How do I know if my battery is fading out?

[sailinglegend420]

I have seen it suggested that leisure type batteries should never be drop-tested as their plates are not robust enough to take it, unlike those of starter batteries.

That's a very interesting point that I have not heard before but it does make a lot of sense. Most of these drop testers are clearly sold as starter battery testers. Starter batteries take a very large current for a very short time. Deep Cycle "leisure" batteries take a very small current for a very long time. Many are "Dual Purpose" and are therefore a "compromise" so they do neither job very well.

 

[Hydrozoan]

So, my personal summary of this discussion is that the extended load test (as described by jwilson, and elaborated to cover voltage recovery by ianj99) is the best test for domestic leisure batteries - albeit that different users may apply somewhat different criteria to the results (William_H). It takes more time and effort (though less cost) than a drop-tester, but tests the capacity of domestic leisure batteries under conditions which reasonably simulates their actual use and avoids subjecting them to loads for which they are not designed.

It's what I have done in the past and am about to do again - so my thanks for a timely and helpful discussion. (I would probably not have thought a drop tester worthwhile for me anyway, but am grateful for the cautions about their use.)

 

[GHA]

So, my personal summary of this discussion is that the extended load test (as described by jwilson, and elaborated to cover voltage recovery by ianj99) is the best test for domestic leisure batteries - albeit that different users may apply somewhat different criteria to the results (William_H). It takes more time and effort (though less cost) than a drop-tester, but tests the capacity of domestic leisure batteries under conditions which reasonably simulates their actual use and avoids subjecting them to loads for which they are not designed.

It's what I have done in the past and am about to do again - so my thanks for a timely and helpful discussion. (I would probably not have thought a drop tester worthwhile for me anyway, but am grateful for the cautions about their use.)

Or to be specific and have something to compare with original spec, which is usually in aH at 20 hour discharge rate, have a load which is a twentieth of the capacity and it should last for 20 hours before the voltage goes down to 10.5v for a brand new battery.
But difficult to do exactly as the current draw will change as the voltage goes down. Hopefully in a day or so I should have some pretty graphs of voltage and amps as this happens.

 

[cryan]

That's a very interesting point that I have not heard before but it does make a lot of sense. Most of these drop testers are clearly sold as starter battery testers. Starter batteries take a very large current for a very short time. Deep Cycle "leisure" batteries take a very small current for a very long time. Many are "Dual Purpose" and are therefore a "compromise" so they do neither job very well.

The difference between most common starter and leisure batteries is the sticky label stuck to them. Proper deep cycle batteries are quite rare on leisure boats. Oh and for the record all the leckys I worked with at sea had been tested on their competency and licensed. The testers were used for testing starter batteries on emergency generators and lifeboats.

 

[Hydrozoan]

Or to be specific and have something to compare with original spec, which is usually in aH at 20 hour discharge rate, have a load which is a twentieth of the capacity and it should last for 20 hours before the voltage goes down to 10.5v for a brand new battery.
But difficult to do exactly as the current draw will change as the voltage goes down. Hopefully in a day or so I should have some pretty graphs of voltage and amps as this happens.

Yes indeed, which is why a car headlamp bulb load (ca 4-5 amp draw) is convenient - though different users may of course still think differently about how far off original specification merits battery replacement. And not an exact business, anyway, as you say - but may we look forward to seeing your graphs?

 

[vyv_cox]

The difference between most common starter and leisure batteries is the sticky label stuck to them. Proper deep cycle batteries are quite rare on leisure boats.

I suggest you read this http://www.advancedbatterysupplies.co.uk/press49differencebetweencarbatteryandleisurebattery.html

 

[cryan]

I suggest you read this http://www.advancedbatterysupplies.co.uk/press49differencebetweencarbatteryandleisurebattery.html

And I counter with http://www.sterling-power.com/support-faq-2.htm
Paragraph 7 under the "Brutal Truth" heading.

 

[sailinglegend420]

And I counter with http://www.sterling-power.com/support-faq-2.htm
Paragraph 7 under the "Brutal Truth" heading.

This article by Mr Charles Sterling is the biggest load of rubbish on the net that talks about batteries - and it has been dismissed by everyone who really knows what they are talking about. This is a VERY OLD article that dismissed all sealed batteries because his chargers were not designed for them. Since about 2009 he introduced "power pack" mode which keeps the charge at Float voltage whilst still supplying boat load currents. He also dismisses AGM batteries in such an ignorant way that I have lost all faith in his products - although many of them do appear to to be quite good and well priced.

His article is really comparing Leisure batteries with Open wet lead acid - I don't think he really believes starter batteries and deep cycle are the same.

I agree with one thing he says - sealed batteries will not have a long life on a boat. I would say that if they can be equalized, like AGMs from Lifeline and Fullriver, then they are OK.

 

[vyv_cox]

I have sealed 'dual purpose' batteries in Greece and in UK, both by Bosch. They seem to perform well but are not old enough yet to judge overall. the Greek ones are the older ones, three years. If I had gone for open cellleisure ones they would have had to be ordered specially from Athens, at a considerable increase in cost.

I bought the UK ones on recommendation from Windjammer at Milford Haven, based on their good and long experience with them. They are a yard whose opinion I respect, so I went with them.

 

[GHA]

- but may we look forward to seeing your graphs?

Got something up and running tonight, still plenty of hurdles to jump, like the voltage calibration doesn't seem to be linear, it's a bit low on the graph, was closer to 12.4v under load. And still need to sort out a transistor triggering a solenoid to turn it off automatically when lower voltage limit is reached. Current seems pretty close to the clamp meter reading.
But potentially useful
And not too expensive, tenner for the main arduino board, something like £15 for the sd card reader/writer, fiver for the current sensor. Plus lots more for the various meters, breadboard etc which have accumulated.