We have 2 battery banks connected to a single bus bar. One bank is a stack of Pylontech 48V which have communication cables to talk to the Cerbo. The other bank is 4x 13.2V LIPO Litimes wired in series. The charge controllers are 3x 150/70 but they only charge the Litime LIPOs to 48V instead of full capacity.
Would adding a Victron shunt allow the Cerbo to see the Litimes and get the charge controllers to properly charge them?
Maby but two battery types is not a recommended way
Hi Robert
Cerbo isn’t designed to handle 2 batteries of different charge V.
The Pylon/Cerbo setup is well developed by Victron and should be fine, but is likely 15S cells. Not compatible with the other’s 16S cells. They really shouldn’t even be connected together. A shunt won’t help.
Not sure what you’re trying to achieve here, but you could consider using one (or 2) of your mppts to charge the Litimes at their required V. So standalone.
Then as you need, transfer from one bank to the other with an Orion 48V DC/DC Converter. These are good for ~400W, but you could use multiples. They don’t communicate and are set manually, but have a Remote port, so easily set up to operate automagically under certain conditions. Like maybe with the Cerbo Generator/Relay.
Can’t offer much more without knowing what you’re trying to do…
As already mentioned, the actual problem is two battery banks sharing a bus bar but needing two different charge voltages makes this scenario impossible.
One will either be overcharged or the other will be under charged
And the cerbo cannot be controlled by two battery systems.
The objective was to increase overall battery capacity without using more Pylontechs. We have 12 but only 11 are working in the system and repeated interventions by the dealer and Pylontech have not resolved the issue.
Any issues with just putting the litimes on a switch to manually add them to the system when the pylontechs drop low due to low PV instead of using the Orion ?
The issues is re charging them. You would need a separate charge source to maintain them.
If you then connect them to a depleted bank they will discharge into that bank.
So the only other way is to switch where load is connected. And you really shouldn’t switch it live.
We have a 48V (58V) AC to DC charger that we can use to top them up when they are disconnected from the main system. Once the Pylontechs would be topped up, we would disconnect them from the main system and when there is enough power in the main system we can recharge them (or use a genset to charge them up.
The idea is to use them like a reserve tank for long periods of low PV input.
Do you have an exact name or a link to your battery?
Connecting an empty 15s battery (Pylontech) to a full 16s battery will cause a huge uncontrollable current flow.
You would connected ~47V to ~53V.
That’s totally not recommended.
Both battery banks have their BMS built into each battery so I am not sure how that would make it incontrollable.
The BMS can’t actively limit the current flow, it can only completely disconnect the charger/discharge current if it is too high.
But that current can also blow an internal fuse (if there is one) or damage the BMS if the BMS can’t disconnect fast enough.
I guess you 11 (or 12) Pylontech can handle the current, but I’m pretty sure that it’s too much for the LiTime battery.
The LiTime will detect that current as short circuit and shutoff.
Again, what you are trying to do is totally not recommended.
It would be better to use a DC to DC charger between the batteries.
Thanks for the explanation!
Given that the Orion can only handle 400w, would it be possible to use several in parallel?
Victron doesn’t have 48/48 DC to DC chargers.
The normal Orions are NOT designed as chargers.
So they would not be suitable in this setup? Do you have any suggestions for other brands of DC to DC chargers?
This transfer would be different from a regular charging approach, yes? I looked at the orion page and it shows 12/24 chargers but only converter for 48V
The 48V Orions never got the ‘Smart’ upgrade. But prior to that all the Converter models were touted as Chargers too. They can be manually set to a flat V. Have a Remote port so can be controlled on/off by shorting the port. Set just below Absorb V should work fine. They don’t communicate though.
I have a 48/12 that I use to top off some 12V batts every day at a set time. Reliable as it gets.
The datasheet of the normal Orions says that they are NOT designed as chargers.
There are plans to make 48V Orion XS but there is no timeline for that.
I’m well aware of when the datasheet changed. And complained about it at the time, to no avail. They still work fine as flat V chargers, but without all the bells’n’whistles…
