THIRD BATTERY, CHARGER WIRING.

[Mtbcol]

Morning all.
About to get a third leisure battery to boost capacity for winter trips.

Does it really matter where the pos and neg connections are made on the batteries (obviously pos to pos and neg to neg). Does the solar, and mains charger need to be one terminal on the furthest battery and the other on the nearest, or will any combination do? I've heard so many conflicting statements.
Hope I've explained that properly?
Also, I guess my Aldi 240 volt smart battery charger would definitely not be up to the job once I've got three batteries? Could someone recommend a decent not massively expensive replacement please?
Thanks everyone

Colin.

 

[trevskoda]

Best to put the pos from solar to one battery and the neg to other one of three, your charger will take longer to charge or float the bigger bank, if within what the makers say id not bother with changing, a slow long charge is ok to float batteries.
Wildbus is your man for electric stuff, should be along soon.

 

[Mtbcol]

Best to put the pos from solar to one battery and the neg to other one of three, your charger will take longer to charge or float the bigger bank, if within what the makers say id not bother with changing, a slow long charge is ok to float batteries.
Wildbus is your man for electric stuff, should be along soon.

Thanks Trev. So as long as pos and neg from chargers are on different batteries I should be ok?

 

[wildebus]

If you have a read of the page on this website, there are excellent diagrams showing the best way to wire multiple batteries (2, 3 or 4 parallel battery examples are given), with an explanation of WHY they should be wired in this manner - https://caravanchronicles.com/guides/how-to-connect-two-batteries-in-parallel-part-2/

Now as long as the batteries are wired +ve to +ve and -ve to -ve, they will all work regardless, but to make the most of your investment, you may as well do it right and correctly, rather than just 'good enough'.

 

[Mtbcol]

If you have a read of the page on this website, there are excellent diagrams showing the best way to wire multiple batteries (2, 3 or 4 parallel battery examples are given), with an explanation of WHY they should be wired in this manner - https://caravanchronicles.com/guides/how-to-connect-two-batteries-in-parallel-part-2/

Now as long as the batteries are wired +ve to +ve and -ve to -ve, they will all work regardless, but to make the most of your investment, you may as well do it right and correctly, rather than just 'good enough'.

Definitely.....off to the linked page now

 

[merl]

Morning all.
About to get a third leisure battery to boost capacity for winter trips.

Does it really matter where the pos and neg connections are made on the batteries (obviously pos to pos and neg to neg). Does the solar, and mains charger need to be one terminal on the furthest battery and the other on the nearest, or will any combination do? I've heard so many conflicting statements.
Hope I've explained that properly?
Also, I guess my Aldi 240 volt smart battery charger would definitely not be up to the job once I've got three batteries? Could someone recommend a decent not massively expensive replacement please?
Thanks everyone

Colin.

You've already had good advice above, hopefully you'll understand that but just in case you're in any doubt and the drawings dont seem to match up with your particular battery arrangement here's a little more input.
After you've connected the 3rd battery into your system you'll have 1 battery that's got 2 wires coming from the + and - terminals, this battery is the CENTRE battery in the diagram and NOTHING else gets connected to this battery so basically ignore it.
So now concentrating on the 2 'end' batteries only.
Connect ALL of the positives for everything (charger, solar controller, main control panel feed, any other feeds etc etc) and connect to EITHER of the 2 available +ve battery terminals. Then connect ALL of the negatives (like you did with the positives) and connect them to the - terminal on the OTHER end battery. You're done!
Regarding the use of your existing charger. Basically you can use any size charger but it's a matter of how long it will take to charge them fully.
As a very rough rule you simply total up your battery amp hour capacity and divide that by your charger current and that will give you the number of hours it's going to take to charge your batteries. So let's say you have 3 X 100Ah batteries (that gives us 300Ah) and a 10A charger. 300 over 10 gives us 30 hours to recharge, very basic but good enough to give you an indication. If you're needing to recharge well drained batteries during a site visit then you're probably going to need at least double that so at least 20A but a lot depends on how much travelling/charging you're able to get and also your solar recovery too so like everything else, your choice will depend on your typical use and your pocket. One thing I will say is that ALL of the cheaper ebay/amazon chargers that I've measured (I've tested several) DONT give you the maximum current they claim, in my experience you need to de-rate them by about 50% so if you actually want 20A of charge you need to buy a 30A charger, Chinese amps are not the same as UK ones! Also watch out because occasionally the cheap chargers need you to set the parameters and/or press a 'start' button, a right faff if you've built your charger away. Finally most of the cheap chargers actually consume power from the 12V system while you're off grid and not charging, it's usually not much but it may be worth considering adding a switch with easy access on the output of the charger so you can isolate this from the batteries.
Good luck

