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  • LiFePo4 legit offer?

    I started looking for LiFePo4 battery cells on Alibaba.com. I got couple of offers and I just need help figuring out how legit they are.
    Both offers are same in price, $125 for 240Ah cells. I talked to these sales persons and everything I asked they answered in timely manner and I did not get any feeling that they try to hide something. First offer is from rj-lithium.com. They state that their 240Ah battery (at 0.2C discharge rate) has 0.1-0.2 mOhms of internal resistance and they are grade A battery cells, manufactured by them. Second company is QH technology and they also offered 240Ah battery (at 0.2C discharge rate) but with internal resistance "around" 0.8 mOhms. They also stated that they get these cells from CATL as grade B cell because their voltages are "a little bit higher" than 3.2V, something like 3.23 to even 3.4V.
    I have two 48V inverters, 3kW and 12kW. I pull no more than 220amps. At least, that's what my monitoring system tells me. I plan to purchase 48 cells and connect them in 3p16s and run BMS on them. Also, I use Victron SmartSolar chargers for my 12kW solar panel system.
    My understanding is that all cells should be with close internal resistance among themselves so cells can discharge evenly.
    Also, I am assuming that these cells are actually 200Ah cell for 0.3C discharge rate.
    Second offer includes copper connectors and insulation. First one, "just batteries". Both company stated that they will match batteries for order: "Max capacity difference less than 0.5Ah. Max voltage difference less than 10mv." but I am more concerned if they match batteries for internal resistance.
    Which offer looks more legit?

  • #2
    Alibaba - unless you know the import & duty fees system well, it's a gamble. Overseas shipments of expensive electronics, unless either store promises how to walk you thru customs.
    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

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    • #3
      They take care of everything. Door to door delivery.

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      • #4
        Originally posted by stekicar View Post
        ......
        Which offer looks more legit?
        I am married to a Chinese woman and she doesn't trust any manufacturers in China unless one of her friends can verify for her. Unless you have a foolproof method of verifying the actual quality of the cells there will always be some risk. I would be especially careful about cells with higher voltages because that is when the dendrites grow the fastest. Check out diyelectriccar.com because there is a lot of Lithium battery purchasing knowledge on that forum. Some have been successful buying from China.
        Last edited by Ampster; 07-25-2019, 12:37 AM.
        9 kW solar. Driving EVs since 2012

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        • #5
          Originally posted by Ampster View Post
          ........there is a lot of Lithium battery purchasing knowledge on that forum. [U][B]Some [/B][/U]have been successful buying from China.
          I emphasize the word " some ".

          "Good Luck Mr Phelps. ... .As always, should you or any of your I.M. Force be caught or killed, the Secretary will disavow any knowledge of your actions."
          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


          • #6
            Is it just me or do they both seem to have a low C rating for discharge? I may be wrong but I always thought that was one indicator of quality. Does not matter if you plan on actually using the full discharge rate. I am curious about the cost when you add up the cost of the cells, BMS, shipping, etc. Are you saving much over going with lifepo4 batteries sold in the US? What is the warranty and what is their reputation in honoring that warranty. If a cell must be replaced, do you have to pay for shipping the old cell back and the new cell to you? I am curious.

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            • #7
              Originally posted by Mike90250 View Post

              I emphasize the word " some "......
              Precisely. And that is why I specifically didn't use "most" or "many". The majority have purchased from US based distributors with a greater certainty. When I converted a VW to electric I found a local distributor that had good prices and allowed me to pick up the cells and save freight.
              9 kW solar. Driving EVs since 2012

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              • #8
                Originally posted by BoloMKXXVIII View Post
                Is it just me or do they both seem to have a low C rating for discharge? I may be wrong but I always thought that was one indicator of quality. ........Are you saving much over going with lifepo4 batteries sold in the US? What is the warranty and what is their reputation in honoring that warranty. If a cell must be replaced, do you have to pay for shipping the old cell back and the new cell to you? I am curious.
                Discharge rates have less to do with quality and more to do with chemistry. For motive application one would want a high discharge rate. For stationary applications discharge rate is less important.

