Li-0n, these look interesting

[GUMPY]

What does the team think?

 

https://www.fogstar.co.uk/products/lithium-leisure-battery-fogstar-drift-105ah

105_SpecSheet_V.2_1.pdf

Edited September 21, 2023 by GUMPY

[nicknorman]

I think they are good. No direct experience but reputationally ok.

[magnetman]

Interesting company with attractive prices and the batteries seem really good. 

 

Never tried one as already have loads of LTO batteries but I would be very tempted by these. 

 

Because they are so good at charge discharge it seems to me if you are running mostly on solar and forget the alternator for the bright season you could use one of these for summer as an in-out battery for daily use then put it away for winter somewhere warm and use the lead batteries and the alternator. 

 

Don't know what they are like when charged with alternator but having two separate battery systems seems the way to go to me. 

 

I'm a low energy consumer.  

 

 

 

 

[David Mack]

Are these simply drop-in replacements for lead acid batteries, or would other changes/equipment be needed?

[Higgs]

In the battery safety section, this could be difficult, if attached to solar: 

 

 

Edited September 21, 2023 by Higgs

[dmr]

Interesting, these look to be just a tad smaller than a Trojan T105 so should would be a physical drop in replacement.

Can only connect 4 together so no good for me 😀

[MtB]

41 minutes ago, David Mack said:

Are these simply drop-in replacements for lead acid batteries, or would other changes/equipment be needed?

 

There is no such thing as a 'simple' LFP drop in yet, as no-one AFAIK has developed a BMS for them that disconnects the charge source politely when fully charged. If it disconnects your alternator whilst (over)charging, that is likely to be the end of your alternator.

 

They are only 'simple', 'drop in' replacements if you are charging from sources other than an alternator. 

 

 

 

One way around this is to use them as 'drop-in' 'additions' rather than replacements. Connect them in parallel with your existing LA battery, then the fully charged disconnect doesn't hurt the alternator.

 

 

[dmr]

5 minutes ago, MtB said:

 

There is no such thing as a 'simple' LFP drop in yet, as no-one AFAIK has developed a BMS for them that disconnects the charge source politely when fully charged. If it disconnects your alternator whilst (over)charging, that is likely to be the end of your alternator.

 

They are only 'simple', 'drop in' replacements if you are charging from sources other than an alternator. 

 

 

 

I need to learn more about this (Maybe Nick Norman will comment).

If lithium is a drop in replacement with solar/mains charging then I am thinking that a full drop in replacement is possible, just need to take the regulator out of the alternator and fit something like the Wakespeed controller.

Is it possible to have a safe lithium system using a system that measures charge voltage and goes into float? or is communication with the battery BMS essential?

 

The Wakespeed is biggish money but not that big as part of a full Lithium system.

[magnetman]

44 minutes ago, Higgs said:

In the battery safety section, this could be difficult, if attached to solar: 

 

 

 

If the battery caught fire and it all went mad I would be tempted to leave it unattended. 

 

I've had a lithium battery thermal runaway on a NMC based jump starter but was fortunate as managed to get it out of the boat before it went mental and let out a massive flame. Surprising how much energy these blighters store. 

 

I expect this is just arse covering for their insurance. These LFP types are known to be quite safe. 

 

 

[Rob-M]

10 minutes ago, dmr said:

I need to learn more about this (Maybe Nick Norman will comment).

If lithium is a drop in replacement with solar/mains charging then I am thinking that a full drop in replacement is possible, just need to take the regulator out of the alternator and fit something like the Wakespeed controller.

Is it possible to have a safe lithium system using a system that measures charge voltage and goes into float? or is communication with the battery BMS essential?

 

The Wakespeed is biggish money but not that big as part of a full Lithium system.

Fitting a Wakespeed is what I am considering doing but I also need to replace the mains charger so that can be controlled from a BMS as well, I think the pricing I was looking at for batteries, regulator, combi inverter\charger and a few other bits was just over £6k.