 

[Mtbcol]

You've already had good advice above, hopefully you'll understand that but just in case you're in any doubt and the drawings dont seem to match up with your particular battery arrangement here's a little more input.
After you've connected the 3rd battery into your system you'll have 1 battery that's got 2 wires coming from the + and - terminals, this battery is the CENTRE battery in the diagram and NOTHING else gets connected to this battery so basically ignore it.
So now concentrating on the 2 'end' batteries only.
Connect ALL of the positives for everything (charger, solar controller, main control panel feed, any other feeds etc etc) and connect to EITHER of the 2 available +ve battery terminals. Then connect ALL of the negatives (like you did with the positives) and connect them to the - terminal on the OTHER end battery. You're done!
Regarding the use of your existing charger. Basically you can use any size charger but it's a matter of how long it will take to charge them fully.
As a very rough rule you simply total up your battery amp hour capacity and divide that by your charger current and that will give you the number of hours it's going to take to charge your batteries. So let's say you have 3 X 100Ah batteries (that gives us 300Ah) and a 10A charger. 300 over 10 gives us 30 hours to recharge, very basic but good enough to give you an indication. If you're needing to recharge well drained batteries during a site visit then you're probably going to need at least double that so at least 20A but a lot depends on how much travelling/charging you're able to get and also your solar recovery too so like everything else, your choice will depend on your typical use and your pocket. One thing I will say is that ALL of the cheaper ebay/amazon chargers that I've measured (I've tested several) DONT give you the maximum current they claim, in my experience you need to de-rate them by about 50% so if you actually want 20A of charge you need to buy a 30A charger, Chinese amps are not the same as UK ones! Also watch out because occasionally the cheap chargers need you to set the parameters and/or press a 'start' button, a right faff if you've built your charger away. Finally most of the cheap chargers actually consume power from the 12V system while you're off grid and not charging, it's usually not much but it may be worth considering adding a switch with easy access on the output of the charger so you can isolate this from the batteries.
Good luck

You've already had good advice above, hopefully you'll understand that but just in case you're in any doubt and the drawings dont seem to match up with your particular battery arrangement here's a little more input.
After you've connected the 3rd battery into your system you'll have 1 battery that's got 2 wires coming from the + and - terminals, this battery is the CENTRE battery in the diagram and NOTHING else gets connected to this battery so basically ignore it.
So now concentrating on the 2 'end' batteries only.
Connect ALL of the positives for everything (charger, solar controller, main control panel feed, any other feeds etc etc) and connect to EITHER of the 2 available +ve battery terminals. Then connect ALL of the negatives (like you did with the positives) and connect them to the - terminal on the OTHER end battery. You're done!
Regarding the use of your existing charger. Basically you can use any size charger but it's a matter of how long it will take to charge them fully.
As a very rough rule you simply total up your battery amp hour capacity and divide that by your charger current and that will give you the number of hours it's going to take to charge your batteries. So let's say you have 3 X 100Ah batteries (that gives us 300Ah) and a 10A charger. 300 over 10 gives us 30 hours to recharge, very basic but good enough to give you an indication. If you're needing to recharge well drained batteries during a site visit then you're probably going to need at least double that so at least 20A but a lot depends on how much travelling/charging you're able to get and also your solar recovery too so like everything else, your choice will depend on your typical use and your pocket. One thing I will say is that ALL of the cheaper ebay/amazon chargers that I've measured (I've tested several) DONT give you the maximum current they claim, in my experience you need to de-rate them by about 50% so if you actually want 20A of charge you need to buy a 30A charger, Chinese amps are not the same as UK ones! Also watch out because occasionally the cheap chargers need you to set the parameters and/or press a 'start' button, a right faff if you've built your charger away. Finally most of the cheap chargers actually consume power from the 12V system while you're off grid and not charging, it's usually not much but it may be worth considering adding a switch with easy access on the output of the charger so you can isolate this from the batteries.
Good luck

