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  • Tesla battery pack?

    I was poking around looking at different used/surplus batteries and came across listings for Tesla Model S battery modules, 24V, 250Ah. Since Li can be discharged a lot further than SLA/AGM would something like this be a good replacement for a 600 Ah AGM bank or could they be ran in parallel? Pricing was in the $1300 - $1400 neighborhood.

  • #2
    I would pass on them. They require cooling and heating management. Using 18650 NCO cells is dangerous and require rigid thermal; management. EV guys will not even use them. As for discharge, AGM can go to 80% DOD. However you would never ever discharge lithium that deeply.

    The other thing is Tesla uses NCO cells which only have 300 to 500 cycles. The reason Tesla warrants them the way they do is because they would never allow the customer to ever fully charge them up. That is how you can get greater cycle life.

    Last is economics. You claim 24 volts @ 250 wh which is 6 Kwh of storage. In a solar application 2 Kwh usable per day, 5 Kwh total usable for 2 day run time without charging. $1400 / 6 Kwh = $230 per Kwh of storage. You can get a top of the line FLA Pb battery for $175/Kwh with a 10 year warranty. Same top of the line FLA Pb battery with 6 Kwh storage is going to cost $1100. The economics do not work and with used batteries you get squat for warranty.

    The best and easiest EV batteries to work with is Nissan Leaf cells. Easy to disassemble and reconfigure using simple BMS techniques top the point you do not need a BMS. .
    Last edited by Sunking; 06-25-2018, 10:47 PM.
    MSEE, PE

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    • #3
      Thanks for the insight, I have a lot to learn... Next week I will head up to the mountains and re-cable my 6 batteries with solid copper buss-bars, individually charge each battery, then hook up my new IOTA charger and my 6 100 watt panels. When these batteries (6 Universal 100 Ah AGM Deep Cycle) reach EOL I'll completely rethink my battery bank.

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      • #4
        No thermal mgmt needed for Tesla packs at fractional-C rates for ESS. At least in normal household/shed environments.

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        • #5
          Originally posted by nebster View Post
          No thermal mgmt needed for Tesla packs at fractional-C rates for ESS. At least in normal household/shed environments.
          I would not necessarily trust that statement. IMO you better have a cooling process or at least some type of fire suppression around that battery.

          Comment


          • #6
            Everything is fine - move along [B]New NTSB Tesla fatal crash report: Model S battery reignited twice after Florida crash[/B]


            https://www.zdnet.com/article/new-nt...florida-crash/
            The NTSB's report into that crash noted that after the fire had been extinguished and the car was taken to storage, the battery "emanated smoke and audible venting" but didn't ignite. However, five days later it reignited and had to be extinguished again.
            Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
            || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
            || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

            solar: http://tinyurl.com/LMR-Solar
            gen: http://tinyurl.com/LMR-Lister

            Comment


            • #7
              Originally posted by SunEagle View Post

              I would not necessarily trust that statement. IMO you better have a cooling process or at least some type of fire suppression around that battery.
              You definitely need runaway management, but the fluid loops do not do that.

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              • #8
                Originally posted by nebster View Post

                You definitely need runaway management, but the fluid loops do not do that.
                Whatever someone would need to keep that battery stable during charging/discharging is what I would install. Either that or put the battery into a concrete vault with fire suppression.

                Comment


                • #9
                  Originally posted by Sunking View Post
                  I would pass on them. They require cooling and heating management. Using 18650 NCO cells is dangerous and require rigid thermal; management. EV guys will not even use them. As for discharge, AGM can go to 80% DOD. However you would never ever discharge lithium that deeply.

                  The other thing is Tesla uses NCO cells which only have 300 to 500 cycles. The reason Tesla warrants them the way they do is because they would never allow the customer to ever fully charge them up. That is how you can get greater cycle life.

                  Last is economics. You claim 24 volts @ 250 wh which is 6 Kwh of storage. In a solar application 2 Kwh usable per day, 5 Kwh total usable for 2 day run time without charging. $1400 / 6 Kwh = $230 per Kwh of storage. You can get a top of the line FLA Pb battery for $175/Kwh with a 10 year warranty. Same top of the line FLA Pb battery with 6 Kwh storage is going to cost $1100. The economics do not work and with used batteries you get squat for warranty.

                  The best and easiest EV batteries to work with is Nissan Leaf cells. Easy to disassemble and reconfigure using simple BMS techniques top the point you do not need a BMS. .
                  Yes, if a solar guys will not use it it means the person is ignorant, lazy (doesn

                  Comment


                  • #10
                    Originally posted by Evmusic View Post
                    .... ignorant, lazy (doesn
                    Try using something other than a phone or portable device, the anti spam forum package blocks odd fonts and characters as spam.