                I agree with your second point. A good distributor can significantly derisk a transaction..
                9 kW solar. Driving EVs since 2012

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                • #9
                  Originally posted by Ampster View Post
                  Discharge rates have less to do with quality and more to do with chemistry. For motive application one would want a high discharge rate. For stationary applications discharge rate is less important..
                  Yes, my experience with lifepo4 is more "motive" in nature.

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                  • #10
                    "Legit" was more related to battery specification, not if company is legit or not. Transaction is secured by Alibaba and in case that delivered goods are not per agreement they get involved in dispute. I talked to Alibaba representative and he explained the process of dispute pretty well. As for the warranty, it is same in US per my experience, it is just a sales pitch. I asked them about warranty and they say that they will guide me on how to test the battery and if bad they will ship new one(s) for free.
                    Offers I got were pretty similar, within $100, shipping included.
                    As for the discharge rate it can peak at 2C but they state 1C continuous. Capacity was rated for 0.2C as per battery specification. My concern was mostly about internal resistance which is stated at 0.1 to 0.2 miliOhms. Doesn't this sound too low for LiFePo4 batteries? I was expecting something like 0.4-0.5 miliOhms.
                    Here is the quote detail:
                    Battery Quote.png
                    Second offer states that batteries are grade B from CATL and they have 0.8miliOhms internal resistance for this batch. Previous batch had 0.4miliOhms.
                    As long as all batteries in pack are within certain range for IR I think it will be ok for my application. My theoretical max amperage is 350Amp.
                    Last edited by stekicar; 07-25-2019, 07:56 PM. Reason: Pictures

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                    • #11
                      Wow! That is $212 per kWhr. (240x3.2x48=32kwhr)
                      I understand why you want to give this a chance.
                      Those look similar to CALB cells. If they are the same or similar I believe the case needs to be insulated. Easy enough to do at that price. I have been using modules from Nissan Leafs and my last ten cost me more per kWhr than that. I even priced Tesla modules whic were $250 per kWhr. Do you have any detailed specs?
                      Last edited by Ampster; 07-27-2019, 11:16 AM.
                      9 kW solar. Driving EVs since 2012

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                      • #12
                        Yes I do. See attached. I asked them to send me technical specification for batteries. I also asked to send me battery test results. And they were responsive.They hid nothing for what I asked. The only thing they refused to talk about is who their customers are. They even declined to tell me if they sell more to individuals or companies which I understand. I also asked for permission to send 4 batteries to some youtube blogger and that he will do the test and they agreed to it. All of them.
                        Attached Files

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                        • #13
                          Originally posted by Ampster View Post
                          Wow! That is $212 per kWhr. (240x3.2x48=32kwhr)
                          I understand why you want to give this a chance.
                          Those look similar to CALB cells. If they are the same or similar I believe the case needs to be insulated. Easy enough to do at that price. I have been using modules from Nissan Leafs and my last ten cost me more per kWhr than that. I even priced Tesla modules whic were $250 per kWhr. Do you have any detailed specs?
                          You might want to check your math.

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                          • #14
                            240Ah times 3 for batteries in parallel times voltage
                            https://convert-formula.com/ah-wh

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                            • #15
                              Originally posted by J.P.M. View Post

                              You might want to check your math.
                              Thanks for the tip. . The price per kWhr is even better at $185. per kWhr.
                              240x3.2x48 equals 36,684

                              $6830 divided by 36.864 equals $185.27. per kWhr.
                              My assumption used a nominal voltage of 3.2 volts per cell or a pack voltage of 51.2 volts
                              Last edited by Ampster; 07-28-2019, 03:02 PM.
                              9 kW solar. Driving EVs since 2012

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