I have a Victron SmartSolar MPPT 100/20 Charge Controller. Can I place a switch between the charge controller's positive output and the positive terminal of the battery? The solar panels would always be connected to the charge controller and I would use the switch to enable or disable charging. I think I read somewhere that you should not connect the solar panels to the charge controller, without first connecting the charge controller to the battery. However, I am not sure if that applies to Victron charge controllers. Will wiring it this way cause any harm or undesirable effects?
Can I add a switch to my charge controller?
- Thread starter Nartmot
- Start date
SolarQueen
Making renewable do-able at www.alteStore.com
Disconnect the solar panels instead of the charge controller.
gnubie
Solar Wizard
- Joined
- Sep 20, 2019
- Messages
- 3,847
If you want to just control the charger you can configure your Victron controller so that one of the pins on the ve.direct connector on the bottom enables / disables the charger. You can do this configuration with the Victron app on your smartphone. It would then be a case of applying voltage (12v? have to check that in the manual) to that pin or not turn turn it on and off.
I don't have a problem with doing that but can I use a standard automotive relay for that? I have two 100w panels that are connected in series so they'll be pushing over 60 volts (just a guess) in full sunlight.
I am not familiar with ve.direct. I will look into that.
I really appreciate everyone's responses. Thank you.
A little more background on the question I asked: I am building a mobile generator for my truck. I want the ability to hit a button and shut down everything that consumes any power (charge controller will use a small amount to run the bluetooth) for long term storage.
The RX pin of the ve.direct port will not work for this because it will only stop charging. It will not turn off the charge controller completely.
I guess I was just confused about relay specifications but I think I found one that will be suitable for connecting/disconnecting solar panels: https://www.arrow.com/en/products/h...SPF-vsd7TmG7U7wJDuiLDpuePbdUDAGgaAkZvEALw_wcB
A regular automotive relay will NOT work.
However, it turns out that the original setup I proposed, with a switch on the positive controller output to the battery, will work. Here is what Victron CS had to say:
Thanks for your inquiry to Victron Energy.
This will not harm the charge controller. There are certain rare circumstances where if you completely power down the MPPT controller, and then connect the solar panels first, it could default to the wrong battery voltage, such as mistaking a 12V system for a very low 24V bank. With all recent models (3 years or so), as long as you set the voltage in the VictronConnect app to the correct one for your system, it will always remember it.
Just be aware that if the battery is switched off and it is night time, you won't be able to log into the unit via bluetooth.
You can also use the VictronConnect app to enable/disable the charger, although this will use a little bit more standby power, as the bluetooth transmitter will still be active and ready for connection.
A little more background on the question I asked: I am building a mobile generator for my truck. I want the ability to hit a button and shut down everything that consumes any power (charge controller will use a small amount to run the bluetooth) for long term storage.
The RX pin of the ve.direct port will not work for this because it will only stop charging. It will not turn off the charge controller completely.
I guess I was just confused about relay specifications but I think I found one that will be suitable for connecting/disconnecting solar panels: https://www.arrow.com/en/products/h...SPF-vsd7TmG7U7wJDuiLDpuePbdUDAGgaAkZvEALw_wcB
A regular automotive relay will NOT work.
However, it turns out that the original setup I proposed, with a switch on the positive controller output to the battery, will work. Here is what Victron CS had to say:
Thanks for your inquiry to Victron Energy.
This will not harm the charge controller. There are certain rare circumstances where if you completely power down the MPPT controller, and then connect the solar panels first, it could default to the wrong battery voltage, such as mistaking a 12V system for a very low 24V bank. With all recent models (3 years or so), as long as you set the voltage in the VictronConnect app to the correct one for your system, it will always remember it.
Just be aware that if the battery is switched off and it is night time, you won't be able to log into the unit via bluetooth.
You can also use the VictronConnect app to enable/disable the charger, although this will use a little bit more standby power, as the bluetooth transmitter will still be active and ready for connection.
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I want a quick and convenient way to cut off all devices that draw power from the battery, before I put the generator in long term storage. The charge controller pulls a small amount of power from the battery to run the bluetooth so just turning off charging would not keep it from draining a small amount of power. I also plan to turn off my low voltage disconnect (also bluetooth) and active balancer with a button.
