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Martinb

Sr3 charging

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Hi all.  We have a air cooled SR 3 with one starter and 3 new 130ah leisure.  We are noticing that despite cruising for 5-6 hours we are not getting above 12.6 at most.  We are running a 2000w inverter and 240v fridge. We have a single alternator charging the batteries.  Even if we turn off the inverter when cruising it doesnt get any higher.  Any ideas why we are not getting a full charge as we are finding we can barely last 24hours with not alot running.

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Do you mean that having been charged for that length of time that the battery voltage is no better than12.6 volts when you stop running the engine?

 

Or do you mean that with the engine running and the alternator charging that the charging voltage doesn't exceed 12.6 volts?

If the latter, there is clearly a problem, because any alternator that is not delivering at least 14 volts into the batteries is not likely to be putting much charge in.

How are you measuring it, and are you confident of the accuracy of the meter in use?

 

Do you have any way of measuring the charging current, (i.e. amps)?

If not a clamp ammeter that will go around the charging cable without needing to modify any electrics and is a very useful diagnostic tool.  If you are buying one it must be specified as being able to measure DC current.  Not all can, and a cheaper one that only does AC current would be no use for this task.

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You may have an alternator but at 12.6v it is not charging the batteries much if at all.

 

Check all the wiring between alternator and batteries, including the negative ground wiring. If there are no bad connections, replace the alternator or get it tested and rebuilt.

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21 minutes ago, alan_fincher said:

Do you mean that having been charged for that length of time that the battery voltage is no better than12.6 volts when you stop running the engine?

 

Or do you mean that with the engine running and the alternator charging that the charging voltage doesn't exceed 12.6 volts?

If the latter, there is clearly a problem, because any alternator that is not delivering at least 14 volts into the batteries is not likely to be putting much charge in.

How are you measuring it, and are you confident of the accuracy of the meter in use?

 

Do you have any way of measuring the charging current, (i.e. amps)?

If not a clamp ammeter that will go around the charging cable without needing to modify any electrics and is a very useful diagnostic tool.  If you are buying one it must be specified as being able to measure DC current.  Not all can, and a cheaper one that only does AC current would be no use for this task.

The 12.6 is seen after switching the engine off and on our smartguage.  Our amp meter on the panel seems to be showing around 15, its an analogue dial.

18 minutes ago, Boater Sam said:

You may have an alternator but at 12.6v it is not charging the batteries much if at all.

 

Check all the wiring between alternator and batteries, including the negative ground wiring. If there are no bad connections, replace the alternator or get it tested and rebuilt.

Sorry boater sam the 12.6 is not the charging but the charge voltage after the engine switches off.

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7 minutes ago, alan_fincher said:

So what is the indicated voltage when you are charging?

The amp meter shows about 15, the smartguage shows voltage at 13 but will drop when the engine is off

Edited by Martinb

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27 minutes ago, Martinb said:

The amp meter shows about 15, the smartguage shows voltage at 13 but will drop when the engine is off

That makes no sense to me.

If you mean 13.0 amps on the SmartGauge whist charging, that's not enough volts to put any serious charge in.  I'm highly dubious that any standard alternator on an SR3 could possibly put 15 amps into the battery bank at only 13 volt charge.  Even at 14 volts, I'm not sure I'd expect that much.

Something isn't giving a true reading, I feel.

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21 minutes ago, alan_fincher said:

That makes no sense to me.

If you mean 13.0 amps on the SmartGauge whist charging, that's not enough volts to put any serious charge in.  I'm highly dubious that any standard alternator on an SR3 could possibly put 15 amps into the battery bank at only 13 volt charge.  Even at 14 volts, I'm not sure I'd expect that much.

Something isn't giving a true reading, I feel.

Sorry my limited knowledge, the smart guage shows between 12.8 and 13volts when the engine is running, the amp meter on the control panel is showing around 15amps.    Does it sound by what I have said our alternator is not up for the job, it was a replacement from RCR when our old one went.  Sadly this was soob after we bought the boat so cant comment if the old one was any better.   There is a QR code on the alternator so will see if i can get the specs for it once the rain dies off a little 

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Is five hours running really enough to recharge three batteries?  Even with that bank of batteries, running a 240v fridge on an inverter for the 19 hours you aren't running the engine would, I'd have thought, run through power at a fair old rate.  I know even just running the lights used to wipe mine out pretty quick during the long nights of winter.

