How to test and assess a second-hand leisure battery?

[alan_fincher]

Alan,

Its a shame that Gibbos gone.

All my batteries die from reduced specific gravity when fully charged but maybe that says something about how I look after them!

A full SG suggests that all the lead suphate is turned bck into sulphuric acid which should be a good battery.

What I am not sure about is what the normal "plate corrosion" does to the fully charged specfiic gravity, maybe this can give a battery that looks good but has very low capacity? Forum needs a new battery expert!

 

.............Dave

Trying to think back, Gibbo couldn't really explain the circumstances surrounding one particular battery I had, but variously offered two explanations that went beyond normal sulphation.....

 

1) Partial failure of one of the internal connections between cells - resulting in a resistance and volts drop across it.

 

2) Substantial shedding of the plate surfaces, but not in a way that actually shorted any cell.

 

Either way, given the batteries had only had light use, and were well under 3 years old, the suspicion was poor manufacture, rather than poor maintenance.

 

I realise whatever had gone wrong may have been untypical, but the worrying thing is it would charge to full voltage, and show a fully healthy SG in every cell, so I'm confident that those two things alone are not full proof of a usable battery.

[dmr]

The plate shedding might be the answer. From my understanding this is the normal ageing process in a battery.

Sulphation is a premature death that really should not happen, but inevitably does where boats are involved, especially off grid liveaboards.

Not sure about a poor connection, I suppose if you charged such a battery for a very long time then it could reach full charge/specific gravity even with a poor connection,

How could we test for a poor internal connection?...oh my god...........Bizzard has got it right!

 

..............Dave

[bizzard]

[Taslim]

Allan Jones' advice, (i.e. "Keeping Up"), is spot on in my view.

 

I intend to do similar with all three batteries currently in Sickle's "domestic" bank, to assess which still have a useful life, and which need swapping out. (They are of different ages, so some are expected to be worse than others).

 

Bear in mind that if the bulb has gone noticeably dimmer by the end of the test, you were no longer drawing amps at the same rate, so you need to adjust any estimate you make about "surviving capacity" to allow for the current slowly falling as you did the test.

 

I don't think drop testing is really a useful test of leisure batteries. A starter battery needs to be able to deliver hundreds of amps, but only for seconds, usually. Leisure batteries are usually only required to deliver "tens" of amps, (often less), but for many hours. A battery may be perfectly fine for this, but quite unable to perform as a starter, if you attempted to use it in that way.

True. Living on a shoe string I have used old tractor & truck batterys that that won't crank an engine as domestics and, treated with respect, they have given good service. A local scrap yard swaps my £10 & seriously knackered battery for the replacement.

 

taslim.

[Justme]

stage 1. take to scrappy

 

stage 2. collect 30p per kilo

 

stage 3. go to pub

 

 

Try a better scrappy. The going rate is 45p per kg

[smileypete]

This has not been my experience, and I have scrapped not particularly old batteries that will charge to the maximum volts you might expect, and where every cell has an SG that indicates it is fully charged.

 

I reckon I have at least one in my current bank of three that is in this state now. I separated them all some days ago, and none were down on volts, and the SGs of all cells in all are good, but I know from last year that the bank is getting beyond being able to go much over a day tied up anywhere without running the engine.

 

The problem is that if you say a battery is good based just on voltage and SG, you really don't know if you add it to an existing bank how much it is contributing, (or not).

 

I'll see if I can find the thread on a battery I had that nobody could really explain away - I certainly couldn't!

I remember that one, I suggested doing some comparative tests with a probe just in the electrolyte and Gibbo had one of his funny turns So do I miss Gibbo? not really...

 

http://www.canalworld.net/forums/index.php?showtopic=36715

 

Reading in between the lines it sounded like the SG had got too high, maybe due to insufficient topping up, and it fell apart internally, more so if it was a cheapo leisure batt which can be quite variable.

 

So I think basic handling precautions, maintenance, and monitoring are best to start with, there's plenty in The Battery FAQ.

