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Kaplan78 avatar image

Multiplus is tripping Battle Born battery BMS

Hello, I have a Multiplus 2000/12 connected to a single Battle Born Lithium battery. Every now and then when I turn the Multiplus on (using on/off switch, not the hard switch on the Multiplus) it trips the BMS on the Battle born. Then I have to disconnect the battery and reconnect to reset the BMS. I have no idea what is causing this. This usually starts happening when I turn off the power to the Multiplus without turning off the Multiplus first. Then it starts this vicious cycle of tripping the battery every time I send power to the Multiplus. I have checked all the wires and everything is tight and isolated. It almost seems like something is bad with the Multiplus or Battle Born. Both the Multiplus and Battle born are brand new. I haven't even started using the Inverter yet just the charging.

I did fire up the inverter on a test run and the buzzing was really loud (normal?) and then it too tripped the BMS after 2-3 seconds.

Thanks for any help. I live in Colorado and I can't find anyone I can pay to come and help figure it out. It seems even the distributors of Victron don't know how to service them. Also, I have had Victron pros in this community validate my schematics, but happy to post again.

BMS
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Maybe charge the battery.

So I thought I had this sorted out and was just not going to use the on/off switch, but that didn't pan out. Using my inverter at 1500watt usage and 60% left on Battle Born battery Voltage was 13.09 (both readings from Victron battery monitor) The appliance running at 1500 watts tripped the battery after 3 seconds of run time. Based on the voltage it had 40% battery, but it read 60%. Either way that should be able enough to run the appliance.

The BIGGER problem. Once the battery tripped, I'm back in the same boat. I reset the BMS on the Battle Born and the DC power came back on, but as soon as I turn the Blue Sea On/Off switch to on it immediately trips the Battle born again. Even when I turn the Multiplus to off. I know Johnc that you said power can build in the caps and I get that, but according to all the documentation from Battle Born I shouldn't need any extra resisters for a 2000 watt inverter only when you start getting into the 4000 watt. Also perplexed that I'm the only one seeming to have this issue, when so many use battle born with muliplus.

So right now I have no way to turn on my Multiplus without tripping the battery period. I'm going to try again in a few hours to see if the energy stored in the Multiplus caps will dissipate, but of course this is a terrible solution in the wild

I guess I'll try the current surge limiter (CSL500) even though it's only recommended for a Multiplus twice my size.

Any other advice is greatly appreciated and thank you to all who have posted already. I keep running through all that has been written.


Are you sure your battery cables from the BB to the Multiplus are large enough in your 12 volt system? Have you tried doubling them up to test? In my Multiplus 24/3000 I use 1/0 (50mm2) cable and with the 12/3000 the recommended two 1/0 or 100mm2 cable 4/0 cable is 120 mm2.

Possibly a damaged BB BMS board in the battery?

Hey Tom, yeah I'm running 2/0 to the Multiplus which should be more than enough to accommodate from the power specs. I have not tried doubling to test

1574371893199.png (100.0 KiB)

Big Clue - So when I turn the On/Off switch to ON which connects the Multiplus directly the battery it trips. So with the switch OFF, I test the load and it was 2 volts. I drained that off with a lightbulb power tester until there was no load at all. I then turn the switch ON and it tripped yet again. So it seems to me the immediate demand for power from the inverter is tripping the BMS. The battery voltage with everything disconnected is 13.05 volts so it makes no sense to me why it would trip. Would the preload resister still work in this scenario?


My workaround. I turned the On/Off switch OFF again disconnecting the Multiplus from the battery. Then I hooked up shore power to the Mutiplus and switched it to "Charge Only" then I turned the On/off switch ON and it did not trip. Now everything is fine. But again in the wild I would be screwed since I wouldn't have shore power.


My conclusion: So either 13.05 volts on a Battleborn battery is not enough power to even turn on your inverter and trips it because of low power OR the immediate demand from the Multiplus is enough to trip the BMS and I need a preload resister? Could it also be a defective BMS?

Such fun, thanks for the help!

It still sounds like its a pre-charge thing. Switching a multiplus through cutting the DC is not the "standard" way of doing things - that's why there's a switch on the multiplus front panel. And I'm pretty sure that when you connect in AC, the multiplus will internally charge the caps, which removes the opportunity for the inrush to occur and trip the BMS.

The most probable sequence of events from what you're describing looks like:

1) switch turned on

2) battery starts inrushing into capacitors

3) capacitor voltage starts rising quickly

4) BMS detects the current above trip threshold

5) BMS operates (integral) safety switch

6) safety switch disconnects battery

7) residual voltage still on capacitor from before the safety switch operates

You can test this easily with a jury rigged resistor of suitable wattage and resistance. Keep your switch upstream of the multiplus off, but ensure the battery is available. bridge both ends of the switch with a resistor. This will cause the capacitor to slowly charge; when it gets close enough to 12v, turn the switch on. That should definitively tell you whether you can solve it with a precharge resistor (because you just pre-charged it).


