Posted by Peter Kennedy on 9/18/2019 to Batteries (Lithium Ion)
I made a Lithium Battery System on a mobile cart to use as a demonstration and to take to the Annapolis Boat Show. This article, Part 2, is about the details of how it was put together and why, and includes all the various settings used. Part 1 of the article can be found here
|System||Lithium Battery||Victron Smart LiFeP04 200 Amp Hrs|
|Inverter/Charger||Victron Multiplus 12/3000 120V|
|Battery Management System||Victron VE Bus BMS|
|Load Disconnect||Battery Protect 65|
|Monitoring||Battery monitoring||BMV 712|
|System Display||Color Controller GX|
|WiFi||Nano Wifi Module|
|Solar Charging||MPPT Charge Controller||MPPT 75/15|
SWITCHING AND CIRCUIT PROTECTION
I have a single 200 Amp Hour Lithium Iron Phosphate Smart Battery from Victron Energy. It is called a smart battery because it has built in Bluetooth and you can talk to it using your phone, even before you open the packing crate it comes in.
I put a pair of Blue Sea 4017 rubber boots directly on the battery terminals and on the positive terminal I modified one of the boots to allow me to put a Blue Sea 5191 terminal fuse block directly on the terminal and fitted it with a 300 Amp fuse. These batteries are so powerful that if you were to drop a wrench across the terminals it would be Armageddon
You need a battery switch so you can turn off the system if there is a malfunction, if you want to work on it without it being live, or if you want to put it away in storage without having to worry about it. I'm using a Blue Sea 6006 battery switch which has a continuous rating of 300 Amps, same rating as the fuse on the battery terminal. I've taken a tap off the battery side of the battery switch for my "always on" circuits. More about this later.
The purpose of circuit protection is to protect the wire, so the circuit protection goes at the power source and is to match the wire size. Where you drop down a wire size additional circuit protection is needed to match the smaller wire.
In my case the primary circuit protection is at the battery terminal and my 300 Amp fuse is protecting the 2/0 Battery Cable which has an ampacity of 330 Amps. I haven't added any additional circuit protection for the inverter because 300 Amps is very close to its power consumption and so the primary fuse is adequate to protect it. If I had more than one battery in the system I would put a 300 amp fuse in the wire to the Inverter
I have used a Blue Sea 5045 fuse block for my "always on" circuits and each has a 2 Amp fuse. My "always on" circuits are the BMS (Battery Management System) and the BMV Meter. I want the BMS to be always on because otherwise the system wont automatically restart when AC power is provided. I want the BMV Meter to be always on because if it went off and was turned back on it would assume the battery was full, even if it wasn't. If I ever want to put the battery in storage for an extended time I will remove the fuse from these two items, because even very small loads like these will in time run the battery down.
I have a Blue Sea 5006 fuse block with a 50 Amp fuse going to the Battery Protect and then a Blue Sea 5035 fuse block for the various other circuits.
The Battery Protect is rated up to 65 Amps but I don't anticipate needing more power than can be carried by the 50 Amp fuse. I will use 8 awg wire which has an ampacity of 80 Amps. Here is a link to the Ampacity Tables Note I am using marine gauge wire with an insulation rating of 105 deg C.
This is what the inside of the MultiPlus looks like. They have double terminals for battery positive and negative in case you want to double up on those cables. To the left of those connections are the AC input and output. Above them are the two VE Bus ports. Along the bottom row is a bunch of smaller connections that we aren't using in this installation. A temperature sensor comes with the MultiPlus but we aren't using it in this installation because the battery has its own sensor built in.
There is one other connection you have to make. The VE Bus BMS comes with a VE Bus Mains Detector as shown below:
The purpose of the VE Bus Mains Detector is to wake the system up if it has been shut down for undervoltage. Even the switch circuit on the MultiPlus uses a tiny bit of power and in the event of a low voltage shutdown even the tiny amount it uses could over time run the battery past its point of no return. So when the BMS shuts down the system it also shuts down the switch. The mains detector wakes it all up again. It comes with some Velcro so you can attach it to the underside of the MultiPlus and it connects into the VE Bus cable.
