Parallel battery conflicting advice.

Emmenay

Emmenay

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Regarding three leisure batteries in parallel, can some knowledgable folk cast their eye over the below statement and kindly offer their opinion.
It seems quite feasible to me but seems to go against the status quo of connecting solar etc at opposite ends...



Parallel connections involve connecting the POSITIVE (+) connection of one battery to the POSITIVE (+) connection of the next battery. The same goes for the negative side; NEGATIVE (-) of the first battery connects to the NEGATIVE (-) of the next battery. You can connect the POSITIVE (+) of your charge controller and/or DC-to-AC inverter to any POSITIVE (+) point in the battery bank, though it is best to make this connection in the middle of the set of batteries rather than from one end (as shown). Same goes for the negative side; connect the NEGATIVE (-) of your charge controller and/or DC-to-AC inverter to any NEGATIVE (-) point in the battery bank, though a point in the middle is best.

By making the system connection in the middle of the battery bank, the charging and discharging cycles are done in a balanced way. If the system connections are made on the ends, then more charge will flow into the first battery and less flow into the last battery. When discharging, the first battery will discharge first and the last battery in line will discharge last. This is not good for the life of a battery bank
 
The last sentence is correct. But If you connect the positive to one end and negative to the opposite end it's balanced though.

By connecting to the middle battery for both + and - it means the middle battery will get slightly more charge /discharge. Probably won't make much difference in use anyway.
 
The method quoted simply moves the ‘problem’ from the first battery to the second battery. Connecting at opposite ends is the recommended solution.

Ian

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I've had three in parallel for a couple of years now with the solar wires connected diagonally opposite and the hab power connected to the other diagonal opposite.
What I have found is the battery with the solar live wire is needing regular topping up as it seems to be doing all of the work, while the opposite end battery which is first in line to supply hab power always seems to struggle according to the on board control unit.
Looking at the theory of connecting to the centre battery with two 'outrigger' batteries does seem to me like a more balanced balance so to speak.
 
If space allows I’d install two small bus bars and connect each battery to the bus bars with equal length cables
 
Robert Clark said:
If space allows I’d install two small bus bars and connect each battery to the bus bars with equal length cables
Click to expand...
I agree. That's "Method 3" in the earlier link.
 
Emmenay said:
Regarding three leisure batteries in parallel, can some knowledgable folk cast their eye over the below statement and kindly offer their opinion.
It seems quite feasible to me but seems to go against the status quo of connecting solar etc at opposite ends...



Parallel connections involve connecting the POSITIVE (+) connection of one battery to the POSITIVE (+) connection of the next battery. The same goes for the negative side; NEGATIVE (-) of the first battery connects to the NEGATIVE (-) of the next battery. You can connect the POSITIVE (+) of your charge controller and/or DC-to-AC inverter to any POSITIVE (+) point in the battery bank, though it is best to make this connection in the middle of the set of batteries rather than from one end (as shown). Same goes for the negative side; connect the NEGATIVE (-) of your charge controller and/or DC-to-AC inverter to any NEGATIVE (-) point in the battery bank, though a point in the middle is best.

By making the system connection in the middle of the battery bank, the charging and discharging cycles are done in a balanced way. If the system connections are made on the ends, then more charge will flow into the first battery and less flow into the last battery. When discharging, the first battery will discharge first and the last battery in line will discharge last. This is not good for the life of a battery bank
Click to expand...
What is this source please?

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Emmenay said:
Unfortunately not, I have one under each front seat and one behind the front seat under the bench seat .

Click to expand...
Ah I see, re-reading your post, I can see where your getting confused.

Your quote refers to "battery bank" and this is a picture of a "bank" from their website
1611584834852.png

Which I am assuming is a couple more batteries than you intend to install?

This picture, again from their web site is the correct way to install small numbers of batteries in parallel
(unless you are installing Lithium Batteries and your installing a largish inverter)
1611584982456.png
 
I think the large bank picture is not referring to the parallel scenario as quoted in my original post, as it is a serial/parallel setup.
Below is the large bank picture with its description.
I always thought more than one battery is a bank of batteries but I stand corrected.
Are we saying that connection to the middle battery is no good or just not the done thing, I'm none the wiser right now :cautious:

Series/Parallel connections​

In some cases, several batteries need to be connected in a series set to achieve the desired system voltage, and then placed in parallel with an identical serial set. This is very typical when 6-volt batteries are used. Much like in the parallel-only case, the connection to the system is ideally done at the center of the battery bank so that charging and discharging is done in a balanced way.

Large battery banks​

battery_config_fig2wn.jpg


Shown above is a typical 48V battery bank made up of a series/parallel connection of 6-volt batteries.
 
