Equalising

[WotEver]

And the answer to how long depends on all sorts of variable factors, the time for our batteries to reach max charge varied from 24hrs to 3+ days, not achievable when off grid so it has to accepted that batteries will always be treated less than ideally.

Absolutely. For off-grid it's always a balance between hassle, time, engine wear, and fuel costs vs cost of replacement batts.

 

Now here's a curious thing. The de-sulphation cycle runs for three hours then reverts to float according to my Sterling Pro Charge Ultra manual.

 

I started the desulphation cycle running at 12 midday exactly and now, at 3.35pm, more than three and a half hours later it is still in de-sulphation mode. Why hasn't it turned OFF and reverted to float? Could the length of the cycle have been increased as temperature compensation perhaps?

 

Its desulphating at a rock solid 31.35V. The starting current was 6.28A and the current now after 3.5 hrs is 4.60A. All cells bubbling steadily.

Maybe (and it's a BIG maybe) the charger is intelligent enough to see that the current is slowly dropping so it's continuing until that stops.

 

But like I say, that's a huge maybe.

[MtB]

The charger has reverted to float now, after 4hrs 5mins of equalising.

 

SG of that low cell is 1.254 now (exactly the same as it was after my last equalise).

 

I've now set up the current pump to equalise a bit longer in silence, until the donor battery expires!

[cuthound]

If the batteries are badly sulphated, then you will need to repeat the equalisation as frequently as possible, until either the lead sulphate is converted back, or you realise that you cannot increase capacity because the sulphate is now unconvertable.

[nicknorman]

The charger has reverted to float now, after 4hrs 5mins of equalising.

 

SG of that low cell is 1.254 now (exactly the same as it was after my last equalise).

 

I've now set up the current pump to equalise a bit longer in silence, until the donor battery expires!

1.254 at 25C is around 88% charged. Presuming you are measuring at somewhat less than 25C then it is perhaps 85%. So it's not as though the batteries should have lost a lot of capacity (and the other cells, one presumes, are better). Bear in mind that if the total capacity is 85% or original, when you take the batteries down to 50% SoC you don't just get 35% of the original capacity, you get 85% of 50% ie 42.5%

 

Trojan recommends equalising only the fully charged gravity is less than 1.250 at 25C, or with a split of more than .030 between cells. So it would seem you just about out of the state where Trojan would recommend an equalise (guessing that your 1.254 roughly equals 1.250 at the higher temperature).

 

So if you still think your capacity is way down, something else is wrong such as a bad connection somewhere.

[MtB]

Thanks Nick.

 

 

1.254 at 25C is around 88% charged. Presuming you are measuring at somewhat less than 25C then it is perhaps 85%.

 

 

This bit troubles me. Why does the SmartGauge say 100% then? Or does it mean that particular cell is charged to 100% of its reduced capacity?

 

Dave says 12 cells in series means the whole bank is only as good as the weakest cell. I wonder if I should replace that one battery...

 

 

 

(and the other cells, one presumes, are better).

 

Yes the best cell (opposite end of the same battery) measured at the same time was 1.269, measured on a prism kept in the warm bit of the boat at about 20C.

 

 

Now I'm using the current pump the cells ARE still coming up. That low cell has risen from 1.254 to 1.266 in the last 40 minutes. And the high cell has risen from 1.269 to 1.278.

 

Looks as though there is hope for that battery yet!

[WotEver]

Thanks Nick.

 

Why does the SmartGauge say 100% then? Or does it mean that particular cell is charged to 100% of its reduced capacity?

The latter, yes.

[nicknorman]

Thanks Nick.

 

This bit troubles me. Why does the SmartGauge say 100% then? Or does it mean that particular cell is charged to 100% of its reduced capacity?

