Charging of domestic batteries

[MtB]

On 17/11/2017 at 09:43, rusty69 said:

But Mike is on a mission to educate others, not have his replaced/fixed,which he has been saying for months.

 

Xactly. 

And mine, as WotEver keeps pointing out, still tell me when to start charging as accuracy is anything but critical. Just a rough idea is plenty good enough. 

So a badly calibrated Smartgauge is still a useful thing, provided you understand when tell you when your batteries are at 100%, it will probably be lying. 

(Even when correctly calibrated, that is. So why bother getting them calibrated?)

[nicknorman]

2 hours ago, Mike the Boilerman said:

 

Xactly. 

And mine, as WotEver keeps pointing out, still tell me when to start charging as accuracy is anything but critical. Just a rough idea is plenty good enough. 

So a badly calibrated Smartgauge is still a useful thing, provided you understand when tell you when your batteries are at 100%, it will probably be lying. 

(Even when correctly calibrated, that is. So why bother getting them calibrated?)

You say that. Repeatedly! But it’s funny that my Smartgauge DOES tell me when to stop charging. Perhaps that’s because it’s correctly calibrated?

[MtB]

On 17/11/2017 at 12:17, nicknorman said:

You say that. Repeatedly! But it’s funny that my Smartgauge DOES tell me when to stop charging. Perhaps that’s because it’s correctly calibrated?

 

According to pages 29 and 30 of the manual this cannot be relied upon, even with a correctly calibrated Smartgauge.

You are just lucky yours indicates accurately as Merlin warn against using it for that.

Edited November 17, 2017 by Mike the Boilerman

[nicknorman]

8 minutes ago, Mike the Boilerman said:

 

According to pages 29 and 30 of the manual this cannot be relied upon, even with a correctly calibrated Smartgauge.

You are just lucky yours indicates accurately as Merlin warn against using it for that.

My manual only has 29 pages! But yes, it does say that earlier in the manual. But that is just Gibbo taking into account the worst possible error. In reality the error is likely to be much less. As I’ve said before, a small error is much better than having no indication as to when the batteries are approaching fully charged, which is often the state people are in before they fit a SG.

[MtB]

On 17/11/2017 at 12:39, nicknorman said:

My manual only has 29 pages! But yes, it does say that earlier in the manual. But that is just Gibbo taking into account the worst possible error. In reality the error is likely to be much less. As I’ve said before, a small error is much better than having no indication as to when the batteries are approaching fully charged, which is often the state people are in before they fit a SG.

 

Curiously my PDF version also has only 29 pages! 

But if you look in the paper version there are 34 pages, and on page 30 it says the following:

"For this reason it may not be wise to place too much faith in the charge status during charging. SmartGauge
will certainly give a very good indication (certainly better than an amp hours counter – and certainly better
than a volt meter [which will tell you nothing more than that the batteries are charging]) but it could be that
SmartGauge shows the charge status to have reached (as a worst case example) 100% when in actual fact the batteries have only reached 90%.
Not charging to 100% charge state is one of the most common reasons for premature battery failure. Not
charging to 100% (or occasionally well in excess of 100%) causes sulfation of the plates which is the main
cause of early battery death."

(Seems to be on Page 23 of my, and probably your, PDF version.)

And when my battery problems first emerged, everyone said I can't use the Smartgauge to know when to stop charging, pointing out this passage of text. Only later did it occur to me to check it for accurate calibration which revealed mine was saying 100% when I was probably barely up to 70%.

My other Smargauge however, only ever goes up to 97%, and usually only when the tail current is down to about 3A. 

Edited November 17, 2017 by Mike the Boilerman

[rusty69]

4 minutes ago, Mike the Boilerman said:

Curiously my PDF version also has only 29 pages! 

But if you look in the paper version there are 34 pages, and on page 30 it says the following

Even my poor maths tells me that is more than 10% different

[nicknorman]

1 hour ago, Mike the Boilerman said:

 

Curiously my PDF version also has only 29 pages! 

