Battery wiring at fault? 12v socket reading jumping.

[Lady_Why]

I am currently on the 12v group on FB about this problem but I thought I'd also ask here.

To make a long story short my batteries are hardly charging from the engine and depleting overnight, placing me in a vicious cycle of having to run the engine 6hrs+ every day just to keep them from dying (they're new). I haven't been able to afford a monitor yet, but my multi-meter shows me bringing the starter up to 12.50 and leisures at 12.20, but then they go below 11.7 overnight despite me having the fridge switched off and only using lights/water-pump. 

Now, yesterday I remembered that I have a 12v socket reader, so using that I noticed that the charge was 14.1 while running the engine indicating the alternator input was fine (yes?). However, once I switched the engine off the readings were all over the place and would not settle (i.e. jumping between 11.5-14.1). Someone has suggested that my wiring is wrong, and I wonder if a jumpy reading like this would be a confirmation of that?

Adding a pic of my current wiring.

[rusty69]

If you intend to try and resolve the problem yourself, i humbly suggest you invest in a multimeter. Perhaps the uni-t clamp meter that is often mentioned on here. 

[NB Lola]

1 minute ago, rusty69 said:

If you intend to try and resolve the problem yourself, i humbly suggest you invest in a multimeter. Perhaps the uni-t clamp meter that is often mentioned on here. 

The post references the use of a multimeter

[Chewbacka]

If your batteries are heavily sulphated and now have very little capacity the voltage will drop by a volt or two when the fridge compressor starts up and then recover a bit after the initial start-up surge, then about 20 mins later the fridge will be cool so the compressor will stop running and volts will rise again.  Water pump coming on and off will do the same. Does this sound like what you are experiencing??

 

added. If you run the engine for 6 hours during which time the voltage measured on the battery posts is 14.1v it means the batteries are charging, but if they then go flat overnight it does sound like your batteries no longer have any capacity.

Edited November 11, 2018 by Chewbacka

[Lady_Why]

No, they're completely new - hence why I am panic charging every day. Unless new batteries can get heavily sulphated very fast & I should still consider your suggestion?

[ I haven't had the fridge on since realising the issue]

[Onewheeler]

If by a '12v socket reader' you mean a plug with three LED digits built into the end, be aware that some of them are utter crap. I have several which I thought would be useful for car and boat and their readings go all over the place.

[Chewbacka]

4 minutes ago, Lady_Why said:

No, they're completely new - hence why I am panic charging every day. Unless new batteries can get heavily sulphated very fast & I should still consider your suggestion?

[ I haven't had the fridge on since realising the issue]

When you say new, how new?  Not charging batteries properly can destroy then in a week or three.  Though it would take a fair bit of abuse to do it that quickly.

Edited November 11, 2018 by Chewbacka

[Lady_Why]

6 minutes ago, Onewheeler said:

If by a '12v socket reader' you mean a plug with three LED digits built into the end, be aware that some of them are utter crap. I have several which I thought would be useful for car and boat and their readings go all over the place.

It reads steadily thought when I run the engine and only jumps when I'm not charging.

5 minutes ago, Chewbacka said:

When you say new, how new?  Not charging batteries properly can destroy then in a week or three.  Though it would take a fair bit of abuse to do it that quickly.

10 days or so. The lowest they've been is 11.40 when I discovered the issue - this is me relying on a multi meter though which no one rates as very exact.

Edited November 11, 2018 by Lady_Why
If they're heavily sulphated shouldn't they be fizzing? They are not fizzing.

[Guest]

It seems as if there may be more than one issue here.

The two most likely causes of a fluctuating reading are either volt drop due to loads varying (as per chewbacka) or a poor connection.

The 6 hour charge time may be sensible depending upon the state of your batteries.  Without being able to monitor the charge current you are not able to tell how far you have got with charging. If you dont get a eeasonable charge daily then the whole situation will rapidly deteriorate.  You need that monitor!!!

Also it may be that we need more info. Is the "charger box" some sort of split charge from a single alternator, or something else?

[Lady_Why]

2 minutes ago, Floating Male said:

It seems as if there may be more than one issue here.

The two most likely causes of a fluctuating reading are either volt drop due to loads varying (as per chewbacka) or a poor connection.

The 6 hour charge time may be sensible depending upon the state of your batteries.  Without being able to monitor the charge current you are not able to tell how far you have got with charging. If you dont get a eeasonable charge daily then the whole situation will rapidly deteriorate.  You need that monitor!!!

Also it may be that we need more info. Is the "charger box" some sort of split charge from a single alternator, or something else?

I wasn't varying the load though (same lights on, no water pump going) and the reading is jumping pretty manically nonstop the moment I switch off the engine. I've cleaned and checked all the connections on the batteries but I'd be a little lost if there's a connection issue elsewhere.

The charger box is next to my Sterling battery charger and looks very much as part of the Sterling set up although I have no clue what it does. 

I think I may need an electrician to come at this point as the situation is indeed deteriorating - does anyone have a recommendation for west London electrician?

[Chewbacka]

I would run the engine for a few hours measuring the voltage on the actual battery posts - that way none of the cables, connections etc are included - I would check the voltage every say 20 mins for the first hour and if steady at more than say 13.9 volts then just check every hour or so.  Then just before stopping the engine make sure everything is turned off, then stop the engine and whilst measuring the voltage on the battery posts get someone to turn on the fridge.  Record the volts before and after starting the fridge. Then leave the fridge switched on and use power as normal and record the battery voltage every hour.  If it drops quickly either you have knackered batteries or something is taking a lot of power, for example an inverter running a microwave or immersion heater etc.

 

Added wasn’t very clear so clarified above

Edited November 11, 2018 by Chewbacka

[Lady_Why]

*notably though: if there was a poor connection, shouldn't the reading jump also when I run the engine?