 

ETA For (careful!) playing around with nearly duff batts a cheapo watt analyser could be quite handy to have:

 

http://www.buyincoins.com/new_en/details/new-digital-60v-100a-battery-balance-lcd-voltage-power-analyzer-watt-meter-product-25818.html

 

 

cheers, Pete.

~smpt~

Edited April 15, 2013 by smileypete

[Keeping Up]

I just wish I could stop my boat from eating batteries.

 

In the past I'd always had at least 4 years use from my leisure batteries, then a couple of years ago I bought a new set of 4 and the boat destroyed them within 6 weeks. The replacement set also lasted only 6 weeks; the next set did a bit better and I got nearly 3 months use from them. I've just done an extended test using a couple of new US2200's which the battery supplier kindly loaned me. After just 3 weeks of careful use and intense monitoring of voltages and current throughout, they are now looking distinctly second hand with the SG apparently incapable of getting above 1200. This is despite discharging by only 85-90 Ah each evening/overnight, charging every day at 14.8 volts, with a 70-amp alternator controlled by an Adverc until they took negligible charging current, and including at least 7 hours charging every other day.

 

It's a real puzzle, and if really good batteries like the US2200 can go down so quickly the only solution I can see is to buy the very very cheapest batteries and expect to replace them monthly. Maybe it would work out cheaper if I just used AA cells from the nearest Pound-shop.

[alan_fincher]

I just wish I could stop my boat from eating batteries.

It's not that use of a "rotary converter" for generating large amounts of 230V AC, is it Allan?

 

(That was tongue in cheek, BTW).

[Keeping Up]

It's not that use of a "rotary converter" for generating large amounts of 230V AC, is it Allan?

 

(That was tongue in cheek, BTW).

 

Only if Pingu has been having secret hair-drying sessions in the middle of the night!

[smileypete]

I just wish I could stop my boat from eating batteries.

 

In the past I'd always had at least 4 years use from my leisure batteries, then a couple of years ago I bought a new set of 4 and the boat destroyed them within 6 weeks. The replacement set also lasted only 6 weeks; the next set did a bit better and I got nearly 3 months use from them. I've just done an extended test using a couple of new US2200's which the battery supplier kindly loaned me. After just 3 weeks of careful use and intense monitoring of voltages and current throughout, they are now looking distinctly second hand with the SG apparently incapable of getting above 1200. This is despite discharging by only 85-90 Ah each evening/overnight, charging every day at 14.8 volts, with a 70-amp alternator controlled by an Adverc until they took negligible charging current, and including at least 7 hours charging every other day.

Are they sitting on a cold counter? If so they could be 'stratifying' where the acid is stronger at the bottom and weaker at the top, instead of being evenly mixed. Shallower discharge/charge cycles are just likely to make it worse. There's an explanation in The Battery FAQ where it's mentioned a few times:

 

http://jgdarden.com/batteryfaq/carfaq14.htm#concrete

https://www.google.co.uk/search?q=site%3Ajgdarden.com+stratification

 

You could try charging/equalizing at C/30 up to 15.5V for 3-6 hours, to get them gassing and helping the acid to mix well. There's more info on the US Battery site, including temperature compensation of the absorption charge voltage.

 

Don't overlook making sure the batts are properly topped up too. It might take a while to get full performance back if the bottom of the plates have got sulphated.

 

If generating the higher voltage is a problem, you could try doing it with an unregulated solar panel or power supply with a current limiting resistor if need be. Or use the start batt alt/charger with a couple of current limiting DC-DC converters:

 

http://www.ebay.co.uk/itm/DC-DC-600W-10-60V-to-12-80V-Boost-Converter-Step-up-Module-car-pc-Power-Supply-/290896438192

 

cheers, Pete.

~smpt~

Edited April 15, 2013 by smileypete

[Keeping Up]

They are inside a plastic battery-box (about 5mm thick) which itself sits on the baseplate. I did have a max/min thermometer in the box too, but somehow a bit of mercury got the wrong side of the marker so it won't record the minimum temperature any more.

