Charging problem

[trebby91]

Hi, All.

Can an alternator loose power?

The reason I ask is I have a battery management system fitted with a 160Amp and a 80Amp connected in parallel, new battery bank 600Ah I was getting a 197amps charge after the batteries were down to 85% now for some reason I only get 80amps and the charge does not go up if I switch on the inverter using a 850 watt drill. The charge in the batteries goes down when the drill is running, never did before. I have a Victron BMV battery monitor so I can see the condition of the batteries.

Regards, Brian.

[bottle]

Simple answer yes.

 

Something to do with diodes and things, hopefully the experts will be along soon.

[nicknorman]

Hi, All.

Can an alternator loose power?

The reason I ask is I have a battery management system fitted with a 160Amp and a 80Amp connected in parallel, new battery bank 600Ah I was getting a 197amps charge after the batteries were down to 85% now for some reason I only get 80amps and the charge does not go up if I switch on the inverter using a 850 watt drill. The charge in the batteries goes down when the drill is running, never did before. I have a Victron BMV battery monitor so I can see the condition of the batteries.

Regards, Brian.

 

It's noteworthy that you have a 80A alternator and are only getting 80A. This perhaps suggests that the 160A alternator is not being connected in parallel. So it could be a problem with the management system but of course it could also be a problem with the alternator. Normally with these things there is an alternator warning light for each alternator. Can you confirm that both the warning lights illuminate when you turn on the ignition but before starting the engine, and that both the warning lights go out after starting? Is there any abnormal behaviour such as a faintly glowing warning light after start?

Edited August 26, 2016 by nicknorman

[Paul C]

Hi, All.

Can an alternator loose power?

The reason I ask is I have a battery management system fitted with a 160Amp and a 80Amp connected in parallel, new battery bank 600Ah I was getting a 197amps charge after the batteries were down to 85% now for some reason I only get 80amps and the charge does not go up if I switch on the inverter using a 850 watt drill. The charge in the batteries goes down when the drill is running, never did before. I have a Victron BMV battery monitor so I can see the condition of the batteries.

Regards, Brian.

 

Why would the charge go up? Think about where the shunt is connected on the BMV battery monitor........

[nicknorman]

 

Why would the charge go up? Think about where the shunt is connected on the BMV battery monitor........

 

The charge as in State of Charge I think. I think what he is saying is that with partially charged batteries and the drill running, before the SoC would be going up and now it is going down.

[Tony Brooks]

Perhaps Trebby had better tell us what this "battery management system" actually consists of

I have seen amp hour counters described as such and also advanced regulators, then there is the Sterling A to B. Once we know that we have a better chance of advising further tests etc.

 

At present I suspect an A to B or amp hour counter. I have a few reports of A to Bs going faulty.

[MtB]

Sounds like a loose vee belt to me!

 

(Or a broken one if each alternator has separate belts.)

[OldGoat]

Running twin alternators wired in parallel is not a good idea (I was told). It's better to separate them with diodes - and that means remote sensing - but I didn't get my head around that. Nevertheless that's what Adverc told me. They supply some heavy kit for ambulances and the like, so I humbly accept they know a whole lot more than I....

 

Secondly, banging 200 amps into a 600 amp battery bank is NOT A GOOD IDEA (unless they are proper heavy duty traction batteries).

Leisure, semi traction batteries are designed to be charged slowly - well, slower than your discharge rate - or they won't last very long.

A simple analogy is comparing a filling a bucket from a tap (slow) versus doing the same from a fire hydrant at full chat (think about that one)....

 

You'll ignore me - but there you go - but there's sense in my argument...

[trebby91]

Hi, nicknorman.

 

Both ignition lights are working correctly, on before start off when running.

I have checked the belts and run both alternators one at a time, never getting more than 80amps when on boost. The remote read out on the Sterling system always use to show a rise in output when the inverter was on now it does not.

Regards, Brian.

[Paul C]

 

Sterling system

 

 

 

What Sterling system? You mentioned a Victron BMV in the first post.

Hi, nicknorman.

 

Both ignition lights are working correctly, on before start off when running.

I have checked the belts and run both alternators one at a time, never getting more than 80amps when on boost. The remote read out on the Sterling system always use to show a rise in output when the inverter was on now it does not.

Regards, Brian.

I am going to take a wild stab in the dark and assume that the Victron BMV shunt (the bit that measures current) is connected so it monitors what goes in and out of the battery - NOT the same as what comes out of the alternator(s) (except in the circumstance when there is no load).

 

Thus, its reasonable to assume that the batteries themselves are limiting the amount of current into them at ~80A, and any additional loads at the time (like an inverter with a large load) is supplied with this because the alternators are able to provide >80A as needs be.

 

I bet if you thoroughly abuse the batteries and flatten them to really low, then turn the engine on and rev it up, you'd see greater than 80A put into them for a short while.

Edited August 26, 2016 by Paul C

[nicknorman]

Running twin alternators wired in parallel is not a good idea (I was told). It's better to separate them with diodes - and that means remote sensing - but I didn't get my head around that.