Ok this is coming together. Thanks for breaking it down. I don't use the DC switch anymore, but the BMS tripped again when I was inverting and I was back in the same boat. But I see now how the two relate. Voltage is left on the capacitors in each scenario. I will look around for a pre charge resister. Hoping I don't have to drop the $280 for the CSL500 and can find something cheaper. If you know of anything more affordable that will work please let me know.

Thanks again, I owe you and everyone else a beer

Can you provide a drawing of how to make and connect the precharge device? I'm not completely understanding. TIA!

the precharge can be done with a resistor in series with a (precharge) switch, the entire thing being in parallel with the primary switching device(s), whether it be a relay contact and/or a mechanical switch.

The exact details can depend on what how your installation is configured.

You really need an installer or someone with design + install experience, with access to your installation to get precharge sorted.

What temperature is the battery at this point. Lithium typically won't operate / charge under 5 degrees, but I stand to be corrected.

battery was room temp and it was 60 degree F out

11 Answers
kai avatar image
kai answered ·

a 2W 100ohm resistor should do the job re: precharge. But see below.

If your BMS is dropping out whilst inverting, the precharge resistor won't help with that- there might be a second / different issue at play. Going back further in the thread, I wonder if you have the right size battery.

You say a single battery is used, that's a 100AH correct? In that case, the datasheet says its rated for 100A continuous draw which means if you try to draw 1.5kW you'll exceed the continuous rating permitted by the built in BMS. It would also line up with your description of BMS trips.

edit: just looked at the other thread. it does look like the battery is undersized for the multiplus. You'll need to think about another battleborn battery to make full use of the multiplus' 2kVA capacity. The undersizing exacerbated the precharge issue.

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Great information thank you! Yes, I just bought one 100AH battery to test it out. I always planned to buy more I just wanted to give it a trial run given the cost. but this makes sense and completely aligns with the issue. I'll just get another BB battery and start there. Thanks again this has been so helpful!

Did you ever solve your issue? I am having nearly identical problem with 4 BB @ 24v and Victron 3000/24/70 Multiplus. I started with 2 BB and thought adding 2 more would solve the problem but it didn't. Good thing I wanted 4 batteries anyway.

JohnC avatar image
JohnC answered ·

Hi K. This is likely just the Multi 'filling it's caps', and the instantaneous surge is enough to trip the bms. If you wanted to test this theory for yourself, try with a separate wire and watch for the *spark*. With a bigger Multi and higher V (say 48), it can be quite spectacular (underwear change level).

Best to leave the Multi connected to the batts, and if you need to turn off inverting do it from the front panel.

There are workarounds, like a resistor (or even a lightbulb) in a wire to precharge, but practicality might impinge there.

Can't speak for your 'buzzing', but symptoms suggest overloading..

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This may not be the same model, but it should cope easily.

"Inverter/Chargers (and other devices having large input capacitance < 10 microF)

Special consideration must be made for connection to devices that have a large input capacitance, because of the tendency of these devices to draw large current spikes upon initial connection to the batteries. This includes inverter/chargers that are greater than 4000 Watts in size. This applies to 12V, 24V, and 48V inverter chargers. Battle Born Batteries requires a current surge limiter (CSL500) that is for sale at Battle Born Batteries to be installed with each inverter/charger greater than 4000 Watts."

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Streborg answered ·

I just encountered this problem. I have 2 Battle Born batteries and a Multiplus 2000. The batteries are in parallel. My testing shows that if the MultiPlus has been disconnected for a while the stored or residual charge disapates over time. If the residual voltage gets to 0.5v the initial current surge causes the battery BMS to shut down the batteries. I have had the system restart successfully with the residual voltage as low as 2v. My temporary solution is to connect the batteries via a switch, measure the battery voltage and if less than it should be immediately disconnect, remove the negative cable to reset the BMS, quickly reconnect the cable, and reconnect the batteries. In multiple attempts this has worked to get the MultiPass going. Apparently there is enough residual charge so the second try does not trigger the BMS protective shutdown.

While not an ideal solution it is a repeatable. If necessary the rate of charge decay can be slowed by turning the switch on the MultiPass to OFF. The rate of charge decay may depend on the amount of vampire devices connected to the DC side of the MultiPass.

I’m actually considering installing a voltage meter in my battery compartment and a switch in my negative battery cable to allow rapid BMS reset. Then I can prime the MultiPlus, reset the BMS, and start it without tools.

