Mixing 15 cell with 16cell banks

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jwnesbitt asked Jan 7, '24

Mixing 15 cell with 16cell banks

struggling with a 15 cell bank (pylontech) and a 16 cell with a pacebms. I have 80kW with the Pace (8 x 200 amp hour) and 37kW with pylontech (11 x us3500c); what happens for me is: when both are connected, only the pace discharges unless the load is extreme (like 10kW, then the pylontech will take a very small % of the load, maybe 5%), If i turn the Pace off and allow the Pylon to discharge as its the only bank, when i turn the pace back on, it dumps whatever it has into the pylon to take that back to 100%. the batteries are connected as follows: 6 pylon, 4 pace to a lynx power in, 5 pylong 4 pace to a second lynx power in, then a lynx shunt , then a lynx distributor which has 3 inverters (voltronic 11kW) the shunt is the aggregator for the battery stats, with the pace connected via can to a cerbo and the pylontech connected to solar assistant for data, i also use SA to monitor the inverters. any insight appreciated.

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Lithium Battery Pylontech lynx shunt 16s

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Matthias Lange - DE answered · Jan 07 at 07:46 AM

As you see that doesn't work and is absolutely not recommended.

The 16s battery has a higher voltage level and because of that will always be used first.
The more dangerous thing is you will overcharge the Pylontech!

I guess the 16s battery is DIY? If yes just remove one cell and it should work.

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jwnesbitt commented · Jan 08 at 06:17 AM

its not a DIY, but i guess i could remove 8 cells from the 8 batteries, then buy 7 more cells, giving me an extra battery, ill investigate this some more

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kevgermany answered · Jan 07 at 07:50 AM

15S means 15 cells in series inside the batteries. 16S means 16.

Pylontechs run at a lower voltage than Pace. So you have two different voltages connected together. Hence the heavy charge transfer.

Although both may be marketed as 48V, it's a nominal figure.

Bottom line is these batteries are not compatible. The BMSs are saving you from a major meltdown. You should rectify this asap. If not done the consequences could be catastrophic. Suggest you get expert advice on how to rectify.

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jwnesbitt commented · Jan 08 at 06:16 AM

thank you, thats what i thought would be the response

when i saw the issue, what i did was turn the Pylontech off, so at the moment, im manually switching between packs, so they are never both on at the same time, this gives me around 5 days usage with little sun (Northern Ireland - so weather is generally grim)

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Additional resources still need to be added for this topic

Battery Compatibility

Did You Know - How to create a battery profile for non-Victron batteries?

Victron Pylontech battery compatibility guide

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Lynx Shunt VE Can online manual

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Modifications Space

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Answer 1 · 2024-01-07T07:49:39Z

the-doon answered · Jan 07 at 07:49 AM

Interested to know why you have mixed the 2 different types of battery? What charge settings are you using?

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jwnesbitt commented · Jan 08 at 06:14 AM

i originally bought the Pylontechs, and decided that i wanted to try go completely off grid, so added the 80kW pack. im using the Pylontech parameters for the charging profiles on both batteries

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