Running Water Heater with Victron Inverter

[ronwakefield]

I will soon be installing a Victron 3000 watt inverter/charger with 300 Ah of lithium batteries and 4 - 5 solar panels. I'm working on my energy audit to get as close as possible with my usage.

Currently I plan to have my outlets and microwave hooked to the inverter but am wondering if I can also connect the hot water heater. Does anyone have any experience with connecting the hot water heater to the inverter? I think that I would only need the hot water heater on for about an hour per day.

Any insights or experience is appreciated.

Ron
2008 Holiday Rambler Vacationer

[jacwjames]

The electric element in my water heater pulls +1400 watts or 12 amps on 120 volt. This would be a substantial draw on your batteries and it is pretty much continuous while the water is heating up.


I believe the water heater on propane would recover more quickly and be a better option. If it is used sparingly a tank a propane lasts a long time.

[oscarvan]

Yup. That would work. On paper.

1400 W at 12V= 116Ah 1 hours..... Your 300A Li 80% down gives 240Ah..... So you'd use half of that. Use the rest for the other stuff you mentioned. (micro a leftover for 2 minutes. Don't plan on cooking a chicken for 30 minutes) Total that day 240x12=3000 watt......

Say you have 4-5 panels.... top of the line? 100W each? 500W/Hr..... 6 hours sun a day.... there's your 3000 back.

On paper.

[jcussen]

Ron
https://www.12voltplanet.co.uk/elect...it-basics.html
Seeing it looks like you will be spending close to $5000 on your hardware, worth spending some time understanding how the basics work. It will really help you in designing your perfect system, that meets your needs.

[twinboat]

The lithium batteries being used are rated at 100 AH capacity @ the 20 hour rate.

That means the charge will last 20 hours with a 5 amp load. The OP has 3, 100 AH batteries, so 15 amps for 20 hours.

Now with the water heater drawing close to 150 amps including inverter losses, you are no longer in the 20 rate. Your in a 2 hour rate.

With lead acid batteries, as the discharge current goes up, the capacity drops. I looked but couldn't find any specs on lithiums at the 2 hour rate.

Assuming they each have 75 AH @ the 2 hour rate, you have 225 AH of capacity.

1 hour of 150 amp draw, will use 150 AH, leaving 75 AH in your 300 AH battery.

That's a lot to replace with solar, and if charging with the generator, you may as well heat the water with it too.

[twinboat]

Originally Posted by twinboat

The lithium batteries being used are rated at 100 AH capacity @ the 20 hour rate.

That means the charge will last 20 hours with a 5 amp load. The OP has 3, 100 AH batteries, so 15 amps for 20 hours.

Now with the water heater drawing close to 150 amps including inverter losses, you are no longer in the 20 rate. Your in a 2 hour rate.

With lead acid batteries, as the discharge current goes up, the capacity drops. I looked but couldn't find any specs on lithiums at the 2 hour rate.

Assuming they each have 75 AH @ the 2 hour rate, you have 225 AH of capacity.

1 hour of 150 amp draw, will use 150 AH, leaving 75 AH in your 300 AH battery.

That's a lot to replace with solar, and if charging with the generator, you may as well heat the water with it too.

I did some more research, on a Trojan battery site, and found that the capacity holds almost the same at the 5 hour rate as the 20 hour rate. That's 20 amps for 5 hours, per battery = 60 amps.

There is no 1 hour or 2 hour rate listed but the 5 hour rate only drops by 1% from the 20 hour rate. You could probability calculate the 100 AH rating at any current draw.

[ronwakefield]

Thank all of you for your insights and help. It looks like I will nix the hot water heater on the inverter idea. Propane is probably the way to go.

Thanks again.

Ron

[ronwakefield]

Thanks for the link - I will read that now. Have a great day.

Ron

[oscarvan]

Originally Posted by twinboat

There is no 1 hour or 2 hour rate listed but the 5 hour rate only drops by 1% from the 20 hour rate. You could probability calculate the 100 AH rating at any current draw.

That's interesting. Another argument for them. If only they weren't so darn $$$