 

Yes it means that the battery is (roughly) charged to 100% of its reduced / available capacity. A battery with some of its sulphur locked away as hard crystals of sulphate, is very similar to a battery of smaller capacity. One has to bear in mind that during charge, the SG doesn't really know what the batteries are doing, it only "sees" the charger's voltage. But I knows that if you start at x% SoC, charge it at voltage y, it will be fully charged after time z. The size/capacity of the battery bank doesn't come into this formula since as we know, provided the charger is capable of supplying enough current to follow a certain voltage profile, a small battery will take the same amount of time to fully charge as an enormous one.

Yes the best cell (opposite end of the same battery) measured at the same time was 1.269, measured on a prism kept in the warm bit of the boat at about 20C.

Now I'm using the current pump the cells ARE still coming up. That low cell has risen from 1.254 to 1.266 in the last 40 minutes. And the high cell has risen from 1.269 to 1.278.

 

Looks as though there is hope for that battery yet!

So the cells at 1.278 don't need any more equalising. Perhaps you should move the current pump so it just charges the one battery with the low cell (reduce the voltage of course!) as this will then only use 1/4 the AH out of the donor battery.

 

Anyway, it sounds as though your batteries should pretty much have their original capacity (presuming you can get that one cell up to 1.27something).

[MtB]

Yes it means that the battery is (roughly) charged to 100% of its reduced / available capacity. A battery with some of its sulphur locked away as hard crystals of sulphate, is very similar to a battery of smaller capacity. One has to bear in mind that during charge, the SG doesn't really know what the batteries are doing, it only "sees" the charger's voltage. But I knows that if you start at x% SoC, charge it at voltage y, it will be fully charged after time z. The size/capacity of the battery bank doesn't come into this formula since as we know, provided the charger is capable of supplying enough current to follow a certain voltage profile, a small battery will take the same amount of time to fully charge as an enormous one.

 

So the cells at 1.278 don't need any more equalising. Perhaps you should move the current pump so it just charges the one battery with the low cell (reduce the voltage of course!) as this will then only use 1/4 the AH out of the donor battery.

 

Anyway, it sounds as though your batteries should pretty much have their original capacity (presuming you can get that one cell up to 1.27something).

 

 

Yes this was running through my mind too, but the current pump voltage won't go down enough when fed from the 24v donkey bank. I'll try it on a 12v battery tomorrow.

 

Anyway I've had to turn the current pump off now as its bellringing tonight. On disconnection the low cell had come up to 1.268 and the high cell was 1.279. So suddenly it all looks rather promising.

[RD1]

 

...Anyway I've had to turn the current pump off now as its bellringing tonight...

 

 

[Iain_S]

If you monitor the specific gravity during the desulphation process, you will hopefully see it rising slowly. It is time to stop the desulphation process when the gravities no longer increase.

 

If the cells are bubbling, the specific gravity will continue to increase, surely?

[dmr]

 

If the cells are bubbling, the specific gravity will continue to increase, surely?

 

I believe that the bubbling is electrolysis (breaking the water down into hydrogen and oxygen) and is an unwanted by-product of equalisation, or any higher voltage charging. However it does stir up the acid a bit so does have some use. If we could charge hard without bubbling then the chore of topping up batteries would be avoided.

 

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

[dmr]

 

 

Yes this was running through my mind too, but the current pump voltage won't go down enough when fed from the 24v donkey bank. I'll try it on a 12v battery tomorrow.

 

Anyway I've had to turn the current pump off now as its bellringing tonight. On disconnection the low cell had come up to 1.268 and the high cell was 1.279. So suddenly it all looks rather promising.

 

Those SGs are now getting reasonable (though it will depend a bit on temperature). Do a bit more equalising as soon as you can and see if you can get them even higher.

Fully charge and check the SGs again in a few weeks time and if the same cell is low again that would suggest it might be worth replacing that single battery.

 

Spent all day trying to fix internet connection problems (and still struggling) so have been on loads of forums, really makes ya appreciate this one....people actually answer questions here.

 

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

[WotEver]

 

Spent all day trying to fix internet connection problems (and still struggling) so have been on loads of forums, really makes ya appreciate this one....people actually answer questions here.

