Electric Cookers

[RupertW]

You're not really comparing like for like there.
It's virtually impossible to use FLA without degrading them. Everything you do shortens their life, by varying degrees. The data sheets for deep cycle batteries tend to show a direct correlation between DOD and cycles. But there is no usage pattern that is sustainable indefinitely.

For LFP, you can use the whole 0-100% range and you will still get hundreds of cycles. There is absolutely no need to stop charging at 80%, you just don't want to leave them sitting at 100% for a long time. If you're using the system daily them obviously that won't be able to happen.
Going below 20% will affect the number of cycles you can get, but it's still going to be several thousand, and way, way more than even the most pampered lead acid.

Well that’s not what the manufacturers say. I am certainly holding off until I start to see all the enthusiasts with new LFP replacing them - until then we don’t know how quickly LFPs are degrading under the kind of use that the manufacturers warn against. If I’m still holding off in 5 years or so when my 2 year old FLAs will need replacing then it will be clear that although the lifetime cost of LFPs versus FLASs is far higher then the lifespan makes the convenience worth it.

Until then almost everybody is abusing their new batteries but nobody is sure whether that matters to the hoped for longer lifespans.

 

[sailaboutvic]

Until then almost everybody is abusing their new batteries but nobody is sure whether that matters to the hoped for longer lifespans.

Isn't that like anything else that new to us all .
Although lithium aren't that new , people have been using them for quite a few years and they still going storng.

It just they now have become more affordable which is why people are fitting them and there a lot more written .

When the time comes to move back into a house , I be fitting as much solar I can and a big Lithium bank , it won't be going back into the grid but I will do some rewire so I can use the power to power high energy stuff as and when I can and just use brought electric when I can't.

 

[RupertW]

Isn't that like anything else that new to us all .
Although lithium aren't that new , people have been using them for quite a few years and they still going storng.

It just they now have become more affordable which is why people are fitting them and there a lot more written .

When the time comes to move back into a house , I be fitting as much solar I can and a big Lithium bank , it won't be going back into the grid but I will do some rewire so I can use the power to power high energy stuff as and when I can and just use brought electric when I can't.

I agree it’s because they are new. I guess it’s like discussing car starter batteries in the 1920s - there were a few dangerous designs which people quickly learnt to avoid but almost everybody was on their first battery so just didn’t know.

Once we return from our planned big trip next year then we will either fit solar to the existing house or downsize and fit to a new one - with battery backup as that’s the main use. Fitting a heat pump though will be a nightmare as the rooms would have to change a lot if there were massively thick radiators everywhere. I’m looking into whether just having a few more slim radiators will do the same job.

 

[sailaboutvic]

I agree it’s because they are new. I guess it’s like discussing car starter batteries in the 1920s - there were a few dangerous designs which people quickly learnt to avoid but almost everybody was on their first battery so just didn’t know.

Once we return from our planned big trip next year then we will either fit solar to the existing house or downsize and fit to a new one - with battery backup as that’s the main use. Fitting a heat pump though will be a nightmare as the rooms would have to change a lot if there were massively thick radiators everywhere. I’m looking into whether just having a few more slim radiators will do the same job.

I not been involved in building for a lot of years now , and don't know much about heat pump , but I made a few enquiry in the last year and so I understand some rad will work fine with a heat pump .
Some thing I be looking into in time .
I think I'm in for a big shock at the cost of move back on land .
Even tho it only be for part of the year

 

[RupertW]

I not been involved in building for a lot of years now , and don't know much about heat pump , but I made a few enquiry in the last year and so I understand some rad will work fine with a heat pump .
Some thing I be looking into in time .
I think I'm in for a big shock at the cost of move back on land .
Even tho it only be for part of the year

We are the other way round - looking forward to spending maybe six months a year afloat which is about double what we do now - and that’s in lots of parts. So our dilemma this Winter is what to do about bills in the house when we leave it Decamber for 5 months. Our plan of a cat sitter paying very low rent would have been fine before but now there is no way the person could afford to heat the house, or for us (as planned) to just pay the bills. But too late to get solar as there is a massive demand and I wouldn’t like to leave a brand new system unattended for 5 months.

 

[geem]

I agree it’s because they are new. I guess it’s like discussing car starter batteries in the 1920s - there were a few dangerous designs which people quickly learnt to avoid but almost everybody was on their first battery so just didn’t know.

Once we return from our planned big trip next year then we will either fit solar to the existing house or downsize and fit to a new one - with battery backup as that’s the main use. Fitting a heat pump though will be a nightmare as the rooms would have to change a lot if there were massively thick radiators everywhere. I’m looking into whether just having a few more slim radiators will do the same job.

Are you fitting a heat pump for the benefit of the planet or because somebody has told you it will be cheaper?

