Electroquest 30 Amp Charger difficulties - Maximum Battery Bank Size?

[alan_fincher]

Plenty of "I'm having trouble charging my batteries" posts, so I thought I'd add another.

I have recently installed an Electroquest 30 Amp charger on the boat.  I have had this some years, but until now it has not been a permanent install, just available for ad-hoc charging.  They no longer seem to be marketed under the Electroquest name, but I believe it to be the same as the Numax 30 Amp charger, and the actual manufacturer seems to be Fairstone.  The model number is 123000HD.

It is charging a bank of 5 x 110AH non-sealed lead acid batteries.  These were new in April.  We have a Smartgauge, but I have no idea if it is one of the ones with calibration issues.

My concern is that the charger seems to want to go into float even though the Smartgauge is not reporting anything like 100% state of charge.  The best I can currently manage is an indicated SOC of around 90%, by which time the charger goes into float, and is only putting about 0.5A into the bank.

There are few obvious adjustments you can make - the charger is only suitable for lead acids, and that's what I have.

One thing I notice is that some retailers are selling the Numax version of this charger and saying it is for a maximum battery bank size of 300AH.  Specifically Midland Chandlers say " for battery capacity 150-300Ah"  Unless I'm missing something, I don't understand why the charger should not work on a bank larger than that.  I would have expected it would just need to run longer to achieve the same state of charges as it could have done quicker with a smaller bank.

I would love to dismiss this as "Smartgauge wrong", (other than that I paid more for the Smartgauge than the charger!), but with the charger that this one replaced, Smartgauge was showing 100%SOC, or close to it.  (The previous charger, an old Heart Interface combi, had to be scrapped because of a fault where it was overcharging the batteries to a point they were putting out Hydrogen, and setting off CO alarms).

Any ideas, please, experts?

Do I just shell out about £150 for a similar charger, and see if it behaves differently, or is there a genuine reason why this 30Amp charger is unsuitable for our 550Ah of batteries?

I have very limited space available where the charger is installed, and fitting another recommendation with a different footprint may not be possible.

 

[cuthound]

All to do with recharge times.

A 30 amp charger is ideal for charging batteries on boats connected to a landlines for significant periods of time,  but would struggle to charge a flat 500Ah battery in much less than a few days.

Edited October 23, 2017 by cuthound

[WotEver]

Many (most?) chargers Switch to float way too early and it looks like yours is one of them. If the float voltage isn’t adjustable then your only recourse will be to switch it off and back on to restart the absorption timer. 

Its unlikely that your SmartGauge is out of calibration, I believe MtB has both of them. If you want to know, ask around for someone who has an accurate multimeter and see if it agrees with the SmartGauge voltage reading. When you see that it does you’ll know that yours is indeed accurate. 

[nicknorman]

“ ... the charger goes into float, and is only putting about 0.5A into the bank” - do you mean in that order, ie the charger goes to float, then you check the current and find it’s 0.5A, or the current falls to 0.5A and then it switches to float?

The capacity range is for a couple of reasons, one being so it can make a reasonable guess at a tail current to indicate fully charged and switch to float, but also because these chargers often have a maximum time limit in absorption. This is to help protect against serious prolonged overcharging damaged batteries to avoid explosions etc. If the capacity is very large for the charger, it may time out on absorption before full charge is reached. If you switch the charger off and on again (maybe need to disconnect it) you should get another bite at the absorption cherry.

Edited October 23, 2017 by nicknorman

[alan_fincher]

23 minutes ago, WotEver said:

If the float voltage isn’t adjustable then your only recourse will be to switch it off and back on to restart the absorption timer.

 

13 minutes ago, nicknorman said:

 If you switch the charger off and on again (maybe need to disconnect it) you should get another bite at the absorption cherry.

 

Unfortunately no - it does it's 30 seconds of "faffing around" to decide what it out to be doing, and goes immediately to float.

The instructions are a mind numbingly poor translation, but I think when I looked at it before, upping the voltage at which it went into float was not an obvious option.  I'll dig them out and look again though!

