Victron MPPT 100/20

[kevdoc]

I am assembling a secondary db board for my Conqueror Compact trailer, comprising mostly of Victron gear.

My intentions are to:

1 - route all ac power (grid and inverter via a changeover switch) to the Conqueror earth leakage

[when you see how campers often run extension leads and multiplugs in the rain, you gotta be wondering if campsite earth leakages aren't often compromised to alleviate frequent tripping]

2 - run dc power to the Conqueror db board (internal charger removed) from the LOAD (not battery) output of the Victron MPPT, which will also be connected to battery and solar respectively.

It's rated at 20A, while the Conqueror db board output overload switches are 16A and 20A.

Does anyone know of any reason why I should not power it in this way, via the LOAD? The objective is to have accurate reporting of regular consumption via the bluetooth app. Of course, other heavier irregular loads, such as inverter, will run directly from battery and will be measured independently.

I don't want to risk doing the layout, wiring it all up, installing the board, and then finding there's an issue.

Many thanks

[rudyb]

When I first received mine, I connected the fridge to the load terminals but each time the compressor kicked in, the MPPT tripped (something to do with load spikes).

Needless to say, I don't have anything connected to the load terminals and opted for the shunt.

[kevdoc]

When I first received mine, I connected the fridge to the load terminals but each time the compressor kicked in, the MPPT tripped (something to do with load spikes).

Needless to say, I don't have anything connected to the load terminals and opted for the shunt.

Aha! That's what I was dubious about. Capacitance spikes on startup, and inductive kickbacks from coils on shutdown. Guess I must at very least first wire a mock-up, and test. The water pump is another concern.

Thanks for the feedback. Much appreciated!

[heyyahhey]

Not really relevant to your question, but, I found a great use of the “load” output on those to be to connect them to specific lights or outlets and you can then use the app as a remote light switch

[kevdoc]

When I first received mine, I connected the fridge to the load terminals but each time the compressor kicked in, the MPPT tripped (something to do with load spikes).

Needless to say, I don't have anything connected to the load terminals and opted for the shunt.

I see now on electronics forums that many have experienced what you have. Disappointing! With fridge on max, lights and fans, I'm only at 7 of 20A; maybe 10A max with charging of cellphones. I have an oscilloscope and will get some data on these dc spikes. Perhaps a choke coil of sorts with a big fat electrolytic capacitor close to the fridge might be a workaround.

[rudyb]

You're definitely talking about things way above my understanding. The only concern I could raise would be overcomplicating your setup. Vibrations from a rough road could cause problems you don't need.

I see now on electronics forums that many have experienced what you have. Disappointing! With fridge on max, lights and fans, I'm only at 7 of 20A; maybe 10A max with charging of cellphones. I have an oscilloscope and will get some data on these dc spikes. Perhaps a choke coil of sorts with a big fat electrolytic capacitor close to the fridge might be a workaround.

[kevdoc]

You're definitely talking about things way above my understanding. The only concern I could raise would be overcomplicating your setup. Vibrations from a rough road could cause problems you don't need.

I have this morning done a mock setup of the Victron gear inside the trailer, with fridge on max out in the hot sun. Monitoring, but haven't seen any problems yet. Apparently less prevalent when on bulk charge. A very small lithium battery connected downstream, as close as possible to the fridge, would probably absorb most of the hit. Also, the MPPT offers customisable algorthims which may help. Come hell or high water, I'm getting this right. I do also have a Victron BMV-712 smart battery monitor that will be fitted, but that is to provide an overall perspective whereas I quite like the idea of being able to (easily) monitor trailer essentials separately.

[MrTolbos]

Did you consider adding a victron battery protect unit, like the BP65? Then you can use your BMV712 to control the BP65 and your battery will be protected on low SOC level, not just low volts level.