Hi merl, and thank you.
Got my third battery in and linked up now, and I think I've got it right.

Just one thing, maybe I've not noticed before l, but I've not got anything attached to the load output side of my victron charger, but it's showing a current of 0.3 Amps and power if 4 watts. I'm harvesting some solar and I've got a trickle charger on the 3 batteries.

 

[r4dent]

I have always thought that multiple leisure batteries should be same type capacity and AGE.

Are you planning to get three new identical batteries?

Maybe continue using just two but have the third one standing by as a single replacement to quickly drop into the circuit

 

[merl]

Hi merl, and thank you.
Got my third battery in and linked up now, and I think I've got it right.

Just one thing, maybe I've not noticed before l, but I've not got anything attached to the load output side of my victron charger, but it's showing a current of 0.3 Amps and power if 4 watts. I'm harvesting some solar and I've got a trickle charger on the 3 batteries.

Great!
Can you clarify:-
When you say Victron charger, is this a solar charger or mains charger?
Is this the same charger that's showing 0.3A?
If you're harvesting solar then that will deliver current to the batteries but only if the batteries are connected.
Likewise with a trickle charger but you don't say if that's a separate charger, your solar system or the Victron.
I ask this because your post suggests you have a charger that has nothing connected to it's output but says that it's delivering 0.3A which is impossible!.
TBH That sort of current suggests the tail end of the trickle phase, sometimes referred to as maintenance as it's pretty low for 3 batteries.

 

[Mtbcol]

Hi merl.
Yes the victron is the solar charger, which is showing the 0.3 amps.

The mains trickle charger is an Aldi smart charger.

 

[merl]

Are you sure it's not connected to the batteries?!

 

[Mtbcol]

Are you sure it's not connected to the batteries?!

Yeah, I forgot to mention it's now connected to all three. Sorry merl, your dealing with a 12volt idiot. I'm kind of panicking a bit as I want it right for our Christmas Cairngorms trip and it all ABIT frantic at the moment. Apologies again.

 

[merl]

I have always thought that multiple leisure batteries should be same type capacity and AGE.

Are you planning to get three new identical batteries?

Maybe continue using just two but have the third one standing by as a single replacement to quickly drop into the circuit

Capacity and age is of no great issue, as long as the batteries are able to contribute significantly then what's the worst that can happen?
There is an issue WRT chemistry and make up though, but just make sure they all have the same parameters for max charge and float voltage and I personally can't see an issue.
Willing to be educated though of course with proper science. Please don't quote X battery sales says so

 

[merl]

Yeah, I forgot to mention it's now connected to all three. Sorry merl, your dealing with a 12volt idiot. I'm kind of panicking a bit as I want it right for our Christmas Cairngorms trip and it all ABIT frantic at the moment. Apologies again.

Do you mind if I tut and call you a pillock?
No problems good luck with the trip

 

[Mtbcol]

I'm with you on this one merl. Although mine are all SFL, I have two 100ah (one if which is my new one), and one 110ah. All three are of different ages. With about a year, maybe more between them all. Nothing wrong with the two I had before my new purchase two days ago, just wanted more ah storage. I've 320 watt of solar by the way.

