Lithiums/Alternator

[Billy123]

On my boat I currently have 4 x 100 ah lithium batteries.   They are a fair few years old and, prior to my ownership, have had a fair bit of use from continuous cruising.  I've had them tested and they are currently running at around 50% capacity.   In the summer the solar keeps them topped up but obviously not at this time of year and the charge level drops quite quickly.  We are not huge power users - just a fridge, TV, etc, no huge appliances.  We are on a mooring with no shore power.  The wiring, to a novice, doesn't look ideal, and each battery has its own external BMS that just sits on top of each battery.

 

We have twin alternators, one for the starter battery and a 175A which charges the lithiums.  This is connected to a Mastervolt Alpha Pro III charge regulator.

 

Given the batteries are probably now past their best, I would like to replace these with a single 460 ah.  This would tidy up the wiring and provide plenty of power.    From what I have read, my understanding is that this would be a simple swap and I don't need anything else to protect the alternator, providing I adjust the charging settings accordingly.  I would be grateful for any advice in case I have missed anything.

 

We also have an 1800w standalone generator and a charger specifically for lithiums.  I would like to use this to charge the batteries in the winter, rather than running the engine.  I have tried this with the current 4 batteries, but without success, but that was probably user error.

 

Many thanks in advance.

 

Bill

[nicknorman]

8 minutes ago, Billy123 said:

On my boat I currently have 4 x 100 ah lithium batteries.   They are a fair few years old and, prior to my ownership, have had a fair bit of use from continuous cruising.  I've had them tested and they are currently running at around 50% capacity.   In the summer the solar keeps them topped up but obviously not at this time of year and the charge level drops quite quickly.  We are not huge power users - just a fridge, TV, etc, no huge appliances.  We are on a mooring with no shore power.  The wiring, to a novice, doesn't look ideal, and each battery has its own external BMS that just sits on top of each battery.

 

We have twin alternators, one for the starter battery and a 175A which charges the lithiums.  This is connected to a Mastervolt Alpha Pro III charge regulator.

 

Given the batteries are probably now past their best, I would like to replace these with a single 460 ah.  This would tidy up the wiring and provide plenty of power.    From what I have read, my understanding is that this would be a simple swap and I don't need anything else to protect the alternator, providing I adjust the charging settings accordingly.  I would be grateful for any advice in case I have missed anything.

 

We also have an 1800w standalone generator and a charger specifically for lithiums.  I would like to use this to charge the batteries in the winter, rather than running the engine.  I have tried this with the current 4 batteries, but without success, but that was probably user error.

 

Many thanks in advance.

 

Bill

 

Yes it should be a straightforward swap, provided you can physically lift the heavy battery and it fits the available space.

 

However I would be concerned about the present state of the existing batteries. Li batteries are generally considered knackered when they reach 80% of badged capacity, and yours are way worse than that. The question in my mind is "why"? Unlike lead acid batteries, Li has a very long life of perhaps 5000 cycles which should be 15 years or so even on liveaboard useage. It seems unlikely that your present batteries are 15 years old? Are they showing any physical signs of distress (ie swelling)?

 

I would therefore question whether the present charging setup is working properly - or rather, is set up properly. I would review all the settings on the Alpha Pro to check it is set up correctly. There are a lot of options!

 

Do you have the ability to connect the Alpha Pro to a laptop etc running MasterAdjust? ie the Masterbus USB interface? If not I would suggest that, before shelling out lost of money on a 460Ah battery, you get that to ensure that the new batteries will be charged correctly.

 

Regarding charging from the generator, you don't mention the charger output (amps). Perhaps it is too big for the generator in terms of initial current?

[Tony Brooks]

11 minutes ago, nicknorman said:

However I would be concerned about the present state of the existing batteries.

 

That was my thought as well, so needs more investigation.

[Jen-in-Wellies]

51 minutes ago, nicknorman said:

 

I would therefore question whether the present charging setup is working properly - or rather, is set up properly. I would review all the settings on the Alpha Pro to check it is set up correctly. There are a lot of options

 

1 hour ago, Billy123 said:

In the summer the solar keeps them topped up

Also, the manufacturer make and models of the existing cells and BMS. Plus the make, model and settings in the solar controller. Somewhere in the system, something has been doing damage. If it is the BMS, then a new big batt will solve it. If one of the controller settings, either alternator, or solar, then perhaps not.