17 minutes ago, nicknorman said:

“ ... the charger goes into float, and is only putting about 0.5A into the bank” - do you mean in that order, ie the charger goes to float, then you check the current and find it’s 0.5A, or the current falls to 0.5A and then it switches to float?

No, I don't actually know what the charge current is if it is coming to the end of absorption, because it is not obvious when it's about to change, and I'm not in the engine room continually monitoring.  From what I have seen it is "a few amps", maybe 3 or 4, but why would that be if the Smatygauge is anywhere near correct that batteries are at only 90% SOC at that stage?

[WotEver]

1 minute ago, alan_fincher said:

The instructions are a mind numbingly poor translation, but I think when I looked at it before, upping the voltage at which it went into float was not an obvious option.  I'll dig them out and look again though!

What would be ideal would be for you to be able to set ‘float’ voltage to be 14.4V. Then it could sit there forever on ‘float’ and still give a sensible charge. But that’s probably not possible. 

[alan_fincher]

29 minutes ago, WotEver said:

Its unlikely that your SmartGauge is out of calibration, I believe MtB has both of them. If you want to know, ask around for someone who has an accurate multimeter and see if it agrees with the SmartGauge voltage reading. When you see that it does you’ll know that yours is indeed accurate. 

I have more than one meter available, each with moderately good accuracy, (Uni-Trend offerings).  They are consistent with each other, but I think Smartgauge is consistently saying 0.1v to 0.2v less.  Do I not recall though that the SmartGauge manual actually claims no great accuracy about the displayed voltage, (which doesn't show hundredths of volts anyway).

[cereal tiller]

3 minutes ago, alan_fincher said:

 

 

Unfortunately no - it does it's 30 seconds of "faffing around" to decide what it out to be doing, and goes immediately to float.

The instructions are a mind numbingly poor translation, but I think when I looked at it before, upping the voltage at which it went into float was not an obvious option.  I'll dig them out and look again though!

I have the same Charger, .has been in use for 3 Years.It will take the S.Gauge to 100%.it will go into float at 14,25-14.3 Volts

If you would like it to charge for longer ,leave a 20-30 Watt load on, then it will never go into float

Methinks there is Some Line resistance, poor connector maybe?

[alan_fincher]

2 minutes ago, cereal tiller said:

I have the same Charger, .has been in use for 3 Years.It will take the S.Gauge to 100%.it will go into float at 14,25-14.3 Volts

If you would like it to charge for longer ,leave a 20-30 Watt load on, then it will never go into float

Methinks there is Some Line resistance, poor connector maybe?

It is wired directly to the bank using cable fatter than those they supply, and not more than 1 metre each

In fact I have just found something elsewhere that worries me, but I can do nothing about, as I'm not on the boat.  A review of the Numax badged version of the charger actually says that if left connected to the battery bank, and switched off, (which mine is), that current will flow through it and discharge the batteries.  I would not have expected that, and notming in my (very poor) instructions I think suggested it could not be left connected, and switched off.

Mind you when the very first translation says....
"Connect the charger system to a wall receptacle strongly"

you know they are not going to be the easiest to interpret for the more technical stuff!

[WotEver]

2 minutes ago, alan_fincher said:

A review of the Numax badged version of the charger actually says that if left connected to the battery bank, and switched off, (which mine is), that current will flow through it and discharge the batteries.  I would not have expected that, and notming in my (very poor) instructions I think suggested it could not be left connected, and switched off.

I’ve seen that said about early Sterling chargers too. No idea if it’s true  

[nicknorman]

3 minutes ago, alan_fincher said:

It is wired directly to the bank using cable fatter than those they supply, and not more than 1 metre each

In fact I have just found something elsewhere that worries me, but I can do nothing about, as I'm not on the boat.  A review of the Numax badged version of the charger actually says that if left connected to the battery bank, and switched off, (which mine is), that current will flow through it and discharge the batteries.  I would not have expected that, and notming in my (very poor) instructions I think suggested it could not be left connected, and switched off.

Mind you when the very first translation says....
"Connect the charger system to a wall receptacle strongly"

you know they are not going to be the easiest to interpret for the more technical stuff!