 

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

What's the problem, Dave? Lots of folk on here know a thing or two too...

 

T

[nicknorman]

If the cells are bubbling, the specific gravity will continue to increase, surely?

Yes. But the specific gravity will increase for 2 reasons. The first is that hard sulphate crystals are being dissolved back into sulphuric acid. This is a relatively rapid process in terms of rate of rise of sg. The second is the dissociation of water into hydrogen and oxygen. This is a relatively slow process in terms of rate of rise of sg since the sg only rises due to water loss. So once all the sulphate is converted, the rate of rise of sg will markedly decrease until it seems to be zero to the causal observer.

 

Alternatively I suppose one could top up the electrolyte to its nominal level before checking the sg (and after waiting for it to get properly mixed up)

[dmr]

What's the problem, Dave? Lots of folk on here know a thing or two too...

 

T

 

Should perhaps start a new thread rather than risk hijacking a good battery thread so if anybody can help please PM me and I will start one.

 

yeah I thought I understood computers too. Laptop connects via wifi to a TP Link router with a 3g dongle plugged into it. Has worked ok for ages. Today cant connect to the router and troubleshooter gives a message about IP address issues. After much messing about can fix it by setting fixed IP address so looks like DHCP is not working. Don't really want fixed IP addresses...might give trouble in wifi hotspots. Have tried all the ipconfig/release type things. Other devices on the boat all connect to router ok.

Maybe a red herring but this started after I tested out if I could connect to Gillies new iPhone wifi hotspot, which did work at first.

Has Apple somehow broken the DHCP in Windows (10)?.

My pretentious laptop does not have a cable network connection, have just ordered a USB adaptor.

 

and I did a little equalisation yesterday.

 

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

[cuthound]

Sounds like the lead sulphate crystals are beginning to break down at last. Keep equalising until sg readings are approximately the same acrossie the bsttery.

 

In my experience it is not unusual for a badly sulphated battery to need to be equalised for some without result, then suddenly begin to charge. I have always always assumed that this is the point when the lead sulphate crystals begin to break down and be absorbed back into the sulphuric acid.

 

Edited to correct autowrong.

Edited January 10, 2017 by cuthound

[WotEver]

 

Should perhaps start a new thread rather than risk hijacking a good battery thread so if anybody can help please PM me and I will start one.

 

yeah I thought I understood computers too. Laptop connects via wifi to a TP Link router with a 3g dongle plugged into it. Has worked ok for ages. Today cant connect to the router and troubleshooter gives a message about IP address issues. After much messing about can fix it by setting fixed IP address so looks like DHCP is not working. Don't really want fixed IP addresses...might give trouble in wifi hotspots. Have tried all the ipconfig/release type things. Other devices on the boat all connect to router ok.

Maybe a red herring but this started after I tested out if I could connect to Gillies new iPhone wifi hotspot, which did work at first.

Has Apple somehow broken the DHCP in Windows (10)?.

My pretentious laptop does not have a cable network connection, have just ordered a USB adaptor.

 

and I did a little equalisation yesterday.

 

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

Very common problem according to Google, Dave. The most oft-repeated "fixed it!" solution appears to be to run the command

net stop dhcp

 

followed by

shutdown /r /f /t 0

 

and then following the relevant steps described at "https://support.microsoft.com/en-us/help/10741/windows-10-fix-network-connection-issues"

 

Good luck

 

Edited to add the word 'relevant'

 

Another approach: http://www.sysprobs.com/fixed-windows-10-limited-connectivity-not-getting-ip-from-dhcp

Edited January 10, 2017 by WotEver

[mross]

If anybody can point me towards a smallish affordable psu than does 30 amps at 15.5v and can charge batteries then I'll get one.