[Billy123]

Many thanks to everyone who has taken the time to respond.

 

To answer some of the comments.  I think the batteries are around 5-6 years old.  No signs of distress or swelling.  They seem to be some kind of obscure Chinese make which came from a company in Poland who have since gone into liquidation.   We don't have much documentation for the batteries, but nowhere does the paperwork quote a recommended charge voltage.

 

There is a Mastervolt USB interface, but unfortunately nothing to plug it into - we are a bit iPad heavy!  We do have an Easyview 5 and I have had a look at some of the settings.  I understand I can change most things via the Easyview?  The previous owner left a screen dump of the current setup which from these I think the charging settings are:

 

Solar - Absorption 13.60v / Float 13.50v

Alternator - Bulk 13.80v / Absorption 13.80v / Float 13.20v

Inverter/Charger - Bulk 14.00v / Absorption 14.00v / Float 13.50v

 

My understanding is the charge voltage settings for lithiums are typically around 14.20v so this may be one issue, although these could be correct for the current batteries but there is no way of knowing.

 

Also, the inverter/charger is quite old and doesn't have a lithium profile, so is set for a gel which isn't ideal.  The charger only works when plugged into shore power so we've not actually used this.

 

As I mentioned, the boat was either out for lengthy periods of cruising with equally lengthy time sat in a marina plugged into shore power.  Would it be reasonable to think a combination of the incorrect charge voltages and battery profile would be enough to kill the batteries over this period of time?

 

Sorry, I don't have the charger here so can't confirm the amps, although it came from the same company who tested the batteries so they knew what we had.  Probably user error!!

 

Thanks again for all your comments.

[MtB]

3 hours ago, Billy123 said:

I've had them tested and they are currently running at around 50% capacity.

 

I'm curious about this bit. How did you have them tested?

 

Its quite a long but simple process to fully discharge them and record the amount of charge they take to 100%.

 

So I'm faintly surprised you didn't just do this yourself. 

 

 

 

[Jen-in-Wellies]

40 minutes ago, Billy123 said:

They seem to be some kind of obscure Chinese make which came from a company in Poland who have since gone into liquidation.  

Was there a capacity test done when new that you are aware of, or is this an assumption that the original capacity bore some resemblence to the numbers printed on the cells? Obscure Chinese make out of a defunct Polish company would not give me confidence of that. Could be you always had four by 50Ahr batteries. Over generous marketing claims (lies) are not uncommon with the greyer end of the market. 

[nicknorman]

1 hour ago, Billy123 said:

Many thanks to everyone who has taken the time to respond.

 

To answer some of the comments.  I think the batteries are around 5-6 years old.  No signs of distress or swelling.  They seem to be some kind of obscure Chinese make which came from a company in Poland who have since gone into liquidation.   We don't have much documentation for the batteries, but nowhere does the paperwork quote a recommended charge voltage.

 

There is a Mastervolt USB interface, but unfortunately nothing to plug it into - we are a bit iPad heavy!  We do have an Easyview 5 and I have had a look at some of the settings.  I understand I can change most things via the Easyview?  The previous owner left a screen dump of the current setup which from these I think the charging settings are:

 

Solar - Absorption 13.60v / Float 13.50v

Alternator - Bulk 13.80v / Absorption 13.80v / Float 13.20v

Inverter/Charger - Bulk 14.00v / Absorption 14.00v / Float 13.50v

 

My understanding is the charge voltage settings for lithiums are typically around 14.20v so this may be one issue, although these could be correct for the current batteries but there is no way of knowing.

 

Also, the inverter/charger is quite old and doesn't have a lithium profile, so is set for a gel which isn't ideal.  The charger only works when plugged into shore power so we've not actually used this.

 

As I mentioned, the boat was either out for lengthy periods of cruising with equally lengthy time sat in a marina plugged into shore power.  Would it be reasonable to think a combination of the incorrect charge voltages and battery profile would be enough to kill the batteries over this period of time?