I’ve got a 20A version of much the same thing in my caravan. I leave it connected to the batteries all the time, and no current flows when it’s off. I’ve checked.

[cereal tiller]

5 minutes ago, alan_fincher said:

It is wired directly to the bank using cable fatter than those they supply, and not more than 1 metre each

In fact I have just found something elsewhere that worries me, but I can do nothing about, as I'm not on the boat.  A review of the Numax badged version of the charger actually says that if left connected to the battery bank, and switched off, (which mine is), that current will flow through it and discharge the batteries.  I would not have expected that, and notming in my (very poor) instructions I think suggested it could not be left connected, and switched off.

Mind you when the very first translation says....
"Connect the charger system to a wall receptacle strongly"

you know they are not going to be the easiest to interpret for the more technical stuff!

Gave up withe "Chinglish" Instructions, pressing the little black Button allows Scrolling between Volts and Amps.

The Distributors say that the Output Voltage cannot be adjusted, hence the Dumb Load modification!

There no current back flow shown on the  Boat's Built in Digital Ammeter

Edited October 23, 2017 by cereal tiller

[WotEver]

13 minutes ago, alan_fincher said:

I have more than one meter available, each with moderately good accuracy, (Uni-Trend offerings).  They are consistent with each other, but I think Smartgauge is consistently saying 0.1v to 0.2v less.  Do I not recall though that the SmartGauge manual actually claims no great accuracy about the displayed voltage, (which doesn't show hundredths of volts anyway).

0.2V is way out and will give incorrect SoC readings. If you can confirm it’s that far out with a known accurate meter then I suggest you don’t do as MtB does but instead return it to Merlin to be fixed. 

[nicknorman]

14 minutes ago, alan_fincher said:

I have more than one meter available, each with moderately good accuracy, (Uni-Trend offerings).  They are consistent with each other, but I think Smartgauge is consistently saying 0.1v to 0.2v less.  Do I not recall though that the SmartGauge manual actually claims no great accuracy about the displayed voltage, (which doesn't show hundredths of volts anyway).

0.1 to 0.2v low is out of spec. Presuming your cheapo multimeters are correct, which is a big presume! The voltage accuracy is important as it affects the SoC reading. Remember, the SG only measure voltage, nothing else!

[alan_fincher]

1 minute ago, WotEver said:

0.2V is way out and will give incorrect SoC readings. If you can confirm it’s that far out with a known accurate meter then I suggest you don’t do as MtB does but instead return it to Merlin to be fixed. 

I will try to take more careful observations when next up there.

Having just found the attached, (not all of which I profess to understand!), I note the following....

 

Quote

Float Charging:

1) Current < 10% of rating, the display will show "End" & "x.x.h." alternately.  (It means that the charger switch to flapt charging stage by current setting, not by timer setting.)  The charger will switch to float charging and green LED lights.

As I just said I feel it is switching to float with charge current at only about 3 amps, as that is 10% of the chargers 30 amp rating, it does seem to explain the basis on which it is going into to float, (or will not go into absorption, even if restated).

Looks like it can be tweaked to do it on time, rather than charge current, but I'm not sure I'm fully understanding how, or the implications thereof. 

[alan_fincher]

15 minutes ago, WotEver said:

0.2V is way out and will give incorrect SoC readings. If you can confirm it’s that far out with a known accurate meter then I suggest you don’t do as MtB does but instead return it to Merlin to be fixed. 

 

14 minutes ago, nicknorman said:

0.1 to 0.2v low is out of spec. Presuming your cheapo multimeters are correct, which is a big presume! The voltage accuracy is important as it affects the SoC reading. Remember, the SG only measure voltage, nothing else!

I'll take a greater selection of meters next time - I reckon I can muster at least half a dozen if I search house and both boats(!)

Perhaps naively, if 5 all read about the same, and one differs, I always suspect the one, but of course the one could be spot on, and the other 5 all miles out.

