Charging of domestic batteries

[rowland al]

6 minutes ago, WotEver said:

Not enough if OP thinks he can fully charge his battery in 2 hours, quite obviously. 

It's a starter battery!

Yes, sorry, my test was after about 3 hours charging.

It read 12.43v after an evenings use, 3 hours charging got it to 12.9v after an hours settling time. It was drawing about 12a after the first 10 mins, then 7a after an hour. 

[rowland al]

3 hours ago, nicknorman said:

So when you are running the engine shortly after the domestics being at 12.4v, what is the voltage across the domestic battery terminals? I find it very hard to believe that you are getting a decent charging voltage if the batteries are only taking 2A. You need to sort out this conundrum before spending money on new batteries.

The Trojans were getting 14.3v across the terminals just after I first started charging them. Never any higher. 

The charging voltage with the new stater battery (being used as a domestic) does get up to 14.6v at times but starts at around 14.0v as it is drawing current, 

The other clue about the Trojans being knackered is the fact that they would lose about 0.3v after the same evenings use. As they were 210ah batteries at 12v, a loss of around 30% isn't right when only 15amps were drawn all evening. 

As I said, I now see the merits of trickle charging using solar panels or shore line to keep the Trojans up to near 100% after each cycle. If I had been able to do this, they may have lasted more than 2 years!

[nicknorman]

19 minutes ago, rowland al said:

The Trojans were getting 14.3v across the terminals just after I first started charging them. Never any higher. 

The charging voltage with the new stater battery (being used as a domestic) does get up to 14.6v at times but starts at around 14.0v as it is drawing current, 

The other clue about the Trojans being knackered is the fact that they would lose about 0.3v after the same evenings use. As they were 210ah batteries at 12v, a loss of around 30% isn't right when only 15amps were drawn all evening. 

As I said, I now see the merits of trickle charging using solar panels or shore line to keep the Trojans up to near 100% after each cycle. If I had been able to do this, they may have lasted more than 2 years!

If you never charge the Trojans at more than 14.3v they will be badly sulphated after 2 years. But it seems a bit odd that there is a difference in charging voltage between the Trojans and the starter battery. Unless you have changed something, they should both reach the same charging voltage once they are approaching fully charged.

[WotEver]

58 minutes ago, rowland al said:

It's a starter battery!

Ahh well, it’s probably full after about ten minutes then

1 hour ago, rowland al said:

It read 12.43v after an evenings use, 3 hours charging got it to 12.9v after an hours settling time. It was drawing about 12a after the first 10 mins, then 7a after an hour. 

At 7A it’s still probably only about 90% full. A 110Ah battery should ideally go down to less than 2A when it gets to high 90’s. 

[rowland al]

18 minutes ago, WotEver said:

Ahh well, it’s probably full after about ten minutes then

At 7A it’s still probably only about 90% full. A 110Ah battery should ideally go down to less than 2A when it gets to high 90’s. 

Exactly, probably about 90% after 1 hour, then after the next 2 hours pretty close to 100%. Don't forget this is only a 75ah calcium starter battery.  Albeit quite a good Yuasa silver at around £90. 

I'll try to do a current measurement after 3 hours charging sometime out of curiosity. 

I think if my evening current useage was much more than 15amps. I'd probably need more than just the one battery as I've read somewhere that starter batteries don't like going below 70% capacity. 

If the experiment goes pear shaped I'll look into a solar panel.

I'm really not sure that a bank of domestic batteries are viable for CC'ers without solar panels (or being prepared to spend a lot on diesel or petrol to trickle charge them up to 100%). Presumibly one of the luxuries of having a mooring in a marina is that you can leave the domestics plugged into a charger via shore line.

 

[WotEver]

4 minutes ago, rowland al said:

this is only a 75ah calcium starter battery.

You’re ideally looking for less than an amp tail current then

[rowland al]

3 hours ago, WotEver said:

You’re ideally looking for less than an amp tail current then

Nope, you've lost me now. What's a tail current and why am I looking for less than 1a of it? :-/

[nicknorman]

4 minutes ago, rowland al said:

Nope, you've lost me now. What's a tail current and why am I looking for less than 1a of it? :-/

The tail current is the charging current at the end of the charging process. It gradually tapers off and once it has fallen to a steady low value, that is a good indication that the batteries are fully charged. If it is still decreasing it means the battery is not yet fully charged. Around 1% of the battery’s capacity is a pretty good target. 75AH battery so 1% is 0.75A, hence the “less than 1A”. You can stop the charge sooner, but that means the battery isn’t fully charged and it might start to sulphate a bit. The charge current will never fall to zero because the battery gasses under charge and this process consumes a small current, but it will tend to a certain set value, around 1%or perhaps a bit less.

[MtB]

On 20/11/2017 at 08:50, WotEver said:

But they can. Do you need me to link to Merlin’s post again so you can read it properly?

