Electric/Battery gremlins

[hoopdriver]

A query since I’m at my wits end - and not being very technically minded my wits end is not very far away.

 

I live on a new boat - well, a year now, and until late September I had absolutely no issues at all with the electrify or battery. I’ve a Victron 330ah lithium battery, a Victron 12-200 BMS, a Victron controller, 600 watts of solar and a Cetus engine with a 95amp domestic alternator. All worked swimmingly through last winter, spring and summer. My electricity use is modest - 12v lights, 12v fridge (no freezer) and charging phone, laptop and camera batteries as required. (I am a writer/photographer.)

 

I do have a washing machine, which I run every week to ten days, quick wash only, and only when the engine is running. For nine months I had no problems whatsoever.

 

in late September I did a wash, engine running, but found afterwards that the BMS had not been letting any charge from the alternator through to the battery. I didn’t notice until I woke up the next morning and saw the voltage at 12.3 on the app. When I ran the engine the app showed 0% to 4% charge going through. Solar though was doing fine and boosted the voltage to 12.9 - better than nothing for sure. I know it was the Solar doing this because I’d shut the engine off.

 

I took the boat to a nearby marina and hooked up to shore power. The battery charged fully. But no way could I get the BMS to allow charge from the engine. 0%.  An electrician tested the alternator (fine) and the fuses (fine). Solar was fine. And when I unplugged from mains the battery discharged as normal. 
 

As it was under warranty I told the dealer about my troubles with the BMS. He dragged his feet big time and took eight weeks to provide a new one. The new one refused to work with the solar - kept giving short circuit warnings - although there had been absolutely no trouble with solar at all and indeed the app shows it producing charge just fine. Anyway, we left the solar disconnected and hooked up the new BMS. At first the problem seemed to be fixed (except for the solar) as the engine was now charging the battery - but only to a point. After 15 minutes for so, when the app shows a charge of 13.34v it ceases charging. According to the app, 36-40% of charge is going through  but you can run the engine for two hours and not see so much as 0.01v increase.

 

Anybody have any idea what is going on? I am about ready to replace the whole thing with lead acids just so I can get out of here. I would think it was the battery except it accepted Solar just fine, charges on mains just fine and discharges just fine. Any suggestions welcome! Thanks!

[MtB]

Well I'm no expert with lithium installations like this but my observation would be that something had busted, as it all used to work perfectly well.

 

The correct action is to trace and diagnose the fault rather than start changing random parts (e.g. the BMS as you say has already been swapped) based on pure guesswork.

 

The hard bit is finding someone who actually understands your LFP installation. Even the designer of the installation may not be that good at fault-tracing. The person best placed to understand it is probably you, as you will have the RCD manual to hand which will (should!) provide chapter and verse about exactly what is installed and how it is wired up. 

 

Do you have your boat manual and what does it say? Or more particularly, can you post some photos of any wiring diagrams in the manual perhaps? Then some of the clever bods on here will be able to guide you with diagnosis. 

Edited December 9, 2024 by MtB

[hoopdriver]

Thanks for your reply. It’s a pretty sad state of affairs if I end up being the expert. I have looked through everything though and have taken the additional step of seeking the advice of responsible adults and so far no one has come up with anything that actually works.

 

I really did expect the new BMS would sort it, and thought that perhaps the problem with solar was a matter of having to perhaps reprogram to controller. But now the new BMS only allows a small bit of charging and cuts out. Clearly something is not right. I’m just grasping at straws now …

[nicknorman]

You have quite a high-tech system, which means that there are more possibilities to consider than a more basic system. So we will need much more detail! Taking it a step at a time...

Firstly the BMS has LEDs to indicate alternator enable status. Is the green LED showing (alternator enabled)? What is the Remote on/off function set to do (look in the Victron App). Is the remote link wire in place (just to the right of the alternator LEDs)?

 

I would say as a general point that as far as I can see you don't seem to have any means to limit the output from the alternator, so when the engine is running the alternator will be producing maximum output continuously, and thus it will get extremely hot which will substantially shorten its life. So, even though you mentioned you had the alternator checked, I would still be suspicious that it is an alternator fault. 9 months life for an over-worked and overheated alternator sounds about right! Can you measure the voltage on the alternator input terminal to the BMS when the engine is running?

