battery capacity test.

[Loafer]

Cyclists are an increasing problem everywhere on the cut.

Trains? those 125's are lovely and look even better in their new GWR green livery.

If you spend a few days between Bedwyn and Crofton you might even get to see a steam special climbing up that Hill.

The Western End (After Devizes "Hill") is spectacular, despite all the old hippy liveaboards (us included?) so don't turn back next time. Avon down to Bristol can be lovely. Mooring is fine, just need a long plank.

I suspect a lot of canal boaters find themselves outside their comfort zone coming up the Kennet and get into a bad mood!

We will be off up North as soon as the Kennet settles so probably won't meet you for a beer!

 

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

 

It's possible to meet en route., although impractical to arrange, really. I wouldn't rule it out!

[Pete & Helen]

Is there a way of checking battery capacity if they are wet sealed or gel type?

[Loafer]

Is there a way of checking battery capacity if they are wet sealed or gel type?

 

Yep - fully charge 'em. Discharge with a C/20 load until about 50% SoC, judged by voltage, and occasionally resting to check. Note Amp hours consumed.

 

Times 2 = Bank capacity innit?

[cuthound]

Given the comments in another thread about batteries always taking the much same length of time to charge to 100%, could the resulting tail current after (say) ten hours of charging be used to estimate the capacity?

 

I.e. might it be roughly correct to say one's 400Ah bank actually only has a capacity of roughly 100Ah if the tail current has fallen to 1A after ten hours of charging (with a suitably large charger)?

No, tail current is an excellent messure of when a battery is fully charged, but useless at indicating capacity.

 

In a good newish battery it will eventually drop to the internal self discharge current, maybe 0.2%, but a healthy but older battery the self discharge current could be as high as 4%.

Is there a way of checking battery capacity if they are wet sealed or gel type?

See my post #3.

[smileypete]

Id like to test my Rolls 230 AGM's. 20hr rate is 210ah. Problem is there are four in a 24v system and I cant move batteries about without removing the prop shaft. Also, the (massive) cables arent long enough to swap about. My question is what can I test each battery with in the shortest possible time? Thanks

 

Charge reasonably full, check sgs are reasonably inline.

 

Then discharge to a low voltage (no less than 21V for 24V setup) with fixed heavy inverter load, measuring current.

 

Then wait a bit and estimate remaining SoC from resting voltage.

 

cheers, Pete.

~smpt~

Edited February 24, 2016 by smileypete

[Markinaboat]

Charge reasonably full, check sgs are reasonably inline.

 

Then discharge to a low voltage (no less than 21V for 24V setup) with fixed heavy inverter load, measuring current.

 

Then wait a bit and estimate remaining SoC from resting voltage.

 

cheers, Pete.

~smpt~

Thanks Pete - if the sgs you mention are specific gravity readings then this cant be done on AGM's as they're VRLA (sealed).

 

Have done this test a few times but not conclusive. Need to test batteries individually to see if one or two are dragging the others down. However, as liveaboards we need continuity of power so have to leave two connected (for 24v lighting & pumps) at anyone time. Will have to wait until I can get the prop out and then man-handle each 61kg from under the BMC floor. Either that or I could get two longer leads made up but they're at least 70mm section cables so not cheap.

[smileypete]

Thanks Pete - if the sgs you mention are specific gravity readings then this cant be done on AGM's as they're VRLA (sealed).

 

Have done this test a few times but not conclusive. Need to test batteries individually to see if one or two are dragging the others down. However, as liveaboards we need continuity of power so have to leave two connected (for 24v lighting & pumps) at anyone time. Will have to wait until I can get the prop out and then man-handle each 61kg from under the BMC floor. Either that or I could get two longer leads made up but they're at least 70mm section cables so not cheap.

 

In what way inconclusive? I'd have thought they have enough capacity, or not!

 

Sounds like 4x 6V in series, so when doing the heavy discharge I'd compare the voltage across each 6V block, check they're broadly inline down towards 21V across the bank, then after resting.