[dmr]

8 minutes ago, Rob-M said:

Fitting a Wakespeed is what I am considering doing but I also need to replace the mains charger so that can be controlled from a BMS as well, I think the pricing I was looking at for batteries, regulator, combi inverter\charger and a few other bits was just over £6k.

As far as I can see its very difficult to get anything (solar etc etc) to actually talk to the BMS in the batteries so working on charge voltage is the only option. The Wakespeed will talk to a few very specific batteries but these need a CANBUS BMS rather than bluetooth.

[MtB]

25 minutes ago, dmr said:

Is it possible to have a safe lithium system using a system that measures charge voltage and goes into float?

 

This takes us straight into the question "What do you mean by 'float'?"

 

Lots of people (including me) tend to take it to mean the same as trickle charging, i.e. maintaining a terminal voltage which keeps enough charge going in to overcome the self-discharge effect. Do this with a LFP and you'll end up overcharging it in the fullness of time according to the Nordkyn Design site, IIRC. 

 

 

[dmr]

The Victron stuff (battery charger and solar controller) has an adjustable float voltage so it should be possible to set this so low that there is no charge going in. Not sure if it can than detect when some charge has been taken out and start charging again.

 

I am getting very interested in a lithium system but don't want really to go to a full bus system and really really don't want to go hybrid.

I am trying to find out if my existing Victron stuff and a Wakespeed can produce a safe system. I don't want to depend upon the auto disconnect in the battery BMS.

I am struggling to get good information on this but suspect some forum people might know 😀

[MtB]

9 minutes ago, dmr said:

The Victron stuff (battery charger and solar controller) has an adjustable float voltage so it should be possible to set this so low that there is no charge going in. Not sure if it can than detect when some charge has been taken out and start charging again.

 

Well that's just where the confusion lies innit! If the voltage is so low that no charge is going in then it isn't 'float charging' is it? Charging is effectively turned off. 

 

The SoC Vs terminal voltage slope is so flat that charge is mostly determined by the internal BMS by AH counting I suspect. Only at the extremes of charge and discharge do the cell voltage rise substantially or fall.

 

And yes the internal BMS is really an emergency disconnect but most 'drop-in' users seem to rely on this as the primary method of control and don't really grasp the subtlety of turning the charge source off before the emergency disconnect. I think the internal BMSs must now be very reliable or there would be endless tales of wrecked batteries.

 

 

 

 

[dmr]

Victron actually have a float setting and a maintenance setting that is a fair bit lower than float.

 

I feel that the auto disconnect in the battery BMS is a bit like saying "My brakes are terrible but I don't mind because the seatbelt always works" 😀

 

I also suspect the BMS power stage is built from lots of little transistors rather than one big expensive one which does not please me.

So, my big question....by setting charge voltages can I reliably stop the charge process at something like 80% or 90% charge????

[nicknorman]

1 hour ago, MtB said:

 

This takes us straight into the question "What do you mean by 'float'?"

 

Lots of people (including me) tend to take it to mean the same as trickle charging, i.e. maintaining a terminal voltage which keeps enough charge going in to overcome the self-discharge effect. Do this with a LFP and you'll end up overcharging it in the fullness of time according to the Nordkyn Design site, IIRC. 

 

In my opinion float for Li batteries means an accurately set charge voltage such that no current flows into the battery, but when a load is turned the charge source provides most of the current, rather than it coming from the batteries. I suppose it depends on how often you use a big load when cruising, but in our case we have electric kettle, washing machine etc that can be fed from the alternator after the batteries have gone to float.

 

Float, for Li, is certainly not trickle charging.

[GUMPY]

On a single alternator system with some form of split charging they would be fine as the alternator would still have the start battery as a "load" 

For my use which is effectively the same as above it looks like one will be fine. Just got to find a way to justify replacing a six month old perfectly fine LA battery

[nicknorman]

4 minutes ago, dmr said:

Victron actually have a float setting and a maintenance setting that is a fair bit lower than float.

