Looking for a little help…..

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Jjenkins5179

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Apr 20, 2024
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Hey everyone. Looking for some assistance/guidance. I have a setup that was intended to allow my wife to brew a cup of coffee when we were dry camping/boondocking. I have 4 Battle Born 100 Ah, 12V batteries, a Victron 12/3000/120-50 2 x 120v Charger/inverter. Batteries are wired in parallel with 4/0 wire, positive wire has a 400A ANL fuse in line before it goes to a battery disconnect switch. From there is goes to a BMV-712 Smart shunt, Lynx distributor. The problem is anytime I try and run anything that consumes any significant power the system dies within seconds. I have checked all connections and they are tight and in the correct spot. All settings have been checked and appear to be right. From what I have seen it seems that I should be able to power a Keurig single cup coffee maker with the battery setup I have. And to make matters worse when I went out to verify everything was tight and secure I noticed that the wire from the ANL fuse holder to the disconnect switch had gotten very hot at some point but the fuse was not blown. I have checked all batteries independently and all are good and fully charged. Factory inverter has been disabled and is not in play. I have included pics of what my settings are. Any help would be greatly appreciated! Thanks!
 

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The problem is anytime I try and run anything that consumes any significant power the system dies within seconds.
Could you explain the "dies within seconds" in more detail? Just what happens? Inverter error msg/code or ? And what is "significant power", i.e. watts load or battery amp draw?

You have more than enough battery capacity and inverter to run an Keurig-type electric coffee maker multiple times between battery charging, so it's not an equipment shortcoming. However, you haven't described the wiring and how the inverter feeds power to the RV and what loads may be present.

One thing that comes to mind from your description is the possibility that the inverter output circuit backfeeds to the inverter input. That would form a power loop that would likely deplete the batteries in just moments. It is critical that the inverter doesn't try to power its own charging function.
 
When we start the Keurig about 3 seconds in we have total power loss of everything. Few seconds later power come back, I get a low battery warning on the Victron App. By Significant power i am referring to the power draw from the Keurig, the same thing happens if we try the microwave, which has a power consumption of 1550W. When I have attempted this the only power being used is the refrigerator and we have that running off the batteries. I have 6/4 wire going into the inverter and to the fuse panel where it’s connected to the 50 amp breaker. I have 2awg wire coming off the Lynx distributor which goes to the busbar for 12v devices but I’m unaware if there is anything that it would be powering that could cause an issue. I am using a Blue Sea system disconnect switch model 6006M. We haven’t been able to use the coffee maker in the past. Funny thing is when we were bookndocking last week after we were set up according to the BMV712 we had about 10 hours of battery left which seemed very low (at that time we had the tv on and fridge was on all) for having the batteries I do. Thanks again for any and all help and suggestions.
 
hot cables suggest a high resistance joint or bad connector crimp
disconnect switch could also be suspect.
at the worst, you could have a battery BMS shutting down.. rare, but does occur.

i run the multiplus 2 but at 24 Volts, it can power a 3000 W load without issue.
your settings appear to be ok.
if you overload the victron it will pop up an overload warning on the app.


try an experiment with progressively higher loads.
start at say 100-200 watts and load it up until it fails.
then check for hot cables. even at 12 V and those size cables, you should not have anything
that is more than slightly warm.
 
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Thoughts on bypassing the disconnect switch, going from the 4/0 wire coming from the ANL fuse holder directly to the Lynx Distributor, just to see if it is the switch? That wire has shown signs of getting very warm and I’m wondering if the switch has gone bad and is not allowing the full current to flow through it?
 
This would be temporary, if the switch is bad I would still have it hooked up after the test so I could disconnect the system if need be until a new switched could be obtained.
 
I agree hot wires indicater high resistance and high resistance will cause exactly the symptoms you have.. What size and how long is that wire. In fact all the wires between battery and inverter what size and how long.

Second on the list does not apply here but on the wires to the inverter.. I will assume the positive is red and negative black for ease of discussion.. Tape them together side by side for as much of the run as possible.. the idea is to imitate what is called "ZIP" cord.
The link is NOT a cable I would recommend (it's that kind of plug is good for 10 amps tops) but it shows what I'm talking about... Plus I have one. (I use it for like 1 amp stuff)

 
Well, I think my switch might have something to do with the issue. I put my multimeter on it and regardless if the switch is on or off current is still passing through it. So I’m wondering if it’s not allowing the full current that is being called for to flow through the switch causing 1) the wire to overheat and 2) causing the system to shut down due to lack of power. I’m obviously no expert in this, just throwing ideas out.
 
All wires coming from the battery bank and to the inverter are 4/0. The wire in question is 10 inches in length. The neg/pos wire from the battery bank to the fuse holder/shunt are both approximately 26 inches in length (that measurement includes the fuse holder for the positive).
 
Well, I think my switch might have something to do with the issue. I put my multimeter on it and regardless if the switch is on or off current is still passing through it. So I’m wondering if it’s not allowing the full current that is being called for to flow through the switch causing 1) the wire to overheat and 2) causing the system to shut down due to lack of power. I’m obviously no expert in this, just throwing ideas out.
That would certainly be a problem, but are you sure you tested it properly? It can be tricky to verify switch operation in a live circuit. Typically you would check for voltage on either side of the switch when the circuit is live, or check for continuity (ohms) across the switch if the circuit is powered down.
 
A Keurig coffeemaker draws 1500 watts, or the same power as an electric room heater or 125 amps at 12 volts not counting inverter losses. Is the switch rated to pass at least 150 amps? This is the first place I would look. For testing purposes you can join the wires going to the switch on a single switch terminal or use a nut and bolt to temporarily hold them together. Disconnect the battery first.
 
That sounds high to me - my Keurig is 950 and I think somewhere around 1000W-1200W is typical. But the point is still valid; 1000W @ 12v is at least 83A and more like 90+ with power losses factored in.
Here's the one I looked at - a Keurig single cup coffeemaker that claims to use 1500 watts. Probably brews a cup a bit quicker than yours, says it takes under a minute.

Amazon.com
 

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