 

Do you need me to tell you that out of the two Smartgauges I purchased (six months apart), two didn't work straight from the box?

Is that shit, or what?

[rowland al]

3 minutes ago, nicknorman said:

The tail current is the charging current at the end of the charging process. It gradually tapers off and once it has fallen to a steady low value, that is a good indication that the batteries are fully charged. If it is still decreasing it means the battery is not yet fully charged. Around 1% of the battery’s capacity is a pretty good target. 75AH battery so 1% is 0.75A, hence the “less than 1A”. You can stop the charge sooner, but that means the battery isn’t fully charged and it might start to sulphate a bit. The charge current will never fall to zero because the battery gasses under charge and this process consumes a small current, but it will tend to a certain set value, around 1%or perhaps a bit less.

Ah, thanks for that. Ok, so it would be interesting to see what the 'tail current' is after 3 hours. 

Would it be fair to say that you'd reach 1% of a starter battery's full capacity before a domestic battery with the same Ah rating?

If the surface area of the plates is larger in a starter battey, wouldn't it take less time for the chemical effect to take place given the same input voltage?

[nicknorman]

6 minutes ago, rowland al said:

Ah, thanks for that. Ok, so it would be interesting to see what the 'tail current' is after 3 hours. 

Would it be fair to say that you'd reach 1% of a starter battery's full capacity before a domestic battery with the same Ah rating?

If the surface area of the plates is larger in a starter battey, wouldn't it take less time for the chemical effect to take place given the same input voltage?

When you say “domestic battery” do you mean something like Trojans? I ask because some domestic batteries are fairly indistinguishable from starter batteries! Anyway yes I think it would be fair to say that a starter battery would charge quicker at the tail end all other things being equal, but not by much. Having gone from 110AH dual purpose leisure batteries to Trojans, I didn’t really notice any difference. But then there are so many variables.

[rowland al]

4 minutes ago, nicknorman said:

When you say “domestic battery” do you mean something like Trojans? I ask because some domestic batteries are fairly indistinguishable from starter batteries! Anyway yes I think it would be fair to say that a starter battery would charge quicker at the tail end all other things being equal, but not by much. Having gone from 110AH dual purpose leisure batteries to Trojans, I didn’t really notice any difference. But then there are so many variables.

Yes, I mean domestic likeTrojans. 

I believe all types of batteries work on the principle that what you take out, you have to put back in. The only variables seem to be price, how quickly you want the power to come out, how long they take to charge, how long they can store the energy for and how long they will last. 

Domestic batteries seem to be more expensive per Ah rating, less able to provide high currents, take longer to charge per Ah rating, not sure if they can store energy for longer than a starter battery,  but apparently they last longer (or do they?).

 

 

[nicknorman]

5 minutes ago, rowland al said:

Yes, I mean domestic likeTrojans. 

I believe all types of batteries work on the principle that what you take out, you have to put back in. The only variables seem to be price, how quickly you want the power to come out, how long they take to charge, how long they can store the energy for and how long they will last. 

Domestic batteries seem to be more expensive per Ah rating, less able to provide high currents, take longer to charge per Ah rating, not sure if they can store energy for longer than a starter battery,  but apparently they last longer (or do they?).

 

Well in my experience they certainly last much longer. Much much longer. Provided they are charged properly! The time difference to reach fully charged is pretty minimal. They are not quite as good at high discharge currents but still adequate.

[rowland al]

8 minutes ago, nicknorman said:

XtWell in my experience they certainly last much longer. Much much longer. Provided they are charged properly! The time difference to reach fully charged is pretty minimal. They are not quite as good at high discharge currents but still adequate.

Yes, so we come back to the ability to charge them 'properly'. So if you usually have access to a shore line or the solar panels are adequate, then probably, all types of battery will last a long time.

For those who don't have access to shore line or have a solar panel, then charging efficiency is more important.    

 

[Dr Bob]

9 hours ago, rowland al said:

Yes, I mean domestic likeTrojans. 

I believe all types of batteries work on the principle that what you take out, you have to put back in. The only variables seem to be price, how quickly you want the power to come out, how long they take to charge, how long they can store the energy for and how long they will last. 

Domestic batteries seem to be more expensive per Ah rating, less able to provide high currents, take longer to charge per Ah rating, not sure if they can store energy for longer than a starter battery,  but apparently they last longer (or do they?).

 

 

You have missed the two most important principles. How deep can you discharge before the battery gets upset and how many cycles can it do before expiring at 50% DoD. 

[Dr Bob]

9 hours ago, rowland al said:

Yes, so we come back to the ability to charge them 'properly'. So if you usually have access to a shore line or the solar panels are adequate, then probably, all types of battery will last a long time.

For those who don't have access to shore line or have a solar panel, then charging efficiency is more important.    