 

[RupertW]

Are you fitting a heat pump for the benefit of the planet or because somebody has told you it will be cheaper?

Neither - but expecting it will become the cheapest option when they stop allowing gas boilers to be sold. I will nurse along the existing one for as long as possible. I aim to be as self sufficient on the boat not to save the planet but to allow me to spend more time without worrying about getting fuel or plugging into mains. If saving the planet was my priority I would probably not keep my boat a 4 1/2 hour flight away and do that return flight less than 6-8 times a year.

 

[geem]

Neither - but expecting it will become the cheapest option when they stop allowing gas boilers to be sold. I will nurse along the existing one for as long as possible. I aim to be as self sufficient on the boat not to save the planet but to allow me to spend more time without worrying about getting fuel or plugging into mains. If saving the planet was my priority I would probably not keep my boat a 4 1/2 hour flight away and do that return flight less than 6-8 times a year.

It's a dilemma at the moment. Currently gas is still cheaper to run than an ASHP.

 

[AngusMcDoon]

A rarely mentioned problem of cooking on electricity is that you can't say that you are 'cooking on gas' any more. 'Cooking on electricity' just doesn't have the same cachet.

 

[gregcope]

Well that’s not what the manufacturers say. I am certainly holding off until I start to see all the enthusiasts with new LFP replacing them - until then we don’t know how quickly LFPs are degrading under the kind of use that the manufacturers warn against. If I’m still holding off in 5 years or so when my 2 year old FLAs will need replacing then it will be clear that although the lifetime cost of LFPs versus FLASs is far higher then the lifespan makes the convenience worth it.

Until then almost everybody is abusing their new batteries but nobody is sure whether that matters to the hoped for longer lifespans.

If your waiting for people to replace LifePo4 banks you might be waiting a decade or so. Check out Rod Collins of Marinehowto.com. He has had some LifePo4 for a decade and they test to a very similar capacity to when new (LiFePO4 Batteries On Boats - Marine How To). If people are replacing then I would suggest there is an issue their use (kept at 100%) or with the design somewhere (BMS issues) as the cells, if used within spec should last a very, very long time.

Am not abusing my LifePo4 according to the cell manufactures datasheets and anything I have read. To be fair mine are very young and lead a sheltered life.

 

[gregcope]

Once we return from our planned big trip next year then we will either fit solar to the existing house or downsize and fit to a new one - with battery backup as that’s the main use. Fitting a heat pump though will be a nightmare as the rooms would have to change a lot if there were massively thick radiators everywhere. I’m looking into whether just having a few more slim radiators will do the same job.

When running the heating, heat pump flow temps will be 35C in order to run efficiently and be comparable to Gas boilers (even with the Gas/Electric KWh cost delta). Most installers favour underfloor heating as this can run at lower flow temps. A decent installer will do room heat calcs and then the required rad size at the lower Delta-T / flow temps.

At 35C flow temps most radiators are at around 30% of their rated output (at Boiler flow temps). We are looking at replacing some Rads. Same size, just going to doubles. From Screwfix these are not too expensive (£90 ea) and should be a simple swap. We are fortunate that our house has lots of single rads that can be replaced with doubles. So allot depends on your existing rad design.

Oh... Domestic House Batteries are LifePO4.

 

[gregcope]

A rarely mentioned problem of cooking on electricity is that you can't say that you are 'cooking on gas' any more. 'Cooking on electricity' just doesn't have the same cachet.

If you've got solar, decent batteries and electric cooking could you not claim your cooking with Fusion which sounds even cooler?

 

[geem]

If your waiting for people to replace LifePo4 banks you might be waiting a decade or so. Check out Rod Collins of Marinehowto.com. He has had some LifePo4 for a decade and they test to a very similar capacity to when new (LiFePO4 Batteries On Boats - Marine How To). If people are replacing then I would suggest there is an issue their use (kept at 100%) or with the design somewhere (BMS issues) as the cells, if used within spec should last a very, very long time.

Am not abusing my LifePo4 according to the cell manufactures datasheets and anything I have read. To be fair mine are very young and lead a sheltered life.

It's hard not abuse lithium in the Caribbean. I saw an interesting statistic that said if your lithium was designed for 15 years life and you kept those batteries at 35 degC then you would halve their expected life. We did some temperature logging on a superyacht. Their batteries in the Caribbean winter were never dropping below 30.5degC and peaking at 35 degC during the day. Another super yacht with batteries in the engine room had batteries permanently above 40degC. It's the reason why I am working on a liquid cooled lithium project. Lithium is no more tolerant of temperature than lead. In fact during aggressive discharge they have quite a temperature gradient across the cells with the terminals being the hottest. This temperature gradient doesn't do the battery any favours in terms of life expectancy. Not a big issue on small yachts with minimal discharge loads but poorly ventilated battery boxes in hot environments could benefit from liquid cooling just to deal with high ambient. You truly would get many years service

 

[AngusMcDoon]

If you've got solar, decent batteries and electric cooking could you not claim your cooking with Fusion which sounds even cooler?

