Upgrading our cabin from AGM batteries to 2 x Pylontech US5000. I’ve read manuals, on this forum and other sources online and I want to verify that I’m not missing something vital, end goal is that the new batteries should be “just working” for many years to come.
This will be the new setup in our cabin/summer house.
Multiplus II 48/5000
MPPT 150/45 with 3S2P 450w panels
MPPT 150/35 with 3S 450w panels
Cerbo GX mk II
Orion 48/12
2 x Pylontech US5000
Daily consumption when the cabin is empty ~1.7kW.
Daily average consumption when we’re there I estimate to less than 3kW.
Estimated yield as per Victron MPPT calculator during the months we use it >10kW/day.
Cabin is off-grid, no heating when not in use and it’s located in Sweden = It can get cold, usually we’re not opening it up for the season until temperature is above 0C average, but can dip to a couple of degrees negative (single digits).
Since the temperature during the winter can drop to -20C I will store the batteries at home in our garage (~15C) for 5-6 months between the seasons, I don’t have a 48v charger and if not needed I’d like to avoid spending money on getting one. Should the batteries be around 60% charge state once stored or is a lower/higher state better for them?
Is there anything I’ve missed or could do better in order to make the batteries life nice and easy?
The BMS for the batteries will control the max charge current, this should be limited to 0.5C for Pylontech. Also limit the max charge voltage to slightly under the Max allowed with the option in DVCC.
with the batteries deactivated and charged to between 25 - 50% you should have no trouble storing them.
Can you get Pytes batteries in the EU? If so, they are plug-n-play with Victron and have internal battery heaters.
Either way, if it were me, I’d leave the batteries in place but completely turned off. Charge them to 50-80%, turn everything off, and come back in the Spring.
For us. Our cabin in Norway. We keep em there and turned on. To keep the lights on. There is always a little bit of daylight (panels at 70% angle in winter time). Just enough to keep em going. Four months are more difficult, but with eight 16kWh DIY batteries, things are looking great when we come back to the cabin. The main reason for us having this much batteries, is just to get over those four months. And to charge the car when we’re at it.
When saying turning off for the winter, it means that also the main power switch of the battery to be in OFF position.
This way Pylontech is in a deep sleep mode and BMS is consuming almost nothing.
I have a battery purchased in 2021 which stayed off since new and was commissioned in 2025.
After 4 years in OFF mode, without any charging at all in between, the battery was, when first started, at 50% SOC.
Charged OK to 99% and the final balancing stage took about 6 hours until min/max cell difference was below 30mV and SOC hit 100%.
Then worked just fine with daily cycling, with no more unbalance.
Also, I am charging mine with maximum C5 (5th part of capacity, in your case max 20A/battery) and take care for the cell voltage to not exceed 3.5V per cell.
Thanks for the feedback everyone!
I removed the AGM and installed the Pylontech batteries today, so far so good and everything seems to be working. Batteries arrived at 60% and are now slowly charging.
I’ve changed the MPPT absorption settings to 52V as per the guide, all other settings as per default and controlled by the BMS.
@alexpescaru
To clarify regarding limiting the battery charging. You’re suggesting to limiting the max charge current to 40A at DVCC? Is it advisable to limit the max voltage there as well as a safety precaution?
From my experience, I’ve observed that the cells are charging much more “in sync” one vs. another when charging with currents smaller than C/5.
When you charge quickly, with currents up to C/2, one (or more cells) tend to overshoot and create high voltage alarms.
I’ve limited the charge current at inverter, as I have only one device with a charger role, but DVCC is the same, kinda global limiter.
As per voltage, in Cerbo’s OS is already implemented an algorithm for holding the batteries’ charging voltage in check, so don’t do anything.
