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Near constant hot water without a generator - Here is how i did it.


Eric Meury
 

We have an santorin with no generator but have 1000 Watts of solar.  400 of those watts are shaded -  200 is behind the main mast flexible panels and 200 is on the new hard top bimini (room for more)  The bulk of the power comes from 600 Watts on the arch. 

Here is what we did.  

1.  Added the Victron 712 Battery Monitor that is bluetooth and replaced the Amel Shunt 

2.  Changed out the AC heating element for a 600 Watt DC element (300 Watt can be used as well)

3.  Added a Victron Battery Protect -  this serves as the relay and what powers the heating element.  - ie the heating element positive cable is connected to the battery protect .
 (BPR065022000 Victron Energy BPR065022000 Smart BatteryProtect with Bluetooth 12/24V - 65A) -  $59 bucks from pkys

4.  Disconnected the thermostat wire from the heating element and attached it directly to the relay.

Here is how it works -  The BMV has a relay setting.  This is set to Default mode but i changed the settings to Invert.  The Low SOC is set to 90 and 96.  What this means is that the relay will be powered when the SOC is anything above 90%.  When it gets to 90% it will turn off and will not turn back on again until the SOC is 96% (these can be changed)  -  This send a signal to the battery protect to "turn on" thus sending power to the heating element.  The battery protect has a shutdown setting of 12.4 volts  (i can change that to really anything but this was set to be an absolule failsafe to never let the batteries go below 12.4).  It turns back on when the batteries are 12.75. I have never seen 12.4 from my bank.   The tempature sensor is set to what ever the factory setting is...i  imagine it is 105 degrees (torried marine water heater).  

So everyday and a couple of times a day depending on how much water is used, my heater will turn on automatically in the mid morning as by that time i have recovered from the nightly discharge and am now above 96%/.  The element will draw a full 600 Watts until such time that either thhe SOC is 90% OR the tempature sensor says - he we are good and have plenty of hot water.  The first time i rant it it took a good 1.5 to 2 hours to get to that tempature. but my batteries never eached 90% as i'm usually producting 400-500 Watts and only have 600 watt drain so max i see going out during the day is 200-250 watts -  (if you use a 300 Watt Element and have plenty of solar you won't go negative but will talke longer)  Since i have this it only needs to run for maybe 15 to 20 mins and occastionally longer to keep the water at the tempature set by the tempature sensor.  

We now take a hot shower everyday and my 2 year old plays in a warm baby pool almost everyday.  -  All of this is powered with solar. (and soon to be wind)   

If i'm on the hard (which i am right now) it still works just the same and If i plug in heat water just by using the battery charger.  

If you have a desire (or don't have one) to not have to run your genset to heat water daily then this is a good way to go provided you have enough solar to make it happen.  We have one fridge and one freezer and a 12 volt home built spectra watermaker.  All of the settings are controlled from my phone via the victron connect app.  I can completley turn off the water heater by accessign the battery protect  - there is a setting to disable.  

I do not have lithium batteries but my bank is large with 4 - L16 Flooded Wet Cell batteries with 840 Amp hours.  