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Additional information. I have been working with Battle Born and after some experimenting we have determined than on small systems it is possible with a short cable run to oversize the wire from the battery to the inverter. This can result in such a large current to the MultiPass the BMS thinks there is a short and shuts down. I was using 2/0 awg for a run of less than 4 feet. I replaced two small sections (battery negative to shunt and battery positive to switch) with a total of about 30” of 4 awg. The assumption was it would restrict the current flow a small amount. In multiple tests where the MultiPass residual voltage was drained to less than 0.025v the MultiPass started without tripping the BMS. 4 awg is too small for safety so I will be replacing it with 1/0 awg before use. Hopefully 1/0 will be just restrictive enough. I will update thread this in a couple weeks with the results.

The BB CSL is almost $300 US. I did discuss using the current limiter with BB. At this point they do not think it should be necessary on small systems.

Dgorman avatar image
Dgorman answered ·

Battle born sells a device for this exact reason so that the MP cap charging doesn’t trip it. Call BB.

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Dgorman answered ·

Battleborn sells a CSL (current surge limiter). Call them and order one.

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mrseas answered ·

4.2 Connection of Battery cables In order to fully utilize the full capacity of the product, batteries with sufficient capacity and battery cables with sufficient cross section should be used. See table. 12/2000/80-50 24/2000/50-50 Recommended battery capacity (Ah) 350–1000 200–500 Recommended DC fuse 300A 200A Recommended cross section (mm2 ) per + and - connection terminal 0 – 5m 70mm2 35mm2 Remark: Internal resistance is the important factor when working with low capacity batteries. Please consult your supplier or the relevant sections of our book “electricity on board”, downloadable from our website. Procedure Proceed as follows to connect the battery cables: Use an insulated box spanner in order to avoid shorting the battery. Avoid shorting the battery cables. Connect the battery cables: the + (red) on the left and the - (black) on the right, to the battery see appendix A. Reverse polarity connection (+ to – and – to +) will cause damage to the product. (Safety fuse inside the Multi Compact can be damaged) Secure the nuts tightly in order to reduce the contact resistance as much as possible.

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Kaplan78 avatar image
Kaplan78 answered ·

Ok thanks everybody for the help. I really hit a wall. I went back trough and reconnected wires to the inverter AC input and output. I also found out that when I was updating my Multiplus I didn't seat the CAT5 cable all the way back into the GX panel so it was disconnected. Upon doing all this everything is running smooth and the inverter is super quiet while inverting. Per Johnc I'm going to keep the Multiplus connected to the battery and not use my on/off switch. I will turn off the Mulitplus using the GX panel. It only seems to pull one extra watt leaving it on which isn't terrible. I'm hoping the tripping doesn't come back, but for right now everything seems solid. If it does come back I'll look at the other suggestions here. Thanks for all the help this is a great community!

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Tom avatar image
Tom answered ·

You should install a pre-charge resistor to charge the compasitors in the Multiplus before turning on the main switch. I have my Multiplus 24/3000 set up this way and just use a 7watt 120ohm resistor.

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Dgorman answered ·

Battleborn sells CSLs. I had two installed for this. I ended up removing them, didn’t need them. Let me know if you want pics.

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Kaplan78 answered ·

Interesting I'll try leaving it connected and turning it off at the panel. I was just trying to prevent phantom draw since I rarely ever need the multiplus. It does seem like some kind of surge issue.

As far as temperature compensation, I'll have to look but it should be zero. I set the exact specifications recommended by Battle Born for the Multiplus. However, everything is cold when I'm doing this, everything has been off so there is zero heat. Not sure if that matters with this setting. I will double-check the setting though

With the buzzing I have never heard a Multiplus run so it may be normal, of course, the battery tripping is not. I have other say that inverters of this size are just really loud. I would say it's loud enough if someone walked in my van when it was running they would say what the heck is that noise?

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it does sound like a surge issue.

I do have a precharge circuit on my install, but its specifically for when I disconnect/reconnect the multiplus to the battery through a DC cut out switch.

When you say you're not using the hard (front panel?) switch on the multiplus, what switch are you using? Are you cutting the DC line with the switch?


theres a couple more threads on this forum on MP noise - one of them has an audio recording of the noise. You might use it for comparison. I found that if I turned the fan off the noise level went down (you'll have to decide if the reduction in power capability is worth it to you)

ejrossouw avatar image
ejrossouw answered ·

@Kaplan78

"Temperature Compensation: Temperature compensation is not needed with our batteries and in some cases, may trigger the built in BMS to go into protect mode. For this reason, we recommend that temperature compensation be shut off or set to 0."

Is this a possibility?

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