A list of battery charging figures

[Loafer]

People are ALWAYS measuring unknowns. That's why they're measuring them, innit?

[swift1894]

How can you measure an unknown?

 

No I would suggest leaving them for 7/8 hours they need recovery time

 

So what should I do tomorrow morning when they've had 8 hours to recover? They'll have been on float(I hope!) all night. Drain em down a bit then recharge or sail off into the blue yonder with them at as full a charge as can be achieved overnight?? Edited December 1, 2015 by swift1894

[Loafer]

So what should I do tomorrow morning when they've had 8 hours to recover? They'll have been on float(I hope!) all night. Drain em down a bit then recharge or sail off into the blue yonder with them at as full a charge as can be achieved overnight?

 

The latter, but keep them as fully charged as you can, with minimum discharge. MY suggestion, not Gospel!

Edited December 1, 2015 by Loafer

[WotEver]

 

How can you measure an unknown?

You're the one who said it was an unknown, not me.

 

100% is known to within a percent or so. Therefore 50% will also be known to within a percent or so. Other than a controlled discharge at 0.1C or whatever the manufacturer specifies you cannot know the battery capacity, and therefore measuring Ah in and out is completely meaningless - a point which you appear unable to grasp.

 

You asked Nick that surely he could measure Ah out. He replied that of course you can, but it's a meaningless figure without knowing the capacity of the bank. Your response to that (after criticising his battery usage) was "You miss the point about knowing the Ahs used, the unit will measure them going back in." Uhhh... so what? That still tells you precisely zero about the SoC or bank capacity.

[Loafer]

If you have a regular discharge/recharge regime, you can 'guess' the capacity by how long it takes to do your 'standard charge'.

 

It used to be about 2 hours with my old Numaxes, 550Ah. From 11V tiny load.

 

Now it takes about a day, into 450Ah of Trojans!

 

I'm therefore 'guessing' that my old bank was only about 100Ah.

 

Any good?

[Boredrider]

Did you get to the hydrometer/refractometer shop that was mentioned umpteen posts ago? Now is the time to measure the SG of each cell, of each battery. That will tell you if further charging is worthwhile, if further equalisation is required, and if you have any duff cells.

 

FWIW we have the same charger as you and 4 trojan T105s which are still in good nick. With the Smartguage at 75%, it takes a minimum of 6 hours on the mains to get to 100% and the charger dropping onto float.

[WotEver]

Note, however, that a Specific Gravity reading is not a foolproof method of checking the SoC. As a battery ages, so will the SG reading drop, in line with the new, reduced battery capacity.

 

Tony

[Top cat]

I didn't intend my comment to start yet another round of Smartgauge vs amp hour counter wrangling. My point is that ANY gauge that purports to tell you the SoC is at best giving you a guess because we dont know the end points or what the capacity is. Unlikeca car fuel gauge where we know all of those.

Too many people read the gauge and believe it has a much higher degree of accuracy than it does. If you have a Smartgauge just read the first digit, if you have a BVM ignore the SoC reading altogether.

 

 

Top Cat

[WotEver]

I would guess (I'm happy to be corrected by any users) that the vast majority of SmartGauge users use their SmartGauge to tell them when to start charging and when to stop charging. For that purpose (the purpose for which it was designed) there's nothing better available.

 

All this discussion as to whether it's 3% accurate or not is pretty irrelevant.

 

Tony

[Graham.m]

So what should I do tomorrow morning when they've had 8 hours to recover? They'll have been on float(I hope!) all night. Drain em down a bit then recharge or sail off into the blue yonder with them at as full a charge as can be achieved overnight?

 

I would suggest tomorrow morning take them off charge use them for a day and then recharge and see if there is any improvement

Just about to take off so it will have to be brief, but where did I say I was grumbling about the life of the batteries? I wasn't, it wasn't too surprising bearing in mind the usage. That's why I decided to go for Trojans.

 

What surprises me is that you did not know the out come before you started. Personally I would not have gone down that road in the first place

[swift1894]

Did you get to the hydrometer/refractometer shop that was mentioned umpteen posts ago? at.

No but I will. I'm far from any such shop with no car, but I will.

[Graham.m]

Note, however, that a Specific Gravity reading is not a foolproof method of checking the SoC. As a battery ages, so will the SG reading drop, in line with the new, reduced battery capacity.

 

Tony

 

I find that an interesting comment, I have a set of basic batteries four years old SG at full charge is still the same as new

[MtB]

I would guess (I'm happy to be corrected by any users) that the vast majority of SmartGauge users use their SmartGauge to tell them when to start charging and when to stop charging. For that purpose (the purpose for which it was designed) there's nothing better available.

 

All this discussion as to whether it's 3% accurate or not is pretty irrelevant.

 

Tony

 

 

I'll have you know my SmartGauge is USELESS. Tells me nothing helpful at all.

