Li-0n, these look interesting

[IanD]

The big problem: LTO cost per kWh is more than 3x higher than LFP -- from the Bimble website...

 

(longer life is irrelevant for canal boats, maybe 120-180 years for LTO vs 20-30 years for LFP)

 

Edited December 4, 2023 by IanD

[magnetman]

Some people seem to like expensive things.

That is a bit shocking though as my LTO 600Wh modules nominal 15v were £80 each. Unused. 

 

 

[IanD]

2 minutes ago, magnetman said:

Some people seem to like expensive things.

That is a bit shocking though as my LTO 600Wh modules nominal 15v were £80 each. Unused. 

 

 

Maybe because secondhand stuff that nobody wants can be dirt cheap... 😉

[magnetman]

Also cost over time seems to be cheaper..

 

This could work out ! 

 

Just now, IanD said:

 

Maybe because secondhand stuff that nobody wants can be dirt cheap... 😉

Except that they are not second hand but yes I see your point .

 

 

[IanD]

8 minutes ago, magnetman said:

Also cost over time seems to be cheaper..

 

This could work out ! 

 

 

What do you mean by "cost over time" -- number of cycles?

 

Yes the claimed 30000 cycles for LTO is a plus point if the batteries are being fully charged and discharged twice every day all year e.g. in a forklift), in theory they'd last 41 years compared to 7 years -- always assuming the cycle claims are correct, there's a lot of uncertainly about this for LTO because of the many things which affect this.

 

No canal boat is ever going to get anywhere near this usage pattern, even an inveterate long-distance CCer who moves most days all year is unlikely to exceed a few cycles per week at most, and usually rather less than that.

 

So if you think having an LTO battery in your boat that might last 200 years is a plus point, go for it. For anyone else, an LFP battery is likely to last longer than the rest of the boat so that'll do... 😉

 

Edited December 4, 2023 by IanD

[magnetman]

You are assuming everyone has large battery banks. 

If the battery is optimised to the real life use then the cycles might actually be quite high. 

There is no reason to have a battery capable of running the boat for a week if the charging is regular. It is a waste of money. 

[IanD]

11 minutes ago, magnetman said:

You are assuming everyone has large battery banks. 

If the battery is optimised to the real life use then the cycles might actually be quite high. 

There is no reason to have a battery capable of running the boat for a week if the charging is regular. It is a waste of money. 

And this regular charging comes from where -- the sun that shines every day, or the generator you run every day?

 

The single biggest complaint of boaters about LFP batteries is how expensive they are; since LTO are at least 3x more expensive still, they're off the board for most people. If you want to spend 3x the money, get a 3x bigger LFP bank so you don't have to recharge so often. Or spend 1/3 the money and get a LFP the same size that will still last longer than most boaters own a boat, even if you use it hard every single day...

Edited December 4, 2023 by IanD

[n-baj]

On 27/11/2023 at 19:07, Tony1 said:

 

 

All that said, I am one of those decadent bourgeois swine who run a fridge in the winter, so perhaps its that making the difference... 

 

 

There you go, I use nature’s fridge in the winter. If the fridge freezer was on 24/7 then I’d have to use the generator for about an hour every day just to replenish what it uses.

 

Im also currently working in the mornings and out on walks in the afternoon so I think my actual consumption is about 250w/h a day for a bit of tv in the evening, lights and water pump and with the panel south facing on sunny days I recon I get about 500w/h so over run of sunny days the surplus does add up.

[nicknorman]

Today I did a complete cycle of the 105Ah fogstar at home. This being to hopefully allow the BMS to calibrate itself properly. I discharged it at around 6A and it ran on for quite a while below 0% SoC before low voltage cutout at 2.75v / cell. Voltage split was not a lot (unfortunately someone phoned me at the wrong moment so not exactly sure what it was). Put it straight on to charge using the Fogstar 40A charger. Which does actually charge at 40A up to at least 50% SoC, but the fan is REALLY noisy! Anyway it's just hit 105Ah / 100% on the App but still 24A going in so clearly the capacity is a bit more than 105Ah. I noticed previously that the high voltage cut out is set to a conservative 3.6v.

 

Oh and cell balance "up the knee" at 3.595v is max 5mV split which is pretty good.

 

App is still saying 105Ah though, not sure if it would adjust itself to the actual capacity it discovered when I cycled it. Seems not.

 

It is still incredible, for someone used to LA batteries, that with the SoC at 5% it is still chucking out 12.8v at 6A discharge. Definitely a bucket of electricity!

