I wouldn't do it... By doing so, you'll likely void any manufacturer's warranty.
If you must do it, I would manually balance the old/new banks every 60-90 days. This involves separating the parallel strings of batteries and charging each string independently to achieve a full charge. If you don't do this, the different ages can cause imbalances, which will lead to problems with the BMS, regardless of whether it is in open-loop or closed-loop configuration. *Steve Higgins* *⋅* *Technical Services Manager* *t* +1.902.597.4020 *m* +1.206.790.5840 *f* +1.902.597.8447 *e* [email protected] ------------------------------ CONFIDENTIALITY: The information transmitted herein is intended only for the addressee and may contain confidential, proprietary and/or privileged material. Any unauthorized review, distribution or other use of or the taking of any action in reliance upon this information is prohibited. If you receive this email in error, please contact the sender and delete or destroy this message and all copies. ------------------------------ On Mon, Jul 14, 2025 at 4:09 AM Jason Szumlanski via RE-wrenches < [email protected]> 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: [email protected] > > Change listserver email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > There are two list archives for searching. When one doesn't work, try the > other: > https://www.mail-archive.com/[email protected]/ > http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org > > List rules & etiquette: > http://www.re-wrenches.org/etiquette.htm > > Check out or update participant bios: > http://www.members.re-wrenches.org > >
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