Hot water heating via Lithium battery bank

[roland stockham]

The normal setup is to have your inverter power the mains curcuit so eveything works just the same as when you are on shorepower. This can either be done with a selector switch, either 2 way inverter/shorepower or 3 If you fit a switch it is essential that it is wired so that you can NEVER connect to power sources, ie needs a break before make type switch. There are various neet one available. If you connect 2 sources they will be out of phase and blow up one source. The alternative is to permanently wire the onboard mains to the inverter then connect a charger to the shorepower inlet thus shorepower only charges the batteries and all mains is generated on board. This has two advantages, first the inverter will generate better quality mains as it is common to find low voltages, poor earths etc in marinas. The second plus is that it isolates the onboard supply (assuming you have an onboard A/C ground which should always be the case with an inverter fitted) and reduced the chance of electrolysis. I effect the charger works as an isolation transformer.

[simonpickard]

Thank you all for the great replies!

[peter57]

100amps from the battery bank through 3000 KVA victron inverter 1200 watt water heater = 10 litres at 78- 80 F in 12mins

[CatNewBee]

On our Lagoon 400S2 we have a 230V / 1200W 40l boiler, that can also be heated by the starboard engine fresh water cooler circuit. We use solar and our inverter for almost everything on board, we have 1650Wp solar, 1000Ah / 12V Winston LiFeYPO4 setup with a Victron Quattro 5kVA and a spare Mastervolt 2kVA inverter. Hot water making takes around 100Ah per day.

See my thread about the conversion to electric galley for details .

[warrior 90]

I find this topic very inspiring as my plan is to protect my Lithium batteries from over charging by using permanently devices that have big power draw on board that are useful such as heating water and a dehumidifier/ heater / AC.
In other words in case of solar, wind or hydro power charging sources will always work at max. There is no regulating, shut off or dump load as those high consumers will always be capable to protect the lithium batteries with there high load capacity.
I would like to know if there are some that have designed there system this way and there experience.
Of course an electric water heater has limits once the water reaches a certain temperature but not so for example a dehumidifier. I am sure everybody agrees.... there is no such thing as too much dehumidifying on board.
The only design feature of critical importance to me is when the renewable energies have a good capacity like on a catamaran and now the boat is motoring 10 hours and charging on top with two alternators.
The idea behind is not to control my charging sources to prevent over charging but to always spent the over production of energy which I believe is technically much less complicated and more efficient and reliable then regulating them to protect the Lithium batteries from over charge.
Of course now some might say I would be happy if I have over production of energy on my boat.
But on the other side if I max out the boat with power sources what if I produce too much ?
I have to put a stupid electronic break on my wind gens to shut them down ?
I take the expensive hydrogen out of the water ?
What if I wanna have plenty choices of energy sources on board to make sure I always have enough and just sometimes I produce too much and that could put my expensive Lithium bank in danger ?

[senormechanico]

"I am sure everybody agrees.... there is no such thing as too much dehumidifying on board."


While on the hard for the summer hurricane season in San Carlos, Sonora Mexico, our Lord Nelson 35's interior teak joinery started showing gaps due to the lack of humidity.

[LoudMusic]

Originally Posted by warrior 90

I find this topic very inspiring as my plan is to protect my Lithium batteries from over charging by using permanently devices that have big power draw on board that are useful such as heating water and a dehumidifier/ heater / AC.
In other words in case of solar, wind or hydro power charging sources will always work at max. There is no regulating, shut off or dump load as those high consumers will always be capable to protect the lithium batteries with there high load capacity.
I would like to know if there are some that have designed there system this way and there experience.
Of course an electric water heater has limits once the water reaches a certain temperature but not so for example a dehumidifier. I am sure everybody agrees.... there is no such thing as too much dehumidifying on board.
The only design feature of critical importance to me is when the renewable energies have a good capacity like on a catamaran and now the boat is motoring 10 hours and charging on top with two alternators.
The idea behind is not to control my charging sources to prevent over charging but to always spent the over production of energy which I believe is technically much less complicated and more efficient and reliable then regulating them to protect the Lithium batteries from over charge.
Of course now some might say I would be happy if I have over production of energy on my boat.
But on the other side if I max out the boat with power sources what if I produce too much ?
I have to put a stupid electronic break on my wind gens to shut them down ?
I take the expensive hydrogen out of the water ?
What if I wanna have plenty choices of energy sources on board to make sure I always have enough and just sometimes I produce too much and that could put my expensive Lithium bank in danger ?