I guess someone will shout at me now, but it works for us

 

[Mtbcol]

Do you mind if I tut and call you a pillock?
No problems good luck with the trip

No, not all, I deserve it. On a serious note, I guess my readings are as they should be then? Just had all my led interior lights on, and my CDH running for an hour and I've got 12.52 v showing and I've disconnected the mains charger so I guess all is well?

 

[merl]

No, not all, I deserve it. On a serious note, I guess my readings are as they should be then? Just had all my led interior lights on, and my CDH running for an hour and I've got 12.52 v showing and I've disconnected the mains charger so I guess all is well?

There's a lot of variables that affect the voltage reading and how it relates to the state of charge (SOC)
Temperature
Whether you're drawing ANY current at the time and also if you're charging.
Battery chemistry
Battery age
Accuracy of the reading
12.52 is well within range of Lead acid.

 

[Mtbcol]

There's a lot of variables that affect the voltage reading and how it relates to the state of charge (SOC)
Temperature
Whether you're drawing ANY current at the time and also if you're charging.
Battery chemistry
Battery age
Accuracy of the reading
12.52 is well within range of Lead acid.

Thanks merl. I'll be sleeping soundly tonight then.

Yours sincerely
I.M.A. PILLOCK. (Mr.)

 

[r4dent]

Capacity and age is of no great issue, as long as the batteries are able to contribute significantly then what's the worst that can happen?
There is an issue WRT chemistry and make up though, but just make sure they all have the same parameters for max charge and float voltage and I personally can't see an issue.
Willing to be educated though of course with proper science. Please don't quote X battery sales says so

I was originally told this by the late Allan Evans of A & N. He was a friend, a colleague and a fellow biker.
Prior to his early passing, A&N were one of the leading UK Motor Home electrical companies but didn't sell batteries so no hidden agenda.
Every article I've read about a second leisure battery repeats the recommendation that they be the same Capacity & Age.
Maybe I am suffering from "everybody says this, it must be true."

Like you I am more than willing to be educated by science, can you quote a source for your belief ?

 

[merl]

One very important point, if you're connecting batteries in series then that's a different story, I think there's a lot misinformation passed on because people fail to distinguish between the 2 and apply the same rule to paralleling them.
My source comes simply from applying common sense, a decent electrical knowledge and physics to the situation. Yep I may have overlooked something and would welcome any scientific explanation contradicting my view but I can find no reliable science based articles anyway to prove either way and the science is pretty basic and electronics 101 TBF.
AGE.
I can see no certain correlation between age and a batteries condition or suitably to be connected in parallel. I think it's an attempt to ensure that both batteries are similarly 'worn out' and hence capacities are the same (which actually isn't important anyway as I'll explain later) but as we all know capacity retention isn't absolutely linked to age and you can easily have an abused, half knackered 6 months old or a 2 or 3 year old that's been well carried for and hardly cycled and still in excellent condition. So therefore 'age' in the case of 'the rule' actually relates to how much work/abuse both batteries have been previously exposed to, if so then the parameter should be ageING rather than age so the rule is either wrong or technically wrong anyway AND poorly written.
SIZE/CAPACITY.
Think about it.
The 2 (or whatever number) batteries are connected in parallel, therefore they all must assume the same voltage as each other.
Assuming all batteries are the same chemistry, all the batteries will reach being fully charged at the same time and ALL the batteries will reach full discharge at the same time. Therefore if you add a 100AH to a 50AH (same chemistry) and you must get 150AH. The chemistry is the same so the discharge curves will be similar therefore they will all follow each other on their charge/ discharge paths and hence they will all have a similar percentage of their full capacity at any point too.
We know how batteries work and we know what needs to be done and what needs to be avoided, we can see from the above that each battery doesn't know that it's actually connected in parallel, it has it's own perfectly acceptable and normal life so obviously there are no issues whatsoever.
So, age/ ageing doesn't matter and size capacity doesn't matter either. Chemistry isn't mentioned even though it's actually the most important factor of all.
Conclusion is the 'age and size' rule is largely nonsense.