Hello everyone, I hope I find some help here…
in my van I have a smart BMS 12-200 and get 16,2V on system+, so my fridge, 12v plugs, electronics get 16,2V.
This happens only when the battery is full and current from MPPT or MultiPlus has no way to go. I have them both wired on system+ side of the BMS, and don’t have any “charge disconnect” wires from BMS to MPPT or multiplus.
As soon I add a load, the voltage drops to 14v or so.
I configured the MPPT float to 13v, no results.
Do I really have to add 2 charge disconnect wires to MPPT and multi?
I thought it was ok as long as they are wired on system+.
My multiplus restarts from time to time having over 16V…
Any help would be nice
Samuel
What’s the absorption voltage set to on the MP & MPPT?
It was 14,2v but I lowered to 14V to try
14V on both? Is the MP & MPPT the only two charge sources?
No other chargers on my system.
I had this problem with the MP, and thought the problem was coming from it as the voltage used to drop to normal when its charger was enabled. Then I added a solar panel, and realised it was the same with the MPPT as it happens when the MP is off and sun is shining. The voltage maintains normal when they are both not charging.
Yes, 14V on both.
Before solar was added, the voltage was high until the MP charger was enabled? Are you measuring this with a voltmeter?
Sorry, I DISABLED the MP charger so the voltage stayed at ~13,8v and stopped the MP from restarting all the time while transferring input to output.
The reading on VictronConnect app said 16,2v to MP, so I checked with a multimeter, and that was accurate.
What do the batteries report via Victron Connect?
Battery side is fine, between 13 and 13,80V, I can’ t remember.
I put a GYSflash 100.12HF battery charger set at 13,5V on system+ side and waited till the battery was full to see if it makes a difference. The voltage stays at 13,5V… this would mean the BMS is not the problem, but on the other side, I can’t believe both multiplus and brand new MPPT have a problem…
“I put a GYSflash 100.12HF battery charger set at 13,5V on system+ side and waited till the battery was full”
To fully charge and balance the battery, you need to follow the Trouble shooting section of the LSBM.
The battery will be fully charged and balanced when Victron Connect reports the battery as “balanced”
OK. I suspect the VE.Bus Smart power/voltage sense wire is also connected to the system output side of the BMS as the voltage it is reporting is different to the batteries/shunt.
The VE.Bus Smart power/voltage sense wire should be connected to the battery, to ensure the multi gets the correct battery voltage when the BMS disconnects the system output. Rectify.
System disconnect also stops the mppts charge reaching the battery. Not good if the BMS trips due to low battery voltage. Rectify. You will need to look at Apendix A # 3 and #4 to determine what method is required for mppt “charge enable”.
VC Smart Networking. If the BMV/Smart Shunt gives a reliable network use this for the mppt to link to. Use the VE.Bus Smart if it has better range.
Make sure the BMS battery charge limit is 14.2v. 3.5.1. Smart BMS settings # 5.4. Might also be worth setting the Multi and Mppt absorp voltage to 14.1v to avoid “system” disconnect.
Ensure the Mppt and multi are all set to the same charge voltages.
Yes, the VE dongle is connected to system output, I did that not to discharge fully the lithium, I will change that. A temp sensor is connected directly to temp input in the multi. the smart dongle is on the battery and has a built in temp sensor, can it stay like that?
I understand the MPPT will not charge in case of low battery, I will change that and add the VE.Direct non inverting remote on-off cable from the BMS to the MPPT.
The BMV is on the smart network, it says it sends voltage and current.
Thank you for your help, I’ ll make the needed changes and come back to you.
Hi all,
Everything seems good now, ve dongle, MPPT and multi are connected direct on battery. The charge disconnect cables are connected to MPPT and multi, I moved dip switches 1 and 2 to off in the multi to activate the remote port.
Cell voltage seemed pretty high to me when the multi is ending charge (3,62v) so I programmed 14,05V bulk in multi and MPPT. I don’t want the multi to getting shut off by the BMS, I don’t want to lose the AC transfer.
I checked multiple times today and yesterday, the voltage on system+ is stable around 14V, everything seems working fine during the tests.
So I thank you all for your help, I’m so glad it works!