[nicknorman]

And as another follow up, initially when I turned on the caravan microwave via inverter (about 103A) the BMS SoC instantly plummeted to 0% and stayed there. But after the full cycling of the battery, it now behaves as it should. So anyone getting one of these would be advised to fully cycle it once so that the BMS “learns” the battery.

[GUMPY]

35 minutes ago, nicknorman said:

And as another follow up, initially when I turned on the caravan microwave via inverter (about 103A) the BMS SoC instantly plummeted to 0% and stayed there. But after the full cycling of the battery, it now behaves as it should. So anyone getting one of these would be advised to fully cycle it once so that the BMS “learns” the battery.

Fully charged mine from 50% 

Headlamp bulb, both filaments so 10amps, on it until it reached 0% recharged to 45%.

Discharge and recharge were linear, discharge took 10+hrs, recharge to 45% took 3hrs on 15amp charger.

Love the linear in and out and the fact that the voltage stays up about 13v until the very last few percent 

 

[GreenHeaven]

The main question for me is can you reprogram the BMS cutoff voltages. Some of these settings are too extreeme imo

[nicknorman]

59 minutes ago, GreenHeaven said:

The main question for me is can you reprogram the BMS cutoff voltages. Some of these settings are too extreeme imo

The BMS is password protected. I think Fogstar will give you the password but then refuse any subsequent warranty claims, which is fair enough.

Fogstar have chosen some fairly conservative settings for the BMS, which is fine by me.

Edited January 15 by nicknorman

[GUMPY]

57 minutes ago, GreenHeaven said:

The main question for me is can you reprogram the BMS cutoff voltages. Some of these settings are too extreeme imo

 Not without a password and I believe they don't give that out for obvious reasons.

The defaults look fine to me and so far and it's behaving as it should.

 

 

[magnetman]

They (Fogstar) seem quite confident about it. They appear to offer a 10 yar warranty. That is quite optimistic but I guess there are conditions attached. 

 

Interesting to see what happens if/when someone makes a claim. I imagine all the charging data is probably stored somehow so abuse would be spotted. 

 

 

All rather interesting.

 

 

One wonders how the warranty would work if someone was routinely charging and discharging at maximum capacity and performing multiple cycles per day. 10 cycles per day for 10 yars would be 36,500 which is way above what LFP are rated for. 

[GUMPY]

9 minutes ago, magnetman said:

 

One wonders how the warranty would work if someone was routinely charging and discharging at maximum capacity and performing multiple cycles per day. 10 cycles per day for 10 yars would be 36,500 which is way above what LFP are rated for. 

So you think you could run a full charge and discharge cycle in 2.4hrs 🤔😭

Edited January 15 by GUMPY

[IanD]

13 minutes ago, magnetman said:

They (Fogstar) seem quite confident about it. They appear to offer a 10 yar warranty. That is quite optimistic but I guess there are conditions attached. 

 

Interesting to see what happens if/when someone makes a claim. I imagine all the charging data is probably stored somehow so abuse would be spotted. 

 

All rather interesting.

 

One wonders how the warranty would work if someone was routinely charging and discharging at maximum capacity and performing multiple cycles per day. 10 cycles per day for 10 yars would be 36,500 which is way above what LFP are rated for. 

 

I expect you'll find in the small print that there are two aspects to the warranty, one is lifetime/age in years (e.g. 10) and the other is total throughput in 100% SoC cycles (e.g. 3000 cycles 0% to 100%, 6000 cycles 25% to 75% and so on), this is what other manufacturers who use data logging do -- for example the BMS LVL15.4 is guaranteed to 10 years and 46MWh, whichever comes first.

Edited January 15 by IanD

[magnetman]

6 minutes ago, GUMPY said:

So you think you could run a full charge and discharge cycle in 2.4hrs 🤔😭

100Ah battery. 100A charge. 100A discharge. 2 hours. 

 

Maybe the max charge is less than that. 

 

 

Maybe charging 'outside of the recommended rate" is classed as abuse. 

 

it says it can be charged at 100 amps. So can it or can't it? 

 

Some people might want to do this for example using a diesel engine to get high efficiency. 

 

If the battery is repeatedly charged at 100A (~1C) will this break the warranty? 

 

• Cell Type - Grade A EVE LF105
• Cell Configuration - 4S1P
• Nominal Capacity - 105Ah
• Energy - 1280Wh
• Cell Chemistry - Lithium Iron Phosphate
• Cell Nominal Voltage - 3.2V *4 (12.8nV)
• Cycle Life - 3500 @ 80% DOD
• Maximum Discharge - 100A
• Maximum Charge - 100A (Recommended charging rate 20/30% of capacity)

 

If one were using such a battery to power a system which needed 1.2kW of mains power continuously you m

[GUMPY]

14 minutes ago, magnetman said:

100Ah battery. 100A charge. 100A discharge. 2 hours. 

