A list of battery charging figures

[swift1894]

When a lead acid battery is discharged lead sulphate is produce by the chemical reaction. Initially this is soft and the action of fully recharging the battery turns it back into lead and sulphuric acid. Unfortunately if the battery is not recharged or fully recharged the lead sulphate turns into hard crystals which are hard or impossible to remove. The effect of this is that the battery’s capacity is reduced it is frequently referred to as sulphation and is one of the major cause of battery failure.

 

Thus it is important to FULLY recharge batteries after discharge.

Unfortunately it's impossible to FULLY recharge batteries, if not plugged into the mains without running the genny for many uneconomical hours.

[bottle]

If you plan to get a hydrometer, I'd recommend the optical refractometer type that you can get from eBay for 20-30 quid. Easier to read IMO and no issues with float sticking etc,

 

Like this:

 

http://www.ebay.co.uk/itm/Battery-Acid-Ethylene-Propylene-Glycol-Antifreeze-ATC-AdBlue-Urea-Refractometer-/181934518426?hash=item2a5c24709a:g:X6EAAOxyOlhS3LyR

 

£17 in fact

 

Oooo! I want one...

 

 

 

Wait a moment my batteries are AGMs.

[Graham.m]

Unfortunately it's impossible to FULLY recharge batteries, if not plugged into the mains without running the genny for many uneconomical hours.

 

Depends on what you mean by uneconomical. You have to take into account the damage done to the batteries and the shortening of life.

 

Just as a rough example lets say you have a bank of 200Ah batteries and your daily use is say 50Ah

 

Day one you recharge to say 9O% so your capacity is down to 180Ah

Day two recharge to 90% so your capacity is down to 162Ah

Day three the same your capacity is down to 146Ah

Day four same capacity is down to 131Ah

Day five same capacity is down to 118Ah

 

So in five days you are down to nearly 50% of the battery capacity. Some of which you may not get back because the battery has sulphated

 

You have also shortened the battery life

[dmr]

 

Depends on what you mean by uneconomical. You have to take into account the damage done to the batteries and the shortening of life.

 

Just as a rough example lets say you have a bank of 200Ah batteries and your daily use is say 50Ah

 

Day one you recharge to say 9O% so your capacity is down to 180Ah

Day two recharge to 90% so your capacity is down to 162Ah

Day three the same your capacity is down to 146Ah

Day four same capacity is down to 131Ah

Day five same capacity is down to 118Ah

 

So in five days you are down to nearly 50% of the battery capacity. Some of which you may not get back because the battery has sulphated

 

You have also shortened the battery life

 

Thats a good description of the downward spiral of sulphation, but it does not happen on a daily basis.

Day one recharge to 90%, avaiable capacity is still pretty much 200Ah

After SEVERAL days of only charging to 90% the capacity will be down a bit, and after a few weeks it will be significantly down.

Its certainly not a simple 0.9 x 0.9 x 0.9 thing.

I don't have exact figures (and life is too short to get them) but I would guess 10% to 25% capacity lost in a month, but whether you charge to 90%, or 95% or 85% might be quite significant.

 

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

[bottle]

Edit: in answer to Graham.m post. Dave beat me in posting.

 

Mmmm.

 

I wonder, I think what you mean is SOC, the capacity has not dropped that quick.

 

Yes you are undercharging but if capacity was lost that fast batteries would only last a week before needing replacing.

 

A 'full charge' would get them to 100%SOC and very nearly the stated capacity.

 

My batteries have been regularly charged to 95% SOC and very rarely to 100% SOC, they are abused but have lasted four years supplying a live aboard CCing boat, that is all electric.

 

When new I was charging them about four hours per 24 hrs it is now 5 hours per 24 hrs. and yes their capacity is well down.

Edited November 22, 2015 by bottle

[Graham.m]

 

Thats a good description of the downward spiral of sulphation, but it does not happen on a daily basis.

Day one recharge to 90%, avaiable capacity is still pretty much 200Ah

After SEVERAL days of only charging to 90% the capacity will be down a bit, and after a few weeks it will be significantly down.

Its certainly not a simple 0.9 x 0.9 x 0.9 thing.

I don't have exact figures (and life is too short to get them) but I would guess 10% to 25% capacity lost in a month, but whether you charge to 90%, or 95% or 85% might be quite significant.

 

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

 

Sorry, please explain to me how if you have a 200Ah battery, you discharge it by 50Ahs and recharge the battery to 90% of its capacity you have nearly 200Ahs.