 

I feel that the auto disconnect in the battery BMS is a bit like saying "My brakes are terrible but I don't mind because the seatbelt always works" 😀

 

I also suspect the BMS power stage is built from lots of little transistors rather than one big expensive one which does not please me.

So, my big question....by setting charge voltages can I reliably stop the charge process at something like 80% or 90% charge????

No. At 80% the battery voltage curve is still very flat, and there is some hysteresis and effect of previous activity (charge or discharge at varying currents).

 

However one could argue that you don’t need to stop charging at a specified SoC. I know people talk about not going over 80% etc but IMO this is probably overkill. The thing is to avoid “going up the knee” so by setting a charge voltage of say 13.7v you will get to 90-something percent without stressing the batteries. I think! It’s got to be massively better than charging until the BMS emergency disconnect triggers.

 

The only thing is that if you have conventional analogue “soft” regulation with a limiting voltage of 13.7, the current will be falling off for a long time as the voltage creeps slowly up, which rather defeats the object. You want a charge source with PID regulation so that the current doesn’t start to decrease until 0.1v or so short of the limit. Pretty difficult to do with analogue.

[Tony1]

2 hours ago, GUMPY said:

What does the team think?

 

https://www.fogstar.co.uk/products/lithium-leisure-battery-fogstar-drift-105ah

105_SpecSheet_V.2_1.pdf 309.38 kB · 5 downloads

 

If I was buying a battery bank for a boat at the moment, I'd be looking at their 460Ah model:

 

https://www.fogstar.co.uk/collections/lithium-leisure-battery/products/fogstar-drift-460ah-leisure-battery

 

User n-baj on this forum has been using one for a month or two, and had no problems with it. 

The built in heating is a nice feature, and that seems like a lot of Ah plus a decent BMS for under £1200.

 

At 38kg its going to be a bugger to shift around, so you'd want to be careful with your back.

 

 

 

 

[nicknorman]

1 hour ago, dmr said:

I need to learn more about this (Maybe Nick Norman will comment).

If lithium is a drop in replacement with solar/mains charging then I am thinking that a full drop in replacement is possible, just need to take the regulator out of the alternator and fit something like the Wakespeed controller.

Is it possible to have a safe lithium system using a system that measures charge voltage and goes into float? or is communication with the battery BMS essential?

 

The Wakespeed is biggish money but not that big as part of a full Lithium system.

Might be worth looking at a Victron smart shunt and the Venus GX or raspberry pi equivalent. Victron smart shunt sends SoC data to the Venus and that can be set to operate a volt-free relay. I don’t know if the wakespeed has a digital input to switch from charge to float, but it’s quite clever so probably does. And maybe it understands the victron VE.Direct protocol, not sure. If so you wouldn’t need the Venus.

 

Incidentally I made a load dump absorber with 12 fat Tranzorb diodes, as a fall back if my battery emergency disconnect went open circuit for some reason. I have spare PCBs if you are interested (supply your own tranzorbs).

[Tony1]

25 minutes ago, nicknorman said:

In my opinion float for Li batteries means an accurately set charge voltage such that no current flows into the battery, but when a load is turned the charge source provides most of the current, rather than it coming from the batteries.

 

I've moved over to using charge voltage to manage my daily charging, rather than SoC- so I'm seeing my MPPT100/50s go into float a lot.

In my case, float means that the MPPTs will put a tiny charge into the batteries (I think its 0.1 amps), but that's not enough to make any material difference to the battery's activities or processes. 

The bulk charge voltage is set at 13.8v (or a bit less), because that means the MPPTs will go into float mode when the battery is about 80-85% full. So the bulk charge voltage, at least routinely, is not something I can really change much. 

(If I do set the bulk charge voltage a bit higher, the batteries will get to a higher SoC before the MPPTs go into float, as you would expect.) 

But during the float phase, if a big load is applied (by me using the kettle, say), the MPPTs will stay in float mode, and will not switch to putting more current into the batteries.

And if they go into float at say noon, they seem to stay that way for the rest of the day, as far as I can tell, and the batteries will just carry on discharging, and their voltage will gradually drop. 

