Battery question

[John C]

I replaced the boats batteries some 3 years ago, the "new" batteries have an indicator that shows when fully charged or not. Its a little round window in the top of the battery that shows green for charged and red(?) for discharged.

 

My question is, how reliable/accurate is this device.

 

John

[churchward]

I replaced the boats batteries some 3 years ago, the "new" batteries have an indicator that shows when fully charged or not. Its a little round window in the top of the battery that shows green for charged and red(?) for discharged.

 

My question is, how reliable/accurate is this device.

 

John

I have always understood them to be about as accurate as me telling you the state of Charge of your Batteries from where I am standing (or rather sitting) now.

[alan_fincher]

They are effectively a simple "yes or no" hydrometer.

 

I would say that if you can see the green ball is floating, then the battery is somewhere close to a full state of charge, but I don't know how much margin they build in. I suspect they may still well float at say 90% SOC, so if you relied solely on them alone, you might never fully charge.

 

More of a problem is when they are not floating. Because that is all or nothing, does it mean (say) 89% charged, or 10% charged.

 

However you are a better man than me if you can actually manage to see the bloody things - I gave up trying!

[Gibbo]

I have one on a battery right here. The battery is at about 20% SoC. The green ball is visible. Because it's stuck. It hasn't chnaged for weeks.

[bottle]

and of course it only tells indicates the charge in the one cell it floats, or not, in.

[boatyboy]

From what i was understand the green bead in the viewing cap is purely to tell you if you need to top the battery up.The bead is in the bottom of a curved plastic tube.when the fluid is up to the correct level it floats to the top.When the level is low the green bead disapears around the curve so you can't see it.Simples...

I've just replaced all 4 of our leisure batteries after one year.(we live and cruise on our boat all year round(CC) So i guess that they must have reached their cycles limit) The new ones have transformed the boat.I'm never going to fart around buying one at a time anymore.

Dave

[Gibbo]

From what i was understand the green bead in the viewing cap is purely to tell you if you need to top the battery up.

 

Sorry but you understand wrong.

[Guest User]

I have one on a battery right here. The battery is at about 20% SoC. The green ball is visible. Because it's stuck. It hasn't chnaged for weeks.

 

I've got an engine starter battery that, well, starts the engine just fine .... but the little green ball went AWOL over a year ago

[bottle]

From what i was understand the green bead in the viewing cap is purely to tell you if you need to top the battery up.

 

Sorry Boatboy as Gibbo says you understanding is wrong, my sealed, lead acid batteries have them and as you know they cannot be topped up. (well they maybe can but it may also destroy the capping )

[John C]

Many thanks for the replies, as I suspected it seems that the indicator is not particularly useful in indicating the true state of the batteries.

 

The "Smart Gauge" is well thought of on this forum as an indicator of battery state etc. I use a (very) cheap multimeter to occasionally check the batteries (1xstart 90ah, 2xleisure 110ah each, charged with a Bosch 90amp alternator), it always shows about 1 volt low. I have checked against other meters and this would be right. The boats not very demanding electrical functions work fine, always have before and after replacing the previous set when they failed very quickly, 1 nine years old and 2 eleven years old.

 

My problem is this, is it worth fitting a smart gauge (or similar) and if I fit some form of battery monitor will it just cause undue worry if all is not perfect?

 

John

[blodger]

Many thanks for the replies, as I suspected it seems that the indicator is not particularly useful in indicating the true state of the batteries.

 

The "Smart Gauge" is well thought of on this forum as an indicator of battery state etc. I use a (very) cheap multimeter to occasionally check the batteries (1xstart 90ah, 2xleisure 110ah each, charged with a Bosch 90amp alternator), it always shows about 1 volt low. I have checked against other meters and this would be right. The boats not very demanding electrical functions work fine, always have before and after replacing the previous set when they failed very quickly, 1 nine years old and 2 eleven years old.

 

My problem is this, is it worth fitting a smart gauge (or similar) and if I fit some form of battery monitor will it just cause undue worry if all is not perfect?John

You pose it as a question but it seems you have worked out that it is hardly going to do a lot for you and your set up & usage. Apparently it's a nice bit of kit to have and talk about having. When you get it and see the SOC when you rejoin the boat it might have you thinking a solar panel will help, etc.; I'd get the solar panel first. Is that what you meant?

Edited October 28, 2010 by blodger

[John C]

You pose it as a question but it seems you have worked out that it is hardly going to do a lot for you and your set up & usage. Apparently it's a nice bit of kit to have and talk about having. When you get it and see the SOC when you rejoin the boat it might have you thinking a solar panel will help, etc.; I'd get the solar panel first. Is that what you meant?

 

Yes, thats about it. I have a solar panel that although small, seems to hold the batteries at whatever state I leave them in.

 

It seems to me that I do not really need a smart gauge (or similar) and searching back through the forum I can find no compelling reason to fit one or have I missed the point?

[blodger]

Yes, thats about it. I have a solar panel that although small, seems to hold the batteries at whatever state I leave them in.

 

It seems to me that I do not really need a smart gauge (or similar) and searching back through the forum I can find no compelling reason to fit one or have I missed the point?

I think liveaboards without mains availability (and even some with) find them essential to maximise on their battery life and use of fuel for gennies/engine and compromises in between to replace the energy they use and to guide their equalising charges. If you have looked at the smartguage site you'll know when you absolutely need one probably but would make a nice Xmas present betwixt!