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Battery charge question


Boat afloat

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2 hours ago, Arthur Marshall said:

 

I'm not entirely convinced by the pixies, but I'm keeping an open mind.

 

Mr Marshall, this disrespect to the electrical pixies is tantamount to blasphemy. I thought you of all people would know better than to make the pixies angry. 

I shall sacrifice an extra gerbil for you tomorrow, and say a quiet prayer for your electrics. 

 

My only worry is that the pixies may at some point demand a human sacrifice in order to keep my electric working smoothly. 

There are any number of people I consider eminently expendable, and highly suited to the role of human sacrifice. I think that goes without saying.

But my legal team are advising that there may be a few snags. 

 

Edited by Tony1
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On 16/04/2022 at 19:44, Tony Brooks said:

 

That is why I wonder if it is stratification because I can't think of anything else that fit it. I am happy to be proved wrong because we all learn.

 

I think it is unlikely to be stratification, provided the boat moves occasionally every few years.

 

We used to get stratification sometimes on wet lead acid cells left on float at BT but only after a few years. A good equalisation charge fixed it. I think the movement and vibration from the engine running would prevent it on a boat.

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21 hours ago, Jen-in-Wellies said:

Completely wrong. It's all done by magic smoke. 😀

 

No it's holes. When it was found that electrons move from negative to positive, and everyone knows that electricity flows from positive to negative, the only explanation left was that electricity is the flow of holes left behind by the electrons.

 

At least I think that what what my lecturer said 50 odd years ago.

16 hours ago, Loddon said:

Whatever happened to the Voles?

I thought it was all done with lots of Voles  running around.

 

 

No you misheard, it was holes not voles. They would be too bit to fit in the space left by the electrons. See my previous post.

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19 minutes ago, cuthound said:

No it's holes. When it was found that electrons move from negative to positive, and everyone knows that electricity flows from positive to negative, the only explanation left was that electricity is the flow of holes left behind by the electrons.

 

At least I think that what what my lecturer said 50 odd years ago.

 

 

I'm sure that is exactly how my Physics teacher explained it - also 50+ years ago.

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1 hour ago, Alan de Enfield said:

 

 

I'm sure that is exactly how my Physics teacher explained it - also 50+ years ago.

 

And it has been turning a great number of students off electrics ever since. They say electrics is too hard. It is far less difficult, in my view, for simple electrics (probably not electronics) to explain at the start about conventional flow and electron flow and from that point stick with conventional flow.

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We hope to be with the boat today so can start to test things out. 
 

first things first I’ll see what the resting voltage is of the batteries because the boat has been sitting for a week.

 

Will my multi meter give me an accurate charging voltage whilst running - any reason it won’t work whilst the batteries are physically being charged by the alternator?

 

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33 minutes ago, Boat afloat said:

We hope to be with the boat today so can start to test things out. 
 

first things first I’ll see what the resting voltage is of the batteries because the boat has been sitting for a week.

 

Will my multi meter give me an accurate charging voltage whilst running - any reason it won’t work whilst the batteries are physically being charged by the alternator?

 

 

As long as you make the correct connections, have set the meter correctly, and the meter battery is good then it will give you an accurate voltage. Be that rested voltage, charging voltage (alternator), ditto (Solar), Ditto (Charger) or even voltage drop and un-rested voltage depending upon what else you do or have done.

 

Just be aware that if you have solar it will not be a rested voltage but the solar charging voltage unless the panel is covered or disconnected from the controller when you left the boat.

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Thanks Tony, that’s a good point on the solar. Sorry for all the questions…

 

- the electrics are turned totally off but the solar is on. Will the solar still charge the batteries even though the electrics are off? I know you don’t know how my boat is wired up but usually the solar would continue to charge even with electrics off? 
 

- I should in theory come back to healthy battery levels given the above (sunny weather and no usage drain for the past week)?

 

- the volt meter in the boat (the one that gives a mis-leading reading I think) will be taking an average of all 4/5 batteries will it?