1 minute ago, Chewbacka said:

I would run the engine for a few hours measuring the voltage on the actual battery posts - that way none of the cables, connections etc are included - I would check the voltage every say 20 mins for the first hour and if steady at more than say 13.9 volts then just check every hour or so.  Then just before stopping the engine make sure everything is turned off, and whilst measuring the voltage on the battery posts get someone to turn on the fridge.  Record the volts before and after starting the fridge. Then leave the fridge switched on and use power as normal and record the battery voltage every hour.  If it drops quickly either you have knackered batteries or something is taking a lot of power, for example an inverter running a microwave or immersion heater etc.

Sorry, I should have added that I've also measured input charge at the battery post regularly and it's been around 13.40 when the multi reader settles down. I'll see if I can get my boat neighbour to help me.

[Lady_Why]

Just for clarification though: a heavily sulphated battery would be fizzing, no?

[Chewbacka]

2 minutes ago, Lady_Why said:

*notably though: if there was a poor connection, shouldn't the reading jump also when I run the engine?

One would think so.  It’s actually very difficult diagnosing these types of issue, and even harder when you are 100 miles away.  To do not much more your really need a clamp meter to confirm power going in and out.  Not many boaters have these, but you might be able to borrow one, and somebody that knows how to use it.

[Guest]

1 minute ago, Lady_Why said:

*notably though: if there was a poor connection, shouldn't the reading jump also when I run the engine?

Not necessarily. It depends where you are measuring and also the extent of the poor connection.  With high currents a poor connection could simply be a terminal not tight.

[Chewbacka]

3 minutes ago, Lady_Why said:

Just for clarification though: a heavily sulphated battery would be fizzing, no?

No.  Over voltage (fast charging) causes fizzing, your voltage isn’t that high.  Do your batteries have caps so you can top them up?

Edited November 11, 2018 by Chewbacka

[Lady_Why]

I suspect I have to get someone coming in and find the money for it somehow. ? Thank you guys for trying to help me out. 

[MtB]

4 minutes ago, Lady_Why said:

*notably though: if there was a poor connection, shouldn't the reading jump also when I run the engine?

Sorry, I should have added that I've also measured input charge at the battery post regularly and it's been around 13.40 when the multi reader settles down. I'll see if I can get my boat neighbour to help me.

 

13.4v simply isn't enough to charge lead acid batteries adequately. Especially if you're only charging for six hours. You need 14.4v or better, 14.8.

 

Battery university says it takes 14 hours to fully charge a flat battery with a properly working charger. 'Flat' means 10.5v. 'Fully charged' depends how picky you are. Like a lock, a battery charges ever more slowly as it approaches fully charged, but unlike a lock it never actually reaches 100% no matter how long you charge for. A leeetle bit more can alsways be squeezed in.

 

On a boat all LA battery charging is a compromise. The way a LA battery gets used means in my experience it is not possible to very fully charge one as there are not enough hours in the day. The better your charging regime the longer they will last. Most liveaboard boaters seem to knacker their cheapo batts every two or three years. 

 

 

 

 

 

 

[NB Lola]

We got any helpers in west London area who could “help”?

[Chewbacka]

On your diagram you say ‘link shunt’ is this just a big negative connection bar or is it a proper current measuring shunt?  If it’s a ‘real’ shunt then you probably have a current meter.  That would help understand what is going on.  If you are not sure what a current measuring shunt looks like it looks like this 

https://www.ebay.co.uk/itm/DC-Current-Shunt-FOR-20A-50A-100A-200A-500A-Digital-LED-Voltmeter-Ammeter-Panel/171906336574?hash=item28066a873e:m:mcV1cAcz-mC1SjelrssYCWg

[Lady_Why]

3 minutes ago, NB Lola said:

We got any helpers in west London area who could “help”?

Thank you for asking for me! ?

[rusty69]

1 hour ago, rusty69 said:

If you intend to try and resolve the problem yourself, i humbly suggest you invest in a multimeter. Perhaps the uni-t clamp meter that is often mentioned on here. 

Oh yeah. Oops 

[Lady_Why]

3 minutes ago, Chewbacka said:

On your diagram you say ‘link shunt’ is this just a big negative connection bar or is it a proper current measuring shunt?  If it’s a ‘real’ shunt then you probably have a current meter.  That would help understand what is going on.  If you are not sure what a current measuring shunt looks like it looks like this 

https://www.ebay.co.uk/itm/DC-Current-Shunt-FOR-20A-50A-100A-200A-500A-Digital-LED-Voltmeter-Ammeter-Panel/171906336574?hash=item28066a873e:m:mcV1cAcz-mC1SjelrssYCWg

It might - I'm heading back to the boat soon to look (charging laptop currently in cafe). Not sure what you mean by current meter though? (you mean I can place the multi meter on it for a reading?)

Edited November 11, 2018 by Lady_Why

[MtB]

Just now, Lady_Why said:

It might - I'm heading back to the boat soon to look (charging laptop currently in cafe). Not sure what you mean by current meter though?

 

An ammeter. 

 

Are you clear in your mind about the difference between voltage and current?

[Chewbacka]

4 minutes ago, Lady_Why said:

It might - I'm heading back to the boat soon to look (charging laptop currently in cafe). Not sure what you mean by current meter though?

It probably looks like a panel mounted volt meter but will measure amps.

i think you are not going to fix this yourself, so if you get someone in, ask them to explain what they are doing, will help for the future.

 

added - sorry I can’t be more help.  I’m actually sat in my garage measuring the capacity in my 5 year old batteries to see if any can be saved.  So far one is good enough for the bow thruster, so saved me a battery for another year.

Edited November 11, 2018 by Chewbacka