Still eatng batteries?

[Keeping Up]

I really have to say, I don't feel the need for a Smartgauge. I honestly don't believe that it would tell me anythng that my voltmeter, ammeter, and hydrometer together don't already tell me.

 

For some reason I can never remember the numbers on the hydrometer. However one thing I have seen now on all 12 of the Varta batteries, is that when delivered brand-new they will not under any circumstances rise more than a gnat's-whisker into the Green sector. I suspect the suppliers may be over-filling them with water; one supplier did admit to me that they always do this so that the customers won't complain under warrantee after they've gassed some of it away. After a month, all my batteries will reach but not enter the Green sector.

 

I reckon that a regular equalisation charge is the best way to go - although I still question why I need it if other users of the same system don't - so given that my existing charger is perfectly adequate for charging but does not have a desulphation function, what do people reckon is the cheapest and most convenient source of desulphation voltage at a suitable current for a 440 Ah bank (or perhaps just one battery at a time? That is easy enough to arrange and actually has some advantages)

[Sir Nibble]

Suck this egg Granny, but.

SG changes are a product of the chemical changes in the battery of course and if the hydrometer is going as high as it did when they were new then just as much chemical conversion of the plates is going on and you have not lost capacity!

Instrumentation problem?

You say your 2.2 amps are accounted for, where is that going please? 24/7 that's a really significant discharge.

[dmr]

I really have to say, I don't feel the need for a Smartgauge. I honestly don't believe that it would tell me anythng that my voltmeter, ammeter, and hydrometer together don't already tell me.

 

For some reason I can never remember the numbers on the hydrometer. However one thing I have seen now on all 12 of the Varta batteries, is that when delivered brand-new they will not under any circumstances rise more than a gnat's-whisker into the Green sector. I suspect the suppliers may be over-filling them with water; one supplier did admit to me that they always do this so that the customers won't complain under warrantee after they've gassed some of it away. After a month, all my batteries will reach but not enter the Green sector.

 

I reckon that a regular equalisation charge is the best way to go - although I still question why I need it if other users of the same system don't - so given that my existing charger is perfectly adequate for charging but does not have a desulphation function, what do people reckon is the cheapest and most convenient source of desulphation voltage at a suitable current for a 440 Ah bank (or perhaps just one battery at a time? That is easy enough to arrange and actually has some advantages)

 

You are correct in that Smartgage will not tell you anything that a Hydrometer won't also tell you, its just more convenient. I look at the Smargage a few times every day, but only resort to the hydrometer a couple of times each year. Turning EVERYTHING off and waiting between ten mins and two hours in order to assess charge from a voltage measurement is not my idea of boating.

If your hydrometer is correct then its sounds like your batteries were part sulphated from new, I have also experienced this.

Many, maybe most, people do not equalise, but those who do get much better performance and life out of their batteries.

 

.........Dave

[Keeping Up]

Suck this egg Granny, but.

SG changes are a product of the chemical changes in the battery of course and if the hydrometer is going as high as it did when they were new then just as much chemical conversion of the plates is going on and you have not lost capacity!

Instrumentation problem?

You say your 2.2 amps are accounted for, where is that going please? 24/7 that's a really significant discharge.

OK, Hello Snibble & welcome, Granny here.

 

The hydrometer is definitely lower, but only by a little bit (so far). I don't think there's an instrumentation problem except possibly too much concentration on the numbers and not enough feeling of "it's still working so why worry"

 

The 2.2A goes to the inverter standing current 0.9A, the dual LPG sensor 0.5A, the TV preamp (too awkwardly placed to switch off at night) 0.1A, two old radio's memories 0.3A, and via the inverter the cooker with its clock 0.2A plus the PVR on standby (it doesn't lke being switched off) 0.1A and a charger for the two PMR handsets 0.1A

 

Yes some of those are unnecessary; so is marriage but I'd like to stay married and that involves me not switching off things like the cooker clock which glows and shows the time durng the night.

 

I have been thinking about a black box with 4 crocodile clips. It would clip on to one battery of a bank, whose usual terminal had been disconnected. it would then also clip on to the others that were still connected as normal and take power from them to drive a 12-24v converter followed by a controlled desulphator output to the first battery, giving maybe 15.5v at 1A (uneducated guess at the numbers) with maybe a timer or other controller. What should be the spec for that output? It could be a useful gadget, used on one battery each month in rotation. Could I make my fortune making and selling them?

[nicknorman]

That's not a bad idea! One amp is perhaps slightly on the low side to reach 15.5v but probably no more than 3A is required to do 1 battery at a time.

 

Ed: although since you have an inverter it would probably be easier to use a bench power supply running on mains.