 

The thing that really surprised me, given that they were being charged daily, was that after just 2 weeks the SG was refusing to rise above 1210. It's almost as if they weren't being charged at all.

 

ETA The other thing that really surprised me, was that at the end of day 1 and of day 2, after wiping off the surface charge by applying a 10 amp load for 30 minutes the open-circuit voltage was 12.6v, but at the end of day 3 it was 12.9v. Over the next 3 weeks it steadily and gradually reduced to 12.8v

Edited April 15, 2013 by Keeping Up

[carlt]

and skin that's like a well worn leather driving glove. :-) :-)

 

Darren

Note to self...."Never, ever, under any circumstances, borrow Darren's gloves."

[dmr]

Keeping Up.....

 

My own experience (with Trojans) is that once any sulphation sets in they will never get to full charge/full SG, not even with an 8 hour charge, the only answer is to equalise them, much as Pete has said. Sulphation starts to happen after about a week of 2 hour charges!.

You say you have been giving yours a full charge every couple of days so I am really surprised that you are having trouble.

 

The manufacturers instructions for Trojan/US/Crown all suggest that these batteries should be finished off with a bit of high voltage (15.5 ish) at the end of every charge cycle, though I suspect very few ever get this luxury.

 

Trojan technical man suggested to me that charging at a fixed 15v might be a good compromise in a liveaboard boat!

 

...........Dave

[Keeping Up]

One problem with finishing off the charge with "a bit of high voltage" is that it can also finish off some of the electrical equipment that you have connected

[dmr]

This is a rel concern!. we have had no trouble yet (he says touching lots of wood).

Quite a lot of stuff is rated at up to 16v,. the more recent LED lights are rated even higher.

We have one or two halogen bulbs left and surprisingly these have been ok so far.

The water pump runs noticable faster at 15.5 volts!

 

I used to turn everything off when we equalised but have got progressively more relaxed about this over the last year

 

..........Dave

[Hawkmoth]

The only thing that yells foul in our boat when equalizing is the heating system crying voltage fault.

[bizzard]

Ah this was the one. Could a Mod please move my post concerning Mike the boilerman from the MK2 thread to this one.

[magnetman]

maybe he is in hostipal with burns to his tongue from doing the 'taste test' on the battery acid to estimate the SG of each cell. a dead cell does taste different to a good one

[smileypete]

The thing that really surprised me, given that they were being charged daily, was that after just 2 weeks the SG was refusing to rise above 1210. It's almost as if they weren't being charged at all.

Yeah, but on the US Battery site, they have a PDF download on charging:

 

http://www.usbattery.com/usb_faqs.html

 

Which goes on to say:

 

'The charging process is intended to fulfill several objectives. First, the charging process should replace the capacity(in amp-hours) removed from the battery during previous discharges. Second, the charging process should return additional capacity (in amp-hours) to offset the thermodynamic inefficiencies inherent in the charging process. This additional capacity can be measured as a charge factor calculated by: charge Ah in / discharge Ah out. The charge factor varies with temperature, condition and age of the battery but is usually in the range of 105 - 150%. Third, the charging process should charge the battery at a voltage and/or charge rate at the end of charge that will result in controlled gassing of the electrolyte. This gassing is required to mix the electrolyte to prevent stratification. Without proper mixing of the electrolyte, the heavier acid generated during charging can sink to the bottom of the cell and will adversely affect performance and life of the battery. Finally, the charging process should result in a fully charged battery with electrolyte specific gravity that is constant over several end-of-charge readings, consistent between and among the cells of the battery pack, and within the proper range for the battery type per U.S. Battery’s specifications.'

 

Now I would almost bet good money that when the batts are 'charged' there's virtually no gassing at all whatsoever. Especially if the charge source isn't temperature compensated, plus it seems the Adverc doesn't hold a steady voltage but cycle up and down instead.