From memory, (but I could be wrong) the Smart Gauge will only display "0" or "5" in the second place of decimals, will it not?  I thought I recalled seeing in the manual that the displayed voltage was not to huge accuracy, but I can see the unit itself must know voltage accurately to do what it should, and I can see no reason why what it displays shouldn't be the number it is using.

My one concern is that before I changed the charger I was regularly seeing an SOC of "high nineties" or even 100%.  But that charger wsa definitely having wobblies, and OVER-charging to the extent of serious gassing, so maybe I shouldm't give too much credence to what happened before I switched to the current charger.

[nicknorman]

5 minutes ago, alan_fincher said:

 

I'll take a greater selection of meters next time - I reckon I can muster at least half a dozen if I search house and both boats(!)

Perhaps naively, if 5 all read about the same, and one differs, I always suspect the one, but of course the one could be spot on, and the other 5 all miles out.

From memory, (but I could be wrong) the Smart Gauge will only display "0" or "5" in the second place of decimals, will it not?  I thought I recalled seeing in the manual that the displayed voltage was not to huge accuracy, but I can see the unit itself must know voltage accurately to do what it should, and I can see no reason why what it displays shouldn't be the number it is using.

My one concern is that before I changed the charger I was regularly seeing an SOC of "high nineties" or even 100%.  But that charger wsa definitely having wobblies, and OVER-charging to the extent of serious gassing, so maybe I shouldm't give too much credence to what happened before I switched to the current charger.

Yes it only displays to 0.05 but that also is the accuracy required, the second decimal place (rounded to 5 or 0) should be correct. But it does dither - by which I mean if the actual measured voltage is 0.75, the display will flip between 0.05 and 0.10 with a roughly equal duty cycle. If the measured voltage is 0.9 then the display will mostly be 0.1 with the occasional 0.05. Thus you can get an idea of what the measurement is to higher resolution even though it only displays to 0.05.

[alan_fincher]

I could still really do with some help on this one, if people haven't become bored with it.

I took some more measurements when on the boat last, but unfortunately have managed to loose my scribbled notes.

However what I can say was that I went armed with half a dozen different multi-meters, and, apart from one old and suspect one, all yielded very similar results when applied to the battery bank, and those results were broadly the same as the Smartgauge's reading.  I tried this both when the batteries were under float charge, and again with the charger turned off, and having rn a bit of a load on the bank for an hour or so, to make sure I was not measuring surface charge.  In both cases the Smartgauge was damn close to 5 different multi-meters all saying similar, so it seems highly unlikely that 1 have 5 poorly calibrated meters and one poorly calibrated Smartgauge.  I couldn't try it wih the charger in absorption, because it will not stay there long enough!

However the situation remains that even if the charger can be persauded into absorption, the charging current falls very rapidly, and it quickly goes back to float.  The documentation implies that once charge current is at 10% of the maximum output of the charger this is expected behaviour, and as it seems to occur at 3 amps when the maximum charger capacity is 30 amps, in that respect, at least it seems to be working.

So it seems that the 550Ah battery bank only wants to accept 3 amps from the charger, but this cut off is occurring at the point the Smartgauge is indicating only about 90%, (or sometimes slightly less) of full SoC.

I conclude that an identical model charger as replacement would still produce the same symptom, unless the actual charge voltage in absorption proved to be higher.  The documentation for the charger suggests that the final part of the absorption stage is done at constant voltage, and this is consistent with the falling current.  The voltage this occurs at is specified as 14.7V +/- 0.2V.  When I can make it do it, I seem to be seeing 14.5V on the Smartgauge, so a bit less than 14.5V, but within the +/- 0.2V quoted.  Even if only 14.5V, is just 3 amps accepted by a 550 Ah bank consistent with still being 10% from fully charged?

I'm not professing to understand this fully, but it seems to me I need a charger that can better 14.5V when charging, and I don't think that's something I can adjust on this charger.

What's the panels view on how much damage I am doing, (or have already done), by not being able to get the Smartgauge above 90%?  I'm hoping I ill not need to buy both a new charger and a new bank!

[WotEver]

3A @ 14.5V into a 550Ah bank is <1% of battery capacity and therefore getting very close to 100% SoC. 