 

Sorry, I don't have the charger here so can't confirm the amps, although it came from the same company who tested the batteries so they knew what we had.  Probably user error!!

 

Thanks again for all your comments.

 

Yes you should be able to configure everything via the Easyview. Charging Lithiums at a lower than recommended voltage is not a bad thing at all and certainly doesn't explain a short life - unlike lead acid batteries lithium doesn't particularly like to be fully charged. I would leave the settings the same when you put the new battery in, perhaps with the exception of increasing the solar absorption a bit to maybe 13.8v, just to make best use of the capacity.

 

It's been hinted that perhaps the 50% capacity figure is wrong - as they said it is a long and tedious process to test the capacity of a lithium battery and without knowing exactly how they did it, we are suspicious! But then again you say it seems to deplete quickly - but of course that depends on how you use it! It doesn't sound as though you have any battery state of charge or current monitoring, I would suggest getting something like a BMV712 so that you can have a better idea of what is going on - without adequate monitoring, electricity is invisible and a complete mystery!

[Tony Brooks]

7 hours ago, Billy123 said:

 I've had them tested and they are currently running at around 50% capacity.

 

By whom, using what equipment, and how. If you just asked a boatyard, rather than a lithium specialist, I would not trust that figure at all.

[MtB]

9 hours ago, Billy123 said:

From what I have read, my understanding is that this would be a simple swap and I don't need anything else to protect the alternator, providing I adjust the charging settings accordingly.

 

 

Was this advice given to you by the same person telling you your cells are at 50% of label capacity?

 

Because it seems unlikely to be correct advice. If the BMS emergency-disconnects while the alternator is charging, then it can easily croak the alternator (unless it is something very fancy and expensive with suitable protection designed in). 

[nicknorman]

4 hours ago, MtB said:

 

 

Was this advice given to you by the same person telling you your cells are at 50% of label capacity?

 

Because it seems unlikely to be correct advice. If the BMS emergency-disconnects while the alternator is charging, then it can easily croak the alternator (unless it is something very fancy and expensive with suitable protection designed in). 

 

I think setting the charge voltage to 13.8v makes this pretty unlikely.

The 175A alternator doesn't have "ordinary" diodes, they are zener diodes. From the spec sheet: "Sandwich construction of the rectifier with press fit Zener diodes provides for low temperatures of the rectifier diodes, high resistance to vibrations and protection of loads on the vehicle against alternator overvoltages."

Depending on how hard the alternator was working at the time I think there would still be quite a large transient into the 20s or 30s of volts, and possibly other 12v appliances connected might suffer so I would prefer not to test it! I think the automotive standard is something like ability to withstand 35v (12v system). On the other hand a high voltage disconnect is most likely to occur towards the top of the charge when the current has decreased significantly, hence less energy stored in the field windings hence lower transient energy. And of course the system has been in operation for a good while without blowing anything up.

Edited November 11 by nicknorman

[MtB]

Thanks Nick.

 

Time I learned what a zener diode actually is, so I can understand this properly...

 

But yes I get your point about the lower charging voltage. 

 

 

[nicknorman]

1 hour ago, MtB said:

Thanks Nick.

 

Time I learned what a zener diode actually is, so I can understand this properly...

 

But yes I get your point about the lower charging voltage. 

 

 

 

A zener diode is pretty much the same as a diode, but with different chemical doping to make the reverse breakdown more stable and predictable. So it conducts in the forward direction like a normal diode. It blocks reverse voltage like a normal diode ... up until its breakdown voltage (which depends on the detail of the chemicals and physical geometry) at which point it starts to conduct in the reverse direction. It will then maintain the rated reverse breakdown voltage across the diode (within its heat dissipation capabilities).

So by using a zener as a rectifier, you get the normal behaviour when things are going normally and the voltage is as expected (say 14.4v)  but if there is a "load dump" event and the voltage in the stator rises too high, the zener diode will start to conduct when the reverse voltage gets to its breakdown voltage (say 35v) and thus shorting the excess energy through itself and converting it to heat. The maximum voltage is then capped at around its rated breakdown voltage (well, a bit higher due to its internal resistance etc). It's analagous to a pressure relief valve in plumbing!