Edited August 5, 2014 by nicknorman

[ditchcrawler]

Or even one of these http://www.theultimatefinish.co.uk/ctek/mxs-3-8-12v-battery-charger-and-conditioner.aspx?utm_source=Google&utm_medium=shopping&utm_campaign=MerchantCentre&variant=6310&gclid=CjwKEAjwpIefBRCuir7wy-f1kCwSJADXBi2aEVRCHvoi63hsIowTg-haT7mD08YoGOfNrOECfOCkJBoCvdrw_wcB

 

Ctex MXS 3.8 12 volt battery charger

Edited August 6, 2014 by ditchcrawler

[bizzard]

Acid indigestion will set in after all this battery eating, I suggest a good dose of bi-carb.

[Grace and Favour]

Acid indigestion will set in after all this battery eating, I suggest a good dose of bi-carb.

That would create terminal wind!

[dmr]

OK, Hello Snibble & welcome, Granny here.

 

The hydrometer is definitely lower, but only by a little bit (so far). I don't think there's an instrumentation problem except possibly too much concentration on the numbers and not enough feeling of "it's still working so why worry"

 

The 2.2A goes to the inverter standing current 0.9A, the dual LPG sensor 0.5A, the TV preamp (too awkwardly placed to switch off at night) 0.1A, two old radio's memories 0.3A, and via the inverter the cooker with its clock 0.2A plus the PVR on standby (it doesn't lke being switched off) 0.1A and a charger for the two PMR handsets 0.1A

 

Yes some of those are unnecessary; so is marriage but I'd like to stay married and that involves me not switching off things like the cooker clock which glows and shows the time durng the night.

 

I have been thinking about a black box with 4 crocodile clips. It would clip on to one battery of a bank, whose usual terminal had been disconnected. it would then also clip on to the others that were still connected as normal and take power from them to drive a 12-24v converter followed by a controlled desulphator output to the first battery, giving maybe 15.5v at 1A (uneducated guess at the numbers) with maybe a timer or other controller. What should be the spec for that output? It could be a useful gadget, used on one battery each month in rotation. Could I make my fortune making and selling them?

 

Both Smiley Pete of this forum and myself have proposed something along these lines but for equalisation rather than driving a desulphator (which many regard as boxes of snake oil). There is a Chinese DC-DC converter sometimes on eBay that would do the job. I have got one but have not got round to playing with it yet, I suspect the same goes for Pete.

I have been equalising a lot less lately, since I got the Trojans I have formed the opinion that you can let them get pretty bad and still restore them fully with an equalise so I only do 3 or 4 over the winter, our manic CCing sorts things out in the summer.

 

.........Dave

[Keeping Up]

Yes sorry when I typed "desulphator" I did mean "equaliser" but it was late and I'd had a lot of wine. I agree with your Snake Oil observation

 

 

Or even one of these http://www.theultimatefinish.co.uk/ctek/mxs-3-8-12v-battery-charger-and-conditioner.aspx?utm_source=Google&utm_medium=shopping&utm_campaign=MerchantCentre&variant=6310&gclid=CjwKEAjwpIefBRCuir7wy-f1kCwSJADXBi2aEVRCHvoi63hsIowTg-haT7mD08YoGOfNrOECfOCkJBoCvdrw_wcB

 

Ctex MXS 3.8 12 volt battery charger

I've already got the bigger version of that one and it is indeed very good but it doesn't do equalisations. Edited August 6, 2014 by Keeping Up

[Paul C]

This is an interesting one, just to start can you confirm a few things:

 

1) I assume you don't have any solar panels, since they've not been mentioned

2) I assume the shunt is connected to the battery bank -ve terminal(s) and NOTHING else is connected to these.

3) How are the battery's parallel wiring connected? Are the positive and negative terminals at opposite ends of the bank; or from batteries 2 & 3 of the bank? Or from the same battery?

4) Are the battery interconnects the same cable size and length?

5) Are you measuring the voltage at the same time of day, you say morning but there might be a variation etc....

6) Have you knocked the fridge temperature setting?

7) Is the fridge full of food, or half full, or almost empty? The reason for this is, if a fridge is almost empty, every time you open the door the cold air whooshes out and warm (ambient temp) air gets exchanged, and the fridge cools this down. Thus a nearly empty fridge, is less efficient, if the door is opened and closed. (The efficiency of a fridge is the same once its contents including the air, are at its set temperature, no matter what the contents are (assuming you've not put something which generates heat etc in it - I don't think anyone would sanely do this but some pedant would point it out!!!))

 

My money is on either 2 or 3. If its 2 then its possible you have a power consuming device after the shunt which doesn't show up on the ammeter reading, and in fact all the ammeter readings including the amp-hours counting will be erroneous. If its 3, then a good test is to remove the battery interconnects, wait around an hour for the batteries to settle, then measure the voltage of each accurately.