 

I'd expect unless the batts are charged and equalised more in line with US Battery's recommendations, they may not perform anywhere as well as they should do.

 

If there's stuff that doesn't like equalisation voltages, maybe supply them via a couple of meaty diodes (in the form of a bridge rectifier) to drop some voltage, then if need be use a switch or changeover relay to bypass them the rest of the time:

 

http://www.ebay.co.uk/itm/KBPC3510-Bridge-Rectifier-x1-KBPC-3510-KBPC35-10-35A-amp-1000V-/320973605982

http://www.ebay.co.uk/itm/5-Pin-12v-40A-CHANGE-OVER-RELAY-For-Aux-Lights-Horns-etc-Car-Boat-Van-Motorbike-/360493356210

 

cheers, Pete.

~smpt~

Edited April 16, 2013 by smileypete

[Starcoaster]

He's been away from the PC until tonight, chill dudes!

One of the batteries in question is currently in Springy, where it is proving at least a little bit more effective than the one it replaced: which was, in fact, totally dead. Meaning I had in effect been running on one battery (that's one in total, not one starter and one leisure) for some time.

[magnetman]

Yeah, but on the US Battery site, they have a PDF download on charging:

 

http://www.usbattery.com/usb_faqs.html

 

Which goes on to say:

 

'The charging process is intended to fulfill several objectives. First, the charging process should replace the capacity(in amp-hours) removed from the battery during previous discharges. Second, the charging process should return additional capacity (in amp-hours) to offset the thermodynamic inefficiencies inherent in the charging process. This additional capacity can be measured as a charge factor calculated by: charge Ah in / discharge Ah out. The charge factor varies with temperature, condition and age of the battery but is usually in the range of 105 - 150%. Third, the charging process should charge the battery at a voltage and/or charge rate at the end of charge that will result in controlled gassing of the electrolyte. This gassing is required to mix the electrolyte to prevent stratification. Without proper mixing of the electrolyte, the heavier acid generated during charging can sink to the bottom of the cell and will adversely affect performance and life of the battery. Finally, the charging process should result in a fully charged battery with electrolyte specific gravity that is constant over several end-of-charge readings, consistent between and among the cells of the battery pack, and within the proper range for the battery type per U.S. Batterys specifications.'

 

Now I would almost bet good money that when the batts are 'charged' there's virtually no gassing at all whatsoever. Especially if the charge source isn't temperature compensated, plus it seems the Adverc doesn't hold a steady voltage but cycle up and down instead.

 

I'd expect unless the batts are charged and equalised more in line with US Battery's recommendations, they may not perform anywhere as well as they should do.

 

If there's stuff that doesn't like equalisation voltages, maybe supply them via a couple of meaty diodes (in the form of a bridge rectifier) to drop some voltage, then if need be use a switch or changeover relay to bypass them the rest of the time:

 

http://www.ebay.co.uk/itm/KBPC3510-Bridge-Rectifier-x1-KBPC-3510-KBPC35-10-35A-amp-1000V-/320973605982

http://www.ebay.co.uk/itm/5-Pin-12v-40A-CHANGE-OVER-RELAY-For-Aux-Lights-Horns-etc-Car-Boat-Van-Motorbike-/360493356210

 

cheers, Pete.

~smpt~

I miss Chris W in this sorts of thread, does anyone know where he's gone and if he still has his fabulously valuable monkey puzzle trees?

 

Peukerts exponent and all that

[alan_fincher]

I miss Chris W in this sorts of thread, does anyone know where he's gone and if he still has his fabulously valuable monkey puzzle trees?

 

Peukerts exponent and all that

 

Chris W moors his boat where we keep one of ours, and we do see him from time to time, but I know nothing of monkey puzzle trees.

 

I have a strange feeling that he does pop up here occasionally under another name, but I've never challenged him on the topic!