In my system I have a VE Bus cable going direct from the MultiPlus to the Color Control GX and another going from the MultiPlus to the VE Bus Mains Detector and then to the BMS.
VE Bus wiring for the mains detector, BMS and remote panel are all quite specific about what connects to what so if you are doing this yourself be sure to get it exactly right as shown above
Settings for the BMV 700
Discharge threshold 5% (default was 50%) This sets the level of discharge that the 'time to go' counter counts to.
Charge efficiency: 99%.
Charged voltage 14.1Vdc. (As soon as we reach 14.2 the battery is full.)
These were set using the Bluetooth Dongle although I couldn't find where to enter the discharge threshold so I had to do that the old fashioned way by pushing the buttons on the BMV
Settings for the MultiPlus
In the Charger settings:
Check the Lithium Battery box in the VE Connect program and then it prompts you to add the Assistant for the VE Bus BMS
Set the absorption time to 3 hours for the first few cycles then back to 1 hour for subsequent operation
We also reduced the max allowable charge current so as not to blow any circuit breakers at the boat show.
In the Inverter settings :
Change the Low DC voltage shutdown to 11.5 Volts ( This is a bit higher than when the BMS stops it inverting which is 11.2 Volts)
Change the DC input low pre-alarm to 12 volts
Change the restart voltage to 12.5 Volts
This is the screenshot of where the charger settings were determined in the VE Configure program. This was done on a PC connected via the MK3USB to the MultiPlus
Here is where we changed the inverter settings. The whole file along with the Assistants was download all at once to the multi plus
Set the display to "C" which is Lithium Ion Battery mode
Initialization and start up.
Follow the instruction for precharging the system which involves charging it at a low rate the first time it is used
For multiple batteries charge each one individually first before connecting them together.
M8 circular connector Male/Female 3 pole extension cable 2m (bag of 2)
I used a shorter than standard RJ12 UTP cable for the BMV meter
Victron Energy VE.Direct Cable 0.3 m long (one each for MPPT and BMV)
Blue Sea 5035 ST Blade Fuse Block for 6 Independent Circuits with terminal jumpers and assorted fuses
This parts list is a bit particular to my demo situation. In a real life situation some of the parts would probably be beefed up a bit. As well as the list above I have some assorted lights and a phone charger USB port to use as my demo loads. And of course as my AC load I have my Victron Energy sign!
HERE IS A WIRING DIAGRAM OF THE SYSTEM - CLICK ON THE IMAGE TO ENLARGE
I revised the drawing to connect the BMS directly to the Digital Multi Control. Before I had the digital multi control connected directly to the Color Control GX. It works wherever you plug it in, but in the event of a low battery shutdown only plugging it directly to the BMS shuts it down. Because the LED display is quite bright it could use enough power over time to run a discharged battery past its limit, so you need the LED to shut off, and to do that you need to connect it to the BMS directly
I corrected this drawing, the original version had a Cyrix between the solar panels and the battery. It turned out that didnt work and now there is a Battery Protect.
I also made a correction to the drawing and removed the negative connection to the BMS. Because the VE Bus has a negative connection, and because we dont want two negative connections, we dont use the negative terminal of the BMS when a multiplus is connected. Its there in the manual somewhere.
This was just a demo system to mount on a cart and take to a boat show. Lately there have been a number of more detailed drawings prepared by Victron. The drawing below is for a fully developed system using Victron Lithium Smart Batteries and a VE Bus BMS. I have a few comments and thoughts about this drawing that will have to be the subject of a later Blog Post. It seems a bit complicated and I find it odd for example that they used two battery switches. The drawing does show what happens if you add more batteries, and include a Class-T main fuse. I wanted to include the drawing here to get the discussion rolling. You can click on the drawing to get the full size version.
