Re: [RE-wrenches] Different LFP Batteries in Parallel

[Jay via RE-wrenches]

Hi Maverick That is a unique to me charging parameters.   Did you figure this out on your own or did you get this from a OEM?   Is the long absorb time for making sure the internal passive balancing has time to work? I don’t understand the very low charge  voltage. Can you explain please? Thanks Jay On Jul 14, 2025, at 11:12 AM, Maverick Brown via RE-wrenches <re-wrenches@lists.re-wrenches.org> wrote: Jason It looks like you are in great shape to do what you’re trying to do.  For legacy inverter systems, I have set the absorb quite long: 4 to 6 hours depending on the quantity of individual batteries. Here at my own house, I have 8 eFlex batteries and 8 Pytes batteries. All in parallel on an outback radian. I have 55.2v absorb set for six hours with zero end amps. For the E flex batteries I have the fortress guardian and I can see the battery state of charge remotely individually. When the individual battery state of charge variation gets too large, I run an equalize session getting the battery voltage up to 56 V. I have other customers with various mixes of batteries. They are all 16 S lithium iron phosphate and as long as somebody is paying attention so far it’s been working fine.  For this customer, I would select Pytes as the brand of battery to add to the system because in the future, you can still add more batteries to that rack. And you can get the individual battery state of charge using solar assistant.  Thank you, Maverick Maverick Brown Off-Grid Solar Commander since 2006 Maverick Solar Enterprises, Inc.  • Solar Commander Remote Power  • SunFlow Systems Cathodic Protection  maver...@mavericksolar.com 512-460-9825 On Jul 14, 2025, at 10:56 AM, Jason Szumlanski via RE-wrenches <re-wrenches@lists.re-wrenches.org> wrote:  ​This client has been advised that it's not a good idea, and any failures might result in a complete battery replacement. If he goes forward, it will be at his own risk. They have a full-time homewatch person who is quite capable. He could monitor SOC and also isolate banks for balancing efforts if necessary. We have a nice Midnite 2000A battery combiner there with breakers for each battery, so it would be pretty convenient.  Self-insured. I don't think any of my off-grid barrier island clients have insurance. The mainland insurance market is messed up in Florida. Forget about the islands. Jason Szumlanski Principal Solar Designer | Florida Solar Design Group NABCEP Certified Solar Professional (PVIP) Florida State Certified Solar Contractor CVC56956 Florida Certified Electrical Contractor EC13013208 On Mon, Jul 14, 2025 at 11:31 AM Dave Angelini Offgrid Solar via RE-wrenches <re-wrenches@lists.re-wrenches.org> wrote: Does the client know that they can't blame you for doing something that has chances of being a bad choice?   Can the client keep track of two different Soc and be responsible about it?   I would also look into how a home insurance policy would react to a claim.   Dave Angelini Offgrid Solar "we go where powerlines don't" https://offgridsolar1.com/ e-mail offgridso...@sti.net text 209 813 0060 On 2025-07-14 6:45 am, Jason Szumlanski via RE-wrenches wrote: They are Lithionics.    Jason Szumlanski Principal Solar Designer | Florida Solar Design Group NABCEP Certified Solar Professional (PVIP) Florida State Certified Solar Contractor CVC56956 Florida Certified Electrical Contractor EC13013208 On Mon, Jul 14, 2025, 9:33 AM jay via RE-wrenches <re-wrenc...@lists.re-wrenches.org> wrote: Hi Jason,   can you let us know what the old battery is so we can dig up the specs and see if there would be any issues.     There are a few odd ball like simpliphi which while a 51.2v has a very narrow window for operation compared to most other prismatic cells.   jay       On Jul 14, 2025, at 5:07 AM, Jason Szumlanski via RE-wrenches <re-wrenc...@lists.re-wrenches.org> wrote: There are never-ending videos on YouTube showing different brands and capacities of LFP batteries working in parallel. I have never tried it myself, and every instinct says don't do it, but I have a situation where it would be very helpful.    I have a client with an older 60 kWh battery that is discontinued and incompatible with any other battery from the same manufacturer. It has a BMS with a 51.2 volt nominal rating. They need another 20 kWh of capacity. It is too costly to scrap the existing battery and start over, and the existing battery has been tested and confirmed to hold very close to its rated capacity.   What is the real deal on mixing and matching? Is anyone doing this safely and successfully? I wonder what the battery manufacturers say about it.    Jason Szumlanski  Florida Solar Design Group    _______________________________________________ List sponsored by Redwood Alliance Pay optional member dues here: http://re-wrenches.org List Address: re-wrenc...@lists.re-wrenches.org Change listserver email address & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org There are two list archives for searching. 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