Emmenay said:
I've had three in parallel for a couple of years now with the solar wires connected diagonally opposite and the hab power connected to the other diagonal opposite.
What I have found is the battery with the solar live wire is needing regular topping up as it seems to be doing all of the work, while the opposite end battery which is first in line to supply hab power always seems to struggle according to the on board control unit.
Looking at the theory of connecting to the centre battery with two 'outrigger' batteries does seem to me like a more balanced balance so to speak.
Click to expand...
If I understand your description then the way they are wired is wrong. As a rule (and I can't see any reason why you would do it any other way) all charging connections should be attached to the same terminals the load is taken from. This allows any loads to draw current directly from the charging power without it having to pass through a battery. :)
 
DBK said:
If I understand your description then the way they are wired is wrong. As a rule (and I can't see any reason why you would do it any other way) all charging connections should be attached to the same terminals the load is taken from. This allows any loads to draw current directly from the charging power without it having to pass through a battery. :)
Click to expand...
Quite possibly, maybe I didn't know better at the time but now I'm trying to educate myself :giggle:

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Emmenay said:
Quite possibly, maybe I didn't know better at the time but now I'm trying to educate myself :giggle:
Click to expand...
It's not critical and will work fine. The small downside is one of the charging systems will have a slightly longer cable length to go pass through to reach the load. The extra length is the cable(s) linking the batteries together. If you connect at the load end the current can go directly to the load.
 
Emmenay said:
Regarding three leisure batteries in parallel, can some knowledgable folk cast their eye over the below statement and kindly offer their opinion.
It seems quite feasible to me but seems to go against the status quo of connecting solar etc at opposite ends...



Parallel connections involve connecting the POSITIVE (+) connection of one battery to the POSITIVE (+) connection of the next battery. The same goes for the negative side; NEGATIVE (-) of the first battery connects to the NEGATIVE (-) of the next battery. You can connect the POSITIVE (+) of your charge controller and/or DC-to-AC inverter to any POSITIVE (+) point in the battery bank, though it is best to make this connection in the middle of the set of batteries rather than from one end (as shown). Same goes for the negative side; connect the NEGATIVE (-) of your charge controller and/or DC-to-AC inverter to any NEGATIVE (-) point in the battery bank, though a point in the middle is best.

By making the system connection in the middle of the battery bank, the charging and discharging cycles are done in a balanced way. If the system connections are made on the ends, then more charge will flow into the first battery and less flow into the last battery. When discharging, the first battery will discharge first and the last battery in line will discharge last. This is not good for the life of a battery bank
Click to expand...
This explanation is correct and it means the connection is made in the middle of the link between the two batteries, half way each way. It replicates exactly as you would have a buss bar like in the link on smart gauge option 3. That is the most balanced.
The opposite ends will work very well to, and if I would of been in this situation, that’s how I would wire it if buss bar was not possible. Buss bar allows for individual battery fuse as well.
 
So in conclusion, its anybody best guess, I think maybe now I concur with pappajohn .
I think I'm going to try the middle option to see how things pan out, damn I might even mix it up a little and put a bigger battery in the middle (call the police) to cope with the stress of it all, maybe that might give my control unit more accurate readings?

It seems that the subject is, well, subjective, and perhaps fits the same category as say, 'which is the best brand of battery or, what is the best adhesive or, to A-frame or not to A-frame amongst many many others :unsure: :winky:

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Emmenay said:
So in conclusion, its anybody best guess
Click to expand...
Not at all..
I dont think you have grasped what's been posted..
There is a way of wiring the 3 batteries which ensures that the load and charging current are shared equally... subject to the battery internal resistances been the same.. that is to connect each battery with equal length wires to a common point ...
Alternatively.. use the other set up (picture posted by Eddie above ) which according to the figures quoted in the link I posted does give a reasonably balanced distribution and is acceptable in most cases..
Your distribution of batteries isn't ideal in either case and will involve longer runs to make the connections..
In both cases the load and any charging sources should be taken from the same points on the bank..
I dont see any grey areas in those explanations..
Andy
 
andy63 said:
Not at all..
I dont think you have grasped what's been posted..
There is a way of wiring the 3 batteries which ensures that the load and charging current are shared equally... subject to the battery internal resistances been the same.. that is to connect each battery with equal length wires to a common point ...
Alternatively.. use the other set up (picture posted by Eddie above ) which according to the figures quoted in the link I posted does give a reasonably balanced distribution and is acceptable in most cases..
Your distribution of batteries isn't ideal in either case and will involve longer runs to make the connections..
In both cases the load and any charging sources should be taken from the same points on the bank..
I dont see any grey areas in those explanations..
Andy
Click to expand...
Thats very clear, thank you.
 

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