 

I think you are forgetting that a battery does not make electricity it only stores what has been put into it. Think of it as a full bucket with capacity 200 litres of water in it. After a day you have used 50 litres. You refill the bucket to 90% of its capacity that is not 200 litres but only 180 litres.

Edit: in answer to Graham.m post. Dave beat me in posting.

 

Mmmm.

 

I wonder, I think what you mean is SOC, the capacity has not dropped that quick.

 

Yes you are undercharging but if capacity was lost that fast batteries would only last a week before needing replacing.

 

A 'full charge' would get them to 100%SOC and very nearly the stated capacity.

 

My batteries have been regularly charged to 95% SOC and very rarely to 100% SOC, they are abused but have lasted four years supplying a live aboard CCing boat, that is all electric.

 

When new I was charging them about four hours per 24 hrs it is now 5 hours per 24 hrs. and yes their capacity is well down.

 

Think there is a quibble over words here. but the useable capacity each day is still only as stated. If it makes it easier to understand use SOC.

 

Ed. Sulphation rates can depend on rate of discharge, depth of discharge, rate of charge and voltage plus level of recharge.

Edited November 22, 2015 by Graham.m

[bottle]

Lets take your bucket, you take out 25% of its fullness and put back 20%, the bucket is only 95% full (SOC) but it still has the potential to hold 100% capacity.

The bucket has not lost capacity it is just not as full.

[nicknorman]

I give up.

[Graham.m]

Lets take your bucket, you take out 25% of its fullness and put back 20%, the bucket is only 95% full (SOC) but it still has the potential to hold 100% capacity.

The bucket has not lost capacity it is just not as full.

 

Yep I don't disagree, but the usable capacity is not 200 litres but 190litres and so it goes on until the battery is fully charged when it will recharge to an availabe capacity which will be less than it would have be had the battery been fully charged each day.

I give up.

hurrah

[dmr]

Lets take your bucket, you take out 25% of its fullness and put back 20%, the bucket is only 95% full (SOC) but it still has the potential to hold 100% capacity.

The bucket has not lost capacity it is just not as full.

 

My post abandoned, I could not have put it better! Another victory for the water analogy.

 

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

[bottle]

OK if you want to quibble over words, this two seem to have suddenly appeared...

 

Usable Available

 

I to am out of here, go and discuss with yourself.

Edit: not you Dave

Edited November 22, 2015 by bottle

[dmr]

I give up.

 

Yeah, your right, I think I'll walk down to the engine room and watch the smartgage for a bit, its good for the soul.

 

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

[nicknorman]

hurrah

I am not sure whether you are pretending to be a complete idiot to get an argument, or whether you actually are a complete idiot. Although for the purposes of the forum I don't think it matters either way.

[Paul C]

I am not sure whether you are pretending to be a complete idiot to get an argument, or whether you actually are a complete idiot. Although for the purposes of the forum I don't think it matters either way.

 

I'd not worry too much, I think its a simple case of actual knowledge being slightly short of perceived knowledge.

[dmr]

Smartgage says batteries at 75% (I believe it) and the Adverc says about 6 amps going out.

I know that with our typical useage we can go about 48 hours between charges (based on taking the batteries down to 50%). When we can't manage this then I know its time to equalise (another use of the smartgage!)

The stoves lit and the dogs asleep in front of it.

Its 22 degrees in the boat and 12 outside (not sure I believe that, the outside sensor sometimes sees a bit of warm air leaking from the pidgeon box).

The water tank meter says 60% (I half believe that but its less accurate than the smartgage)

The poo tank is half full (direct reading optical guage on a dump through so I know thats right).

The nearest pub is about 200yds but its £3.90 for a pint.

I like living on a boat.

I'm sat at the PC writing software to earn a bob or two to finance this wonderful lifestyle. I think it might be Sunday but when you live on a boat everyday is a weekend!

 

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

[Graham.m]

I am not sure whether you are pretending to be a complete idiot to get an argument, or whether you actually are a complete idiot. Although for the purposes of the forum I don't think it matters either way.

Oh a complete idiot definitely

 

 

Think you need to read thinks in context and not be pedantic. It was quite obvious I was referring to available capacity.

 

 

I'd not worry too much, I think its a simple case of actual knowledge being slightly short of perceived knowledge.

 

Don't thinks so, but then you don't know my experience nor qualification. Maybe not being able to read a quick short note without being pedantic is the problem

[Paul C]

All I'm saying, is when I read Nick's posts they make sense to me. When I read some of yours, there's times when it doesn't make sense or appears incorrect/illogical - in fairness it might simply be due to uncommon terminology.

[Graham.m]

Smartgage says batteries at 75% (I believe it) and the Adverc says about 6 amps going out.