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1 minute ago, Arthur Marshall said:

Is five hours running really enough to recharge three batteries?  Even with that bank of batteries, running a 240v fridge on an inverter for the 19 hours you aren't running the engine would, I'd have thought, run through power at a fair old rate.  I know even just running the lights used to wipe mine out pretty quick during the long nights of winter.

True, friends on another boat can run there boat for 2 days with no charge and have all manner of electrial items on board, microwave, large tv coffee machine.   We can only dream of such luxuries 😴

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10 minutes ago, Tony Brooks said:

and isn't the SR alternator cam shaft driven. If so what is the pulley ratio and how fast are you running the engine.

Pass sorry my technical knowledge is limited

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23 minutes ago, Martinb said:

Sorry my limited knowledge, the smart guage shows between 12.8 and 13volts when the engine is running, the amp meter on the control panel is showing around 15amps.    Does it sound by what I have said our alternator is not up for the job, it was a replacement from RCR when our old one went.  Sadly this was soob after we bought the boat so cant comment if the old one was any better.   There is a QR code on the alternator so will see if i can get the specs for it once the rain dies off a little 

Can you clarify what type of meter is being used to measure the current?

This type of thing, perhaps?

52mm-2-Inch-DC-12V-60-0-60-AMP-Ammeter.j

 

Are you saying that it records around 15 amps from the point you are starting the day with quite discharged batteries right through until you stop the engine some hours later?  That would not be a typical behaviour - normally you will start with a high current, that falls of considerably over time.

 

If not, what does it read at the start of the charging process, and what has this fallen to just before you tart the engine?

I still don't think you can actually get 15A out of a typical alternator on a Lister SR, if it is genuinely putting out no more than 13 volts.

If you were getting 1A, and that reading is genuine, it hardly points to a knackered alternator to me.

 

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2 minutes ago, alan_fincher said:

Can you clarify what type of meter is being used to measure the current?

This type of thing, perhaps?

52mm-2-Inch-DC-12V-60-0-60-AMP-Ammeter.j

 

Are you saying that it records around 15 amps from the point you are starting the day with quite discharged batteries right through until you stop the engine some hours later?  That would not be a typical behaviour - normally you will start with a high current, that falls of considerably over time.

 

If not, what does it read at the start of the charging process, and what has this fallen to just before you tart the engine?

I still don't think you can actually get 15A out of a typical alternator on a Lister SR, if it is genuinely putting out no more than 13 volts.

If you were getting 1A, and that reading is genuine, it hardly points to a knackered alternator to me.

 

Yes we have a meter like this.  It never drops throughtout a journey.  The engine has been running now for a couple of hours and its around 13 at the moment, not the greatest dial to get a accurate reading.  They only time we ever see it any lower is when we have gone from our marina on hook up and then out with fully charged batteries.   Normally for a odd weekend we dont notice it but we are out on the thames currently and have seen a difference in what power we have despite 5+hours cruising a day.

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OK, lets see what others say, but this just doesn't sound right to me.

I simply can't equate the charge current you are getting with such a low indicated charging voltage.

 

If you have a SmartGauge what percentage state of charge is it showing when you start the engine up, and what has this risen to when you shut the engine down "5 hours plus" hours later?

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2 minutes ago, alan_fincher said:

OK, lets see what others say, but this just doesn't sound right to me.

I simply can't equate the charge current you are getting with such a low indicated charging voltage.

 

If you have a SmartGauge what percentage state of charge is it showing when you start the engine up, and what has this risen to when you shut the engine down "5 hours plus" hours later?

The smartguage is showing 61% charged and the volt shows 12.8 with engine running

Just now, Martinb said:

The smartguage is showing 61% charged and the volt shows 12.8 with engine running

I think we perhaps need someone with electrical knowledge to take a good look and see if there is anything that doesnt look right or isnt working as it should.   We have limited knowledge of these things so are a little blind to all this.