Edited December 9, 2024 by nicknorman

[hoopdriver]

1 minute ago, nicknorman said:

You have quite a high-tech system, which means that there are more possibilities to consider than a more basic system. So we will need much more detail! Taking it a step at a time...

Firstly the BMS has LEDs to indicate alternator enable status. Is the green LED showing (alternator enabled)? What is the Remote on/off function set to do (look in the Victron App). Is the remote link wire in place (just to the right of the alternator LEDs)?

Thank you for your response. Yes, the green light for alternator enabled status glows brightly on the new BMS (it did not in the old one) The electrician who originally set up the system has been out four times and gone over everything he could think of re: the app etc 

[nicknorman]

39 minutes ago, hoopdriver said:

Thank you for your response. Yes, the green light for alternator enabled status glows brightly on the new BMS (it did not in the old one) The electrician who originally set up the system has been out four times and gone over everything he could think of re: the app etc 

See my edit, can you put a multimeter probe on the alternator input terminal on the BMS (with the other meter probe to 0v somewhere) and measure the voltage on it with the engine running? I would expect to see perhaps 13.6v or so. If it is close to the resting battery voltage (around 13.2v perhaps) then it points to an alternator problem, or something in the wiring from the alternator to the BMS such as an isolator switch.

 

Scrub what I said earlier about no current limiting for the alternator, in fact the BMS does that. But I would still check that a suitable charging voltage is reaching the BMS alternator input terminal when the engine is running.

 

What size fuse is installed at the alternator input? Has it been checked for good connection (since the fuse doubles as a shunt, and a poor connection would shut the charge current right down).

Edited December 9, 2024 by nicknorman

[hoopdriver]

Thanks - I have not personally done this, but a civil engineer friend of mine did and found the alternator was healthy and the charge was getting to the BMS. I realise that it does not help my cause to be so ignorant of these thing - although I have had something of a crash course lately - but I have had qualified people looking at it and trying all the basic things. 
 

when it first happened the electrician who installed the system went over everything and diagnosed a dry solder or similar in the BMS. It made sense. What has happened since is just weird 

[nicknorman]

Ah, qualified people! The problem with narrowboats is that there is no qualification in narrowboat electrics, especially high tech systems like yours! I am not saying your friend didn't know what he was doing, but there are a lot of cowboys out there! You can either pay some "qualified professional" lots of money and hope they have some idea what they are doing, or you can work through the system yourself with a multimeter and most likely, with a bit of patience and guidance, find the problem. One BMS going wonky might be conceivable, but not 2! If you are going to get a professional, make sure they are familiar with Lithium batteries and Victron systems. Most "marine electricians" will not be.

Anyway just so you understand, the fuse on the BMS alternator input terminal also acts as a shunt. In other words, it is used to measure the current coming from the alternator. It does this by measuring the voltage dropped across the fuse which is proportional to the current, and which will be very small probably around 0.01 volts. If the fuse is a bit "high resistance" or the connections are even slightly dirty, the voltage drop will be much greater for a given current and the BMS will read this as a high current flowing, and thus throttle the charge current right down.

 

So armed with a multimeter you can check for yourself that the alternator is putting out a good voltage when the engine is running, and you can remove the fuse and fit a new one of the same rating, checking that the connections are clean and bright and tight.

 

I am to some extent clutching at straws in the dark but we have to start somewhere!

Edited December 9, 2024 by nicknorman

[hoopdriver]

Thank you for your thoughtful reply. Yes, I know there are lots of cowboys out there. The qualified person I was thinking of was the electrician who installed it in the first place, it worked beautifully for nine months of continuous cruising so he must have set it up properly. He has checked the fuses and tried swapping them out - but no change in anything.

 

My friend the civil engineer just checked the voltages with s multimeter.

 

I appreciate your advice and ideas . 

[jonathanA]

Not withstanding Nicks advice, I'm wondering if there if there is a configuration issue somewhere. Lots of things that you can tweak or enable/disable in Victron kit. Probably worth working through all the settings menus on the Victron kit and seeing if there is anything that might be causing the problem. Although you would have hoped that the guy who set it up would have done that, but perhaps has just checked the things HE changes.... 