But if you look in the paper version there are 34 pages, and on page 30 it says the following:

"For this reason it may not be wise to place too much faith in the charge status during charging. SmartGauge
will certainly give a very good indication (certainly better than an amp hours counter – and certainly better
than a volt meter [which will tell you nothing more than that the batteries are charging]) but it could be that
SmartGauge shows the charge status to have reached (as a worst case example) 100% when in actual fact the batteries have only reached 90%.
Not charging to 100% charge state is one of the most common reasons for premature battery failure. Not
charging to 100% (or occasionally well in excess of 100%) causes sulfation of the plates which is the main
cause of early battery death."

(Seems to be on Page 23 of my, and probably your, PDF version.)

And when my battery problems first emerged, everyone said I can't use the Smartgauge to know when to stop charging, pointing out this passage of text. Only later did it occur to me to check it for accurate calibration which revealed mine was saying 100% when I was probably barely up to 70%.

My other Smargauge however, only ever goes up to 97%, and usually only when the tail current is down to about 3A. 

Yes. you'll note it says "as a worst case example" which clearly comes out of stating the accuracy of the device during charging is 10%. As we have repeatedly said, the best way to know when approaching fully charged is to use an ammeter, but most people don't have an ammeter and they are not that easy to install (shunts etc). Compared to having nothing, a SG is a reasonably accurate way to know when to stop charging. Certainly better than those folk who say "well, the charge voltage reached 14.4v and wasn't going any higher, so I turned the charger off"! Or even "I charged until the voltage reached 12.7v, that's fully charged, right? But now after just using a couple of leds for 5 minutes its only showing 11.5v"

What your smartgauges read is of no consequence since they are both way out of calibration.

Edited November 17, 2017 by nicknorman

[WotEver]

2 hours ago, Mike the Boilerman said:

Only later did it occur to me to check it for accurate calibration which revealed mine was saying 100% when I was probably barely up to 70%.

Which has way more relevance to your problem than the <10% error that it might have during charging. 

Instead of basing your ‘advice’ on what you believe to be the case, why don’t you get at least one of yours fixed and then you can speak with the benefit of actual experience. 

[Col_T]

Okay - which the definitive, no arguments method of determining when to stop battery, tail current or Smartgauge showing 100%??

[cuthound]

58 minutes ago, Col_T said:

Okay - which the definitive, no arguments method of determining when to stop battery, tail current or Smartgauge showing 100%??

Always tail current. Once the readings have stabilised for 3 consecutive readings, each 30 minutes apart the battery is pretty much fully charged

Note this is true even with an calibrated ammeter. 

Edited November 17, 2017 by cuthound
To unmangle the effects of autocorrect.

[smileypete]

4 hours ago, Mike the Boilerman said:

"For this reason it may not be wise to place too much faith in the charge status during charging. SmartGauge

 

will certainly give a very good indication (certainly better than an amp hours counter – and certainly better
than a volt meter [which will tell you nothing more than that the batteries are charging]) but it could be that
SmartGauge shows the charge status to have reached (as a worst case example) 100% when in actual fact the batteries have only reached 90%.
Not charging to 100% charge state is one of the most common reasons for premature battery failure. Not
charging to 100% (or occasionally well in excess of 100%) causes sulfation of the plates which is the main
cause of early battery death."

Kind of misleading to omit that an ammeter  (and voltmeter) is the best practical way to tell when a battery is fully charged. Like some other of Gibbos writings, there is a certain economy with the truth.

Edited November 17, 2017 by smileypete

[smileypete]

3 hours ago, nicknorman said:

Yes. you'll note it says "as a worst case example" which clearly comes out of stating the accuracy of the device during charging is 10%. As we have repeatedly said, the best way to know when approaching fully charged is to use an ammeter, but most people don't have an ammeter and they are not that easy to install (shunts etc).

Not that old chestnut!

I would expect they get installed the same way as the big inverter and matching bank.

I am sorry but having oodles of reliable off grid power supplied via batteries, just needs 'something'. It's like the govt saying 'lets install a nuclear reactor, but we won't install any containment as it's not that easy to install - what could go wrong?'

44 minutes ago, Col_T said:

Okay - which the definitive, no arguments method of determining when to stop battery, tail current or Smartgauge showing 100%??

It needs the correct charge voltage too.