I later wrote a Blog Post about how to test and document the finished system
USING VICTRON EQUIPMENT WITH OTHER LITHIUM BATTERIES:
The extent of Victron support for other lithium battery systems can be seen here
More blog posts in this series can be found below
- Installing your Victron MultiPlus Inverter Charger
- Demo Lithium Battery System
- Programming your Victron MultiPlus inverter charger with the VE Configure program - Part 1 - The Procedure
- Programming your Victron MultiPlus inverter charger with the VE Configure program - Part 2 - The Settings
- Programming your Victron MultiPlus inverter charger with the VE Configure program - Part 3 - "The Assistants"
- Lithium Battery Installation - example from Sailbits.Com
- Testing your Lithium Ion battery system
Since I wrote this post I realize I made a mistake and used the Cyrix-Li-Charge to shut off the solar load when the battery is full. This was a mistake, it doesn't work in this particular application and I should have shown a Battery Protect instead.
Hi Peter, very detailed & informative. I read about not using the Cyrix-Li-Charge but instead using a Battery Protect. However, my question is, since the MPPT is connected to the Color Control GX via a VE-direct cable, can’t the Color Control GX switch the MPPT off when the batteries are full? regards, Sebastian
The Color Control cannot control the MPPT, I dont know why, it just cant.
Hi Peter, another question, why doesn't the Cyrix-Li-CT do the job? Any advantage to use a BP instead?
The MPPT charge controller needs to be able to sense the battery in order to get started first thing in the morning. The Battery Protect lets just enough voltage through that it can sense it and get going. Any other shutoff device shuts it off so completely that the MPPT will not start up by itself in the morning
Hi Peter, in this blog post you are using a BP to protect the lithium batteries against over charge. In your other post (https://shop.pkys.com/Demo-24V-System-wiring-diagram.html) the MPPT Solar Charge Controller is connected without a BP... Which one is the right solution? Can the MPPT be controlled through VE.Direct to switch it off in the event of maximum cell voltage? You are stating it can´t, but the other schematics implies it can... Please enlighten me on this, since I´m planning a Lithium/MPPT System with a CCGX. Thanks a lot, Martin.
When using a Lithium Battery you need some way to shut off the charge. Because the VE Direct port of the MPPT is in use for something else we cant shut it off that way, so the Battery Protect is used instead. In the other drawing you refer to we are not using a Lithium Battery, it shows just a conventional AGM battery, so we dont need that extra level of security. The MPPT is a three stage charger and so it wont overcharge the battery.
Hi Peter, thanks for the fast answer! Understood with the Lithium / non-Lithium Batteries. So, I understand that the statement "the CCGX can´t control the MPPT through VE-Direct Bus" is still valid? Then I will plan my system with the BP to cut off charge...
You are correct. It is not possible for the CCGX to control the MPPT using the VE Direct Port. The VE Direct Port can be used to control the MPPT but not while it is simultaneously connected to the CCGX
Hi Peter, I have set up a system nearly exactly like you did. I wonder what is the right way to turn off the system with regard to the MPPT. If I turn the system off with the battery switch and the solar panels are still connetced to the MPPT, does this do any harm to the MPPT? Victron says one should always first connect the battery and then the solar panels. But in this situation it would be vice versa. Do you think this is a problem? Thanks alot for your help, best regards from Germany, Daniel.
I see in manual, Victron Battery protect do not allow the current going reverse. I see you have low voltage cutoff BP in front of DC distribution. What happen when the Multiplus is in charger mode, current flow from multiplus to to DC distribution. Is the BP ok in this case?
Hi Peter! Thanks for the awesome blog series - it's really helpful and interesting. I was wondering though, what software did you use to create the system diagrams? I've been looking around for something similar and haven't found anything remotely as clear and consise.
The one on this page was done using Adobe Illustrator. This is a program that takes a lot of learning. I later switched to Microsoft Visio which is a bit easier. I recently learned of a free drawing program draw.io that I haven't tried yet but looks very promising.