                    Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
                    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
                    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

                    solar: http://tinyurl.com/LMR-Solar
                    gen: http://tinyurl.com/LMR-Lister

                    Comment


                    • #11
                      Thanks. I wrote a long articles explaining why the Tesla battery modules the best for solar application. (E.g. you can use 5Kwh per day not just 2Kwh as you said. I will not going in a details. There are ample information out there proving the previous statement incorrect including detailed charge and discharge curves). Try to make a quick summary. These modules are designed to use on 400V and have the ability to charge and discharge 60-80KW less then an hour. In a usual 48V configuration for a solar application you might use max 10% of the capabilities of the modules and if you size properly your average load will be like 3-4% what this battery modules are designed for. I will not go to write up long winded calculation as I did previously but any reasonable person with appropriate electrical knowledge would realize that including why these batteries effectively gross over design and such safe for solar. Anyway, I have a 100Kwh+ (plus plus plus ) Tesla module battery system as my whole house backup or primary system (simple switch decision) with my 25KW+ solar system. I know what I am talking about and I know it safe and works flawlessly.

                      Comment


                      • #12
                        Originally posted by Evmusic View Post
                        Thanks. I wrote a long articles explaining why the Tesla battery modules the best for solar application. (E.g. you can use 5Kwh per day not just 2Kwh as you said. I will not going in a details. There are ample information out there proving the previous statement incorrect including detailed charge and discharge curves). Try to make a quick summary. These modules are designed to use on 400V and have the ability to charge and discharge 60-80KW less then an hour. In a usual 48V configuration for a solar application you might use max 10% of the capabilities of the modules and if you size properly your average load will be like 3-4% what this battery modules are designed for. I will not go to write up long winded calculation as I did previously but any reasonable person with appropriate electrical knowledge would realize that including why these batteries effectively gross over design and such safe for solar. Anyway, I have a 100Kwh+ (plus plus plus ) Tesla module battery system as my whole house backup or primary system (simple switch decision) with my 25KW+ solar system. I know what I am talking about and I know it safe and works flawlessly.
                        And I would state that if what you say is true about using a Tesla battery for a home storage system then you are in the 1% category of having the knowledge and understanding on how to safely use that hardware.

                        As for the other 99% of the populace I say don't do this because it can be dangerous to you and others.

                        Comment


                        • #13
                          Originally posted by Evmusic View Post
                          Thanks. I wrote a long articles explaining why the Tesla battery modules the best for solar application. (E.g. you can use 5Kwh per day not just 2Kwh as you said. I will not going in a details. There are ample information out there proving the previous statement incorrect including detailed charge and discharge curves). Try to make a quick summary. These modules are designed to use on 400V and have the ability to charge and discharge 60-80KW less then an hour. In a usual 48V configuration for a solar application you might use max 10% of the capabilities of the modules and if you size properly your average load will be like 3-4% what this battery modules are designed for. I will not go to write up long winded calculation as I did previously but any reasonable person with appropriate electrical knowledge would realize that including why these batteries effectively gross over design and such safe for solar. Anyway, I have a 100Kwh+ (plus plus plus ) Tesla module battery system as my whole house backup or primary system (simple switch decision) with my 25KW+ solar system. I know what I am talking about and I know it safe and works flawlessly.
                          Can you tell me where I might get a look at the information you write of ?

                          Seems that would save all the angst and time you are reluctant to go through to provide.

                          Also a convenient and usually accepted way to meet the put up or shut up criteria.

                          Not saying you're wrong, but claims need support.

                          Extraordinary claims need lots of support.

                          Comment


                          • #14
                            Originally posted by SunEagle View Post

                            And I would state that if what you say is true about using a Tesla battery for a home storage system then you are in the 1% category of having the knowledge and understanding on how to safely use that hardware.

                            As for the other 99% of the populace I say don't do this because it can be dangerous to you and others.
                            I am not sure about what are you talking about. 99% of the population doesn't do electric work in their house and doesn't install solar system alone. In this case we are talking about the 1% who are either professional or understands it. I expect people making claim here understands it.

                            Comment


                            • #15
                              I would also like to see more info about [USER="51976"]Evmusic[/USER]'s installation. What CCs are you using? Which inverter? Show us pics too. I also ask because I am interested, but without much info, all is fuss about nothing.

                              Comment

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