Forget what the Smartgauge displays while charging, what does it show once you start using the batteries?

[nicknorman]

... and what would be expected is for the SG to linger at 90% for a while, and then start to decrease once the actual SoC falls below 90%.

The only other thing you could try is to put on some electrical load so that the charger current is maintained at over 3A,  this should keep it in Absorption for longer.

[alan_fincher]

15 minutes ago, WotEver said:

3A @ 14.5V into a 550Ah bank is <1% of battery capacity and therefore getting very close to 100% SoC. 

Forget what the Smartgauge displays while charging, what does it show once you start using the batteries?

The same.

The batteries are being used on the mooring, but use is currently restricted to.....

1) LED lights
2) Water pump

3) Nothing else I an immediately think of.

Computers and any other charging are on the 240V land-line.

So not a lot of demand, I would say.

what was on the notes I failed to bring home was what voltage is it indicating when it is saying 90% SOC, and the battery charger is off, (and after no charging for a while).  I think 12.7v, but I'm not sure, so I'll confirm that on next vist, and take some readings to replace those I have "mislaid".

17 minutes ago, nicknorman said:

The only other thing you could try is to put on some electrical load so that the charger current is maintained at over 3A,  this should keep it in Absorption for longer.

Yes, I haven't done that yet.  I doubt despite lots of LED lighting that if I turn the lot on it makes 3 amps in total.  I'll have to find am artificial load, (unless I leave the tunnel lamp turned on, maybe - that should be enough).

[nicknorman]

36 minutes ago, alan_fincher said:

The same.

The batteries are being used on the mooring, but use is currently restricted to.....

1) LED lights
2) Water pump

3) Nothing else I an immediately think of.

Computers and any other charging are on the 240V land-line.

So not a lot of demand, I would say.

what was on the notes I failed to bring home was what voltage is it indicating when it is saying 90% SOC, and the battery charger is off, (and after no charging for a while).  I think 12.7v, but I'm not sure, so I'll confirm that on next vist, and take some readings to replace those I have "mislaid".

Yes, I haven't done that yet.  I doubt despite lots of LED lighting that if I turn the lot on it makes 3 amps in total.  I'll have to find am artificial load, (unless I leave the tunnel lamp turned on, maybe - that should be enough).

Tunnel lamp would do it. You don’t necessarily have to load with 3 A. I you loaded with 1A then the charger would stay in Absorb until the battery current fell to 2A, etc.

[WotEver]

2 hours ago, alan_fincher said:

what was on the notes I failed to bring home was what voltage is it indicating when it is saying 90% SOC, and the battery charger is off, (and after no charging for a while)

I don’t think that’ll tell us much. I suspect your batts are probably up in the high 90’s, maybe as high as 98% or so but SmartGauge just hasn’t had a chance to work it out yet. 

[alan_fincher]

7 minutes ago, WotEver said:

I don’t think that’ll tell us much. I suspect your batts are probably up in the high 90’s, maybe as high as 98% or so but SmartGauge just hasn’t had a chance to work it out yet. 

The reason I would query this is that the previous charger (actually an old Heart Interface combi) had the Smartgauge showing 100% SOC more or less permanently.

However as that wasremoved because of obvious evidence that it was going into some kind of fault condition resulting in overcharging and gassing, maybe I should not read too much into that.

Am I right in thinking that SG really needs to see the batteries go well below my current 88% to 90% numbers to get its "knowledge" more accurate, or did I imagine that?

EDIT:

For clarity, the Smartgauge was disconnected from the battery bank for several days whilst I reconfigured and rewired everything.  (Will that have caused it to forget everything it "knew" at the point it was disconnected.  Sorry if that's a very basic question that has been answered 100 times before!)

Edited October 30, 2017 by alan_fincher

[WotEver]

Just now, alan_fincher said:

Am I right in thinking that SG really needs to see the batteries go well below my current 88% to 90% numbers to get its "knowledge" more accurate, or did I imagine that?

No, you didn’t imagine that. Once SmartGauge can see the voltage dropping it can work out exactly where you are. Until then it’s guessing because it has no real data to base its calculations on.