I understand the desire to send that excess energy somewhere. My current idea is to have a 3000psi dive compressor and a large (100L?) tank in the bilge. Any time the batteries are >95% and power is being produced, the compressor kicks on and we start squeezing air. It can then be used to refill personal dive tanks, or to run power tools. I just need to find a rotary hull scrubber that is compressed air powered ...

[mbartosch]

Originally Posted by warrior 90

In other words in case of solar, wind or hydro power charging sources will always work at max. There is no regulating, shut off or dump load as those high consumers will always be capable to protect the lithium batteries with there high load capacity.

Personally I would not consider this as an option. It is debatable if one really needs a BMS, some go without one, but at least pack voltage monitoring and pack based HVC and LVC cutoff are needed IMO for a number of reasons.
I can imagine several fault conditions in which the bank will be overcharged without HVC, and from reading the long LiFePO4 thread (you did, didn't you?) you should know that this will very likely scrap the bank.

[warrior 90]

Originally Posted by mbartosch

Personally I would not consider this as an option. It is debatable if one really needs a BMS, some go without one, but at least pack voltage monitoring and pack based HVC and LVC cutoff are needed IMO for a number of reasons.
I can imagine several fault conditions in which the bank will be overcharged without HVC, and from reading the long LiFePO4 thread (you did, didn't you?) you should know that this will very likely scrap the bank.

I would not argue on the cell voltage monitoring neither the pack voltage monitoring. Also the LVC shut down is a must to protect the battery.
But on the HVC cut off there is a choice and it makes much more sense to me to use the extra energy then to dump it as a general design feature of the system.
Of course there should be a HVC cut off but only to protect the battery as the last step in the system and not as a general design feature to handle extra energy produced.
It seems to me that devices for climate control in general are high consumers and ideal for this function.The rest would be just programming the pack voltage monitor to give a signal at the desired moment just the way systems are designed right now but not to regulators up till a point of switch off and instead to consumers with enough capacity.
If this is done correctly as a basic general design feature only the extra energy is shaved off and there should be no effect on the battery.
As some on this thread already use energy for heating hot water with good results why not integrating the hot water function permanently instead of for example a dump load for the wind gen or total shut down ?
Lithium batteries can handle much higher charge rates.
It is much more simple to activate a simple switch to a consumer then sensing a getting close to HVC situation from the charging sources and regulating them to produce less and depending on state of charge finally shut them down.

[warrior 90]

Originally Posted by LoudMusic

There were also times we were heating water and still putting power into the batteries. But now I'm just bragging

I can imagine with Your system depending on weather conditions and situation this can happens more often but specially when You are motoring for longer time while Your battery is already close to full charge or let´s say with the alternators after a few hours later they are.
So now the batteries are full, the alternators are charging while also do Your other sources but now I asume also Your engines are heating the water.
So now all the charging sources are throttling down to manage.
Well, I guess with 900 amps of Lithium You have a good buffer but did it actually happen that the solar charge controller for example started to throttle down while You had to motor for an extended period like it could happen for example cruising for some days on the ICW ?

[CatNewBee]

We do it manually, we topp up the fresh water tanks, make the laundry, bake bread or heat up water. In hot climate we may run the A/C.

But, not necessarily to protect the battery, the chargers and the BMS do a fine job there, it is more to use the excess energy for comfort.

[tanglewood]

Originally Posted by john61ct

12V is too low, DC elements in general pretty ineffectual.

Why is it too low, and why ineffectual?