 

No, this is not true.

 

 

Secondly, banging 200 amps into a 600 amp battery bank is NOT A GOOD IDEA (unless they are proper heavy duty traction batteries).

Leisure, semi traction batteries are designed to be charged slowly - well, slower than your discharge rate - or they won't last very long.

 

Well we put 175A into a 450A bank. Are we very naughty too? But seriously, yes it is not ideal in terms of battery life, but that is not the only factor. I would rather replace my batteries a little prematurely than have to wait for hours with the engine or genny droning away at 45A. So I would say there is nothing seriously wrong with putting up to 200A into a 600AH battery bank.

Hi, nicknorman.

 

Both ignition lights are working correctly, on before start off when running.

I have checked the belts and run both alternators one at a time, never getting more than 80amps when on boost. The remote read out on the Sterling system always use to show a rise in output when the inverter was on now it does not.

Regards, Brian.

Ok well I think you will need to give us more information about the "sterling system". Just curious, how did you run one alternator at a time? Did you slaken the belt on one at a time?

[WotEver]

It sounds to me that the big alternator is no longer connected, or dead.

 

But we really need to know more about this battery management system. What model is it?

[Sea Dog]

You know, for the amount of time the additional alternator is contributing to the amount your domestic bank will accept when you've already got a 160 amp alternator which could be dedicated to it, I don't think I'd have ever bothered with linking the two. I'd say it'll only be a matter if minutes before your domestic bank will be accepting anything close to more than 160 amps, but you have a Victron BM so you can see for yourself what your actual current draw is when first staring on a morning . Certainly your engine start battery alternator doesn't need any help, but I don't think a 160 amp domestic one does either, even with a 600Ah domestic bank. I'd be tempted to separate the two by taking the Sterling unit out of circuit and see how you get on. Just my five pennorth.

[Paul C]

It sounds to me that the big alternator is no longer connected, or dead.

 

But we really need to know more about this battery management system. What model is it?

 

If the batteries have 80A input to them, while the inverter is running an 850W load, then one or both alternators must be developing more than 80A

[WotEver]

 

If the batteries have 80A input to them, while the inverter is running an 850W load, then one or both alternators must be developing more than 80A

From the first post I don't believe your assumption about where the shunt is connected is correct.

 

The charge as in State of Charge I think. I think what he is saying is that with partially charged batteries and the drill running, before the SoC would be going up and now it is going down.

I think he means charge current.

[trebby91]

Sorry but I think some people need to read the post again!

Everything is connected as it should be.The victron BMV 600 is only a monitor, the shunt is connected as it should be the monitor is confirming what the read out on the Sterling Battery Management remote is only 80amps Max going into the batteries.

Nothing as been added to the system or taken away, no modifications have been made, its not been kicked!

In short I am not getting the charge I got last week.

Regards, Barry

[Paul C]

Sorry but I think some people need to read the post again!

Everything is connected as it should be.The victron BMV 600 is only a monitor, the shunt is connected as it should be the monitor is confirming what the read out on the Sterling Battery Management remote is only 80amps Max going into the batteries.

Nothing as been added to the system or taken away, no modifications have been made, its not been kicked!

In short I am not getting the charge I got last week.

Regards, Barry

 

Can you clarify why you have a Victron BMV600 yet are quoting readings from a Sterling Battery Management thing?

[Sea Dog]

Sorry but I think some people need to read the post again!

Well I thought, given the reports you'd made re belts and indications, we were leaning towards a Sterling unit fault hence my suggestion you take it out of the circuit and go back to a single alternator for each of the domestic and engine banks. This splitting of the systems will at least help to identify where your problem lies - most likely either an alternator or the unit linking them. If it turns out to be an alternator, the solution is likely to be a straight forward replacement. If it turns out to be the Sterling device, you might consider running without it. If you think that's unhelpful, I'm out.

 

Edited to change an autocorrect of 're' to 'redundant' back again!

Edited August 26, 2016 by Sea Dog

[WotEver]

Okay, so you did mean charge current as indicated by the unnamed Sterling unit as I suspected.

 

I think it's broken.

 

I also think you don't need it. Wire it as Sea Dog suggests.

 

Tony

 

An alternative prognosis is as I've already suggested - the 160A alternator is dead/faulty/wire fallen off.

[arcsyst]

There seems to be some conflicting information/confusion of terms.

 

Firstly a lead acid battery will self limit its charge to something close the amount of charge used, e.g. if you've used 80Ah then after a short while the charge current will be 80A or thereabouts.

 

Secondly the reason most batteries die is sulphation which is due to inadequate charging, so better to 'abuse' your batteries with high charge rate than leave them not fully charged.

 

Thirdly alternators weren't designed to charge massive banks of domestic batteries, they were designed for cars to replace the tiny amount of charge used to start an engine and then provide power to run everything electrical thereafter, without help it will struggle to fully charge a well used domestic bank in a reasonable time. That's where the A to B device helps by boosting the 13.8v (more likely 12.5 under load) to around 14.5 to charge the batteries in a shorter time.