 

I think (guessing!) that historically it was difficult to make a zener diode that performed well as a high current rectifier diode AND was a zener, but things have moved on.

 

I added my own load dump transient absorber not to protect the alternator, but to protect the 12v services that might not like 35v. My diodes should hopefully limit the voltage to about 18v, but I have never tested in anger!

 

 

Edited November 12 by nicknorman

[MtB]

Many thanks Nick. I understand much better now.

 

Duly greenied! 

 

[Billy123]

Many thanks to everyone for their comments.  

 

With regard to the battery testing, this was done by Groves Batteries in Cheltenham, who said:

 

"We've done the first full discharge test - a 400Ah lithium battery should be able to run for 600 minutes at our discharge rate of 40A - yours lasted 310 minutes. We set the voltage threshold to 10.8V which is a generous low threshold so we'll recharge and discharge again but set it to 10.0V, however when lithium goes below 12V, it tends to decline fast, even if it's a healthy battery so I don't think we'll get much better than about 50% state of health on these.

No distinct individual failure on the cells - all are more or less at the same level. Cells 1 and 2 are 2.8V, and cells 3 and 4 are 2.9V, so it's likely all cells are at 50% state of health, rather than just one being an issue. "

 

They did repeat the test with similar results.   I have attached the battery details.  The BMS is a 123SmartBMS (Gen 2) - https://123electric.eu/products/123smartbms-gen3/ - this is the previous version.

 

Is that helpful?

 

Thanks again for all your comments.

 

 

Winston_DS_LFP400AHA.pdf

[nicknorman]

You had a proper battery test done then! This must be a first! Usually people report the "battery health" from one of those halfords type car battery testers, which of course are totally useless for leisure batteries.

 

Well I think everything I said perviously, stands. The Winston cells are top quality and should have a long life. The BMS looks a pukka one. So really I think something in the setup is wrong, if the cells have died after 5 or 6 years. I see there is an App for the BMS, do you have it and if so you could read the settings and let us check them.

In order to kill the cells in that fairly short time I would think they have been over-discharged (BMS failed to isolate the cells), over charged (ditto), charged at very low temperature a few times (ditto), or some such. Also have a look at the two external relays for charge and discharge disconnect, are they working correctly and not bypassed?

[Jen-in-Wellies]

Don't forget the solar controller that has been feeding these batts too. Make, model and settings. 

[Billy123]

Thanks again.  Having a proper battery test seemed to be thing to do as that felt like the best place to start.  

 

In answer to the queries raised, I do have the app.  I am a weekend boater so will note the settings next time we go - this probably won't be for another couple of weeks but I will come back and update then.  I really appreciate everyone's time and wouldn't want you all to think I had read and ran!

 

Re the solar, from the info that came with the boat:

 

"The boat has 660w of solar linked in series to the Mastervolt SCM 60 MPPT MB Charger.  

 

The Mastervolt SCM will automatically switch on when there is enough sunlight and then switch off at dusk.  You can see how much power is being generated on the Mastervolt display panel. The default for the solar is to charge the batteries to 13.5v and keep them floated when the batteries are full or that voltage has been reached.

 

There is also a Victron Battery Protect in the circuit which acts as a safety device to protect the batteries from either over current or discharging them too far and damaging them.  In both cases it will cut off the battery power if this happens."

 

I have attached a pdf the previous owner left showing the charging settings, etc, which may shed some light.

 

Once again, many thanks.

 

Mastervolt 2023.pdf

[Jen-in-Wellies]

Looking at the SCM60 destructions, the Lithium battery setting may be relying on a  Mastervolt Li batt for a stop charging signal, which it may not get from another battery manufacturer. Possible the solar was overcharging them? This is assuming it was set to the Li charging algorithm. Worth checking

https://images.mastervolt.nl/files/10000009952_03_Manual_SolarChargemaster60_EN.pdf

 

[nicknorman]

1 hour ago, Jen-in-Wellies said:

Looking at the SCM60 destructions, the Lithium battery setting may be relying on a  Mastervolt Li batt for a stop charging signal, which it may not get from another battery manufacturer. Possible the solar was overcharging them? This is assuming it was set to the Li charging algorithm. Worth checking

https://images.mastervolt.nl/files/10000009952_03_Manual_SolarChargemaster60_EN.pdf

 

However, the solar voltages (assuming as per the pdf) are set to 13.6v absorb and 13.5v float, so prolonged exposure to those voltages shouldn't be an issue.