 

 

(Probably because it's sitting on the worktop in my galley, awaiting installation

[WotEver]

 

I find that an interesting comment, I have a set of basic batteries four years old SG at full charge is still the same as new

Good for you.

 

I'm still right though.

[Graham.m]

You're the one who said it was an unknown, not me.

 

100% is known to within a percent or so. Therefore 50% will also be known to within a percent or so. Other than a controlled discharge at 0.1C or whatever the manufacturer specifies you cannot know the battery capacity, and therefore measuring Ah in and out is completely meaningless - a point which you appear unable to grasp.

 

You asked Nick that surely he could measure Ah out. He replied that of course you can, but it's a meaningless figure without knowing the capacity of the bank. Your response to that (after criticising his battery usage) was "You miss the point about knowing the Ahs used, the unit will measure them going back in." Uhhh... so what? That still tells you precisely zero about the SoC or bank capacity.

 

Sorry you can't have it both ways I suspect Nick the guru is right or closer to right than you +/-20%. I really believe that if what you are writing was 100% correct Merlin would be yelling it from the tree tops. Know nothing about your qualifications to say what you are stating

I would guess (I'm happy to be corrected by any users) that the vast majority of SmartGauge users use their SmartGauge to tell them when to start charging and when to stop charging. For that purpose (the purpose for which it was designed) there's nothing better available.

 

All this discussion as to whether it's 3% accurate or not is pretty irrelevant.

 

Tony

 

Not really, if it tells you too late battery damage, if it tells you it is fully charged and it is not gradual deterioration. Do you not trust your charging system to go to float when the battery is fully charged.

Edited December 1, 2015 by Graham.m

[Loafer]

 

 

I'll have you know my SmartGauge is USELESS. Tells me nothing helpful at all.

 

 

(Probably because it's sitting on the worktop in my galley, awaiting installation

 

Well get it installed then! It's only 3 wires! Then tell me the results!

[Graham.m]

Good for you.

 

I'm still right though.

 

But then you always think your right.

No but I will. I'm far from any such shop with no car, but I will.

 

Good idea a hydrometer, will tell us a lot about the batteries. need to know the rough temp when you take the readings.

[MtB]

 

Well get it installed then! It's only 3 wires! Then tell me the results!

 

 

No it isn't..!

[Loafer]

 

 

No it isn't..!

 

How many is it then!

[bottle]

Two unless you wish to monitor the start battery voltage, and that also assumes that the start battery is the same voltage as the boat domestics.

 

I cannot monitor my start battery as my boat domestic is 24v.

 

Of course there is another scenario the engine is hand start.

[cuthound]

Agreed. 4p

Nope. That is the ONLY way to know. It's what battery manufacturers do and it's what Gibbo has done literally thousands of times, which is why he was able to design SmartGauge.

 

I thought so, but wondered if anyone had an easier way of assesing a batteries capacity. I have done it (or witnessed it) a fair few times myself in myself in my career.

 

I also did it to the domestic batteries on DQ when I bought her. About 70% capacity at 7 years old on Lifeline AGM's

 

Edited for spillung.

Edited December 1, 2015 by cuthound

[cuthound]

Note, however, that a Specific Gravity reading is not a foolproof method of checking the SoC. As a battery ages, so will the SG reading drop, in line with the new, reduced battery capacity.

 

Tony

When I first started working for BT, way back in 1972, I was responsible for amongst other things exchange battery maintenance. We took weekly SG readings on batteries that were up to 20 years old. The records showed no significant SG drop with age, only with state of charge (and sulphation).

 

Edited for spilling.

Edited December 1, 2015 by cuthound

[WotEver]

When I first started working for BT, way back in 1972, I was responsible for amongst other things exchange battery maintenance. We took weekly SG readings on batteries that were up to 20 years old. The records showed no significant SG drop with age, only with state of charge (and sulphation).

 

Edited for spilling.

Yes, the SG reading will lower with sulphation.

Sulphation = lowered capacity.

 

http://www.smartgauge.co.uk/sg_soc.html

 

Tony

Edited December 1, 2015 by WotEver

[cuthound]

Yes, the SG reading will lower with sulphation.

Sulphation = lowered capacity. http://www.smartgauge.co.uk/sg_soc.html

Tony

Agree, but sulphation only occurs when batteries are either discharged and not quickly recharged, ovnever fully charged.

 

In its early stages it is easily recovered by charging until gassing commences, ceasing charging and then repeating the process until SgG's return to notrmal. If left too long the lead sulphate crystals grow too large and harden, preventing them from being converted back into spongy lead.

[swift1894]

OK. Gave them 2.5 hours on equalization.

Started at 15.29v 30.4A

After 25 mins 15.18v 26.6A

Another 20 mins 15.17v 23A

Another 55 mins 15.16v 23A

Another 20 mins 15.16v 23A

Another 25 mins 15.15v 24A

Switched charger off.

No smell from batteries, not warm but could hear bubbling.

Are they doomed??

Edited December 1, 2015 by swift1894