 

If the voltages are inline I'd hazard a guess they should be OK at slower discharges to 20% SoC.

 

cheers, Pete.

~smpt~

Edited February 25, 2016 by smileypete

[Markinaboat]

In what way inconclusive? I'd have thought they have enough capacity, or not!

 

Sounds like 4x 6V in series, so when doing the heavy discharge I'd compare the voltage across each 6V block, check they're broadly inline down towards 21V across the bank, then after resting.

 

If the voltages are inline I'd hazard a guess they should be OK at slower discharges to 20% SoC.

 

cheers, Pete.

~smpt~

Sorry Pete, been very busy. Have lots of info in my notes but have too much work to do right now.

 

Very basically, 4 x 12v Rolls 230 AGM's. 2 x 2 in series giving 24v. 210ah each @ 20hr rate so equivalent of 420ah which is programmed into MV system.

 

Switch off shorepower/chsrging and they msy last for 8 hrs before hitting 21v but only around 30a consumed and MV stating 85-90% remaining. If fully charged and dusconnected, left to rest for 2hrs, all show around 12.7v.

 

It would appear thst they've had it but. Following figures probably wont make much sense but as you've given the time ....

 

11:30hrs

AC Power off so on inverter.

Reads 25.92v

99%

Draw -2.3A

Consumed 3Ah

 

11:55hrs

Batt compartment temp 6.2C

Draw -4.1A

Batt 1 - 12.76 Pair 25.4/5

Batt 2- 12.73

 

Batt 3 - 12.76 Pair 25.4/5

Batt 4 - 12.73

Group - 25.4/5

 

Some TV, 3 X kettle boils (draws 80-90A on panel), lights, pump, webasto ran 16:30-17:00hrs

 

16:48hrs

24.65v (so not looking too bad here considering usage)

91%

Draw -6.5A

Batt 1 - 12.1

Batt 2- 12.6

 

Batt 3 - 12.4

Batt 4 - 12.4

 

THEN

18:00hrs

20.8v on panel

90% capacity remain

Draw -4.2A

Cap consumed only -38Ah

Batt 1 - 10.49

Batt 2 - 10.2

Batt 3 - 10.44

Batt 4 - 10.37

[Loafer]

Seems like a big collapse in voltage after 17:00. Battery 1 seemed to go first ( at 16:48) and probably pulled the others down.

 

How old are they?

[Markinaboat]

Seems like a big collapse in voltage after 17:00. Battery 1 seemed to go first ( at 16:48) and probably pulled the others down.

 

How old are they?

Coming up for six years but Rolls say usually last 7-10. They've been weel msintsined on a srste of the art system, hosever, the ore ious owner had jot used the boat much in the past 18 mths so could be lack of cycling. Not repkscing oike for like as around £1800 after discounting.

[Loafer]

Coming up for six years but Rolls say usually last 7-10. They've been weel msintsined on a srste of the art system, hosever, the ore ious owner had jot used the boat much in the past 18 mths so could be lack of cycling. Not repkscing oike for like as around £1800 after discounting.

 

Why not see if they can take an equalising charge? Rolls are good batteries. I'm guessing you'd have to look that up. If they can take one, I suggest isolating a pair at a time, or even one at a time with a 12V source. If they are dying, it is probably sulphation.

[Markinaboat]

Why not see if they can take an equalising charge? Rolls are good batteries. I'm guessing you'd have to look that up. If they can take one, I suggest isolating a pair at a time, or even one at a time with a 12V source. If they are dying, it is probably sulphation.

Cant equalise AGM's unfortunately. Strictly verboten on Roll's site.

 

Want to take two out of the loop to test but dont want to be spending fortunes on having long enough 70mm cables made just for the job. To remove batts I need to remove prop shaft and directly lift out 63kg batteries!

Edited February 26, 2016 by Markinaboat

[Loafer]

Cant equalise AGM's unfortunately. Strictly verboten on Roll's site.

