Sorry for the long post, I am looking to implement a Victron based Lithium system using the Smart Lithium Batteries on my yacht. Having done lots of research and reading I started to put my design together for load disconnect, charge disconnect, solar, alternator, Multiplus, etc and then came across the following schematic which includes everything.
I will be adding a dedicated high output alternator with a Balmar MC-614 external regulator and wind generator (already installed). I will use the Orion-TR Smart as a backup alternator charging source, as the existing alternator on the Volvo D2-55 is only a 60A and can’t easily be externally regulated. In addition I have a wind generator who’s charge controller can be programmed for Lithium and by various means can be shut down on charge disconnect. These extra charge sources mean that the Cyrix-LI Charge will need to be 230A rather than 120A version.
Having done all my research and reading and selecting this schematic as my basis, I started to think about the detail and configuration. I have become confused about a few elements, due to the many approaches people have used and hopping the community can help clear them up and ensure it is all configured and implemented to protect the investment.
Low Temperature charge disconnect question
There are lots of solutions being suggested in the forum and blogs, including using a BMV712 to monitor the temperature and disconnect; another using the Venus GX system to monitor temperature, turn on a heat mat and disconnect charging sources. While this works I would like to use the BMV to monitor both the Lithium bank and the starter battery as per the schematic. Reading the Smart Lithium manual it does state that the additional functions of the BMS are too “Stop charging the battery in case of under temperature”. I also read a blog regarding a firmware update to the Smart Lithium Battery regarding low temperature
https://www.victronenergy.com/blog/2018/11/28/victronconnect-now-with-smart-lithium-update/
There is a screen shot of Victron connect showing charging is blocked below +5°C and further
“Disabling charging is done because Victron Energy tests and research have shown that lithium iron phosphate batteries charged below +5°C will start to damage the cells. If they were charged at that or lower – and whilst they may appear to be charging normally – permanent damage would be done. Lithium Smart Battery update (set to default) ensures that is not a possibility.”
It would seem that the battery can stop excepting charge, but is not clear if the VE.Bus BMS also signals charge disconnect.
When reviewing the VE.Bus BMS manual there is no reference to low temperature disconnect of charge sources via the Charge Disconnect output. In fact it just references that the BMS will shut down or disconnect loads in case of imminent cell under voltage; reduce charge current in case of imminent cell over voltage or temperature; and shut down or disconnect battery charges in case of imminent cell over voltage or over temperature.
So my question is can the Smart Lithium with the VE.Bus BMS, disconnect charge sources on low temperature or is the only solution to shut down charge source to use the BMV712 with a temperature probe on it’s second port?
Lithium Battery Protection (Cell Low Voltage and High Voltage) Question
Reading the Smart Lithium Battery manual it clearly covers the need to manage a cells high and low voltage situation. The battery/BMS will give a charge disconnect if a cell exceeds 3.75v or load disconnect if a cell drops below 2.8v (configurable in the Victron Connect App between 2.6v and 2.8v.
The BMS Data Sheet says that the load disconnect is when a cell reaches 3.1v, but adjustable between 2.85v and 3.15v. There is no reference to charge disconnect cell voltage. Further the BMS manual has load disconnect at cell < 2.8v and charge disconnect at cell > 4v. Clearly the battery has a set of measurements that it passes to the VE.Bus BMS and the VE.Bus BMS then triggers the load disconnect or charge disconnect to go from high to floating free.
What is the correct figures at which these are triggered, those in the Battery Manual; or BMS data sheet; or BMS manual ?
Lithium Battery Protection (Battery Low Voltage and High Voltage) Question
There does not seem to be any high or low battery voltage control within the BMS, just cell level. The Smart Battery manual states that maximum charge voltage is 14.4v, with 14.2v recommended, and cell disconnects at 3.75v. Should something happen and charging voltage increases above 14.4v, it could get as high a s almost 15v before a cell over voltage event occurs (4 x 3.75v). I am aware that a few people (and a Journey with Jono video) has connected the charge disconnect to the BMV relay and set the BMV to trigger the relay to open on a high battery voltage, this then gives both cell and battery protection. However to also do this on low voltage as well (cell voltage < 2.8v, battery nominal voltage of < 11.2) would require two BMV devices.
Are there any other solutions for high and low battery voltage disconnect rather than just cell disconnect. The expense of moving to Lithium really does require the devices to be protected to ensure a long life.
Orion-Tr Smart isolated DC-DC charger question
The schematic has used an isolated version. Looking at the wiring there is a common negative between the start battery and the charge side of the Orion-Tr. Just wondering why the non-isolated version had not been used. This would have made the integration with the BMS easier as the “isolated remote on/off cable” would not have had to be used.
My current setup has a common negative between the start battery and house battery, and actually isolates the entire system with a common switch in the negative feed back to the batteries.
I assume using the non-isolated version would not be a problem for me?
As already mentioned the manual for this device shows the BMS charge disconnect connected to the Orion-Tr Smart and the engine ignition. This has not been shown in the schematic. I assume the reason for this is related to being an example and there are no issues having both the ignition and the BMS controlling if this device can provide charge or not?
VE.Bus BMS Question
I have seen reference to both 4 and 5 port variants of the VE.Bus BMS, with the 5th port being a pre alarm. In fact the schematic I chose and referenced above is a 4 pin variant, there is the exact same schematic showing the 5 pin.
Further just checking the data sheet it is describing a 5 pin variant with the pre-alarm, which when I started my research was a 4 pin variant.
Is it possible to get the 5 pin variant? What is the part number? Are there any other differences between the two versions, other than the addition of the pre-alarm.
MultiPlus Compact 12-2000-80
Is it possible to mount this on it’s side in the vertical plain. I do not have enough space to mount it in the normal manor, but by rotating it through 90deg I can fit it in.
If not then an option might be to install two Victron Phoenix Sine Wave MultiPlus. 12V, 1200VA Inverter with 50 Amp Charger (IP21) and run them in parallel as it looks like these could be mounted on their side.
Many Thanks
Mark