Matt Salatino
 

Eric,
Excellent configuration. Where do you get $C heating elements? And is there really a difference between AC and DC elements? Seems it would just be a resistance heater? Different resistance?

~~~⛵️~~~Matt

On May 17, 2020, at 10:04 AM, Eric Meury <ericmeury@...> wrote:

We have an santorin with no generator but have 1000 Watts of solar.  400 of those watts are shaded -  200 is behind the main mast flexible panels and 200 is on the new hard top bimini (room for more)  The bulk of the power comes from 600 Watts on the arch. 

Here is what we did.  

1.  Added the Victron 712 Battery Monitor that is bluetooth and replaced the Amel Shunt 

2.  Changed out the AC heating element for a 600 Watt DC element (300 Watt can be used as well)

3.  Added a Victron Battery Protect -  this serves as the relay and what powers the heating element.  - ie the heating element positive cable is connected to the battery protect .
 (BPR065022000 Victron Energy BPR065022000 Smart BatteryProtect with Bluetooth 12/24V - 65A) -  $59 bucks from pkys

4.  Disconnected the thermostat wire from the heating element and attached it directly to the relay.

Here is how it works -  The BMV has a relay setting.  This is set to Default mode but i changed the settings to Invert.  The Low SOC is set to 90 and 96.  What this means is that the relay will be powered when the SOC is anything above 90%.  When it gets to 90% it will turn off and will not turn back on again until the SOC is 96% (these can be changed)  -  This send a signal to the battery protect to "turn on" thus sending power to the heating element.  The battery protect has a shutdown setting of 12.4 volts  (i can change that to really anything but this was set to be an absolule failsafe to never let the batteries go below 12.4).  It turns back on when the batteries are 12.75. I have never seen 12.4 from my bank.   The tempature sensor is set to what ever the factory setting is...i  imagine it is 105 degrees (torried marine water heater).  

So everyday and a couple of times a day depending on how much water is used, my heater will turn on automatically in the mid morning as by that time i have recovered from the nightly discharge and am now above 96%/.  The element will draw a full 600 Watts until such time that either thhe SOC is 90% OR the tempature sensor says - he we are good and have plenty of hot water.  The first time i rant it it took a good 1.5 to 2 hours to get to that tempature. but my batteries never eached 90% as i'm usually producting 400-500 Watts and only have 600 watt drain so max i see going out during the day is 200-250 watts -  (if you use a 300 Watt Element and have plenty of solar you won't go negative but will talke longer)  Since i have this it only needs to run for maybe 15 to 20 mins and occastionally longer to keep the water at the tempature set by the tempature sensor.  

We now take a hot shower everyday and my 2 year old plays in a warm baby pool almost everyday.  -  All of this is powered with solar. (and soon to be wind)   

If i'm on the hard (which i am right now) it still works just the same and If i plug in heat water just by using the battery charger.  

If you have a desire (or don't have one) to not have to run your genset to heat water daily then this is a good way to go provided you have enough solar to make it happen.  We have one fridge and one freezer and a 12 volt home built spectra watermaker.  All of the settings are controlled from my phone via the victron connect app.  I can completley turn off the water heater by accessign the battery protect  - there is a setting to disable.  

I do not have lithium batteries but my bank is large with 4 - L16 Flooded Wet Cell batteries with 840 Amp hours.  


 

Bravo Eric. and I do not believe there is any difference in AC vs DC resistance heating element...but ask an electrician.

CW Bill Rouse Amel Owners Yacht School
Address: 720 Winnie, Galveston Island, Texas 77550 
View My Training Calendar


On Sun, May 17, 2020 at 9:40 AM Matt Salatino via groups.io <helmsmatt=yahoo.com@groups.io> wrote:
Eric,
Excellent configuration. Where do you get $C heating elements? And is there really a difference between AC and DC elements? Seems it would just be a resistance heater? Different resistance?

~~~⛵️~~~Matt

On May 17, 2020, at 10:04 AM, Eric Meury <ericmeury@...> wrote:

We have an santorin with no generator but have 1000 Watts of solar.  400 of those watts are shaded -  200 is behind the main mast flexible panels and 200 is on the new hard top bimini (room for more)  The bulk of the power comes from 600 Watts on the arch. 

Here is what we did.  

1.  Added the Victron 712 Battery Monitor that is bluetooth and replaced the Amel Shunt 

2.  Changed out the AC heating element for a 600 Watt DC element (300 Watt can be used as well)

3.  Added a Victron Battery Protect -  this serves as the relay and what powers the heating element.  - ie the heating element positive cable is connected to the battery protect .
 (BPR065022000 Victron Energy BPR065022000 Smart BatteryProtect with Bluetooth 12/24V - 65A) -  $59 bucks from pkys

4.  Disconnected the thermostat wire from the heating element and attached it directly to the relay.

Here is how it works -  The BMV has a relay setting.  This is set to Default mode but i changed the settings to Invert.  The Low SOC is set to 90 and 96.  What this means is that the relay will be powered when the SOC is anything above 90%.  When it gets to 90% it will turn off and will not turn back on again until the SOC is 96% (these can be changed)  -  This send a signal to the battery protect to "turn on" thus sending power to the heating element.  The battery protect has a shutdown setting of 12.4 volts  (i can change that to really anything but this was set to be an absolule failsafe to never let the batteries go below 12.4).  It turns back on when the batteries are 12.75. I have never seen 12.4 from my bank.   The tempature sensor is set to what ever the factory setting is...i  imagine it is 105 degrees (torried marine water heater).  