 

Another possibility is one of the four batteries is "dud", the above test will quickly reveal this. Hydrometer readings would too, but you'd need to check 24 cells......so it would take longer.

PS equalisation will temporarily cure the issue but isn't the solution to the root cause of the problem (or perceived problem if the measurements aren't right).

[Keeping Up]

No there's no solar.

 

Yes the shunt IS directly connected on its own to the negative.

 

The battery leads are to the diagonally opposite corners, batteries 1 and 4.

 

The interconnects are not all the same size and length because one of the batteries is sideways on, but in fact the sizes are deliberately tailored after careful calculations so that the bank is extremely well balanced, for example the ones nearest the take off are thicker.

 

I'm measuring at about the same time. There may be an hour's variation but that wouldnt make much difference. I also glance at the meter every day when I get up, of course it's under 2a load but the downward trend is still evident.

 

The fridge setting is OK, and I would expect the Ah figure to show if it was misbehaving. It is full (of food and drink, not lighted candles!)

 

I'd be surprised if it's a duff cell, after the number of sets of batteries that have behaved in the same way, but maybe I'll try the hydrometer in all 24 cells before I start the engine, it's not too difficult and could be revealing.

[Paul C]

Thanks for the answers (apologies I gave you such a long list of stuff to work through!) and your answers suggest you certainly know about the importance of balancing the batteries so one doesn't take the lion's share of charging or discharging. My money is still on there being a dud battery in the set, given the amount of other stuff you've already checked and eliminated. And its quite possible that your previous battery bank had one dud (ie much worse than the others) but the others were not in their prime of youth.

[system 4-50]

How has your starter battery performed during this saga?

[Keeping Up]

The starter battery is OK, but of course it gets no overnight usage. It's showing 12.8v in the mornings.

 

Last night we went to the pub so our total usage was only 54 Ah. I measured all 24 cells this morning, every one was the same with only insignificant differences, around 1215. The difference between on-load (2 amps) and off load rested voltage seems to have increased from 0.15 to 0.25 which means this week the meter shows less when I first look at it but after a rest it is the same as last week.

[nicknorman]

As I understand it (which may be wrong!) the best way to use a hydrometer in these circumstances is to check the SG with the batteries fully charged. If the SG is down, that indicates chemicals "lost" due to being tied up in sulphation.

[nb Innisfree]

FWIW regular Victron equalisation charges failed to rescue our AGMs (8x480ah @20hr rate) but several long Victron float charges on shorepower did (26.4v) Charge current would stabilise at various levels, usually about 0.5 amps (24v) after a day or two, longest period before it stabilized was 4 days IIRCC, terminal amps 0.2.

 

Our Victron is set to the max of 8hrs absorption, then it switches to float (27.2v?) then reduced float of 26.4v (after 24 hrs I think)

 

It did the trick and recovered what seemed to be a capacity of 45% or less to near 100%.

Edited August 7, 2014 by nb Innisfree

[by'eck]

FWIW regular Victron equalisation charges failed to rescue our AGMs (8x480ah @20hr rate) but several long Victron float charges on shorepower did (26.4v) Charge current would stabilise at various levels, usually about 0.5 amps (24v) after a day or two, longest period before it stabilized was 4 days IIRCC, terminal amps 0.2.

 

Our Victron is set to the max of 8hrs absorption, then it switches to float (27.2v?) then reduced float of 26.4v (after 24 hrs I think)

 

It did the trick and recovered what seemed to be a capacity of 45% or less to near 100%.

 

Yes I too have always found several off/on cycles with a smart charger, forcing it each time into the timed absorb mode, to be of great benefit to batteries that haven't had the benefit of a full charge for a while. Its undoubtedly the absorb mode that benefits them though, not float.

 

Although with my Sterling Combi I have the opportunity to use a true equalisation charge, I've never found the need, and of course cycling the charger is much kinder to batteries with fewer dangers.

[nicknorman]

I had the float voltage set a little low on our new Trojans, 13.1v. Having been away from the boat with everything off except shore power charger for a couple of weeks, came back to find the Smartgauge reading 98% and when I put the charger into Absorb they gobbled lots of current. I upped it to the recommended 13.2 and next time the SG showed 100%, but clearly that sort of voltage is barely enough to achieve fully charged even after weeks.

[Keeping Up]

As I understand it (which may be wrong!) the best way to use a hydrometer in these circumstances is to check the SG with the batteries fully charged. If the SG is down, that indicates chemicals "lost" due to being tied up in sulphation.

Fully charged they are at about 1235 now, compared to 1245 a couple of weeks ago and 1255 when they were new. I did the additional test this morning to see particularly if any cells lost their charge overnight. Perhaps the only good sign is that they only lost about 20 units of SG overnight for 54 Ah of discharge.