 

- given all the leisure’s are linked when I stick the multimeter on one battery am I effectively getting an average of them all, or genuinely getting that particular batteries reading? They were all within very tight tolerances when I last checked, hence me wondering.


- your point about solar voltage, so if I understand the point it’s that whilst the solar is charging any reading taken at the +ve and -ve terminals of an individual battery isn’t the voltage of that battery but a function of what the solar is chucking in…a bit like doing it whilst the engine is running…that makes sense now you point it out. 

Thanks

 

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18 minutes ago, Boat afloat said:

Thanks Tony, that’s a good point on the solar. Sorry for all the questions…

 

- the electrics are turned totally off but the solar is on. Will the solar still charge the batteries even though the electrics are off? I know you don’t know how my boat is wired up but usually the solar would continue to charge even with electrics off? 
 

- I should in theory come back to healthy battery levels given the above (sunny weather and no usage drain for the past week)?

 

- the volt meter in the boat (the one that gives a mis-leading reading I think) will be taking an average of all 4/5 batteries will it?

 

- given all the leisure’s are linked when I stick the multimeter on one battery am I effectively getting an average of them all, or genuinely getting that particular batteries reading? They were all within very tight tolerances when I last checked, hence me wondering.


- your point about solar voltage, so if I understand the point it’s that whilst the solar is charging any reading taken at the +ve and -ve terminals of an individual battery isn’t the voltage of that battery but a function of what the solar is chucking in…a bit like doing it whilst the engine is running…that makes sense now you point it out. 

Thanks

 

 

1. Normally the solar will charge the batteries when the isolator is off so you won't have a rested voltage. The closest you can get to it will be to run the water pump for 3 or four minutes, turn it off and wait a short time and then measure the voltage. That won't be far off rested.

 

2. As long as you ignore the engine battery then yes, you will be measuring the bank voltage. Unless you find it below about 12.6V it won't tell you anything about battery capacity or internal shorts.

 

3. Yes. It is the solar charging voltage.

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1 hour ago, Boat afloat said:

- the volt meter in the boat (the one that gives a mis-leading reading I think) will be taking an average of all 4/5 batteries will it?

 

- given all the leisure’s are linked when I stick the multimeter on one battery am I effectively getting an average of them all, or genuinely getting that particular batteries reading? They were all within very tight tolerances when I last checked, hence me wondering.

 

 

Not quite right. Your 4 domestic batteries are almost certainly all connected to each other in parallel, so there is no such thing as an 'average voltage' for them, they will (or should be) all exactly the same. They have to be because the terminals are all connected together!

 

If there is any difference this can only be caused by poor connections on the terminals or in the interconnects. 

 

 

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OK - at the boat now.

 

solar was showing 12.7V and batteries tested 12.7v

 

solar disconnected and batteries tested at 12.79v

 

turned inverter on and they dropped to 12.78v

 

downside is solar is now not wanting to work but maybe it takes a little time after removing the fuse to work again?

 

OH is now about to hoover so let’s see what happens!!

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You need a fair load to remove surface charge in a short time so your 12.7x is not rested voltage. Lets see what it is after the hoover has been run for a while.

 

If you have a decent inverter it may well  draw under an amp when turned on and doing nothing.

Edited by Tony Brooks
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15 minutes ago, Boat afloat said:

OK - at the boat now.

 

solar was showing 12.7V and batteries tested 12.7v

 

solar disconnected and batteries tested at 12.79v

 

turned inverter on and they dropped to 12.78v

 

downside is solar is now not wanting to work but maybe it takes a little time after removing the fuse to work again?

 

OH is now about to hoover so let’s see what happens!!

Where/how did you disconnect the solar? is the fuse between the panel/s and the controller or between the battery and the controller?

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Right. Hoover worked for a minute and then cut out. 
 

fuse was between the controller and the battery packs.

 

woth engine running (apparently the hoovering is the main priority I am told) the batteries are testing at 12.3v…WHAT???

 

alternator belt looks tight and alternator looks fairly new.

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2 minutes ago, Boat afloat said:

fuse was between the controller and the battery packs.

