Big Victron upgrade done but how do I use spare solar to heat hot water with a alde system

[Gazthediver]

Ok we have just had installed 2x230amp lithium frogstar batteries with 3x215w Victron solar to go with our 100w original panel 2x Victron mppt 150/60 and 100/20 and a Victron multi plus 2 3000w inverter and now looking to find out how I can use spare solar when batteries are full to power up the truma water heater, I have heard it can be done but don’t know how ? Vehicle is a fiat ducato 2020 on a swift kontiki sport 599

 

[Sonar]

Member wildebus is the person to ask

 

[wildebus]

The way I did this was to use the Relay output on the Victron BMV-712 Monitor to control a power relay that switches the electric supply to the Water Heater on and off based on the Battery SOC value.
That automates the process but another way if you don't have this type of monitor with a relay is to manually kick off the water heater process and start a timer like this - https://amzn.to/3W93aDP . Using a timer will ensure you don't forget to turn the heater off.

FWIW, I use a combination of basing the action on the Battery SOC and using a timer if I want to heat the water on electric regardless but don't want to have to remember to turn it off afterwards.

 

[Gazthediver]

The way I did this was to use the Relay output on the Victron BMV-712 Monitor to control a power relay that switches the electric supply to the Water Heater on and off based on the Battery SOC value.
That automates the process but another way if you don't have this type of monitor with a relay is to manually kick off the water heater process and start a timer like this - https://amzn.to/3W93aDP . Using a timer will ensure you don't forget to turn the heater off.

FWIW, I use a combination of basing the action on the Battery SOC and using a timer if I want to heat the water on electric regardless but don't want to have to remember to turn it off afterwards.

I do have the BMV-712 Monitor and know about the power relay thanks but not sure how to get it to power the heating element

 

[wildebus]

I do have the BMV-712 Monitor and know about the power relay thanks but not sure how to get it to power the heating element

ok. what you could do is this ...
(this is based on the inverters sole job is to provide power to the water heater)

Replace the on-off switch on the controller with an on-off-on switch
move the existing wires from the 'on' and centre connections on the contoller to the centre and one of the 'on' connections
connect the other 'on' connections to the BMV relays "NC" terminal (and connect the BMV Relays "COM" to 12V)
Program the Relay with the SOC parameters - set it to say 99% and 90%.

Then if you want the heater on manually, switch to the manual ON; and if you want it on when the battery is full, switch to the other ON.

You could do the same thing away from the inverter by fitting an on-off-on switch to control an 240V SSR (Solid State Relay) via the BMV and have that in line with the AC cable to the heater. This is the way I did it on my last self-build camper.
I used the CBE switch for lights and water pump, but used the left 'lights' side for the water heater, swapping out the normal switch for a 3-way on-off-on one as you see from the photo below.

 

[Gazthediver]

ok. what you could do is this ...
(this is based on the inverters sole job is to provide power to the water heater)

Replace the on-off switch on the controller with an on-off-on switch
move the existing wires from the 'on' and centre connections on the contoller to the centre and one of the 'on' connections
connect the other 'on' connections to the BMV relays "NC" terminal (and connect the BMV Relays "COM" to 12V)
Program the Relay with the SOC parameters - set it to say 99% and 90%.

Then if you want the heater on manually, switch to the manual ON; and if you want it on when the battery is full, switch to the other ON.

You could do the same thing away from the inverter by fitting an on-off-on switch to control an 240V SSR (Solid State Relay) via the BMV and have that in line with the AC cable to the heater. This is the way I did it on my last self-build camper.
I used the CBE switch for lights and water pump, but used the left 'lights' side for the water heater, swapping out the normal switch for a 3-way on-off-on one as you see from the photo below.

Thanks I look in to that

 

[Gazthediver]

Sorry it’s a Alde wet heating and not a truma system

 

[wildebus]

Sorry it’s a Alde wet heating and not a truma system

don't think it matters - you want to just control the power availability. (mine was not a alde or a truma, it was an Ariston 240V heater, but that is by the bye).