Dave, how much would you pay? £228 for this https://www.reichelt.com/?LANGUAGE=EN&CTYPE=0&MWSTFREE=0&CCOUNTRY=447&ARTICLE=146018&PROVID=2788&wt_guka=22596711737_79177291337&PROVID=2788&gclid=Cj0KEQiAqdLDBRDD-b2sv6-i6MsBEiQAkT3wApHJYV3vNUT-_TUIOlSEGShS48vOhGLooimejPI9YfwaAjdQ8P8HAQ

 

I'll search eBay where there must be something cheaper.

[dmr]

Dave, how much would you pay? £228 for this https://www.reichelt.com/?LANGUAGE=EN&CTYPE=0&MWSTFREE=0&CCOUNTRY=447&ARTICLE=146018&PROVID=2788&wt_guka=22596711737_79177291337&PROVID=2788&gclid=Cj0KEQiAqdLDBRDD-b2sv6-i6MsBEiQAkT3wApHJYV3vNUT-_TUIOlSEGShS48vOhGLooimejPI9YfwaAjdQ8P8HAQ

 

I'll search eBay where there must be something cheaper.

 

Thanks, that looks quite good, I wonder if it will charge batteries (able to cope with a accidental voltage input to its output terminals). I will try to ask them.

 

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

[mross]

The PSU I have is very fussy about the order of connecting and powering up. I can't remember the order. But I imagine PSUs are often used on capacitive circuits so it should not be damaged by a voltage on the output. Please let me know what they say!

[dmr]

Yes. But the specific gravity will increase for 2 reasons. The first is that hard sulphate crystals are being dissolved back into sulphuric acid. This is a relatively rapid process in terms of rate of rise of sg. The second is the dissociation of water into hydrogen and oxygen. This is a relatively slow process in terms of rate of rise of sg since the sg only rises due to water loss. So once all the sulphate is converted, the rate of rise of sg will markedly decrease until it seems to be zero to the causal observer.

 

Alternatively I suppose one could top up the electrolyte to its nominal level before checking the sg (and after waiting for it to get properly mixed up)

 

I suspect we are getting a bit pedantic here. I think the increase in sg due to the loss off water during a typical equalisation will be so small as to be of no practical significance (though you have in effect said that). I think I put maybe 300mL into each cell each year. A rough calculation suggests that we would need to loose about 100mL to increase the sg by 10 (like 1.260 to 1.270). I just can't see a single equalisation loosing 100mL. (that would be a lot of hydrogen)

 

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

[dmr]

The PSU I have is very fussy about the order of connecting and powering up. I can't remember the order. But I imagine PSUs are often used on capacitive circuits so it should not be damaged by a voltage on the output. Please let me know what they say!

 

Just downloaded the user manual, it does rather stress that this power supply should never be used for battery charging and that device damage might occur. Suppose I could connect via a big diode, but it would need to be on a heatsink.

 

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

[nicknorman]

On another thread someone has just mentioned a Ring charger that seems at first sight to be a great idea for those wanting to charge from a genny (not me) - very cheap and with a Calcium mode that has the high finishing voltage beloved of Trojans etc, and a 4 hour reconditioning mode at up to 16v. Worth a look MtB http://www.canalworld.net/forums/index.php?showtopic=89227&p=1943031

Edited January 10, 2017 by nicknorman

[MtB]

On another thread someone has just mentioned a Ring charger that seems at first sight to be a great idea for those wanting to charge from a genny (not me) - very cheap and with a Calcium mode that has the high finishing voltage beloved of Trojans etc, and a 4 hour reconditioning mode at up to 16v. Worth a look MtB http://www.canalworld.net/forums/index.php?showtopic=89227&p=1943031

 

 

Good call Nick, except that I'd need two of them in series and I'm not sure that pulse charge at the start would necessarily synchronise!

[dmr]

 

 

Good call Nick, except that I'd need two of them in series and I'm not sure that pulse charge at the start would necessarily synchronise!

 

They do do a 24 volt version but only at 8amps which is just about enough to equalise but not a good battery charger.

If you used two with each charging a pair of batteries then there is no need to synchronise, but using two chargers is a bit undignified (naff?) even though it might actually make a better job of the charging.

 

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