 

Maybe the max charge is less than that. 

 

 

Maybe charging 'outside of the recommended rate" is classed as abuse. 

 

it says it can be charged at 100 amps. So can it or can't it? 

 

Some people might want to do this for example using a diesel engine to get high efficiency. 

 

If the battery is repeatedly charged at 100A (~1C) will this break the warranty? 

 

• Cell Type - Grade A EVE LF105
• Cell Configuration - 4S1P
• Nominal Capacity - 105Ah
• Energy - 1280Wh
• Cell Chemistry - Lithium Iron Phosphate
• Cell Nominal Voltage - 3.2V *4 (12.8nV)
• Cycle Life - 3500 @ 80% DOD
• Maximum Discharge - 100A
• Maximum Charge - 100A (Recommended charging rate 20/30% of capacity)
•  

 

If one were using such a battery to power a system which needed 1.2kW of mains power continuously you m

You might just as well run the genset instead🥴

[IanD]

17 minutes ago, magnetman said:

100Ah battery. 100A charge. 100A discharge. 2 hours. 

 

Maybe the max charge is less than that. 

 

 

Maybe charging 'outside of the recommended rate" is classed as abuse. 

 

it says it can be charged at 100 amps. So can it or can't it? 

 

Some people might want to do this for example using a diesel engine to get high efficiency. 

 

If the battery is repeatedly charged at 100A (~1C) will this break the warranty? 

 

• Cell Type - Grade A EVE LF105
• Cell Configuration - 4S1P
• Nominal Capacity - 105Ah
• Energy - 1280Wh
• Cell Chemistry - Lithium Iron Phosphate
• Cell Nominal Voltage - 3.2V *4 (12.8nV)
• Cycle Life - 3500 @ 80% DOD
• Maximum Discharge - 100A
• Maximum Charge - 100A (Recommended charging rate 20/30% of capacity)
•  

 

Perhaps you should read the warranty small print, or failing that ask Fogstar? 😉

 

Usually charging LFP at the maximum rate (e.g. 100A here) is fine until you get close to 100% SoC, when the charge rate reduces -- this is what all EVs do to maximise battery life. Maybe Fogstar don't care (because 1C rate is not actually that high, and it may be the BMS that limits current not the cells), or maybe they do.

 

If the battery includes logging and you regularly charged all the way to 100% SoC at 100A, I would expect there might be some debate about liability if the battery failed early... 🙂

Edited January 15 by IanD

[magnetman]

5 minutes ago, GUMPY said:

You might just as well run the genset instead🥴

If the genny was big enough to run my 1.2kw continuous load and charge the battery at 100A I could run the genny for one hour then stop it for one hour then start again. 

 

Ad nauseam

[GUMPY]

The BMS reduces the charge rate when near 100% 

[nicknorman]

34 minutes ago, GUMPY said:

The BMS reduces the charge rate when near 100% 

I don’t think so. The charge rate naturally reduces as the SoC approaches 100% due to the chemistry, and most charge sources have “soft” regulation which means the supplied current gradually reduces as the regulated voltage is approached.

 

A BMS can’t control the charge rate, the FETs are either on or off. They can’t be partially on otherwise there would be massive heat dissipation and they’d fry in moments. I suppose they could PWM but that would seriously screw up any inductive charge sources such as an alternator.

[GUMPY]

13 minutes ago, nicknorman said:

I don’t think so. The charge rate naturally reduces as the SoC approaches 100% due to the chemistry, and most charge sources have “soft” regulation which means the supplied current gradually reduces as the regulated voltage is approached.

 

A BMS can’t control the charge rate, the FETs are either on or off. They can’t be partially on otherwise there would be massive heat dissipation and they’d fry in moments. I suppose they could PWM but that would seriously screw up any inductive charge sources such as an alternator.

Good point 

I just noticed it dropped off near full charge. 

Whatever the cause is, it does drop off fractionally lengthening the charge time. 

[nicknorman]

1 hour ago, GUMPY said:

Good point 

I just noticed it dropped off near full charge. 

Whatever the cause is, it does drop off fractionally lengthening the charge time. 

It is interesting comparing my boat system - bare cells with no FETs in the way (I use a bistable relay for emergency disconnect) - with the Fogstar that has FETs and a BMS - configured as directional switch so that charge and discharge can be turned on and off separately. Charging at a similar C rate, the Fogstar gets to a higher terminal voltage earlier and thus has a longer "flattening off" period of charge current. I am guessing this could be due to the slightly higher internal resistance of the cell and FET combination.

But of course although I say "longer", it is still massively quicker than lead acid.