 

Not if you go out regularly and park somewhere remote in Dec/Jan. We are out now. Solar is almost non existent. Power usage is higher with the telly on all the time and the eberspacher on or say 3 hours a day. Unless you run the engine a lot it won't be long before cheap batteries are suffering. 

I agree charging efficiency is critical.

[nicknorman]

9 hours ago, rowland al said:

Yes, so we come back to the ability to charge them 'properly'. So if you usually have access to a shore line or the solar panels are adequate, then probably, all types of battery will last a long time.

For those who don't have access to shore line or have a solar panel, then charging efficiency is more important.    

 

Our cheapo starter type leisure batteries lasted 6 months before starting to play up and were dead by 2 years. Our Trojans still have as-new capacity after 4 years. Charge efficiency is the same for both, around 94%. Same charging regime.

[rowland al]

1 minute ago, Dr Bob said:

You have missed the two most important principles. How deep can you discharge before the battery gets upset and how many cycles can it do before expiring at 50% DoD. 

Aren't these factors which relate to 'how long they will last' ? 

[rowland al]

1 minute ago, nicknorman said:

Our cheapo starter type leisure batteries lasted 6 months before starting to play up and were dead by 2 years. Our Trojans still have as-new capacity after 4 years. Charge efficiency is the same for both, around 94%. Same charging regime.

I guess I will find out for myself at some point! At least the battery I got is s good quality one (allegedly). 

Do you get to charge your Trojans up a lot overnight on shore line? 

6 minutes ago, Dr Bob said:

Not if you go out regularly and park somewhere remote in Dec/Jan. We are out now. Solar is almost non existent. Power usage is higher with the telly on all the time and the eberspacher on or say 3 hours a day. Unless you run the engine a lot it won't be long before cheap batteries are suffering. 

I agree charging efficiency is critical.

Yes, I can see that solar panels are not so helpful just at the time of year you need them.

Wind power?

[Dr Bob]

5 minutes ago, rowland al said:

Aren't these factors which relate to 'how long they will last' ? 

The 'how long they last' also depends on how often you are out on the boat so more important to understand DoD and cycles. Your description simplifies it too much if you are trying to compare starting batteries, leisure, cheapos or trojians.

 

[nicknorman]

4 minutes ago, rowland al said:

I guess I will find out for myself at some point! At least the battery I got is s good quality one (allegedly). 

Do you get to charge your Trojans up a lot overnight on shore line? 

When we leave the boat in the marina, yes. But we are out a lot, for example this summer we did an 8 week trip off shore power. No loss of battery performance or any hint of sulphation, but we do cruise most days. 

[WotEver]

11 hours ago, rowland al said:

Would it be fair to say that you'd reach 1% of a starter battery's full capacity before a domestic battery with the same Ah rating?

I read all the other replies before posting this and I’m not sure that any of the answers made it clear to the OP that the answer to this question is ‘No, not really’. Any lead-acid battery will take many hours to get down to 1% tail current. 

Oh, and Ah rating doesn’t have much bearing on it either. Once the initial bulk charging phase is completed it takes the same amount of time for absorption more or less regardless of battery capacity. 

[rowland al]

2 hours ago, WotEver said:

I read all the other replies before posting this and I’m not sure that any of the answers made it clear to the OP that the answer to this question is ‘No, not really’. Any lead-acid battery will take many hours to get down to 1% tail current. 

Oh, and Ah rating doesn’t have much bearing on it either. Once the initial bulk charging phase is completed it takes the same amount of time for absorption more or less regardless of battery capacity. 

If a starter battery has a higher surface area of plates so that it can release energy at a higher rate, then surely it will accept charge at a higher rate. So wouldn't it charge quicker at all stages?

[nicknorman]

4 minutes ago, rowland al said:

If a starter battery has a higher surface area of plates so that it can release energy at a higher rate, then surely it will accept charge at a higher rate. So wouldn't it charge quicker at all stages?

Yes maybe in theory, but in reality the difference isn’t noticeable. Things like battery temperature are far more significant.

Both my cheapo leisures and now my Trojans can run the 2kw electric kettle (~200A). The voltage with the Trojans is a little lower but not massively so. They are of course “semi traction” batteries. Perhaps full traction batteries would have a more noticeable difference.

Edited November 30, 2017 by nicknorman

[rowland al]

21 hours ago, nicknorman said:

Yes maybe in theory, but in reality the difference isn’t noticeable. Things like battery temperature are far more significant.

Both my cheapo leisures and now my Trojans can run the 2kw electric kettle (~200A). The voltage with the Trojans is a little lower but not massively so. They are of course “semi traction” batteries. Perhaps full traction batteries would have a more noticeable difference.

Yes, well I'm not sure whether I can use my experience with the 2 x Trojans as a comparison with the new starter battery as I suspect they became knackered due to them not getting a full trickle charge every night after use.

Only time will tell, but at least if this one dies after 2 years, it will only cost me £90 to replace! 

Edited December 1, 2017 by rowland al