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Just now, Martinb said:

The smartguage is showing 61% charged and the volt shows 12.8 with engine running

Yes, but what percentage does it show at the tart and end of each days charging process?  That would allow us to see if there is any correlation between that and the number of amps you say it is charging at.

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6 minutes ago, alan_fincher said:

Yes, but what percentage does it show at the tart and end of each days charging process?  That would allow us to see if there is any correlation between that and the number of amps you say it is charging at.

We never see it go.above around 63%

Just now, Martinb said:

We never see it go.above around 63%

We normally start between 55 and 60%

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The alternator drive pulley on the camshaft needs to be the large diameter pulley 9,10 or 12'' diameter to get a decent charge rate at reasonabe rpm. The ordinary standard pulley as fitted to industrial SR's and maybe yours is only about 6 or 7'' dimeter, which means that the engine has to be revving very high to get a decent charge. Measure the diameter of that pulley. If its a large diameter one it should be obvious to the eye without measuring.

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7 minutes ago, bizzard said:

The alternator drive pulley on the camshaft needs to be the large diameter pulley 9,10 or 12'' diameter to get a decent charge rate at reasonabe rpm. The ordinary standard pulley as fitted to industrial SR's and maybe yours is only about 6 or 7'' dimeter, which means that the engine has to be revving very high to get a decent charge. Measure the diameter of that pulley. If its a large diameter one it should be obvious to the eye without measuring.

I do recall this being mentioned before so will check,

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1 hour ago, alan_fincher said:

OK, lets see what others say, but this just doesn't sound right to me.

I simply can't equate the charge current you are getting with such a low indicated charging voltage.

 

If you have a SmartGauge what percentage state of charge is it showing when you start the engine up, and what has this risen to when you shut the engine down "5 hours plus" hours later?

I agree it sounds odd but just maybe a low alternator speed into well discharged batteries may allow it to happen. I think we need an answer to the pulley ratio question before we go any further.

 

 

1 hour ago, Martinb said:

The smartguage is showing 61% charged and the volt shows 12.8 with engine running

I think we perhaps need someone with electrical knowledge to take a good look and see if there is anything that doesnt look right or isnt working as it should.   We have limited knowledge of these things so are a little blind to all this.

Is the boat in Hampshire? If so where, on the Basingstoke? After the weekend I could drive over Odiham way to have a look at it with you (FOC).

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I've got a meter like that on mine but the electrician told me it didn't measure the amount that the alternator was putting in but, I think, what the leisure battery was putting out. It goes up a bit when the engine kicks off, but very shortly reverts to around 12.something. He said it was basically pointless. 

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1 hour ago, Arthur Marshall said:

I've got a meter like that on mine but the electrician told me it didn't measure the amount that the alternator was putting in but, I think, what the leisure battery was putting out. It goes up a bit when the engine kicks off, but very shortly reverts to around 12.something. He said it was basically pointless. 

 

I think someone is at cross purposes with that. It will depend upon where in the circuit that type of meter is wired but if it is in the same place as a shunt would be then it will show domestic battery discharge and domestic battery charge amps. The wiring instructions sometimes say put it in the main alternator charging lead but then it should never sow a negative reading and only show the total alternator output. If, for some reason it is in the main supply to the domestic busbar/fuse board then it will only show  the amount of discharge unless you have a battery charger that is connected to the busbar/distribution board. IN that case it will show the discharge and whatever the said charger is putting into the batteries.

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7 minutes ago, Tony Brooks said:

 

I think someone is at cross purposes with that. 

You're almost certainly right. It was said by the guy who rewired me in such a way I had to do it all again four years later. Another of my series of boat experts who have done stuff that cost me twice as much later to get put right... 

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On 14/08/2019 at 14:47, Tony Brooks said:

I agree it sounds odd but just maybe a low alternator speed into well discharged batteries may allow it to happen. I think we need an answer to the pulley ratio question before we go any further.

 

 

Is the boat in Hampshire? If so where, on the Basingstoke? After the weekend I could drive over Odiham way to have a look at it with you (FOC).

Hi Tony, we are on the wey, due to be back sunday then on and off over the next week

 

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