So the float mode is not keeping the voltage 'propped up' in any way, which was my initial query. 

If I do want to get the MPPTs charging again (e.g. because I've heated a tank of water with the immersion), then I have to switch them off for about 10-15 mins. Then when I switch them back on, they will go into bulk charge- unless the battery is already very full and the voltage is still 'highish', in which case they go straight into float.  

 

 

Edited September 21, 2023 by Tony1

[dmr]

8 minutes ago, nicknorman said:

No. At 80% the battery voltage curve is still very flat, and there is some hysteresis and effect of previous activity (charge or discharge at varying currents).

 

However one could argue that you don’t need to stop charging at a specified SoC. I know people talk about not going over 80% etc but IMO this is probably overkill. The thing is to avoid “going up the knee” so by setting a charge voltage of say 13.7v you will get to 90-something percent without stressing the batteries. I think! It’s got to be massively better than charging until the BMS emergency disconnect triggers.

 

The only thing is that if you have conventional analogue “soft” regulation with a limiting voltage of 13.7, the current will be falling off for a long time as the voltage creeps slowly up, which rather defeats the object. You want a charge source with PID regulation so that the current doesn’t start to decrease until 0.1v or so short of the limit. Pretty difficult to do with analogue.

Getting a bit electogeeky here, but I am not sure about PID. The Adverc manages to do a tight voltage control and I suspect its actual control loop is analog and also not PID. I suspect it can be done with high loop gain, a biggish time constant and maybe an over-ride of some sort to prevent over voltage on step changes.

I would hope that the Wakespeed (or Alpha Pro) gets the voltage control right. (and also the Victron stuff).

I did find an article on the www a while ago from the bloke who designs alternator regulators, it is quite a challenge. 

[magnetman]

Tranzorbs sound pretty cool. 

 

 

[nicknorman]

3 minutes ago, dmr said:

Getting a bit electogeeky here, but I am not sure about PID. The Adverc manages to do a tight voltage control and I suspect its actual control loop is analog and also not PID. I suspect it can be done with high loop gain, a biggish time constant and maybe an over-ride of some sort to prevent over voltage on step changes.

I would hope that the Wakespeed (or Alpha Pro) gets the voltage control right. (and also the Victron stuff).

I did find an article on the www a while ago from the bloke who designs alternator regulators, it is quite a challenge. 

Well you can of course do PID with analogue electronics, it’s just so much easier to do it with digital. The chip I use only starts to decrease current when within about 100mV whereas a conventional alternator regular the same thing is more like 0.5v or maybe more. I would imagine that both the wakespeed and Alpha Pro have digital regulation at their hearts.

[dmr]

9 minutes ago, nicknorman said:

Might be worth looking at a Victron smart shunt and the Venus GX or raspberry pi equivalent. Victron smart shunt sends SoC data to the Venus and that can be set to operate a volt-free relay. I don’t know if the wakespeed has a digital input to switch from charge to float, but it’s quite clever so probably does. And maybe it understands the victron VE.Direct protocol, not sure. If so you wouldn’t need the Venus.

 

Incidentally I made a load dump absorber with 12 fat Tranzorb diodes, as a fall back if my battery emergency disconnect went open circuit for some reason. I have spare PCBs if you are interested (supply your own tranzorbs).

I think Wakespeed only does CANbus rather than Victron, but they are pretty similar????

A good project would be to make a "system integrator" box based on a micro controller, a bit like an open source version of the Victron system. This could talk to the batteries and the various charge devices using VE bus and CANbus etc, and have a good display. But there is still the issue that most battery BMS systems only do Bluetooth.

Trouble is I just don't have any time. Took last year off to build a mooring so neglected the boat a bit. Next year need to come out of the water to do the baseplate, an engine rebuild (or replacement), quite a lot of painting, and investigate a big land based solar setup at the mooring. And I am still doing a bit of software writing to earn a bit of money. And I want to go and look at the Lee and Stort and Wey 😀