I know that with our typical useage we can go about 48 hours between charges (based on taking the batteries down to 50%). When we can't manage this then I know its time to equalise (another use of the smartgage!)

The stoves lit and the dogs asleep in front of it.

Its 22 degrees in the boat and 12 outside (not sure I believe that, the outside sensor sometimes sees a bit of warm air leaking from the pidgeon box).

The water tank meter says 60% (I half believe that but its less accurate than the smartgage)

The poo tank is half full (direct reading optical guage on a dump through so I know thats right).

The nearest pub is about 200yds but its £3.90 for a pint.

I like living on a boat.

I'm sat at the PC writing software to earn a bob or two to finance this wonderful lifestyle. I think it might be Sunday but when you live on a boat everyday is a weekend!

 

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

 

Have a good weekend

Sun is shining here, temp order of 5C and only a light breeze. Stove and central heating on temp about 22C

Surely you can afford 3.90 for a pint, mind you I would not know if that is expensive as I dislike beers.

[Graham.m]

All I'm saying, is when I read Nick's posts they make sense to me. When I read some of yours, there's times when it doesn't make sense or appears incorrect/illogical - in fairness it might simply be due to uncommon terminology.

 

Maybe I use too close to engineering terminology. I know my people would understand exactly what I meant. The deliverable capacity or available capacity the battery can give at point X.

 

Could also be my dyslexia, only discovered at 44 when I did a heavy course with a lecturer who refued to give notes and only wrote on a whoite board. Who knows life goes on and still there is a poor guy who has a probably major battery problem.

[Top cat]

Unfortunately it's impossible to FULLY recharge batteries, if not plugged into the mains without running the genny for many uneconomical hours.

This is where solar panels earn their keep, putting that last 5% in silently and for free. Except today when I'm getting 150W out of 4Kw of panels but yesterday was a different story.

 

Top Cat

[nicknorman]

Maybe I use too close to engineering terminology. I know my people would understand exactly what I meant. The deliverable capacity or available capacity the battery can give at point X.

For me it is your frequent dimensionally incorrect statements, use of dimensionally wrong units, use of incorrect engineering terminology and a lack of logical analysis and other fundamental mistakes that tells me you are definitely not an engineer. You might however be an installer or technician. If your dyslexia was not discovered until you were 44, presumably (according to you) having obtained a degree etc, I suggest it is not too bad and thus not an excuse for fundamental mistakes.

[Graham.m]

For me it is your frequent dimensionally incorrect statements, use of dimensionally wrong units, use of incorrect engineering terminology and a lack of logical analysis and other fundamental mistakes that tells me you are definitely not an engineer. You might however be an installer or technician. If your dyslexia was not discovered until you were 44, presumably (according to you) having obtained a degree etc, I suggest it is not too bad and thus not an excuse for fundamental mistakes.

 

You make lots of incorrect assumptions Nick. Dyslexia does not have to be life long, I suspect I and the doctors know cause, same way my disability did. But the rest is private

[nicknorman]

But the rest is private

Of course it is. Although I can have a pretty good guess.

 

Anyway if you struggle with the basics of engineering because of your condition, you can't do anything about that. But what you can do is not come over so dogmatic and opinionated whilst being so incorrect. Then we would all get along better.

[Paul C]

 

Depends on what you mean by uneconomical. You have to take into account the damage done to the batteries and the shortening of life.

 

Just as a rough example lets say you have a bank of 200Ah batteries and your daily use is say 50Ah

 

Day one you recharge to say 9O% so your capacity is down to 180Ah

Day two recharge to 90% so your capacity is down to 162Ah

Day three the same your capacity is down to 146Ah

Day four same capacity is down to 131Ah

Day five same capacity is down to 118Ah

 

So in five days you are down to nearly 50% of the battery capacity. Some of which you may not get back because the battery has sulphated

 

You have also shortened the battery life

 

I looked back, this was the one that struck me as being wrong, I gave you credit by describing the terminology as "uncommon". The way you've used "capacity" in two different ways, to mean two different things (in red, amount of stored energy; in green, actual battery capacity) is the illogical bit.

[Graham.m]

Of course it is. Although I can have a pretty good guess.

 

Anyway if you struggle with the basics of engineering because of your condition, you can't do anything about that. But what you can do is not come over so dogmatic and opinionated whilst being so incorrect. Then we would all get along better.

 

As my guys say the oldman know more than enough to keep up with us and get ahead of us. So I don't think my engineering is at fault, brain still works well. Fingers may not be able to keep up.

 

As for guessing I doubt it. I suggest you take me as I am or not that is up to you.