 

When calculating max charge a rough rule of thumb is thus:

 

Alternator rated current x 0.8

If using an A to B giving a 20% voltage boost including losses. x 0.7

Unless you have seriously large cables joining all this up x 0.95 for cable losses

 

Putting all that together you have a max available current of about 55% of the rated alternator output, subtract your electrical load from this and there what's left to charge the batteries.

 

As regards diagnosing your particular problem I recommend investing in a cheap DC clamp ammeter for about £30 that you will use time and time again and is the best way to find this and similar faults.

 

Measuring Ah in and Ah out is a really good way of assessing battery state as a lead acid battery is close to 100% efficient if you measure this way unless overcharged, it is not 100% efficient if you measure Wh in/out.

[Tony Brooks]

Sorry but I think some people need to read the post again!

Everything is connected as it should be.The victron BMV 600 is only a monitor, the shunt is connected as it should be the monitor is confirming what the read out on the Sterling Battery Management remote is only 80amps Max going into the batteries.

Nothing as been added to the system or taken away, no modifications have been made, its not been kicked!

In short I am not getting the charge I got last week.

Regards, Barry

 

Well I think that you should read all the posts and reply to them when requested.

 

You still have not identified exactly which Sterling battery "management" system you have. One of the simple advanced controller models can be simply disconnected by removing one wire so in that way it is easy to rule them out. Their A to B system needs rather more work to isolate.

 

As you do not mention any form of charge splitting, do not say you have a manager on both alternators, and imply they are both connected to the batteries I would suggest that you have an A to B system and as I said I have known the occasional one go faulty.

 

If you only get 80 amps revving on first start I feel the most likely thing is a failed 160 amp alternator but as the warning lamp goes out it could just as well be a wiring problem with the 160 amp alternator or a failed A to B (assuming that is what you have). However it could just as well be a slipping belt on the larger alternator. WE need to guide you with the diagnostic steps you nee to follow and we can not do that until you tell us what we are dealing with.

 

Oh, by the way, far too often in the past simple assertions like yours about everything being connected a it should be have proven wrong once the we had wrung the correct information out of the OP. I doubt anyone can give you a definitive diagnosis based on what you have written so far, hence the variety of possibilities.

 

 

 

 

[WotEver]

... That's where the A to B device helps by boosting the 13.8v (more likely 12.5 under load) to around 14.5 to charge the batteries in a shorter time.

 

When calculating max charge a rough rule of thumb is thus:

 

Alternator rated current x 0.8

If using an A to B giving a 20% voltage boost including losses. x 0.7

Unless you have seriously large cables joining all this up x 0.95 for cable losses

 

Putting all that together you have a max available current of about 55% of the rated alternator output...

Sorry, but the above is total and utter tosh.

 

Firstly, any modern alternator (built within the last 30 years or so) will have an output of around 14.4V or higher. Any battery sensed alternator can be upped by a further 0.7V by the simple expedient of adding a diode into the sense lead.

 

Secondly, if an alternator is correctly pulleyed (and not over-hot) it will give its full output over a very wide range of revs. Just look at any alternator spec sheet to confirm.

 

Lastly, alternators should be cabled with suitable cable commensurate with the size of the alternator. 90mm² in the case of the 160A alt would drop less than 0.01V over a 250mm length.

 

Tony

[WotEver]

 

Well I think that you should read all the posts and reply to them when requested.

 

You still have not identified exactly which Sterling battery "management" system you have...

 

Well said Tony.

 

Most of us have been saying from the start that either the mysterious unnamed Sterling kit is faulty, or the 160A alternator is faulty (less likely as the charging light goes out) or there is a wiring fault.

 

We can't have 'everything is as it was' yet a different result this week than last week. Something is broken.

 

Tony

[MtB]

 

Oh, by the way, far too often in the past simple assertions like yours about everything being connected a it should be have proven wrong once the we had wrung the correct information out of the OP. I doubt anyone can give you a definitive diagnosis based on what you have written so far, hence the variety of possibilities.

 

It's sometimes worse than that. As a fault-tracing professional myself I notice people sometimes avoid answering questions because in their heart of hearts they know the questions are probing in the right direction, a direction they are uncomfortable with and have decided (often for emotional reasons) cannot be the problem.

 

So they don't want to be asked about it. I think this might be happening here. We are asking questions the OP doesn't want asked.

[Tony Brooks]

I think anyone who gets involved with the public and doing diagnostics for them has come across that but it seems to me that such "blindness" is far more prevalent on internet based resources and if they do not like the answer are just as likely to go and ask elsewhere or, as in this case get very mildly abusive to those who are trying to help.

 

I just wish people who ask questions would realise that they will probably need to enter a dialogue before the right answer is arrived at, just as they would when being questioned about a fault on (say ) their car at a garage.

 

Initially it is unfair to expect every questioner to know what is and is not relevant to the question but its just plain rude not to answer questions raised or if you do not understand them ask for more guidance.