230 volt through inverter batteries

[Seastoke]

So we don’t use our system much , as we have gennny but was wondering what power we can generate. We have 3, 110amp leisure batteries , through a smart charger inverter . So say we have use a 1kw to hot the water how long would the batteries last , I realise it would switch off when hot but assume it is running all the time.

 

[GEM43]

You can use 50% of your 330ah, so 165ah. A 1 kw heater will pull about 80A @ 12.3v so your batteries would be consumed in two hours. Your inverter should be wired such that inverter power can’t be drawn to heat water, it’s not practical.

 

[BlueJasper]

Are you sure the hot water heater is only 1 kWh? Our tank is only 25 litres and has a 1.5kWh heater.

 

[PaulRainbow]

You can use 50% of your 330ah, so 165ah. A 1 kw heater will pull about 80A @ 12.3v so your batteries would be consumed in two hours.

Rule of thumb for 12v inverters is DC amps in = AC out watts / 10, so a 1kw water heater will draw 100 amps from the batteries.

Your inverter should be wired such that inverter power can’t be drawn to heat water, it’s not practical.

It is practical if enough solar is fitted. We can heat water, use the combi oven or use the induction hob, obviously not all at once ! We do have 900w of solar though.

 

[PaulRainbow]

Are you sure the hot water heater is only 1 kWh? Our tank is only 25 litres and has a 1.5kWh heater.

Depends on the make of calorifier.

 

[GEM43]

Rule of thumb for 12v inverters is DC amps in = AC out watts / 10, so a 1kw water heater will draw 100 amps from the batteries.

It is practical if enough solar is fitted. We can heat water, use the combi oven or use the induction hob, obviously not all at once ! We do have 900w of solar though.

What size house bank?

 

[Trident]

I have two 800w calorifiers which run perfectly well off my inverter - I have lots of battery and solar but there is absolutely no reason the OP can't do it with his set up if the inverter is big enough.

 

[GEM43]

I have two 800w calorifiers which run perfectly well off my inverter - I have lots of battery and solar but there is absolutely no reason the OP can't do it with his set up if the inverter is big enough.

Big bank and big solar makes a difference. As ever it is the replacement of consumed power that is all important. I choose not to place heavy long duration loads on my 750ah house bank as a matter of routine because replacing that energy is hard. (Sailing yacht in Scotland).

 

[Trident]

Big bank and big solar makes a difference. As ever it is the replacement of consumed power that is all important. I choose not to place heavy long duration loads on my 750ah house bank as a matter of routine because replacing that energy is hard. (Sailing yacht in Scotland).

That makes sense but the OP has a motorboat so the moment he decides to move he’s recharging

 

[wonkywinch]

We use that massively thermally inefficient ICE to heat our water.

 

[PaulRainbow]

What size house bank?

At the moment, 220ah @ 24v Have to keep an eye on things as the bank really needs to be bigger. The solar and inverter are recent additions as part of a general refurb of the "new to us" boat. Next phase of the electrics update will be changing the batteries to LifeP04

 

[Sticky Fingers]

At the moment, 220ah @ 24v Have to keep an eye on things as the bank really needs to be bigger. The solar and inverter are recent additions as part of a general refurb of the "new to us" boat. Next phase of the electrics update will be changing the batteries to LifeP04

Is that to allow more inverter usage? Do you also have a generator?

 

[Timeless 2]

It would be great if you could do thread on converting a motor boat to LifePO4. I have this in mind as the existing battery bank is aging and struggling. I can live with it as I have a generator but I’d like to upgrade the system from its original 1998 install.

 

[Sticky Fingers]

It would be great if you could do thread on converting a motor boat to LifePO4. I have this in mind as the existing battery bank is aging and struggling. I can live with it as I have a generator but I’d like to upgrade the system from its original 1998 install.

My thoughts too. 1999, albeit not on original batteries or charger in my case.

 

[PaulRainbow]

It would be great if you could do thread on converting a motor boat to LifePO4. I have this in mind as the existing battery bank is aging and struggling. I can live with it as I have a generator but I’d like to upgrade the system from its original 1998 install.

I'll see what i can do.

 

[PaulRainbow]

Is that to allow more inverter usage? Do you also have a generator?

The battery bank is a bit small to use the inverter to take full benefit of the solar installation. It works OK during the day if there is a decent amount of sunshine and we don't overdo it with cooking, but because of the size of the battery bank it gives the batteries a hard time, sometimes. With them being lead acid they also charge slowly (compared to LifePo4) so don't fully take advantage of the available solar yield.

The batteries are a few years old and likely due for a change soon anyway. It looks like i can build a LifeP04 battery for about the same money as wet lead acid and less than AGMs, so it makes sense to change now (soon).

The boat is also fitted with a 12kva generator, but we don't use it much. We did use it a little before i fitted the inverter, mostly for light use when underway, as we are all electric. Seemed a bit extreme using a big generator to boil the kettle. We have a 1kw kettle, which the inverter copes with comfortable and when underway the alternators will put out more current than the kettle uses.

 

[Sticky Fingers]

The battery bank is a bit small to use the inverter to take full benefit of the solar installation. It works OK during the day if there is a decent amount of sunshine and we don't overdo it with cooking, but because of the size of the battery bank it gives the batteries a hard time, sometimes. With them being lead acid they also charge slowly (compared to LifePo4) so don't fully take advantage of the available solar yield.

The batteries are a few years old and likely due for a change soon anyway. It looks like i can build a LifeP04 battery for about the same money as wet lead acid and less than AGMs, so it makes sense to change now (soon).

The boat is also fitted with a 12kva generator, but we don't use it much. We did use it a little before i fitted the inverter, mostly for light use when underway, as we are all electric. Seemed a bit extreme using a big generator to boil the kettle. We have a 1kw kettle, which the inverter copes with comfortable and when underway the alternators will put out more current than the kettle uses.

Sounds like a good plan, that’s a big generator for the uk, I assume you have aircon?

 

[PaulRainbow]

Sounds like a good plan, that’s a big generator for the uk, I assume you have aircon?

No aircon, not sure why they fitted such a big generator.

 

[Sticky Fingers]

No, but that’s a happy result compared to the other options, too small, or missing completely!

 

[Seastoke]

Are you sure the hot water heater is only 1 kWh? Our tank is only 25 litres and has a 1.5kWh heater.

I was just going on a known wattage.