Master Dalor
Self made Master
Hello. I = P/V = 200W/60V = 3.333333 Amp only.
200W/12V = 16,666666 Amp.
If you use a bathroom light interrupter (shema 2 bipolar) it is 2 interrupters in one, cutting the 2 wires (phases here in europe) exists for 20Amp.
You connect the solar pannels + on one phase, the corresponding interrupter outlet on the controller inlet.
You connect the controller + outlet to the other interrupter phase, the corresponding interrupter outlet to the battery +.
This way, you connect and disconnect the two sides of the controller at once.
Everybody is happy, no need for energy consuming 12V relay and the 2 sides of the controller are isolated.
200W/12V = 16,666666 Amp.
If you use a bathroom light interrupter (shema 2 bipolar) it is 2 interrupters in one, cutting the 2 wires (phases here in europe) exists for 20Amp.
You connect the solar pannels + on one phase, the corresponding interrupter outlet on the controller inlet.
You connect the controller + outlet to the other interrupter phase, the corresponding interrupter outlet to the battery +.
This way, you connect and disconnect the two sides of the controller at once.
Everybody is happy, no need for energy consuming 12V relay and the 2 sides of the controller are isolated.
Thanks @Master Dalor . That is an interesting idea and will certainly keep it in my mental toolbox for future projects. I am sure others looking to do this with a non Victron charge controller would benefit from this information too.
Master Dalor
Self made Master
I hope to help as many people as possible, sure I thought off it after our vitron friend told you/us the battery could be disconnected when the voltage is set in the controller. Now, I wish I can do the same on my epever 5420 in my van. In the manual, Epever says it can break the controller to connect the pv without battery. I'll read it again, and maybe ask them. Thank you too.
Master Dalor
Self made Master
Yes, we can do that, or put one interrupter on each side and action them in the right order, maybe I will do that In my van as I am the only master onboard. :D If there are other masters onboard it can be dangerous, and I would be forced to search for a staggered switch.
Thank you.
I hope to help as many people as possible, sure I thought off it after our vitron friend told you/us the battery could be disconnected when the voltage is set in the controller. Now, I wish I can do the same on my epever 5420 in my van. In the manual, Epever says it can break the controller to connect the pv without battery. I'll read it again, and maybe ask them. Thank you too.
My original idea was to use a delay relay. The switch connects the charge controller to the battery, and also triggers the delay relay. Then the delay relay, after maybe 10-15 seconds, connects the PV to the charge controller. I figure this would give the charge controller adequate time to boot up before connecting to the panels. It would also make it impossible to connect the PV to the controller without first connecting the controller to the battery, making the setup idiot-proof. To be honest with you, I am still not sure why other manufacturers warn against connecting the PV first. In the Victron's case, it was just because it needed the connection to the battery to detect what voltage to set itself to, not because it would have caused any damage to the controller itself.
Probably a lot of trouble just to save a few mAh, but for me its more about the journey than the destination. I just really enjoy learning and tinkering with things.
Master Dalor
Self made Master
yes good idea, but the victron friend told its ok, once the voltage is set, for other brands it could be useful. I also think alot about losses when the power source is limited, any little gain added to other little gain can make the difference at the end. I pacticed that in computer tunning, antenna and line matching, for ham radio, for small 50cc and 80cc motor bike race engines, bicycles that doesn't kill you, easy to ride, and now ebikes with long range. and certainly off grid solar in my van. On a house, a big property, you can always add more pannels, more batteries, I try to stay simple, something we can do is use the fatest, and as short as possible cables, the minus point is the weight therefore I think about aluminium cables, but aluminium will react in some conditions, and it needs to be 1.666 times bigger than copper, for the same resistance and for example on the epever the connectors are only 16 square mm, we could use a short copper wire to a busbar, and from there go to or come from the pv with aluminium, but each connection adds resistance, and risk of troubles, maybe someone will give us the easy solution. .
