Charging of domestic batteries

[MtB]

On 18/11/2017 at 08:41, WotEver said:

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. 

 

Yes I agree there is plenty of scope for putting the shunt in the wrong place, so it fails to see all the current, but the physical skill required to make up and install the fat cables is different but no greater than required to install thin cables, and that is what we were talking about, I thought!

[WotEver]

1 minute ago, Mike the Boilerman said:

 

Yes I agree there is plenty of scope for putting the shunt in the wrong place, so it fails to see all the current, but the physical skill required to make up and install the fat cables is different but no greater than required to install thin cables, and that is what we were talking about, I thought!

No. We were talking about Mr Average Boater (whoever he is) who knows he needs some monitoring but knows nowt about electrics. Even he can connect two thin wires and get it right. It would be a huge step (for all the reasons already explained) for the same person to connect up a shunt. 

[rusty69]

Just now, WotEver said:

No. We were talking about Mr Average Boater (whoever he is) who knows he needs some monitoring but knows nowt about electrics. Even he can connect two thin wires and get it right. It would be a huge step (for all the reasons already explained) for the same person to connect up a shunt. 

I am a below average boater, who has installed both a Smartgauge and a shunt based meter. Although the shunt cabling was more difficult to install, there is a larger potential (no pun intended) for greater damage to occur should it have been done incorrectly imo.

[Dr Bob]

18 hours 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. 

In theory, this is excellent advice. In practice......my 2 methods of charging, the alternator/Sterling AtoB and the Victron combi battery charger have switched to float mode long before the 90 minutes is up - so the voltage has dropped so I can not rely on tail current. What am I doing wrong? Typically I get down to circa 10A tail current for 10 mins or so before they both go to float (660Ahrs domestic bank).

[smileypete]

13 hours ago, nicknorman said:

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.

And it's a Hudson!

I get the impression most boats are marketed as second homes and Mr Boatbuilder doesn't want to frighten off potential buyers with technical stuff.

Somewhere in another topic I suggested three main scenarios for batt ownership:

    Plan A for most (95%?) of boaters would be decent brand leisure batts.

    Plan B would be Trojans but only if they can be provided with the correct charge and EQ voltages, and required maintenance and monitoring. I expect this needs a genuine long term interest, hmmm...

    Plan C is to use a less common battery make/type/chemistry/desulphators etc, but then you may be the guinea pig on that one.

I guess most second home type boats fall into Plan A, and most off grid liveaboards move towards Plan B at some point.

Edited November 18, 2017 by smileypete

[Dr Bob]

1 hour ago, WotEver said:

No. We were talking about Mr Average Boater (whoever he is) who knows he needs some monitoring but knows nowt about electrics. Even he can connect two thin wires and get it right. It would be a huge step (for all the reasons already explained) for the same person to connect up a shunt. 

I installed a shunt on our lumpy water boat and it was simple - but there was very easy access and loads of room. If I had to install one our current nb (I dont cause there is already one  there) then it would be a lot more of a challenge with little room and tight access.

[Tony Brooks]

1 minute ago, Dr Bob said:

In theory, this is excellent advice. In practice......my 2 methods of charging, the alternator/Sterling AtoB and the Victron combi battery charger have switched to float mode long before the 90 minutes is up - so the voltage has dropped so I can not rely on tail current. What am I doing wrong? Typically I get down to circa 10A tail current for 10 mins or so before they both go to float (660Ahrs domestic bank).

Well, if you had chosen any other form of advanced alternator regulator this would not happen and if by some chance it did you could just disconnect the flylead from the alternator brush box.

The Victron can be switched off and back on again to force it back to absorption for a while. I doubt you can do anything to the A to B apart from bridging the large alternator pos in terminal to the pos domestic out terminal and also the corresponding negatives so you bypass it and revert to simple alternator charging.

You are doing nothing wrong, its a well recorded and commented on "feature" of such systems so maybe the A to B was not such a bright choice.

 

[smileypete]

25 minutes ago, Dr Bob said:

In theory, this is excellent advice. In practice......my 2 methods of charging, the alternator/Sterling AtoB and the Victron combi battery charger have switched to float mode long before the 90 minutes is up - so the voltage has dropped so I can not rely on tail current. What am I doing wrong? Typically I get down to circa 10A tail current for 10 mins or so before they both go to float (660Ahrs domestic bank).

Something that might work for reasonably healthy batts could be wait till the tail current falls by less than a third over one hour. This should happen at <2% for Trojans and <1% for sealed leisures.

Of course tail current only works with a correct temperature compensated charge voltage as stated by the manufacturer. Seems in practice some sealed leisures need more than this though, if it can be provided safely and responsibly.

Edited November 18, 2017 by smileypete

[Dr Bob]

11 minutes ago, Tony Brooks said:

Well, if you had chosen any other form of advanced alternator regulator this would not happen and if by some chance it did you could just disconnect the flylead from the alternator brush box.

The Victron can be switched off and back on again to force it back to absorption for a while. I doubt you can do anything to the A to B apart from bridging the large alternator pos in terminal to the pos domestic out terminal and also the corresponding negatives so you bypass it and revert to simple alternator charging.

You are doing nothing wrong, its a well recorded and commented on "feature" of such systems so maybe the A to B was not such a bright choice.