[MtB]

42 minutes ago, hoopdriver said:

My friend the civil engineer just checked the voltages with s multimeter.

 

So it sounds as though you have confidence in him. May I suggest you show him this thread and ask him to carry out the checks Nick has suggested, then you post the results here?

 

 

[hoopdriver]

Thank you. I was wondering that too. I have reset the BMS back to the default settings in case the guy changed anything that might have caused an issue but it didn’t make any difference 

 

Ive gone over the app and don’t see anything odd 

[nb Innisfree]

It could be the alternator playing up as it reaches a certain temp, changing the it for a new one, or one that works OK would be my next step, expensive maybe but it will eliminate a poss prob, if it doesn't work you have a spare.

Also I would look at introducing some extra cooling for the alternator. 

[hoopdriver]

Thank you. Pardon my ignorance- what kind of extra cooling do you mean and how would one add it? 

[David Mack]

1 hour ago, nicknorman said:

Anyway just so you understand, the fuse on the BMS alternator input terminal also acts as a shunt. In other words, it is used to measure the current coming from the alternator. It does this by measuring the voltage dropped across the fuse which is proportional to the current, and which will be very small probably around 0.01 volts. If the fuse is a bit "high resistance" or the connections are even slightly dirty, the voltage drop will be much greater for a given current and the BMS will read this as a high current flowing, and thus throttle the charge current right down.

This sounds like a recipe for unreliability, since fuse connections are well-known as sources of extra resistance. Why not just fit a proper shunt resistor and fuse in series?

[nicknorman]

40 minutes ago, David Mack said:

This sounds like a recipe for unreliability, since fuse connections are well-known as sources of extra resistance. Why not just fit a proper shunt resistor and fuse in series?

You'd have to ask Victron! But I suppose it is a way to set the current limit without having to set a current limit - a smaller fuse will be higher resistance than a larger fuse, so the system just has to detect a specific voltage drop to know the current as a % of the fuse in use. In other words, the rating of the fuse you use sets the max current ( at some % of the fuse used). It is quite a clever idea ... apart from the liklihood of bad/corroded connections!

Edited December 9, 2024 by nicknorman

[PeterF]

I know a bunch of stuff has gone before this, I have read it but not taken it all in.

 

Nick said to measure from ground to the alternator input terminal on the BMS. You should also measure from ground to the alternator output terminal on the alternator itself to make sure you do not have a problem with the alternator cable. You should also measure from ground to the other side of the alternator fuse, this should be fractionally lower. Then you should measure from ground to the battery terminal on the BMS and from ground the the battery positive post on the battery, both of which should be marginally lower again. If no charge current is flowing then they will be very close. If the BMS is restricting charge there will be a higher voltage drop from terminal to terminal. If you have a high resistance in the battery lead then you will see a high drop there, but I do not think this is the case as the alternator would climb to 14.2V before being dialled back by the BMS.

 

The app has only 2 settings that should affect performance, the charged voltage which for Victron Smart Lithium is 14.2V and the value of the alternator fuse on the BMS.

 

Other things to check are connect to the battery via the app and check the battery temperature is above 5degC and it says it is balanced, if not what are the highest and lowest cell values. As the green light on the alternator is lit this means the BMS wants to let current through which is a sign that the battery to BMS comms cables are OK.You

 

I agree with an earlier comment that the alternator may not be working properly and not generating a high enough voltage. If the BMS was limiting the current for some odd reason then the alternator would be well over 14.0V.

[hoopdriver]

5 minutes ago, PeterF said:

I know a bunch of stuff has gone before this, I have read it but not taken it all in.

 

Nick said to measure from ground to the alternator input terminal on the BMS. You should also measure from ground to the alternator output terminal on the alternator itself to make sure you do not have a problem with the alternator cable. You should also measure from ground to the other side of the alternator fuse, this should be fractionally lower. Then you should measure from ground to the battery terminal on the BMS and from ground the the battery positive post on the battery, both of which should be marginally lower again. If no charge current is flowing then they will be very close. If the BMS is restricting charge there will be a higher voltage drop from terminal to terminal. If you have a high resistance in the battery lead then you will see a high drop there, but I do not think this is the case as the alternator would climb to 14.2V before being dialled back by the BMS.

