Li-0n, these look interesting

[MrFish]

This is the battery that has peeked my Interest.

https://www.fogstar.co.uk/products/fogstar-energy-15-5kwh-48v-battery?variant=41546193174587&currency=GBP&utm_medium=product_sync&utm_source=google&utm_content=sag_organic&utm_campaign=sag_organic&gad_source=1&gclid=CjwKCAiAgeeqBhBAEiwAoDDhn-A2VbUpjzciyhEbAik9omnMPJ2-upk7HnugzJfIS35pAB0qtqvmWhoClDEQAvD_BwE&fbclid=IwAR0beROroJ_6Ti7p4KSh9oPtnQiiO6uprLchsJarbA02dbHumnBEiqento4

 

[IanD]

6 minutes ago, MrFish said:

This is the battery that has peeked my Interest.

https://www.fogstar.co.uk/products/fogstar-energy-15-5kwh-48v-battery?variant=41546193174587&currency=GBP&utm_medium=product_sync&utm_source=google&utm_content=sag_organic&utm_campaign=sag_organic&gad_source=1&gclid=CjwKCAiAgeeqBhBAEiwAoDDhn-A2VbUpjzciyhEbAik9omnMPJ2-upk7HnugzJfIS35pAB0qtqvmWhoClDEQAvD_BwE&fbclid=IwAR0beROroJ_6Ti7p4KSh9oPtnQiiO6uprLchsJarbA02dbHumnBEiqento4

 

That's exceptionally cheap for the capacity. Size and shape might make it a bit awkward to fit into a boat (or not), depending on where you have space. Output current vs. capacity is a bit low for electric propulsion, but absolutely fine for onboard power -- would pair nicely with a Multiplus II 48/10000... 😉

[MrFish]

Sadly I already have by batteries otherwise I would have bought a pair of these and put them in parallel. They seem to have Victron compatability  too.

[magnetman]

Looks really good. If I was doing a new fitout with ample solar and need for domestic comfort I'd definitely have a 48v system. 

[IanD]

13 minutes ago, magnetman said:

Looks really good. If I was doing a new fitout with ample solar and need for domestic comfort I'd definitely have a 48v system. 

You also end up needing a lower-voltage system for all the other DC bits which are easily available in 12V and 24V but not 48V -- 24V via a DC-DC converter means you don't need another battery bank, wiring is a lot easier than 12V, and 24V gear is widely available.

 

For those who don't think they're the work of the devil, 48V also means you can run reasonable size/cost cable (~25mm2) from the 48V bank to a bow thruster instead of needing a local battery for it... 😉

[magnetman]

A lot of people fitting out a boat with considerable comforts and an adequate power supply will probably find that mains equipment can be used. Water pump, refrigeration and other appliances can certainly be mains powered via inverter. There will be other things which need lower voltage but these will be much smaller consumers so can be run from step down transformers. 

 

Of course one can also have a 12v circuit as well. The main reason for the 48v is if you run a lot of things from an inverter. I don't as am a caveman but a lot of people do like their creature comforts. 

 

 

[IanD]

17 minutes ago, magnetman said:

A lot of people fitting out a boat with considerable comforts and an adequate power supply will probably find that mains equipment can be used. Water pump, refrigeration and other appliances can certainly be mains powered via inverter. There will be other things which need lower voltage but these will be much smaller consumers so can be run from step down transformers. 

 

Of course one can also have a 12v circuit as well. The main reason for the 48v is if you run a lot of things from an inverter. I don't as am a caveman but a lot of people do like their creature comforts. 

 

 

Of course the big issue with a big 48V DC/inverter/LFP system with a lot of creature-comfort AC loads is where all the power to charge it up comes from, especially in winter when solar is pretty much useless. A big alternator/travelpower is one solution but is inefficient and means running the propulsion engine, a diesel generator is more efficient but also a lot more expensive and needs installation space.

 

It's all a great deal of effort and cost if you're doing it just to get a more house-like 230V supply for appliances, unless the driver is also to go gas-free -- which still doesn't solve the charging problem. Unless you're going to spend most of the time plugged into shoreline in a marina, in which case what do you do if you ever venture outside?

 

On an electric/series hybrid boat it all makes sense because a lot of this is needed anyway and you get other advantages, but on a diesel boat it's all a big and expensive overhead for rather less benefit...