1 hour ago, Billy123 said:

Thanks again.  Having a proper battery test seemed to be thing to do as that felt like the best place to start.  

 

In answer to the queries raised, I do have the app.  I am a weekend boater so will note the settings next time we go - this probably won't be for another couple of weeks but I will come back and update then.  I really appreciate everyone's time and wouldn't want you all to think I had read and ran!

 

Re the solar, from the info that came with the boat:

 

 

"The boat has 660w of solar linked in series to the Mastervolt SCM 60 MPPT MB Charger.  

 

The Mastervolt SCM will automatically switch on when there is enough sunlight and then switch off at dusk.  You can see how much power is being generated on the Mastervolt display panel. The default for the solar is to charge the batteries to 13.5v and keep them floated when the batteries are full or that voltage has been reached.

 

 

There is also a Victron Battery Protect in the circuit which acts as a safety device to protect the batteries from either over current or discharging them too far and damaging them.  In both cases it will cut off the battery power if this happens."

 

I have attached a pdf the previous owner left showing the charging settings, etc, which may shed some light.

 

Once again, many thanks.

 

Mastervolt 2023.pdf 1.66 MB · 3 downloads

 

That is a very comprehensive system, must have cost a fortune to install!

 

I can't see anything signficantly wrong with the settings, assuming they are actually as per the pdf.

 

A couple of observations - the battery state of charge monitoring seems to be based on the Mastershunt. This is a straightforward coulomb-counting device that suffers (like all of its ilk) from a gradual drift away from accuracy over a few weeks. The cure is to occasionally fully charge the batteries (eg 14.4v until current falls to 5% of capacity) at which point the Mastershunt will reset to 100%. I can't immediately see an easy way for you to do this as the solar voltage is set low and it looks like the Mastershunt tells the alternator to go to float at (what it think is) 90% SoC. Possibly the Alter Float button on the Easyview 5 will do this, it's not quite clear to me - but only when charging from the alternator. Anyway the point is that it is advisable to fully charge the batteries eg once a month to get correct SoC readings from the Mastershunt.

 

Also I notice that in the Alpha Pro, the "small engine" rpm settings seem very high. I am pretty sure that if the pole pairs number, and pulley ratio, are set correctly (as they seem to be) then the rpm numbers reflect the engine rpm, not the alternator rpm. I don't know what engine you have but it seems unlikely that it will rev to 4500 especially on the canals! I wonder what charge current you actually get at canal cruising speed (or a fast idle speed, say 1200rpm if it's a modern japanese type engine) because it looks to me as though its unlikely to go over 20% field current at normal speeds, giving you only about 20% output.

 

Anyway, none of this explains why the batteries are knackered so I think you should go ahead with the new ones and just keep an eye on how the system behaves in practice, in terms of charge voltage etc. Could it be that the batteries were second hand when installed, having previously been abused? Who knows!

Edited November 14 by nicknorman

[Billy123]

Many thanks for your comments.  

 

The story goes the boat was commissioned by a drug dealer from Goole who had it built to launder some of his ill gotten gains, so no expense was spared.   Some of the "goodies" have unfortunately been removed, for example, a 31 inch TV built into the end of the bed with electric raising and lowering, a self-seeking satellite dish, a Mastervolt Whisper 3.5kw onboard generator, and my personal favourite, a cream enamelled multi-fuel stove at the aft end of the cabin.  They did leave the over bed multicoloured LED star lights though, so every cloud!

 

The previous owner said they were the current settings at the time.  I've no reason to doubt that and he went to great pains to explain everything.  We've not altered any of the settings since then.  The instructions do say if the battery charge is over 90% the alternator will go into float to top the batteries up slowly, and if charging via the engine when static to increase the revs slightly until 80 amps are going into the battery.  The engine is a Beta 43.

 

It has taken us a while to get our heads around the electrics, but I am pretty sure the batteries were in this condition when we bought the boat.  If anything, it seems slightly improved now, but probably only because we have become better at managing it.

