or something similar. That is opening yourself up to a lawsuit much more than the tesla thing. Someone could then grab a leaf battery, touch the + and - and get injured. Then say, the moderator said it was safer than Tesla. The point is, the difference between the batteries is the possibility of fire. Coming from someone that was Director level of a company, you will not reduce the likely hood of being sued, what you need to address is how to defend those law-suits. And by addressing everything with either a simple (we disagree and do not endorse this) or a, Either way is very dangerous and should not be attempted unless you really know what you are doing, but here are some resources to figure it out on your own if you want to attempt this even though we don't endorse it, you will be much more likely to defend the lawsuit.

                          Just saying.

                          Comment


                          • Originally posted by AaronTSchultz View Post
                            Lastly, and I know you guys are probably discussing a ban on me. Your default to "We don't want to get sued" is a bit naive. Earlier in this post one of the moderators stated "I would use leaf batteries, they are safer and more configurable" or something similar. That is opening yourself up to a lawsuit much more than the tesla thing. Someone could then grab a leaf battery, touch the + and - and get injured. Then say, the moderator said it was safer than Tesla. The point is, the difference between the batteries is the possibility of fire. Coming from someone that was Director level of a company, you will not reduce the likely hood of being sued, what you need to address is how to defend those law-suits. And by addressing everything with either a simple (we disagree and do not endorse this) or a, Either way is very dangerous and should not be attempted unless you really know what you are doing, but here are some resources to figure it out on your own if you want to attempt this even though we don't endorse it, you will be much more likely to defend the lawsuit.

                            Just saying.
                            My priority concern is for people's safety not about being sued.

                            Maybe you are right and there should be a blanket statement made by the Moderators that this Forum Does Not approve of certain actions. Yet a blanket statement does not always clear everyone of everything.

                            Comment


                            • Sun Eagle. If you tell people not to use matches for their entire life you grow and ignorant person that is much more likely to injure themselves when exposed to said danger. If you explain, This can start a fire which will get very hot and kill you or destroy everything you love. Don't touch the paint, or you will get paint on your hands, and it will mess up my paint job which I will then have to repaint, is more effective than a dictatorial "Don't touch this". You are not telling them what not to do and why, you are just telling them not to do something. As far as your electricians analogy, it's irrelevant and completely off topic. With than reasoning we shouldn't do anything then for fear of becoming complacent. Don't drive a car, or you could get complacent and get in an accident, Don't go outside or you might risk getting distracted because you are complacent and die from a falling tree. And especially don't Ride a bike, or you could DIE!!!. See how crazy that is. I'm sorry the people you knew got electrocuted, but that has nothing to do with teaching someone how to do the job in the first place. Someone didn't just scare them from being an electrician, they said... There are risks and here is how to avoid them and be as safe as possible. So I guess... Thanks for proving my point with your analogy.

                              Comment


                              • Sun Eagle. You are never going to clear everybody from everything... but by stating the dangers, and being as vague as possible, is going to help you not get sued. Avoid liability by stating that you don't agree with what this person is saying and there are dangers, but blocking them didn't seem necessary. It seemed like you did that because he disagreed with you. Which makes you look very immature. Also by stating you would do something because it's safer, puts much more liability on you. ( I only say this because I hope it helps). There is a way for you to avoid liability, but still offer the opportunity for users to discuss and grow in their knowledge. Again Someone is much more likely to eventually hurt themselves if they don't have the information and how to avoid a problem.

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