Edited November 28, 2023 by IanD

[matty40s]

Apparently Fogstar were rather taken aback by the demand...delivery is December, and they are insisting that you confirm that you are in prior delivery.

[MtB]

3 hours ago, matty40s said:

Apparently Fogstar were rather taken aback by the demand...delivery is December, and they are insisting that you confirm that you are in prior delivery.

 

December is tomorrow!!

 

 

[GUMPY]

My battery was due to arrive tomorrow, arrived today. 

Its 50% charged, app seems good and it will sit in the workshop until March when we go away again.  

 

I did have to confirm when I would be here to receive it, not a bother

[nicknorman]

My battery is in my caravan where it has been -7 for a couple of days. So it was interesting to try out the heating side of things. The  battery duly refused to take any charge but it was taking about 3.5A for the heaters. The temperature gradually crept up but it didn't start charging when it got to +5, I'm not sure when it would have done so because I cycled the charger and then it started charging. Having proved that point I stopped the charging again.

 

I think keeping the charge off for a while after the temperature indicates +5 makes sense because both the heater and the temperature sensor are on the outside of the cells, and it must take a while for the heat to propagate into the interstices of the cell which is the bit that actually matters.

 

Anyway all that did highlight another slight problem. As previously mentioned, that BMS's SoC estimation seems pretty rubbish - although I'm going to fully cycle the battery a few times to see if that helps. My fallback position was to continue to use the BMV712 but that is problematic - when the battery is cold and not taking charge, the BMV sees the voltage up at 14.3v and just 3.5A current. This is below the BMV's "fully charged detection" threshold of 5% (5A) and so it resets to 100% SoC even though the battery might well be very low. Hmmm... I suppose I could go down to a 3% "fully charged" figure but that is not the optimal value which is 5%.

 

In better news it has occurred to me that I might as well get into the habit of taking the battery home during the week, to charge. There is a massive difference between a 105A Li battery vs the 2 x Trojan T105s ( which had similar usable capacity) in terms of weight and propensity to leak sulphuric acid over something. Carrying the Li around is trivial.

Edited December 4, 2023 by nicknorman

[Tony1]

4 hours ago, nicknorman said:

I think keeping the charge off for a while after the temperature indicates +5 makes sense because both the heater and the temperature sensor are on the outside of the cells, and it must take a while for the heat to propagate into the interstices of the cell which is the bit that actually matters.

 

I've been wondering what the 'lag' factor is when the batteries get really cold. 

My working assumption is that there will be a lag during the cooling phase through the night- thus if the temp sensors read 2 degrees at 7am, I assume the batteries will be a degree or two warmer than that. 

 

But if the cold has gotten right into the core of the batteries, as it might with below zero temps for say 18 hours, then I assume that there will be a significant lag before the core of the battery warms up to the temp that are initially shown by the sensors, and I avoid doing any engine charging early in the morning if at all possible.  

 

I'm still trying to decide whether to direct air from the cabin into the battery box as per your rather nifty idea a while back. The fan only uses about half an amp so it could be left on overnight, and in fact during a lot of the day if needed. Its only a trickle of air really by the time it goes through a 20mm wide and 2 metre long ducting tube, but I bet its enough to keep the batteries above zero on all but the most extreme nights.

 

Or I might just bite the bullet and shift them back indoors and under the bed.

My general impression is that they do seem to behave a bit better at room temp, and if we have a really cold dec/jan I don't want to have any concerns about charging them if I go cruising first thing in the morning when they might still be freezing. 

 

 

[IanD]

9 minutes ago, Tony1 said:

 

I've been wondering what the 'lag' factor is when the batteries get really cold. 

My working assumption is that there will be a lag during the cooling phase through the night- thus if the temp sensors read 2 degrees at 7am, I assume the batteries will be a degree or two warmer than that. 

 

But if the cold has gotten right into the core of the batteries, as it might with below zero temps for say 18 hours, then I assume that there will be a significant lag before the core of the battery warms up to the temp that are initially shown by the sensors, and I avoid doing any engine charging early in the morning if at all possible.  

 

I'm still trying to decide whether to direct air from the cabin into the battery box as per your rather nifty idea a while back. The fan only uses about half an amp so it could be left on overnight, and in fact during a lot of the day if needed. Its only a trickle of air really by the time it goes through a 20mm wide and 2 metre long ducting tube, but I bet its enough to keep the batteries above zero on all but the most extreme nights.