[john61ct]

to get over 25A is rare, and that's barely 300W

mains power even 1500W takes a long time

GordMay calculated "to heat 6 gallons of water 45°F (from 75° to 120°F), in 1 hour:

≈ 67 Amps @ 12.5 Volts for 1 hour) (or 837 W/Hr)

[LoudMusic]

Originally Posted by warrior 90

I can imagine with Your system depending on weather conditions and situation this can happens more often but specially when You are motoring for longer time while Your battery is already close to full charge or let´s say with the alternators after a few hours later they are.
So now the batteries are full, the alternators are charging while also do Your other sources but now I asume also Your engines are heating the water.
So now all the charging sources are throttling down to manage.
Well, I guess with 900 amps of Lithium You have a good buffer but did it actually happen that the solar charge controller for example started to throttle down while You had to motor for an extended period like it could happen for example cruising for some days on the ICW ?

Yes, when the voltage in the system goes up, all the charging sources reduce their output. This includes solar charge controllers and alternators.

[warrior 90]

Originally Posted by LoudMusic

Yes, when the voltage in the system goes up, all the charging sources reduce their output. This includes solar charge controllers and alternators.

Ain´t that a petty to throttle all that extra capacity away with some mighty expensive and unreliable electronic regulator devices ?
I always think of better wasting that energy with some more automatic better quality life on board then automatic throttling or at least have some fun.
To be a little sarcastic I would prefer that automatically my 2000 watt coffee machine invites me to tell me I get close to over charge condition and that I have 30 minutes time to think where and how I can waste some energy !
If I have no better use I could waste some energy with the water maker and pressure washer to clean of the salt of the deck and the windows with hot water. Now that might sound a little like over kill but I just wanna get my point across. The electronics to handle over charge condition this way would be a lot more simple and reliable then to automatically throttle and regulate all my charging devices.
Of course system failure requires automatic shut down for protection but treating my lucky situation of producing more then I use at the moment is not a very dangerous situation of system failure.
IT´S A BLISS and WORTH CELEBRATING
What I am trying to say is.... there is a big difference between producing more energy then I need and system failure but the with the basic concept behind the current BMS systems technology there is no difference. Both situations are treated the same way and only to protect the battery while I believe this could be done much more efficient.
Prove is this thread and how some already do it. The just do it manually. Why not designing a concept to for example switch on the water heater, the AC, the water maker etc or what ever to protect the battery from over charge then throttle and regulate ?
That would only require a signal from the pack monitor to a relay switch to certain consumers compared to sensitive calibrated sensors that gradually actuate in conjunction with all the corresponding regulators of the different charging devices.
Now does that make sense ? Ain´t it just a lot easier more efficient and more reliable ?
Why is there no kind of a BMS that can do this automatic what already some do manual ?
To take it to the next level.... why do I have to install some fancy expensive black boxes that I can´t repair myself to protect my expensive Lithium batteries if I could do it with just some cheap reliable switches and relais that I can buy of the shelf any place and protect my Lithium batteries much safer.
I might wanna add on that I agree with some that I also question the quality of the components of BMS manufactures that are standard for the marine recreation industry. I believe that they sell us a false impression of protection and safety. I believe if today´s Lithium batteries are maintained well with in spec they will out last those components and if Lithium batteries don´t last up to their expectation it´s not because of failure of the battery itself but most likely because of failure of the same systems and components that we buy for top $$$ that are supposed to prevent that.
Now resuming all I believe this approach of general concept could also result in a much safer system in regards to the situation of producing more energy then I actually use in a certain moment that would trigger over charging.
Of course I am aware that there is lot´s of speculation and personal opinion in my thoughts and we could argue forever as usual on al all threads about Lithium batteries on CF but this is not my intention.
The headline of the thread is " Hot water heating via Lithium battery bank !!"
Some try to do it but the capacity of the charging sources is critical. They will never ever need an over charge protection. Others already play with there systems for some time and get good results and try to optimize because hot water is really a sweet added comfort on board. And others have really abundance and could run what is usually classified as a "" dangerous over charge condition !! " That in my opinion is an absolute false evaluation.
In my opinion treating over charge capacity the same way then system failure is simply inefficient, much more sensitive to failure, and might even be much less safe with current devices.