Initially I also wanted to use the load output to be able to log the data, but then I added the BMV712 that does so much more, and never thought of using the load output again

[kevdoc]

I have this morning done a mock setup of the Victron gear inside the trailer, with fridge on max out in the hot sun. Monitoring, but haven't seen any problems yet. Apparently less prevalent when on bulk charge. A very small lithium battery connected downstream, as close as possible to the fridge, would probably absorb most of the hit. Also, the MPPT offers customisable algorthims which may help. Come hell or high water, I'm getting this right. I do also have a Victron BMV-712 smart battery monitor that will be fitted, but that is to provide an overall perspective whereas I quite like the idea of being able to (easily) monitor trailer essentials separately.

I've run this test now for 2 days and have experienced no problems. Nonetheless, at midday today I changed the load output from 'Always On' to 'User Define Algorithm', which apparently looks at state over a period of 2 minutes rather than instantly. This should handle spikes. I'll test it a bit more, perhaps with a greater load added, and then will make a decision.

[kevdoc]

Did you consider adding a victron battery protect unit, like the BP65? Then you can use your BMV712 to control the BP65 and your battery will be protected on low SOC level, not just low volts level.

Initially I also wanted to use the load output to be able to log the data, but then I added the BMV712 that does so much more, and never thought of using the load output again

Awesome suggestion! I'm going to order the smart version tonight. Many thanks! 😀

As regards running a fridge from the MPPT load output, have done so for 2 days in the hot sun and have experienced no problems

[kevdoc]

Awesome suggestion! I'm going to order the smart version tonight. Many thanks! 😀

As regards running a fridge from the MPPT load output, have done so for 2 days in the hot sun and have experienced no problems

Eish, on second thoughts I see that the BP65 is uni-directional, while running Load and PV terminals on the MPPT means the Battery terminals are bi-directional. Bit of a conflict of interest there. Hmmm . . .

[kevdoc]

My fridge is less than a year old. National Luna Smart Legacy. Has a wide dc input voltage range, so no doubt has a dc-dc converter inside. Perhaps also sorted out the startup spikes. I'm seeing no problems.🤷

[MrTolbos]

Eish, on second thoughts I see that the BP65 is uni-directional, while running Load and PV terminals on the MPPT means the Battery terminals are bi-directional. Bit of a conflict of interest there. Hmmm . . .

If you’re still going to use the load output of the mppt then yes the BP65 is probably a bit of a overkill, but you will then still only be able to protect your battery via a low voltage set point, and not SOC set point, and the SOC set point is better if you want to use a lithium battery. The idea of the BP65 is to use it between the battery itself and all the loads, while your mppt’s PV out is connected directly to the battery.

It also sounds like victron changed the shutdown characteristics of the mppt’s load output, I can’t recall that there was any options when I installed my system 6 years ago.

Just make sure that you can rewire the loads from your mppt load output, to your battery directly. It’s not going to be fun drinking warm beer because the mppt suddenly decide to not switch on the load output anymore. I added a bypass circuit breaker in my system to connect my loads directly to the battery. It’s nice to have the electronics, but I only trust it as far as I can throw it, so I always try to add a plan b

[bigboy529]

A couple of years ago at one stage the load output on Victron MPPT's had a lot of limitations when it came to higher current draw and especially spikes experienced when fridge compressors start.
They however sorted this at some point and all newer Victron MPPT's should handle the rated current just fine on the load output.

My older 100/20 from around 2017 sometimes gave issues with starting up my fridge especially if the battery voltage was a bit lower, but my newer one year old 75/15 never had any problems running the fridge.

[kevdoc]

I have a confession to make.

I started this solar/mppt test with trailer in the hot sun and saw the load current graphs going high and low. Then I cranked the empty fridge to -24/-18 and nothing tripped whatsoever. Awesome!?

Then it dawned on me that the fridge was NOT reaching temperature. Running permanently and therefore defeating the very purpose of the test. Barely 8 months old and a shadow of its former self. Long story short, I dropped it at National Luna in Edenvale this morning.

Testing will resume once they have sorted it out. Thank goodness I picked this up now, rather than on the eve of departure.