Now with new technology, led lights, and others, we can consume less, lithium batteries are light and powerful, we can adapt our lives to use the power during daylight, put small batteries on everything dc, use cheap square wave inverter when it fits, and pure sine when mandatory, and disconnect them when we want, because we are the masters of those machines, we decide what is best to do. Hehehe :D
.Now with new technology, led lights, and others, we can consume less, lithium batteries are light and powerful, we can adapt our lives to use the power during daylight, put small batteries on everything dc, use cheap square wave inverter when it fits, and pure sine when mandatory, and disconnect them when we want, because we are the masters of those machines, we decide what is best to do. Hehehe :D
Master Dalor
Self made Master
Another solution to use thinner cables is to start with more volts from the pv.
Because the loss in the line is counted in volts per meter, so if you must go 10 meters away with 12V and you loose 1v per meter ( It's not that much in reality for example only) you end with 2V. If you start with 120V, you still get 110V at the end. as P = V x I , I = P/V, If P is 120W and V is 12V, 120/12=10Amp , If V is 120V, 120/120=1Amp .
Why must aluminium be 1.61111 times bigger than copper? Sorry for the mistake in previous post.
Because of the resistivity.
Al: 0.0278 Ohm x square mm/ meter
Cu: 0.017 Ohm x square mm / meter
or maybe more obvious, the inverse, the conductivity.
Al: 36 meter/(Ohm x square mm)
Cu: 58 meter/(Ohm x square mm)
58/36=1.61111
so a copper wire of 58 meter long and 1 square mm surface as the same resistance as a wire 116 meter long and 2 square mm surface.
For the same resistance an aluminium wire would be only 36 m for 1 square mm.
How much is the diameter of 1 square mm?
S = pi x D squared / 4
D squared = 4 S / pi
D = square root of 4S / pi
4/3.1415927= 1.27 so much decimals for pi is for the show. 3.14 is close enough. :D
square root of 1.27 = 1,127 mm that you can measure with your caliper.
for 4 square mm, common pv cable.
16/3.14=5.095
root=2.26 mm
16 square mm = 4.515 mm
35 square mm = 6.672 mm
Well good night, or good morning.
Ps: if you prefer inches 1 inch is 25.4 mm
You can redo my math, because I make mistakes.
Because the loss in the line is counted in volts per meter, so if you must go 10 meters away with 12V and you loose 1v per meter ( It's not that much in reality for example only) you end with 2V. If you start with 120V, you still get 110V at the end. as P = V x I , I = P/V, If P is 120W and V is 12V, 120/12=10Amp , If V is 120V, 120/120=1Amp .
Why must aluminium be 1.61111 times bigger than copper? Sorry for the mistake in previous post.
Because of the resistivity.
Al: 0.0278 Ohm x square mm/ meter
Cu: 0.017 Ohm x square mm / meter
or maybe more obvious, the inverse, the conductivity.
Al: 36 meter/(Ohm x square mm)
Cu: 58 meter/(Ohm x square mm)
58/36=1.61111
so a copper wire of 58 meter long and 1 square mm surface as the same resistance as a wire 116 meter long and 2 square mm surface.
For the same resistance an aluminium wire would be only 36 m for 1 square mm.
How much is the diameter of 1 square mm?
S = pi x D squared / 4
D squared = 4 S / pi
D = square root of 4S / pi
4/3.1415927= 1.27 so much decimals for pi is for the show. 3.14 is close enough. :D
square root of 1.27 = 1,127 mm that you can measure with your caliper.
for 4 square mm, common pv cable.
16/3.14=5.095
root=2.26 mm
16 square mm = 4.515 mm
35 square mm = 6.672 mm
Well good night, or good morning.
Ps: if you prefer inches 1 inch is 25.4 mm
You can redo my math, because I make mistakes.
Master Dalor
Self made Master
Pps: one last thing, with one eye closed, I don't go more than 24V , with my 6 x 100 W panels, I could get 72V, but on mobile systems, there could be shadows when it's impossible to find the best place to park, with all panels in series only one panel in the shadow means, no more production, with 2s 3p, one panel, or 2 from the same, serie, in the shadow means I still get 24V and 2/3 production.