 

Or I might just bite the bullet and shift them back indoors and under the bed.

My general impression is that they do seem to behave a bit better at room temp, and if we have a really cold dec/jan I don't want to have any concerns about charging them if I go cruising first thing in the morning when they might still be freezing. 

 

 

If the batteries are in a boat and sitting on the steel baseplate like mine, they're unlikely to ever get below 0C because the water underneath the baseplate doesn't. In the cold spell last week when I believe the water in the marina froze they never went below +4C.

 

In a caravan or motorhome or unheated garage (or GRP boat?), they can freeze... 😞

 

Edited December 4, 2023 by IanD

[GUMPY]

That's the reason I'm not changing the van battery until the end of February. The solar won't provide 3amps over winter to heat the battery so if it is cold and sunny the battery is unlikely to see much charge.

Seriously thinking of keeping the LA battery and swapping back when the van is laid up over winter, it's only to run the alarm so the 120w panel should cover that.

[Tony1]

10 minutes ago, IanD said:

 

If the batteries are in a boat and sitting on the steel baseplate like mine, they're unlikely to ever get below 0C because the water underneath the baseplate doesn't.

 

In a caravan or motorhome or unheated garage (or GRP boat?), they can freeze... 😞

 

That's part of my concern really- the battery box has a wooden base, so they don't sit on the bare metal, and that 20mm or so of plywood might be enough insulation from the steel that they could fall below zero on a really bad night. 

On the worst night we've had so far the sensors got down to 1 degree when the outside air temp was probably about minus 3.

But given there might be an accuracy issue to allow for, that felt too close to freezing for my liking, so I will be doing something with them soon- just haven't decided what's the easiest/best option yet.

I never feel like getting involved in laborious outdoor jobs during the really cold months!

 

ETA - there's also that concern that if I leave the boat for a few days their core will get well below zero, and it will take a few hours to get them back above freezing when I return, before I can even consider doing any charging. 

My hope would be that under the bed it would take much longer for the temp to fall below zero, and it might not fall so far as it would in the engine bay.

 

 

 

Edited December 4, 2023 by Tony1

[IanD]

8 minutes ago, Tony1 said:

 

That's part of my concern really- the battery box has a wooden base, so they don't sit on the bare metal, and that 20mm or so of plywood might be enough insulation from the steel that they could freeze on a really bad night. 

On the worst night we've had so far the sensors got down to 1 degree when the outside air temp was probably about minus 3.

But given there might be an accuracy issue to allow for, that felt too close to freezing for my liking, so I will be doing something with them soon- just haven't decided what's the easiest/best option yet.

I never feel like getting involved in laborious outdoor jobs during the really cold months!

 

 

If they're in a closed wooden box (like mine) then the underside will be at the baseplate temperature and the sides/top at the air temperature surrounding them, so they'll end up somewhere in between.

 

In my case the other things that dissipate power (about 100w total, mainly the inverter) are in the same space under the stern so the air is never as cold as outside. The diesel boiler is also in the same space, so every time it fires up (frost protection) that also warms things up. I don't have the air temperature in there but I do have the generator and motor (which are not dissipating any power) and these are about 6C warmer than the batteries -- always assuming the temperature sensors are accurate, obviously... 😉

 

Edited December 4, 2023 by IanD

[magnetman]

17 minutes ago, GUMPY said:

That's the reason I'm not changing the van battery until the end of February. The solar won't provide 3amps over winter to heat the battery so if it is cold and sunny the battery is unlikely to see much charge.

Seriously thinking of keeping the LA battery and swapping back when the van is laid up over winter, it's only to run the alarm so the 120w panel should cover that.

Its a shame nobody is selling a small LTO battery for this. The LA is probably the answer. 

 

[IanD]

2 minutes ago, magnetman said:

Its a shame nobody is selling a small LTO battery for this. The LA is probably the answer. 

 

The real shame is that LFP batteries are perfectly capable of being charged at reduced rates below 0C (down to -20C for BYD IIRC) but this needs a more sophisticated BMS and better cell characterisation, which few suppliers bother to do... 😞

[magnetman]

My LTOs go below freezing with no BMS or cell characterisation needed. 

 

 

charge them up, discharge them, charge them up &c. Doesn't seem to be a problem.