[dmr]

Yeah, but on the US Battery site, they have a PDF download on charging:

 

http://www.usbattery.com/usb_faqs.html

 

Which goes on to say:

 

'The charging process is intended to fulfill several objectives. First, the charging process should replace the capacity(in amp-hours) removed from the battery during previous discharges. Second, the charging process should return additional capacity (in amp-hours) to offset the thermodynamic inefficiencies inherent in the charging process. This additional capacity can be measured as a charge factor calculated by: charge Ah in / discharge Ah out. The charge factor varies with temperature, condition and age of the battery but is usually in the range of 105 - 150%. Third, the charging process should charge the battery at a voltage and/or charge rate at the end of charge that will result in controlled gassing of the electrolyte. This gassing is required to mix the electrolyte to prevent stratification. Without proper mixing of the electrolyte, the heavier acid generated during charging can sink to the bottom of the cell and will adversely affect performance and life of the battery. Finally, the charging process should result in a fully charged battery with electrolyte specific gravity that is constant over several end-of-charge readings, consistent between and among the cells of the battery pack, and within the proper range for the battery type per U.S. Battery’s specifications.'

 

Now I would almost bet good money that when the batts are 'charged' there's virtually no gassing at all whatsoever. Especially if the charge source isn't temperature compensated, plus it seems the Adverc doesn't hold a steady voltage but cycle up and down instead.

 

I'd expect unless the batts are charged and equalised more in line with US Battery's recommendations, they may not perform anywhere as well as they should do.

 

If there's stuff that doesn't like equalisation voltages, maybe supply them via a couple of meaty diodes (in the form of a bridge rectifier) to drop some voltage, then if need be use a switch or changeover relay to bypass them the rest of the time:

 

http://www.ebay.co.uk/itm/KBPC3510-Bridge-Rectifier-x1-KBPC-3510-KBPC35-10-35A-amp-1000V-/320973605982

http://www.ebay.co.uk/itm/5-Pin-12v-40A-CHANGE-OVER-RELAY-For-Aux-Lights-Horns-etc-Car-Boat-Van-Motorbike-/360493356210

 

cheers, Pete.

~smpt~

Two things puzzle me,

 

I believe Trojan, Crown and US all make batteries with pretty similar construction so its interesting they suggest different charge regimes.

But more puzzling........

Lots of people are using Trojans on boats and I imagine very few (if any) are doing a high voltage end of charge, I suspect most just use i14.8, so why don't we hear more about problems with low specific gravity? People generally say tht their Trojans last really well?????

 

..........Dave

[smileypete]

I miss Chris W in this sorts of thread, does anyone know where he's gone and if he still has his fabulously valuable monkey puzzle trees?

 

Peukerts exponent and all that

Not Commandant Peukert, spare me!!!

 

I believe Trojan, Crown and US all make batteries with pretty similar construction so its interesting they suggest different charge regimes.

But more puzzling........

Lots of people are using Trojans on boats and I imagine very few (if any) are doing a high voltage end of charge, I suspect most just use i14.8, so why don't we hear more about problems with low specific gravity? People generally say tht their Trojans last really well?????

True, maybe they get lucky or never look at the SG or don't use them that hard and get by OK somehow, who knows?

 

With any kit if and when it goes wrong, a good first step is to 'read the fine manual'

 

cheers, Pete.

~smpt~

Edited April 16, 2013 by smileypete

[MtB]

Thank you far all the repies everyone.

 

I was using my coolbox to test the battery. I was hooking it up, taking a note of the time, then coming back to it after five hours (for example) and finding voltage had dropped to 11.8v (for example) with the load still attached, then forgetting about it for another ten hours and noting a terminal voltage of about 4.3v, or something ludicrously low.

 

But then after fitting it to Coasty's bote as an experiment, it was able to turn over the engine enthusiastically for at least two or three minutes before I released the key, six weeks after being discharged by my test 'method'. Puzzling, unless I charged it in the interim without remembering!

 

But I was hoping for something sort of constant current method. The current obviously reduced as battery voltage falls. And the battery seems to behave a whole lot better installed than my test results suggested it was going to.

 

I'll go and read Alans MkII thread now!

 

MtB