 

One thing I am curious about.  Is there any reason why the charge voltages are set at slightly different levels for each method of charging?   If I'd just gone ahead and changed the battery, I would have set each method the same.

 

Thanks again for your help.

 

[nicknorman]

11 minutes ago, Billy123 said:

Many thanks for your comments.  

 

The story goes the boat was commissioned by a drug dealer from Goole who had it built to launder some of his ill gotten gains, so no expense was spared.   Some of the "goodies" have unfortunately been removed, for example, a 31 inch TV built into the end of the bed with electric raising and lowering, a self-seeking satellite dish, a Mastervolt Whisper 3.5kw onboard generator, and my personal favourite, a cream enamelled multi-fuel stove at the aft end of the cabin.  They did leave the over bed multicoloured LED star lights though, so every cloud!

 

The previous owner said they were the current settings at the time.  I've no reason to doubt that and he went to great pains to explain everything.  We've not altered any of the settings since then.  The instructions do say if the battery charge is over 90% the alternator will go into float to top the batteries up slowly, and if charging via the engine when static to increase the revs slightly until 80 amps are going into the battery.  The engine is a Beta 43.

 

It has taken us a while to get our heads around the electrics, but I am pretty sure the batteries were in this condition when we bought the boat.  If anything, it seems slightly improved now, but probably only because we have become better at managing it.

 

One thing I am curious about.  Is there any reason why the charge voltages are set at slightly different levels for each method of charging?   If I'd just gone ahead and changed the battery, I would have set each method the same.

 

Thanks again for your help.

 

 

On the alternator float thing, the bulk and absorption is set to 13.8v (which is on the low side) and the float is set to 13.2 which is below the natural voltage for a LiFePO4 battery at 90% SoC and will not result in any charge going in at all. So with those settings I can't see how it could ever be charged above 90% SoC, and that is 90% according to the Mastershunt, which could be way off after a year or two.

 

We have the Iskra 175A alternator and Beta 43, with custom alternator regulator. I find that at around 1200 or 1300 engine rpm, it will put out about 120A whilst keeping the temperature within 90degC. So I think your 80A is very cautious and wastes a major benefit of Li batteries which is fast charging ability. If it were mine I would adjust the "small engine" parameters, reducing the rpm figures to get more charge current.

 

You still have the protection of the alternator temperature sensor to avoid alternator overheating. And although I have a target temperature of 90C, that is pretty cautious too and yours would probably settle at about 95-100C which is fine - bearing in mind the alternator spec says maximum ambient temperature of 110C. That is ambient temperature, not the temperature of the alternator which would of course be a lot hotter! Alternators can run pretty hot without a problem.

The purpose of the "small engine" parameters is to avoid mechanically overloading the engine at low revs, but the Beta 43 can happily drive the full load of the alternator at and above 1300 rpm (engine speed).

 

There is nothing to stop you charging using both the alternator and a generator and charger or Combi at the same time - the batteries should be quite happy up to about 1/2 their capacity as current, ie 200A for a 400Ah battery. We can fast charge our Li using the 175A alternator at about 120A, plus the Combi in charger mode fed from the travelpower (or could be an external generator) to get about 200A. This means you can put back a day's worth of electrical usage in about an hour, which minimises nuisance engine noise etc.

 

You mentioned a separate charger I think, but did you realise that if you plug the genny into your shore power inlet, the Mass Combi will act as a charger? - it is set to 14.0v and 75A. So you too could have 200A charging with the combination of genny and alternator, and the Combi will take the SoC right up to about 99.5% which is enough to sync the Mastershunt to 100%

 

To answer your question about different voltage settings, the solar is perhaps set to a lower voltage because it is charging every day regardless, and in summer you get lots of solar and less electrical consumption, every day the batteries will be taken up to the set voltage, even if perhaps you are away from the boat for a few days and using nothing. Perhaps they felt that 13.8v was a bit high for that, since there is no means to stop charging at a specified SoC below 100%, hence 13.6v. IMO 13.8v would be OK though, the max charge voltage is 14.6 so you are not really "climbing the knee" at 13.8v