 

These batteries are strange. When I stop charging I expect to see a fairly rapid decline until say 12.8v and then a slower decline. These drop rapidly to 13.3v when I switch off the engine but then seem to decay at a fairly constant rate until 12.2v (I've not yet taken them further than that). Taking that in conjunction with what seems to me to be a fairly high recovery (0.25v) half an hour after removing a modest 2A load, it's as if they were working mainly on surface charge - or am I letting my imagination get the better of me?

[Sir Nibble]

The elephant in the room is that the only way these symptoms make sense is if the batteries are getting insufficient charge or are under a hidden standing discharge. It does sound to me especially with the rapid fall in voltage when the engine is stopped like the latter.

[Keeping Up]

The elephant in the room is that the only way these symptoms make sense is if the batteries are getting insufficient charge or are under a hidden standing discharge. It does sound to me especially with the rapid fall in voltage when the engine is stopped like the latter.

I would agree except that (1) the engine is run for between 5 and 8 hours every day, by which time the charging current at 14.6v is less than 1A, which surely cannot be regarded as undercharging and (2) there is categorically no opportunity for any other standing discharge. And surely I am right in thinking that a fairly rapid discharge down to an on-load voltage of 13.3v is normal?

Edited August 7, 2014 by Keeping Up

[by'eck]

I would agree except that (1) the engine is run for between 5 and 8 hours every day, by which time the charging current at 14.6v is less than 1A, which surely cannot be regarded as undercharging and (2) there is categorically no opportunity for any other standing discharge. And surely I am right in thinking that a fairly rapid discharge down to an on-load voltage of 13.3v is normal?

 

Yes I feel certain that the initial fairly rapid drop in off load volts from a previous charge situation at 14.6 volts is entirely normal. A very modest discharge current or just leaving them standing will quickly cream off the excess surface charge bringing them down to say 12.7 - 12.8 volts, which in fairness is still equal to the normally perceived off load voltage of a fully charged 12 volt lead/acid battery.

 

Can I assume this is your realistic starting voltage and that the drop is much slower from this figure under modest loads?

[nicknorman]

Fully charged they are at about 1235 now, compared to 1245 a couple of weeks ago and 1255 when they were new. I did the additional test this morning to see particularly if any cells lost their charge overnight. Perhaps the only good sign is that they only lost about 20 units of SG overnight for 54 Ah of discharge.

These batteries are strange. When I stop charging I expect to see a fairly rapid decline until say 12.8v and then a slower decline. These drop rapidly to 13.3v when I switch off the engine but then seem to decay at a fairly constant rate until 12.2v (I've not yet taken them further than that). Taking that in conjunction with what seems to me to be a fairly high recovery (0.25v) half an hour after removing a modest 2A load, it's as if they were working mainly on surface charge - or am I letting my imagination get the better of me?

Surely the steady drop in SG must indicate either failure to fully charge, or a loss of reactive chemicals due to sulphation? I think we can dismiss the former from the description of your charging, so that just leaves the latter. You need to get a means of pushing them up to 15.5v!

 

Maybe it is a feature of calcium batteries? Despite numerous equalisation cycles, normal charging at 14.6v and the batteries being in the engine space at about 35 deg C when running, in 2 years I never had to add water.

 

In 4 months with the Trojans ( lead antimony) and no equalisation charges yet, I have had to add water. (Well didn't HAVE to but they had definitely used water.)

 

Perhaps, although we think 14.6v is plenty, in fact it is just not enough for lead calcium batteries.

 

Anyway, you now know what your next batteries should be!

[Naughty Cal]

Surely the steady drop in SG must indicate either failure to fully charge, or a loss of reactive chemicals due to sulphation? I think we can dismiss the former from the description of your charging, so that just leaves the latter. You need to get a means of pushing them up to 15.5v!

 

Maybe it is a feature of calcium batteries? Despite numerous equalisation cycles, normal charging at 14.6v and the batteries being in the engine space at about 35 deg C when running, in 2 years I never had to add water.

 

In 4 months with the Trojans ( lead antimony) and no equalisation charges yet, I have had to add water. (Well didn't HAVE to but they had definitely used water.)

 

Perhaps, although we think 14.6v is plenty, in fact it is just not enough for lead calcium batteries.

 

Anyway, you now know what your next batteries should be!

Is it really as clear cut as that?

 

With the number of sets of batteries they have killed in such a short space of time with what appears to be a decent charging regime I dont think it can be!

 

If it was a case of faulty batteries you would expect more people to pop up saying they have also had problems with the same ones.

 

I dont know what the solution is but I'm not convinced that switching to more expensive batteries is necessarily the right course of action. You can still kill expensive batteries........