Mixing Amps on a House Bank?

[Unregistered-1]

In series, no. In parallel, yes, but the larger ones won't charge properly.

I wouldn't add batteries. I'd swap the too-small ones out for another job and upgrade the whole pack, or just use them until they died and replace them.

[LargeMarge]

Back in the olden days, I was an A&P aircraft mechanic. My nickname was 'Sparky'.

The fellows always gave me plenty of room anytime I fussed about with wiring. My go-to phrase was "Well, it looks like that's working..."

From outside the hanger door, there came a chorus of "So far..."

Mixing battery types and ages and capacity? Garsh, around aircraft, we have a name for folks like that == test pilot.

[Roniszoro]

Originally Posted by LargeMarge

Back in the olden days, I was an A&P aircraft mechanic. My nickname was 'Sparky'.

The fellows always gave me plenty of room anytime I fussed about with wiring. My go-to phrase was "Well, it looks like that's working..."

From outside the hanger door, there came a chorus of "So far..."

Mixing battery types and ages and capacity? Garsh, around aircraft, we have a name for folks like that == test pilot.

Perhaps if you had read my original post and subsequent ones on this topic, your answer would have been more accurate and articulate.

[Icarus]

Charging batteries of different capacity together is not a good idea, obviously a larger capacity battery has different charging parameters then a battery with a lower capacity.
The same goes for mixing older and new batteries even though they are of the same capacity. .older batteries develop more resistance.
I have a Link 2000 and 4xT105 , 2 batteries for some reason had a bad cell, so while charging they started to heat up, the whole charging cycle got compromised, I replaced the old batteries and had no more problems.
Just mu thoughts. .

[foggysail]

Originally Posted by Waveform

I’m an electrical engineer. It makes no difference. You can combine any size batteries. Just have to be the same chemistry. It’s that simple.

Yeah, also an EE here. Circuit theory is a hard sell when in competition with rumors, habits and a mechanic said........

[john61ct]

Again, in parallel not a problem for

safety

nor effectiveness, **in the short term**.

Fine for someone really broke, or looking for a "limp home" solution when far from civilization.

But for those who design and purchase components for 8-10 year bank lifetimes,

it is a ridiculous approach.

The less similar the more the bank as a whole will perform as well as the weakest link.

[sailorchic34]

Originally Posted by Waveform

I’m an electrical engineer. It makes no difference. You can combine any size batteries. Just have to be the same chemistry. It’s that simple.

^^^ This is 1000 percent correct.

Provided that wiring is sized and installed for balanced resistance across all batteries and all battery plates are constructed with the same chemistry mix in the plates you can mix and match Group 24's, 27's, 31's, GC-2's etc.

A major part of the key is that the wiring must be routed in such a way that all batteries see the same resistance across +/-. If the batteries are the same and the wiring is installed for balanced resistance then they all will charge and discharge at the same rate.

Mind you many multiple battery house banks are not wired to provide balanced electron flow. That is the reason some batteries charge or discharge faster then others (assuming the same plate chemistry.)

[john61ct]

The intra-bank connections should all be the same gauge and length.

Trying to match different resistances of connection wiring to different sized or aged batts?

A classic display of engineer's syndrome.

I'm really not arguing just for the sake of arguing here.

Again, also not overstating this issue's importance, not a concern of safety or immediate effectiveness.

But KISS is a very important design principle, and having all batts in a bank match is industry standard best practice on land or at sea for good reasons, **if** you want to do it right.

In the end, your boat your choice.

[Unregistered-1]

Originally Posted by john61ct

A classic display of engineer's syndrome.

Yep, overlay additional facts over all the overlays until the topic is a complete ball of **** and any way forward is indecipherable. A standard narcissistic tactic - unfortunately, everyone loves to follow them don't they.

It's simple ;

1.) Never parallel-connect in any battery bank for any reason. Any failure at all, anywhere, WILL take down your entire battery system in just hours and force the charging and inverter systems into failure modes. You will be stopped. ANY fault or unusual battery condition will shut down your system within only hours, then it will force your charging systems into an overload charging state and leave them there. <--- read that sentence again. Don't do this. Read the "stopped" word again and again until you get it. Stamp it on your forehead if necessary.

2.) Install series strings of identical batteries for the required capacity or to take up the available space, and THEN alter charging and inverter schemes to match terminal voltage. A single cell failure is now easily diagnosable, non-critical, and can be replaced at your leisure.

