Jump to content

Leisure battery charge level


Jak
 Share

Featured Posts

 

Please read the post and do not miss out a vital few words see:-

 

The basic rule for most boaters with this type of meter is to only use the amps scale while charging and keep going at least once a week until the charge drops to 1% of bank capacity or less, then manually resynchronise the meter. Then you can note the Amphours out and percentage of charge and calculate the current capacity of the bank. e.g. 50Ah out that takes it to 75% of charge tells you the battery bank capacity is 200Ah because 50Ah is 1/4 of the bank capacity.

 

It should be clear that you need to fully (or as near as possible) charge the battery first - then zero it - and only then will the amp hours out be meaningful. As you had just set the capacity to 100% when you re-calibrated the meter the 75% will be 75% of whatever the actual capacity is.

 

 

Just a thought Tony and I know this applies on my boats with BMV 602s. The meter reads amps out and amps in. If the meter is correctly set, the meter will make allowances for the charging overheads and the net result should be, at least when the correct number of amps have been put back in. The meter amps used reading will be at zero or very near zero +or-.Personally that is the point at which I start checking tail current and it is not normally far off.

Link to comment
Share on other sites

 

Please read the post and do not miss out a vital few words see:-

 

The basic rule for most boaters with this type of meter is to only use the amps scale while charging and keep going at least once a week until the charge drops to 1% of bank capacity or less, then manually resynchronise the meter. Then you can note the Amphours out and percentage of charge and calculate the current capacity of the bank. e.g. 50Ah out that takes it to 75% of charge tells you the battery bank capacity is 200Ah because 50Ah is 1/4 of the bank capacity.

 

It should be clear that you need to fully (or as near as possible) charge the battery first - then zero it - and only then will the amp hours out be meaningful. As you had just set the capacity to 100% when you re-calibrated the meter the 75% will be 75% of whatever the actual capacity is.

 

No, I didn't miss the 'resync'. That is something I must do after every discharge and recharge cycle otherwise after only 3 cycles it will be way out and can be totally confusing. I guess what you are saying is after the resync it will be the best accuracy you are going to get. So to put it into a working example. I currently have 6 110Ah batteries. If I did such test and came up with 500Ah, just for arguments sake. If I then changed my battery bank capacity setting from 660 to 500 is it likely to be more accurate for subsequent cycles?

Link to comment
Share on other sites

The problem with amp hour counting is that electricity going out of the battery is used, but charging batteries heat as well as charge so the amphours that do the heating are lost from the charge - discharge process. Count 100AH out and count 100amphours back in neglects this IR heating loss, so for every 100AH taken out more than 100AH must be replaced.

Link to comment
Share on other sites

No, I didn't miss the 'resync'. That is something I must do after every discharge and recharge cycle otherwise after only 3 cycles it will be way out and can be totally confusing. I guess what you are saying is after the resync it will be the best accuracy you are going to get. So to put it into a working example. I currently have 6 110Ah batteries. If I did such test and came up with 500Ah, just for arguments sake. If I then changed my battery bank capacity setting from 660 to 500 is it likely to be more accurate for subsequent cycles?

 

I think the answer is yes but only for the %charged/discharged and the time left function if fitted.

Link to comment
Share on other sites

 

I think the answer is yes but only for the %charged/discharged and the time left function if fitted.

I'll give it a go thanks. The MasterVolt MICC is supposed to be self learning but as it looses roughly 10% every cycle it is easy to loose track. Worse still the used Ah count looks ridiculous as it doesnt reset so loosing -50Ah every cycle even before you start.

Link to comment
Share on other sites

Personally I would only use the amps and volts function. Amps to end charge and volts as I turn in a night to assess how discharged the batteries are. At this time of year I would do it as I got up as well before any solar kicked in.

 

You soon get to know what is typical for your boat and your use of it so when non-typical readings crop up you can either explain them or start looking for a fault.

Link to comment
Share on other sites

No, I didn't miss the 'resync'. That is something I must do after every discharge and recharge cycle otherwise after only 3 cycles it will be way out and can be totally confusing. I guess what you are saying is after the resync it will be the best accuracy you are going to get. So to put it into a working example. I currently have 6 110Ah batteries. If I did such test and came up with 500Ah, just for arguments sake. If I then changed my battery bank capacity setting from 660 to 500 is it likely to be more accurate for subsequent cycles?

 

That would suggest (to me, anyway) that the batteries may not be getting fully charged. Kelpie has a Merlin AH/ammeter/voltmeter, as well as a Smartgauge, and I find it tends to re-synch early, even after adjusting various "fiddle factors".

 

I have adjusted the battery capacity on the gauge to match calculated capacity, and the percentage readings then agree roughly with the Smartgauge, but it's a never ending task, as the calculated capacity will go up if the batteries are FULLY charged for several days in a row. (My calculated capacity is still well below ( about 25%) the nominal capacity, though.

Link to comment
Share on other sites

 

 

That would suggest (to me, anyway) that the batteries may not be getting fully charged.

 

I used to think so but even after several days on mains power, switching charger off and back on several times % charge would not rise above 92% and show amps-50. Yet the charge current would be less than 5% of battery capacity. If I don't resync next time it would be 86% and - 100 amps and so on.

Link to comment
Share on other sites

On Kelpie, I also find that the battery charger goes into float MUCH too early, such that it takes well over 24 hours to get the Smartgauge to 100%. (Not a problem for us, as the alternator does the job, usually)

 

(I know, it's RTFM timecheers.gif )

Link to comment
Share on other sites

On Kelpie, I also find that the battery charger goes into float MUCH too early, such that it takes well over 24 hours to get the Smartgauge to 100%. (Not a problem for us, as the alternator does the job, usually)

 

(I know, it's RTFM timecheers.gif )

 

Not really. This is a well known problem with "intelligent" chargers - more like as thick as a plank when it comes to deciding when to drop to float.

 

The only thing you need to read up on is how to disable adaptive charging and then, when on shoreline use the charger more like you use the alternator by turning it off when the charging current falls to about 1% at ABSORPTION voltage - not float voltage unless you are going to turn a heavy load on.

 

Edited to add I think that you will find the Smartguage manual actually says it can be up to 10% out when charging. I understand it sorts itself out soon after stopping charging. Sounds to me as if you're OK.

Edited by Tony Brooks
Link to comment
Share on other sites

Thanks Tony.

 

The charger and alternator are two very different beasts when it comes to charging. The alternator does it for us in between 4 to 6 hours, whereas the charger doesn't. I'm pretty sure the charger only needs a round tuit, which I'll get sometime. cheers.gif

 

So far, we've really only used the battery charger once, when we were moored at an event. Neither it nor the portable solar panel did much!

 

(The solar problems have been sorted, mainly rubbish connections.)

Link to comment
Share on other sites

I have a NASA BM2.

 

If I charge until Ah in are around 1% of capacity, (say, 4Ah), then use say, 200Ah, then charge until the BM2 shows I've put 200Ah in, the batteries are still generally drawing around 40Ah, so obviously not fully charged.

 

I usually find the BM2 has to show about 40 more Ah put in before the Amps being drawn are around 4Ah. This is about 4 more hours of charging.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.