 

Want to take two out of the loop to test but dont want to be spending fortunes on having long enough 70mm cables made just for the job. To remove batts I need to remove prop shaft and directly lift out 63kg batteries!

 

A good test is to see if they work on your boat, and it seems that they are failing that. If I read correctly, you're getting about 40Ah from them. I don't see how that breaking your back and having them 'drop-tested' will do you any good.

 

It's time for the heavy brigade here, methinks. They'll be along shortly.

Personally I think your No 1 battery is shot, and the others aren't far behind. They'll get worse quicker with a shot battery connected to them, I think.

 

If it's time for a new bank, I can recommend Trojans but you'd need to be able to water them (they do sell a rig for this, but it's pricey).

 

Edit: Your kettle runs are a BIG hit on your batteries. What power is it? I don't think running that is a good idea unless your engine is running.

Edited February 26, 2016 by Loafer

[Markinaboat]

A good test is to see if they work on your boat, and it seems that they are failing that. If I read correctly, you're getting about 40Ah from them. I don't see how that breaking your back and having them 'drop-tested' will do you any good.

 

It's time for the heavy brigade here, methinks. They'll be along shortly.

Personally I think your No 1 battery is shot, and the others aren't far behind. They'll get worse quicker with a shot battery connected to them, I think.

 

If it's time for a new bank, I can recommend Trojans but you'd need to be able to water them (they do sell a rig for this, but it's pricey).

 

Edit: Your kettle runs are a BIG hit on your batteries. What power is it? I don't think running that is a good idea unless your engine is running.

A sparks thought it was no 2 for some reason based on the following, temp compensation could have played a part:

On charge (pairs are 1&2/3&4)

 

Batt 1 - 14.8

Batt 2 - 15

Batt 3 - 15.1

Batt 4 - 14.7

 

I was all set on 8 x T105's but theyre too tall due to the prop. I think the clearance would have been iro 35mm with some of the caps in the wrong place so to speak.

 

Kettle (1800-2200w) was for test purposes to load the batts, always on shoreline - hob based whistler if out and about cruising!

 

Thanks for your input guys.

Edited February 26, 2016 by Markinaboat

[WotEver]

Cant equalise AGM's unfortunately. Strictly verboten on Roll's site.

What voltage are you charging the AGMs at? You can go up to 14.9V @25C according to this doc: http://www.es-store.co.uk/documents/product/S12_230.pdf

 

Tony

[Markinaboat]

What voltage are you charging the AGMs at? You can go up to 14.9V @25C according to this doc: http://www.es-store.co.uk/documents/product/S12_230.pdf

Tony

Exactly 29.7!

[WotEver]

Exactly 29.7!

Well... You could raise that by 0.1V I guess

[Loafer]

Hey'retay uckedfay.

[WotEver]

They are indeed

[Markinaboat]

But if they were all uckfayed, would they still show the following voltages after 5hrs of being disconnected at rest?

 

13.62

13..55

13..47

13..48

[Loafer]

I think so, as can ANY very low-capacity battery. I imagine your batteries are very quick to charge, and equally quick to discharge.

 

Is it just like having one small battery?

[smileypete]

Sounds like they may have had a troubled history under a previous owner...

 

For sulphated batts I'd reckon there's a good 50% chance of recovering some useful capacity with proper charging or equalisation. But it seems to me that in 80% of these cases people prefer the convenience of buying a new set of batts.

 

That said someone else on the forum faced similar issues with AGMs and was able to recover capacity. (If the batts will be replaced anyway then some very careful eq at higher than normal voltages may be considered.) :

 

http://www.canalworld.net/forums/index.php?showtopic=68885&p=1370773

 

Bear in mind the charge voltages need to be temperature compensated, for 24V batt bank near freezing temps, that could add a volt to the charging voltage:

 

http://support.rollsbattery.com/support/solutions/articles/4345-agm-charging

 

If access is limited there are watering kits available for Trojan type batts, not tooo pricy...:

 

http://www.globalbatteryshop.com/stealth-float-valve-system-92-c.asp

 

cheers, Pete.