So everyday and a couple of times a day depending on how much water is used, my heater will turn on automatically in the mid morning as by that time i have recovered from the nightly discharge and am now above 96%/.  The element will draw a full 600 Watts until such time that either thhe SOC is 90% OR the tempature sensor says - he we are good and have plenty of hot water.  The first time i rant it it took a good 1.5 to 2 hours to get to that tempature. but my batteries never eached 90% as i'm usually producting 400-500 Watts and only have 600 watt drain so max i see going out during the day is 200-250 watts -  (if you use a 300 Watt Element and have plenty of solar you won't go negative but will talke longer)  Since i have this it only needs to run for maybe 15 to 20 mins and occastionally longer to keep the water at the tempature set by the tempature sensor.  

We now take a hot shower everyday and my 2 year old plays in a warm baby pool almost everyday.  -  All of this is powered with solar. (and soon to be wind)   

If i'm on the hard (which i am right now) it still works just the same and If i plug in heat water just by using the battery charger.  

If you have a desire (or don't have one) to not have to run your genset to heat water daily then this is a good way to go provided you have enough solar to make it happen.  We have one fridge and one freezer and a 12 volt home built spectra watermaker.  All of the settings are controlled from my phone via the victron connect app.  I can completley turn off the water heater by accessign the battery protect  - there is a setting to disable.  

I do not have lithium batteries but my bank is large with 4 - L16 Flooded Wet Cell batteries with 840 Amp hours.  


Eric Meury
 

hey matt. 

im not 100% sure if there is a difference but i do know that my AC element way to many watts going out.  This is the unit i purchased.  https://globalsolarsupply.com/product/diversion-load-water-heating-element-60a12v-30a24v/

it will work for 12 or 24 volt.  I think if you goole the type of water heater you have you can find out the size of the element.   You will most likely need the professional tool to remove the water heater element.  The cheap home ones will simply not do the job.  at least on my tank that was the case.  ...What brand of water heater do you have?


Matt Salatino
 

Our water heater is an Isotherm.
I haven’t looked at the element nut size.

~~~⛵️~~~Matt

On May 18, 2020, at 7:36 AM, Eric Meury <ericmeury@...> wrote:

hey matt. 

im not 100% sure if there is a difference but i do know that my AC element way to many watts going out.  This is the unit i purchased.  https://globalsolarsupply.com/product/diversion-load-water-heating-element-60a12v-30a24v/

it will work for 12 or 24 volt.  I think if you goole the type of water heater you have you can find out the size of the element.   You will most likely need the professional tool to remove the water heater element.  The cheap home ones will simply not do the job.  at least on my tank that was the case.  ...What brand of water heater do you have?


Ryan Meador
 

There's nothing special about "AC" vs "DC" for these heater elements, but the voltage does matter, and in common boating usage these current types imply a voltage as well.  The element is just a resistor, so to achieve the desired number of watts, the resistance is sized for a specific voltage.  If you run a 240V element at 24V, you'll get 1/10th the rated output (and vice versa will likely explode).  The other electronics involved (like the thermostat) may actually care about AC vs DC and the voltage; I'm not sure.

Some marine water heaters have two ports so you can have both AC and DC elements at the same time.  I've heard using a DC water heater element as a wind generator's dump load works well.

Ryan and Kelly
SM 233 Iteration
Boston, MA, USA


On Mon, May 18, 2020 at 3:25 AM Matt Salatino via groups.io <helmsmatt=yahoo.com@groups.io> wrote:
Our water heater is an Isotherm.
I haven’t looked at the element nut size.

~~~⛵️~~~Matt

On May 18, 2020, at 7:36 AM, Eric Meury <ericmeury@...> wrote:

hey matt. 

im not 100% sure if there is a difference but i do know that my AC element way to many watts going out.  This is the unit i purchased.  https://globalsolarsupply.com/product/diversion-load-water-heating-element-60a12v-30a24v/

it will work for 12 or 24 volt.  I think if you goole the type of water heater you have you can find out the size of the element.   You will most likely need the professional tool to remove the water heater element.  The cheap home ones will simply not do the job.  at least on my tank that was the case.  ...What brand of water heater do you have?