You can parallel, in a pinch, but you must remind yourself that regularly that it WILL shut you down hard eventually.

Put even simpler - you can survive a down-cell in a series system, but NOT in a parallel system.

[Stu Jackson]

Originally Posted by SteveWrightNZ

Yep, overlay additional facts over all the overlays until the topic is a complete ball of **** and any way forward is indecipherable. A standard narcissistic tactic - unfortunately, everyone loves to follow them don't they.

It's simple ;

1.) Never parallel-connect in any battery bank for any reason. Any failure at all, anywhere, WILL take down your entire battery system in just hours and force the charging and inverter systems into failure modes. You will be stopped. ANY fault or unusual battery condition will shut down your system within only hours, then it will force your charging systems into an overload charging state and leave them there. <--- read that sentence again. Don't do this. Read the "stopped" word again and again until you get it. Stamp it on your forehead if necessary.

2.) Install series strings of identical batteries for the required capacity or to take up the available space, and THEN alter charging and inverter schemes to match terminal voltage. A single cell failure is now easily diagnosable, non-critical, and can be replaced at your leisure.

You can parallel, in a pinch, but you must remind yourself that regularly that it WILL shut you down hard eventually.

Put even simpler - you can survive a down-cell in a series system, but NOT in a parallel system.

What you've siad, simply put, is: If a cell goes bad sh*t will happen.


All I can contribute is: Of course.


In all seriousness though, it doesn't answer the question. What you're saying is like: Yup, your entire engine will die a quick death if the oil drain plug falls out.


No kiddin'.


saliorchic answered the question correctly, as did many others, none quite as clearly.


Sometimes we engineers apply rocket science and laboratory conditions to issues that do not require that level of intricacy.



Mix & match same chemistry with adequately sized and routed wiring. I've been doing it for 20 years. My Link 2000 still "sees" the entire bank, and I check the resting voltage of the individual batteries often. Since they are wired together in parallel, the voltages are identical. So, too when disconnected before measuring.



If they aren't, there's something else at play.

[john61ct]

I like a single pair of strings paralleled, just for the redundancy, far from civilization and a unit goes bad.

But 3 strings is the limit to avoid inherent imbalance issues.

[Unregistered-1]

Originally Posted by Stu Jackson

What you've siad, simply put, is: If a cell goes bad sh*t will happen.

No I didn't. I said if a cell goes bad in a PARALLEL setup, it will destroy every aspect of your operation, overnight.

Then I went on to point out that this does not happen when wired in series.

Originally Posted by Stu Jackson

What you're saying is like: Yup, your entire engine will die a quick death if the oil drain plug falls out.

.... when you wire in parallel. Yes. Don't do that.

The OP didn't mean to ask the question "should I parallel AT ALL", but the answer is the same, regardless of the technicalities of it. "NO", never do that. It doesn't matter about wire sizes or AH ratings - that's all a distraction.

Originally Posted by Stu Jackson

Sometimes we engineers apply rocket science and laboratory conditions to issues that do not require that level of intricacy.

Did you? I don't do that. I have had a number of parallel setups and they've all been a complete disaster! If I could convert them all to series I'd just do that. (Some I have...)

Originally Posted by Stu Jackson

Mix & match same chemistry with adequately sized and routed wiring. I've been doing it for 20 years. My Link 2000 still "sees" the entire bank, and I check the resting voltage of the individual batteries often. Since they are wired together in parallel, the voltages are identical. So, too when disconnected before measuring. If they aren't, there's something else at play.

The thing is, with your and my experience I can see exactly what you're testing for, and why, and how.... But many, if not most of the people here, and in general on yachts are not going to have the foggiest idea what you implied in that paragraph, or why on earth you would even be disconnecting the entire bank to test, or even what you were looking for, or why it was IMPERATIVE to do something about it pronto, or at the very least to not plan a passage with an impending fault condition.......

And THEREIN LIES THE PROBLEM.

You know, and I know, that if that bank isn't monitored and disconnected and tested regularly - then it's a disaster waiting to happen.

You know, and I know, that if one cell is sightly down then its about to fail - and pull the whole battery system down to 11.5V - a disaster!

But does the casual or even the experienced yachtie know? Is there a simple test to do?

The answer to those questions is "no", and therefore it cannot be safely used.

[Stu Jackson]

Originally Posted by SteveWrightNZ

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

The answer to those questions is "no", and therefore it cannot be safely used.