 

The app has only 2 settings that should affect performance, the charged voltage which for Victron Smart Lithium is 14.2V and the value of the alternator fuse on the BMS.

 

Other things to check are connect to the battery via the app and check the battery temperature is above 5degC and it says it is balanced, if not what are the highest and lowest cell values. As the green light on the alternator is lit this means the BMS wants to let current through which is a sign that the battery to BMS comms cables are OK.You

 

I agree with an earlier comment that the alternator may not be working properly and not generating a high enough voltage. If the BMS was limiting the current for some odd reason then the alternator would be well over 14.0V.

Thank you for this. I’ll check these things with the alternator.

 

the cells are all balanced and always have been, and the temp has never dropped to 5°C . 

 

Both the settings on the app that you mention are correct.

 

 

[nb Innisfree]

10 hours ago, hoopdriver said:

Thank you. Pardon my ignorance- what kind of extra cooling do you mean and how would one add it? 

Some sort of fan cooling, bringing cool outside air, would take a bit of inventiveness to achieve. 

[MtB]

16 minutes ago, nb Innisfree said:

Some sort of fan cooling, bringing cool outside air, would take a bit of inventiveness to achieve. 

 

I'd have thought a commercial LFP installation such as the OP has would have alternator temperature monitoring and protection anyway.

 

In fact with God turning off the solar recently I'm beginning to wonder if this charging system is actually working correctly, and all the extra charging load caused by the alternator running so much longer is the source of a genuine overheat, and the Victron gubbins is turning it off so it can cool down. 

[hoopdriver]

Well, it didn’t do anything like this last winter and charging stops after only about ten minutes, although the app says anywhere between 36% and 40% of the charge is still going through to the battery.

 

The battery temperature itself has remained steadily in the 11°C to 17°C range throughout. 

Edited December 10, 2024 by hoopdriver

[PeterF]

9 hours ago, MtB said:

 

I'd have thought a commercial LFP installation such as the OP has would have alternator temperature monitoring and protection anyway.

 

In fact with God turning off the solar recently I'm beginning to wonder if this charging system is actually working correctly, and all the extra charging load caused by the alternator running so much longer is the source of a genuine overheat, and the Victron gubbins is turning it off so it can cool down. 

This version of the Victron BMS includes a current limiting circuit so you choose a fuse (which acts as a shunt) to limit the alternator delivery. It does depend on the installer putting in the correct fuse, i.e. for example Beta 175A alternator, fit a 120A fuse and the BMS limits the current to 100A.

 

@hoopdriver you said you had a 95A alternator, what fuse do you have in the alternator slot in the BMS and have you ever checked the alternator temperature.

[hoopdriver]

As per the electrician who installed the system, I’ve a 100A fuse ticked in the selection box.

 

how does one check the alternator temp?

[nicknorman]

11 minutes ago, hoopdriver said:

As per the electrician who installed the system, I’ve a 100A fuse ticked in the selection box.

 

how does one check the alternator temp?

100A fuse setting means the current is limited to 90A. This is nearly the maximum output from the alternator. As I mentioned before, alternators fitted to boats are automotive (vehicle) types which are not designed to give full output for prolonged periods. If you run that alternator at 90A it will get extrememly  hot (well over 100C, so don't touch it!) and its life will be short. This is why I suspect there is actually an alternator issue.

 

The Victron BMS manual says "Choosing the right fuse will prevent overheating of the alternator and/or DC cabling." I suggest the right fuse to prevent overheating of the alternator is not the one that corresponds to the alternator's maximum output. Here, your installation electrician has made a major mistake.  Once your present issue is resolved I suggest fitting a fuse and adjusting the setting to a rating around 2/3rds of maximum output. So in your case that would be the 80A fuse and setting, which limits the alternator current to 60A. Then the alternator will last for many years.

Edited December 10, 2024 by nicknorman

[hoopdriver]

So assuming the issue is with the alternator, are you saying I would need to replace the alternator or just the fuse - or both?