[cereal tiller]

2 hours ago, WotEver said:

Which has way more relevance to your problem than the <10% error that it might have during charging. 

Instead of basing your ‘advice’ on what you believe to be the case, why don’t you get at least one of yours fixed and then you can speak with the benefit of actual experience. 

Too Easy..

[WotEver]

40 minutes ago, cuthound said:

Always tail current.

At  >14.4V

[WotEver]

16 minutes ago, smileypete said:

I would expect they get installed the same way as the big inverter and matching bank.

From the pos & neg take-off points then?

[smileypete]

8 minutes ago, WotEver said:

From the pos & neg take-off points then?

Errr, someone puts it in and connects it up? It doesn't just magically appear with all the required connections....

[Col_T]

1 hour ago, cuthound said:

Always tail current. Once the readings have stabilised for 3 consecutive readings, each 30 minutes apart the battery is pretty much fully charged

Note this is true even with an calibrated ammeter. 

 

20 minutes ago, WotEver said:

At  >14.4V

Many thanks, gentlemen.

That's me educated!

[WotEver]

27 minutes ago, smileypete said:

Errr, someone puts it in and connects it up? It doesn't just magically appear with all the required connections....

Here we go again!

Why can’t you accept that there are some boaters who are perfectly capable of connecting up a couple of 2mm cables from the battery to a SmartGauge and thereby gaining a huge improvement from ‘nothing’ but who would be incapable of competently wiring in an ammeter?

Not all boaters have unlimited amounts of money to throw at professionals and not many are interested in the finer points of battery management. 

54 minutes ago, cereal tiller said:

Too Easy..

He’d also have nothing to moan about

25 minutes ago, Col_T said:

Many thanks, gentlemen.

That's me educated!

However... it is most likely that you’ll find that the 100% point as measured by the ammeter coincides pretty closely with SmartGauge’s estimation. 

When you’ve done it please report back and let us know. 

[smileypete]

1 hour ago, WotEver said:

Here we go again!

Why can’t you accept that there are some boaters who are perfectly capable of connecting up a couple of 2mm cables from the battery to a SmartGauge and thereby gaining a huge improvement from ‘nothing’ but who would be incapable of competently wiring in an ammeter?

How do said users get their combi or charger/inverter and battery bank installed?

Horses for courses though, for part time boaters or marina based liveaboards, slowly declining battery performance is more of an irritation really.

But for 24/365 off grid liveaboards with non trivial power use, there's no easy answer (yet!)

[WotEver]

3 minutes ago, smileypete said:

How do said users get their combi or charger/inverter and battery bank installed?

Very often by the boatbuilder or some other yard judging by the number of folk posting on here who have both but zero monitoring. 

[nicknorman]

In our case, our boat came new with a 2.5kva Combi, a Travelpower, a 175A alternator, 4 x 110AH domestic batteries. And absolutely zero monitoring. As did most of Steve’s boats, unless the buyers were savvy enough to specify battery monitoring.

So the first thing I did was add a Smartgauge. Dead easy.

Some time later, when I’d plucked up the courage, bought the crimping tool and some 75mm^2 cable, crimp eyes etc, I fitted the shunt.

[MtB]

On 17/11/2017 at 22:57, nicknorman said:

Some time later, when I’d plucked up the courage, bought the crimping tool and some 75mm^2 cable, crimp eyes etc, I fitted the shunt.

 

And shockingly easy to do, wasn't it?!

No harder than the Smartgauge.

[nicknorman]

6 minutes ago, Mike the Boilerman said:

 

And shockingly easy to do, wasn't it?!

No harder than the Smartgauge.

No, it was quite a bit harder and required special tools.

[MtB]

On 17/11/2017 at 23:22, nicknorman said:

No, it was quite a bit harder and required special tools.

 

You must have been doing it wrong then. I find heavy gauge wiring a complete breeze compared to fiddling about with the thin stuff.

[WotEver]

9 hours ago, nicknorman said:

No, it was quite a bit harder and required special tools.

And even after buying heavy duty cable and special tools it leaves plenty of room for error with the existing negative connections to the starter battery and other services if you're not 100% sure of what you're doing.  Unlike the Smartgauge which simply requires two thin wires and zero modification of the original installation.