Steve, I've heard this POV expressed many times over the years. What I have failed to glean from ANY OF THEM is:


What is the solution?


To make a nominal 400 ah house bank, I have used (3) 130 ah G31 batteries.


Pray tell how does one do this without paralleling 12V batteries into a bank? Same deal with two 6V in series/parallel. Does this mean we are all limited to just the largest single 12V battery available? And well know that 4D and 8D batteries are far from being true deep cycle.



I have yet to hear a cogent response after the "warnings" that have been issued about the "dangers" of paralleling 12V batteries.


Perhaps I'm missing something, maybe you've already covered it, but I didn't see it, please help. Thanks.

[Unregistered-1]

Originally Posted by Stu Jackson

To make a nominal 400 ah house bank, I have used (3) 130 ah G31 batteries.

In parallel, yes.

Originally Posted by Stu Jackson

Pray tell how does one do this without paralleling 12V batteries into a bank? Same deal with two 6V in series/parallel. Does this mean we are all limited to just the largest single 12V battery available? ..trim not-relevant..

Don't think "Amp hours".
Think "Watt hours".

Consider the following ;

1.) Modern solar panel controllers will put out any voltage you tell them. They don't care.

2.) Modern lighting solutions (LED?) don't care about the input volts.

3.) Cheap regulators down to 12V are indeed cheap - a few dollars now, so throw a regulator at anything that MUST have 12V DC.

4.) Modern high-power inverters are much happier at a higher LT terminal voltage. 24V or 48V inverters are cheap and easy to find.

5.) Modern hybrid (household) combined inverter/MPPT/chargers in the multi-kilowatt range are now well under the $1k mark.

You see where I'm going with all this? Use a higher battery terminal voltage by using series rather than parallel.

You want 400AH @12V ? Lets do the maths ;
400x12 = 4.8KWH (kilo-watt-hours)

But at 24V, you only need 200AH to get 4.8KWH.

And at 48V, you only need 100AH to get 4.8KWH.

Two 260AH 12V batteries in series is 520AH @ 24V = 12KWH plus.... lots...

The solar panel doesn't care. The solar charger loves it. The inverter loves it. The batteries are far safer and happier, and so are the crew.

The only person who really cares is the person who can't persuade you to wire it up wrong - so they can bill you for repairs and a replacement system. Boo hoo for them.

[Stu Jackson]

Originally Posted by SteveWrightNZ

In parallel, yes.

Don't think "Amp hours".
Think "Watt hours".

Consider the following ;

1.) Modern solar panel controllers will put out any voltage you tell them. They don't care.

2.) Modern lighting solutions (LED?) don't care about the input volts.

3.) Cheap regulators down to 12V are indeed cheap - a few dollars now, so throw a regulator at anything that MUST have 12V DC.

4.) Modern high-power inverters are much happier at a higher LT terminal voltage. 24V or 48V inverters are cheap and easy to find.

5.) Modern hybrid (household) combined inverter/MPPT/chargers in the multi-kilowatt range are now well under the $1k mark.

You see where I'm going with all this? Use a higher battery terminal voltage by using series rather than parallel.

You want 400AH @12V ? Lets do the maths ;
400x12 = 4.8KWH (kilo-watt-hours)

But at 24V, you only need 200AH to get 4.8KWH.

And at 48V, you only need 100AH to get 4.8KWH.

Two 260AH 12V batteries in series is 520AH @ 24V = 12KWH plus.... lots...

The solar panel doesn't care. The solar charger loves it. The inverter loves it. The batteries are far safer and happier, and so are the crew.

The only person who really cares is the person who can't persuade you to wire it up wrong - so they can bill you for repairs and a replacement system. Boo hoo for them.

OK, Steve, let's proceed.


If I have a 12V system, i.e., one that uses components that require a nominal 12V, please tell us how going to 24, 48V or or magavolts helps me out with the "consumers" of my "power."


I understand the watt hours / amp hours debates. Given any NOMINAL voltage, it simply is a straight line swap, is it not? Sure, higher voltage, smaller wires. Gee, what's new?


But (sputter...) what do I have to do to get 12V to my:


--- fridge, autopilot, lights, water pumps, AO, and all the rest.


Serious question that remains unanswered in these kinda diatribes about watt hours.


If "all it is" is a B2B at the "user" end, then please let us know what hardware you suggest.


I "get" the "charging end."


Thanks again for leading us along.