 

One of them (6s so about 15v nominal) I ran it down to 2v and it charged up fine. Maybe one day it will explode in an awful shower of terrible nigthmares but is seems alright for now..

 

 

 

 

[IanD]

10 minutes ago, magnetman said:

My LTOs go below freezing with no BMS or cell characterisation needed. 

 

charge them up, discharge them, charge them up &c. Doesn't seem to be a problem.

 

One of them (6s so about 15v nominal) I ran it down to 2v and it charged up fine. Maybe one day it will explode in an awful shower of terrible nigthmares but is seems alright for now..

 

 

The reason LTOs are not widely used is low energy density and high cost compared to LFP -- for most applications these matter far more than the long lifetime and low-temperature charging which is why hardly anyone uses them.

 

https://www.ecolithiumbattery.com/lithium-titanate-battery/

 

1. Low energy density and high cost.

The price of lithium ion titanate battery is high (high production cost and high humidity control requirements), about $1.6USD per watt-hour, and the gap between lithium iron phosphate battery and LTO battery is about $0.4 USD per watt-hour.

 

 

Edited December 4, 2023 by IanD

[magnetman]

 

 

https://www.ecolithiumbattery.com/lithium-titanate-battery/

Disadvantages Of lithium Iron Phosphate Battery,

The tap density and compaction density of lithium iron phosphate batteries are very low, resulting in low energy density of lithium ion batteries; the preparation cost of materials and the manufacturing cost of batteries are high, and the yield of batteries is low."

 

 

Oops ! Try again ? 

 

 

 

On  canal Boat domestic battery system the weight doesn't matter. 

 

They arrr a bit lighter than lead acid. 

 

 

 

The link you provided might be more credible if it wasn't so badly written that they got the battery chemistry wrong ! 

 

 

Edited December 4, 2023 by magnetman
edit to remove blatant racism

[IanD]

8 minutes ago, magnetman said:

 

https://www.ecolithiumbattery.com/lithium-titanate-battery/

Disadvantages Of lithium Iron Phosphate Battery,

The tap density and compaction density of lithium iron phosphate batteries are very low, resulting in low energy density of lithium ion batteries; the preparation cost of materials and the manufacturing cost of batteries are high, and the yield of batteries is low."

 

Oops ! Try again ?

 

On  canal Boat domestic battery system the weight doesn't matter. 

 

They arrr a bit lighter than lead acid.

 

The link you provided might be more credible if it wasn't so badly written that they got the battery chemistry wrong ! 

 

Yeah, corrected, that site is a bit rubbish innit?

 

The disadvantages of LTO (low density and especially high cost) are well known -- loads of links out there, all you have to do is go and look, but that would mean reading something written by someone else .. but it's the cost that's the real killer.

Edited December 4, 2023 by IanD

[magnetman]

I know this but as I said on a canal boat domestic battery bank the weight is irrelevant. People have had Lead Acid batteries for decades nobody every complained about the weight. 

 

Even for a propulsion bank it would work as most canal boats have weight deliberately added to submerge the propeller. 

 

 

[nicknorman]

12 minutes ago, magnetman said:

I know this but as I said on a canal boat domestic battery bank the weight is irrelevant. People have had Lead Acid batteries for decades nobody every complained about the weight. 

 

Even for a propulsion bank it would work as most canal boats have weight deliberately added to submerge the propeller. 

 

 

You do have a bit of a thing about LTO. The main disadvantage apart from those already mentioned, is the big range of voltage during discharge, compared to the very flat voltage profile of LFP. And it is difficult to get an integer number of cells that gives a voltage compatible with 12v systems.

 

Compare the flatness of LFP

with the unflatness of LTO

 

 

 

 

With LFP, 4 cells gives you from 13v to 12v over pretty much the full discharge range.

 

With LTO if you have 5 cells it is 13v to 10.85v - too low. And with 6 cells it is 15.6v to 13v - too high. And just too  much variation to be useful.

[magnetman]

13-15.8v is exactly what all 12v inverters want to see as an input voltage. Whats more they will cut out at around 11.8v which happens to be the point where the discharge of a 6S LTO battery will drop very quickly. 

 

I run them at 15.2v and none of the 12v appliances have popped. Excellent voltage for starter motors. 

 

Most people with modern systems will be running the majority of their heavy consumers via inverters. Have a look at your inverter specs. 15.8v?