~smpt~

 

 

 

 

[Markinaboat]

Sounds like they may have had a troubled history under a previous owner...

 

For sulphated batts I'd reckon there's a good 50% chance of recovering some useful capacity with proper charging or equalisation. But it seems to me that in 80% of these cases people prefer the convenience of buying a new set of batts.

 

That said someone else on the forum faced similar issues with AGMs and was able to recover capacity. (If the batts will be replaced anyway then some very careful eq at higher than normal voltages may be considered.) :

 

http://www.canalworld.net/forums/index.php?showtopic=68885&p=1370773

 

 

As mentioned above Pete, they are set to charge at the correct voltages (29.74 for bulk/absorb to be precise) with temp compensation taken care of by the Mastervolt Mass 100a charger.

 

Ill look at the links you included but AGM's can not be equalised. Before I shell out, it will do no harm to up the charge to 15a for around a couple of hours and keep an eye on the temperatures. If one or two of them are far below the other two, I could remove them and get by for the best part of this year as permanently hooked up at home.

 

Temp under back cabin floor diesnt drop below 5/6c as boat always warm.

 

Bear in mind the charge voltages need to be temperature compensated, for 24V batt bank near freezing temps, that could add a volt to the charging voltage:

 

http://support.rollsbattery.com/support/solutions/articles/4345-agm-charging

 

If access is limited there are watering kits available for Trojan type batts, not tooo pricy...:

 

http://www.globalbatteryshop.com/stealth-float-valve-system-92-c.asp

 

cheers, Pete.

~smpt~

 

Sounds like they may have had a troubled history under a previous owner...

 

For sulphated batts I'd reckon there's a good 50% chance of recovering some useful capacity with proper charging or equalisation. But it seems to me that in 80% of these cases people prefer the convenience of buying a new set of batts.

 

That said someone else on the forum faced similar issues with AGMs and was able to recover capacity. (If the batts will be replaced anyway then some very careful eq at higher than normal voltages may be considered.) :

 

http://www.canalworld.net/forums/index.php?showtopic=68885&p=1370773

 

Bear in mind the charge voltages need to be temperature compensated, for 24V batt bank near freezing temps, that could add a volt to the charging voltage:

 

http://support.rollsbattery.com/support/solutions/articles/4345-agm-charging

 

If access is limited there are watering kits available for Trojan type batts, not tooo pricy...:

 

http://www.globalbatteryshop.com/stealth-float-valve-system-92-c.asp

 

cheers, Pete.

~smpt~

 

Sorry, formatting/positioning of my reply screwed up by this damed iPad!

 

Also mentioned in an earlier post why I cant have Trojans.

[smileypete]

New batts time then I guess, I kinda expected it

 

Nevertheless, anyone interested in the equalisation or possible restoration of AGMs could try a google search on 'VRLA equalisation', read the above linked post relating NB Innisfree's experiences, and very carefully read the above linked page on Rolls charging advice for their AGMs.

 

One final thought, it might be worth measuring the batts temperature with an IR thermometer and work out the compensated charge voltage based on the lowest temp. values, in case the charger isn't quite getting it right.

 

cheers, Pete.

~smpt~

Edited February 27, 2016 by smileypete

[Markinaboat]

New batts time then I guess, I kinda expected it

 

Nevertheless, anyone interested in the equalisation or possible restoration of AGMs could try a google search on 'VRLA equalisation', read the above linked post relating NB Innisfree's experiences, and very carefully read the above linked page on Rolls charging advice for their AGMs.

 

One final thought, it might be worth measuring the batts temperature with an IR thermometer and work out the compensated charge voltage based on the lowest temp. values, in case the charger isn't quite getting it right.

 

cheers, Pete.

~smpt~

Yes Pete, voltages are higher in line with temperature and of course whilst floaring.