 

I disagree. All you do with the sterling AtoB is stop the engine and restart it. Same as the victron in that it forces it back to absorption. Both switch to float at similar times and I expect other regulators do the same. Without the sterling AtoB I would never be over 14V.

Lets then ignore the Sterling AtoB. How do you use tail current from the victron if it switches to float too soon?

[smileypete]

1 minute ago, Dr Bob said:

Lets then ignore the Sterling AtoB. How do you use tail current from the victron if it switches to float too soon?

Cycle the power or put a heavy load on so it kicks off a new charge cycle?

[Dr Bob]

3 minutes ago, smileypete said:

Cycle the power or put a heavy load on so it kicks off a new charge cycle?

Yes, I understand that, and that is what I do with both the Sterling AtoB or the Victron but then the amps go up and we never have the 3 periods of 30 mins to watch a steadily decreasing (or not) current. My comment on Cuthounds post was really about the time issue of watching tail current for 90 mins. I can get my tail current down to 6A by 'rebooting' the charger but it would be nice not to.

[smileypete]

 

46 minutes ago, Dr Bob said:

Yes, I understand that, and that is what I do with both the Sterling AtoB or the Victron but then the amps go up and we never have the 3 periods of 30 mins to watch a steadily decreasing (or not) current. My comment on Cuthounds post was really about the time issue of watching tail current for 90 mins. I can get my tail current down to 6A by 'rebooting' the charger but it would be nice not to.

Why not just use the 1/3 less thing to get a baseline, or check hourly if you have to. Or just use 2% or 1% according to batt type.

How long does the tail current take to stabilise after the charger is cycled? Nick posted a chart and a spreadsheet somewhere but I can't find it.

ETA: Here goes, seems to indicate a fairly short blip when restarting charging:

https://canalworld.net/forums/index.php?/topic/82614-battery-charging-graphs/

Edited November 18, 2017 by smileypete

[rowland al]

7 hours ago, Mike the Boilerman said:

 

Yes I agree there is plenty of scope for putting the shunt in the wrong place, so it fails to see all the current, but the physical skill required to make up and install the fat cables is different but no greater than required to install thin cables, and that is what we were talking about, I thought!

It's arrived! Quite a chunky shunt too. The wires supplied to the digital meter are just a few inches long so I'll have to do something about that.

So where does the shunt go again? Was it between the -ve and +ve posts?

[WotEver]

1 hour ago, rowland al said:

So where does the shunt go again? Was it between the -ve and +ve posts?

Plenty of heat lays in that path...

[rowland al]

2 minutes ago, WotEver said:

Plenty of heat lays in that path...

It's bloody cold out here you know.

[WotEver]

1 minute ago, rowland al said:

It's bloody cold out here you know.

It will be very warm for a few seconds once you wire it up

[cereal tiller]

8 hours ago, WotEver said:

No. We were talking about Mr Average Boater (whoever he is) who knows he needs some monitoring but knows nowt about electrics. Even he can connect two thin wires and get it right. It would be a huge step (for all the reasons already explained) for the same person to connect up a shunt. 

I met MR Average Boater on the Clapham Omnibus, he confessed to Knowing nothing about Smartgauges, Ecofans , shunts or Punts.was a bit Underwhelmed by his Status TBH

[rowland al]

18 minutes ago, cereal tiller said:

I met MR Average Boater on the Clapham Omnibus, he confessed to Knowing nothing about Smartgauges, Ecofans , shunts or Punts.was a bit Underwhelmed by his Status TBH

Well you are the ''Cerial Tiller'. Good luck matey. 

[WotEver]

39 minutes ago, cereal tiller said:

I met MR Average Boater on the Clapham Omnibus, he confessed to Knowing nothing about Smartgauges, Ecofans , shunts or Punts.was a bit Underwhelmed by his Status TBH

Hey, I resemble that remark...

[Dr Bob]

12 hours ago, cereal tiller said:

I met MR Average Boater on the Clapham Omnibus, he confessed to Knowing nothing about Smartgauges, Ecofans , shunts or Punts.was a bit Underwhelmed by his Status TBH

Did he know where he was going?

 

Edited November 19, 2017 by Dr Bob
Speeeling

[cereal tiller]

7 minutes ago, Dr Bob said:

Did he know where he was going?

 

He said he was going to the Beach at somewhere called Clacton, he was with his Friend Eric.

[Dr Bob]

2 minutes ago, cereal tiller said:

He said he was going to the Beach at somewhere called Clacton, he was with his Friend Eric.

Eric the half a bee?

[cereal tiller]

4 minutes ago, Dr Bob said:

Eric the half a bee?

 

4 minutes ago, Dr Bob said:

Eric the half a bee?

Eric the Fish,I think?there was some Licensing Issue

Edited November 19, 2017 by cereal tiller

[Dr Bob]

9 minutes ago, cereal tiller said:

 

Eric the Fish,I think?there was some Licensing Issue

He would be a fish out of water then?

[rowland al]

This is what was inside the £6 package. No instructions of course, I'm going to order a short battery link to wire the shunt up In series with the domestic negative battery connection lead (I think that's where it goes although not sure why it can't be on the positive feed?!). 

Any ideas how the wires from the meter connect? I also need to work out how to extend the wires to the digital meter as it's pretty useless having it on top of the batteries. Might just use a chock block for now.