I was afraid of that. You probable now have a blown controller.  The panels in bright sun will damage the controller if there is no battery connected to absorb the current.

The disconnect should be between the panels and the controller.

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1 minute ago, Boat afloat said:

Right. Hoover worked for a minute and then cut out. 
 

fuse was between the controller and the battery packs.

 

woth engine running (apparently the hoovering is the main priority I am told) the batteries are testing at 12.3v…WHAT???

 

alternator belt looks tight and alternator looks fairly new.

 

As I am sure you have been told before in this thread your batteries are almost certainly knackered. They either are sulphated to hell and only have a few Ah capacity now or hey have internal shorts so they never charge and when any charge manages to get in it promptly discharges through the shorts.

 

You may also have undersized inverter cables and/or bad connections. Ditto the battery leads, including clamps, to the domestic distribution board and negative bus bar.

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17 minutes ago, Tony Brooks said:

 

As I am sure you have been told before in this thread your batteries are almost certainly knackered. They either are sulphated to hell and only have a few Ah capacity now or hey have internal shorts so they never charge and when any charge manages to get in it promptly discharges through the shorts.

 

You may also have undersized inverter cables and/or bad connections. Ditto the battery leads, including clamps, to the domestic distribution board and negative bus bar.


OK. I am prepared for it being the batteries so I’m not in denial, just trying to look at the other options before having to sort out a load of new ones only to find it is something else.

 

Engine running 10 mins now and they are back up to 13.

 

inspection eye still looks green…)

 

ps solar now sorted, I found a loose connection!

1542787E-90ED-4574-A760-E1BE2C13F17B.jpeg

Edited by Boat afloat
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1 minute ago, Boat afloat said:


OK. I am prepared for it being the batteries so I’m not in denial, just trying to look at the other options before having to sort out a load of new ones only to find it is something else.

 

what’s the thought about them only charging at 12.3v through the alternator, simply the hoover killed the pressure and it needs to slowly build up? I thought hey would suddenly spring to 14+ under alternator? 

 

ps solar now sorted, I found a loose connection!

 

Alternators are designed to reduce their charging voltage as the current rise. This is supposed to prevent them burning themselves out as dynamos used to do. The result of this is that as the current approaches the maximum the charging voltage may be very low indeed. Now I have a feeling 12.3 is a bit lower than I would expect but without a multi-meter to check voltages at various parts of the circuit it might be correct,  especially if you have cell shorts putting more load on the alternator.

 

Batteries do not need time to "build up pressure" to the extent 12.3V volts imply. A few tenths of a volt is all the difference time will make.

 

Several day on solar charge gives 12.7 battery voltage. A few minutes with perhaps at 100 amps load (from the rating plate of our hoover) and the batteries drop to 12.3, so from fully charged to about half charged in a few minutes should tell you something.

 

Without testing with a meter I doubt anyone here can give you a definitive diagnosis. It sounds as if the inverter may have shut down on ow voltage but I would not expect it to do that until around 12 volts or less so there may be volt drop on the inverter supply cables , fuse and connections. Without test data I certainly can't say that is the case but batteries should not drop form nominally fully charged to half charged in minutes.

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OK. A bit of further inspection done. 3 of the 4 batteries have green spots in the inspection eyes, one is black. Could a single battery failure be the issue, presumably not? Wondering whether to isolate that one (along with the one already isolated).

I did bring a spare (small ish) battery I had in the garage at home just in case it might be useful. It’s in the car now…


mo’s engine still running and volts now 13.4 and rising so charging is happening at least.

Edited by Boat afloat
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3 minutes ago, Boat afloat said:

OK. A bit of further inspection done. 3 of the 4 batteries have green spots in the inspection eyes, one is black. Could a single battery failure be the issue, presumably not? Wondering whether to isolate that one (along with the one already isolated).

I did bring a spare (small ish) battery I had in the garage at home just in case it might be useful. It’s in the car now…

 

The green eye is snake oil.

 

It means that there is liquid in that one single cell, that is all.  Ignore them.   They are toast.

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