One could claim that one was 'cooking on plasma' I suppose.

 

[gregcope]

@geem you make a valid point. Yes, LifePo4 likes about 20C and not much more. My battery box is under the waterline and hullside so I see very little above 24C even when the air temps have got a bit warm this year!

I am assuming that those considering LifePo4 would know not to install them in a hot engine bay without having seen the impact to cycle life at warmer temps.

Also I doubt mine will see anything more than 0.5C discharge rates.

I can see that careful design would be needed for high C rates and also in higher ambient temps

 

[geem]

@geem you make a valid point. Yes, LifePo4 likes about 20C and not much more. My battery box is under the waterline and hullside so I see very little above 24C even when the air temps have got a bit warm this year!

I am assuming that those considering LifePo4 would know not to install them in a hot engine bay without having seen the impact to cycle life at warmer temps.

Also I doubt mine will see anything more than 0.5C discharge rates.

I can see that careful design would be needed for high C rates and also in higher ambient temps

I monitored my lead batteries from January to July this year in the Caribbean. I left the battery box lid off for the whole of this period whilst at anchor. Only when sailing did we replace the lid. We have no aggressive charge and discharges but during the day with the batteries on charge and the ambient temperature in the cabin in January/February we could hold the batteries below 30degC. At night they would drop to no lower than 25degC. By July in Curacao where the seawater was over 30degC and the ambient hitting over 30degC during the day and not dropping below 27degC at night we couldn't keep the batteries below 30degC.
Sailing with the batteries box lid on we saw battery temperatures about 5degC higher. The boat is in Curacao Marine in the yard. Battery temperatures will be pushing into the 40s. Three months at these temperatures does little for lead or lithium life expectancy. Lead batteries are not that expensive. My four Trojans cost me £600. Converting to lithium would cost me about £3k. At this pont adding liquid cooling starts to make sense if you sail in a hot climate

 

[Kelpie]

Lead batteries are not that expensive. My four Trojans cost me £600. Converting to lithium would cost me about £3k.

I'm curious to see how you arrive at the £3k figure.
As I've said before my costs were £407 for my DIY lithium battery vs £690 quoted for four Trojans. Approximately the same useable capacity.
Obviously I had other costs as well but these would have been the same regardless of battery type.
I do not have alternator charging for the lithium system, some would say that is a major compromise. I just revert to gas cooking rather than engine charging.

 

[geem]

I'm curious to see how you arrive at the £3k figure.
As I've said before my costs were £407 for my DIY lithium battery vs £690 quoted for four Trojans. Approximately the same useable capacity.
Obviously I had other costs as well but these would have been the same regardless of battery type.
I do not have alternator charging for the lithium system, some would say that is a major compromise. I just revert to gas cooking rather than engine charging.

Vic quoted £3k for his set up. I don't know your set up but I priced up everything I believe I need to make the system safe and reliable. Good grade A cells are not cheap. A b2b charger alone is £250. Class T fuses, good BMS. My boat is 24v so I need 8 cells and the BMS to run it. I would probably use Winston cells as they are easier to liquid cool. The would add a whole load of extra money on top of the £3k. The rig we are building at the moment uses Winstone cells

 

[sailaboutvic]

Mine was around the 3k tho I didn't use the alumni cells, I use calbs plastic cells which are much more expensive plus because where was base at the time I couldn't get them from china so had to buy them from Germany, so I did have to pay a bit more.
I also used the 123 smart BMS again a bit more expensive then what some people have used .
The 3k including everything , breakers, cables ,B2B , copper to make new bars and so on .

The sad part is when I sold the boat in march the guy said his insurance wanted the set up check by an expert as the surveyor had no experience on lithium,
So he paid for the lituim expert to check them over and the first thing the guy said was ( his words ) this is the future
After give the set up his full approval, not long after buying the boat , the lithium where remove for AGM as I understand there where worried about fire , which is a real shame , and disappointing after the money I spend .
The only good thing that came out of it was the batteries was sold to friends to add to their bank who I help with their lithium a year earlier,
I lay money Geem sooner or later you join the club .?

 

[sailaboutvic]

Just to add to the last posting , I probably could had cut a good lump of the 3K by using cheaper cells stright from China, cheaper bms and didn't re wire some of the batteries cabled and putting in bigger cables but I plain to use the system to do things like Cook on it as well knowing at times there be more then one heavy load used at any one time , like microwave and cooker , or kettle and hot water .