Hello, first post, and first time installing a lithium-Victron system in a Winnebago RV. Upon power-up, the Multiplus is going into overload mode (Overload-fully lit, Inverter on-half lit, low battery-half lit) immediately upon powering up in inverter mode. This happens with no AC connections present, only 12v power, ground, and system ground connected. I have verified battery wiring, all 12v systems in the RV work normally, I can start my generator, run slides, etc. with battery power. Battery is a Wattcycle Ultra 314ah, reporting 56% charge. I’m unable to connect to the Victron Connect software when on battery power only.
Today I connected the AC wiring to the Multiplus, started the generator, and put the Multiplus into charger only mode. All 110v systems in the RV work normally -outlets, microwave, etc. I could now connect to the Multiplus with Victron Connect, and made relevant settings changes for my Li-Ion battery. However, as soon as AC external power stops, I lose the Victron Connect - Multiplus connection, even in Charger only mode. All attempts to use Inverter mode, whether AC is present or not, end the same, a click and immediate overload indicators. Any help would be appreciated - thanks, Jim.
Double check this: no AC connections. Temporarily disconnect ALL ac wiring from the inverter.
Check DC is correct polarity, then turn on.
IF the inverter is not operating normally, try connecting the Mk3. If you can connect, do a reset to factory defaults. If the problem persists, then return the unit for warranty.
Thanks for the reply - the first thing I did was remove all AC connections (I only have two, a shore/generator power in, and panel power out). I’ve verified polarity is correct, as my RV 12 systems work normally, as well as the Victron BMV-712 and Orion XS. The Multiplus will not connect to the MK3 in either charger or inverter mode - the only way I was able to connect to the MK3 was when I hooked up AC and had AC power present from the generator. Should I try to reset to factory defaults as you mentioned, or just return the unit for warranty? Thanks again, Jim
Hi Bjorn, thanks for the help. The Multiplus doesn’t seem to like my battery for sure, but I can’t pinpoint any obvious problems. I have a 3’ run of 4/0 cable from the batteries to the Lynx distributor, and voltage matches at the battery terminals, before the master switch, at the shunt, and at the Multiplus terminals.
Please measure voltage on battery connection terminal at MP2 while it is off.
You have at least 7 break points for minus and also for plus.
Each cable lug, each cable and the fuse can be broken/blown.
I had another case where the fuse to the battery was blown.
In the case the cable was broken, the MP2 created the right voltage on battery terminals matching the battery voltage.
Than remove each connection, clean it with isopropanol and tighten again while wearing gloves.
I recommend doing a methodical
failure analysis.
Exclude potential root causes one by one. Start in the middle of the system to get rid of 50% of the potential issue.
The most easy ones are the static issues like broken connections.
After that you can deep dive into dynamic behavior.
That’s why measuring connections step by step is important to narrow down the root cause.
If you disconnect cable, you can also measure resistance. You can start by whole connections like remove from battery and from MO2 and measure restate over the whole connection. If it below 1 Ohm you are good.
Update, I’ve verified that all connections are good, voltage matches throughout the system, and resistance is reading zero throughout the system. As a test, I made up a new set of 2g patch cables, and connected the MP2 directly to both the AGM start battery, and the Wattcycle house battery. In each case, the MP2 clicks immediately and the overload light turns on. It draws about 1.5 amps for about a half second during the process.
I’m now trying to initiate a return or repair of the unit….and we were hoping to take our maiden voyage in the RV in two weeks to somewhere warmer than Pennsylvania…
