Batteries in parallel with different amps on positive and negative

daromer

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clamp meter is your answer.... Dont use that if you want to measure below 5A. Especially if you want higher accuracy.

As said before and i say it again. Negative and positive of a cell must always have the same current going/in/out if you say it like that. Its the law of phsysics. It cant be anything else because if it would be the laws around and how people build inverters, devices. yes everything around electronics are flawed.

Dont mix up current on pos/neg on one cell comparing to current going into different paralelled batteries. 2 totally different things and both relies perfectly on how u=i*r is setup. Please just draw it up on paper and calculate it and then go back and ask your self why your device doesnt show the same values. Then read up on how a clamp meter works.

And im still waiting on a drawing showing exactly how you held the device and where you meassured. Ie the current that is introduced in the circuit + voltage and then every point you meassured.
 

Cheap 4-life

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if the battery pack is discharging, how would the amps go into both polarities of the lower capacity battery from the higher capacity battery. I would think the power transfer (from battery to battery) has to happen so the voltage of each battery stays the same. Only option is for the amps to go in the lower capacity battery the way the amps are flowing during the discharge to the load.

I held the clamp meter on the wire at a 90 degree angle to the wire. I measured roughly 6 inches from each battery on it’s positive then negative terminals. I measured this way many different times with different amounts of load and when the batteries were at various states of charge.

I also measured when there was more than 5 amps (12amps) going into each battery.
 
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Cheap 4-life

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If you are correct and it’s just a meter inaccuracy or error, then I wouldn’t expect to see the same amp polarity differences when I remove the lower capacity batteries and add higher capacity batteries. The lower capacity batteries would then be batteries 1 and 2 (the previous high capacity). If the polarity amps differences move to battery 1 and 2 then it’s not a meter problem. We will see

I would go out there now and remove the 2 higher capacity batteries to see if the lower capacity batteries continue to have amp polarity differences. But I don’t want the 4 batteries to get out of balance with each other
 

daromer

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Please show us what it is you are trying to explain because it does not makes sense. Yes different cells have different curents as shown by Wolf and this is also shown by u=i*r. Nothing weird here.
Also If you have current going into a single battery you have 2 leads to it. those 2 leads will ALWAYS have the same measured current but in opposite directions. That's how electricity works. You have electrons moving. They cant just dissapear out into nothing. The only thing that changes are the potential of them and not the amount of them.
 

Cheap 4-life

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Please show us what it is you are trying to explain because it does not makes sense. Yes different cells have different curents as shown by Wolf and this is also shown by u=i*r. Nothing weird here.
Also If you have current going into a single battery you have 2 leads to it. those 2 leads will ALWAYS have the same measured current but in opposite directions. That's how electricity works. You have electrons moving. They cant just dissapear out into nothing. The only thing that changes are the potential of them and not the amount of them.
Electrons are different than amps. Electrons move in the opposite direction of amps. The amps are not disappearing they are going into the lower capacity battery to keep it at the same voltage. If the amps from the higher capacity battery was showing on the positive (while discharging) and not just the negative then those amps would appear to be going to the load and not into the lower capacity battery. That’s because the direction of amps is going out of the positive to the load
 

daromer

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Sorry No :) current doesnt dissapear into the battery so you got 5a in positive and less on negative :) its Always the same in a circuit. Only the potential aka voltage changes.


IF your assumption would have been right O'boy what many things i must have designers wrongly
;)

Sorry. I give Up.
 
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Cheap 4-life

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I tried to upload a video, it says file is too large for server to process. It’s only a minute long
 

Cheap 4-life

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The video shows exactly like I describe. I went and got the father in-laws clamp meter and it shows exactly the same.
There is a 1.4amp difference on the wires for each polarity on the lowest (#4) capacity battery. On the 2nd lowest capacity battery (#3) its a .8amp difference on its positive vs negative. The other 2 batteries are the highest capacity (newer less miles from the same vehicle) and both of their positives and negatives have the same amp readings.
Important to note again that when discharging vs charging the polarity with the higher amps switches. But the difference between on the individual batteries polarity is still the same amount.
I’ll try to do a shorter video so maybe my server can upload it.
 

Wolf

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Till you give us all the readings as described in my previous post .........................
I'm not sure why you won't do that. If I was trying to solve a problem the first thing I would be is to gather all the facts.
Then certain extrapolations can be made.
1617126540770.png
Till then...........................................???????????

Wolf
 

Cheap 4-life

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Till you give us all the readings as described in my previous post .........................
I'm not sure why you won't do that. If I was trying to solve a problem the first thing I would be is to gather all the facts.
Then certain extrapolations can be made.
View attachment 24468
Till then...........................................???????????

Wolf
I think I have given all of that information. I gave the amps in and out of each battery. I’m not sure what you mean by voltage drop. Each battery is in parallel and are being kept the same voltage because of being paralleled. The voltage on the main positive and negative to the busbars is the same. I could give the amps going into or out of the busbars but with the amps differences in question only being 1.5amps I don’t see how that will help.

Atm my batteries are not being charged or discharged because the chargecontroller is floating the loads. When the hotwater heater gets fully heated I’ll shut down the pv input and do a video similar to your video while the batteries are discharging.
 

Wolf

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Voltage drop - Wikipedia​

https://en.wikipedia.org › wiki › Voltage_drop


Voltage drop is the decrease of electrical potential along the path of a current flowing in an electrical circuit. Voltage drops in the internal resistance of the source, across conductors, across contacts, and across connectors are undesirable because some of the energy supplied is dissipated.

Very important
 

Cheap 4-life

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Voltage drop - Wikipedia

https://en.wikipedia.org › wiki › Voltage_drop

Voltage drop is the decrease of electrical potential along the path of a current flowing in an electrical circuit. Voltage drops in the internal resistance of the source, across conductors, across contacts, and across connectors are undesirable because some of the energy supplied is dissipated.

Very important
Yeah I know what voltage drop is.. there isn’t any voltage drop in my system of any kind of amount to be concerned about. But I’ll check it again
 

OffGridInTheCity

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Nice youtube - pictures really help discussions.

My guess (from the youtube) is that you're seeing the inaccuracy of a loop/amp meter. I know it doesn't seem like that could be an explanation, but I've experienced similar 'strange' readings.

When I measure solar panel purchases I
- check voltage - which is very close such as 42v to 44v for panels of the same batch. And then...
- short the leads (connect the MC4 connectors together) and measure amps with a loop/amp meter over the panel wires
I notice the amp readings vary wildly by a full amp (e.g. 6.4 -> 7.4) by simply sliding the loop up closer to the diode box and down further the cable and/or twisting it around and/or preclamping it. Doesn't make sense to me that it would change so wildly... and seem consistently higher closer to the diode box... but I've observed this over several different sessions over the years and you may be experiencing something similar.

Using a different approach to test, such as inline meters (more accurate?), might shed some light on this.

In any case, just offering my suspicions about loop/amp meter testing as an anecdotal piece of info.

Looking forward to see if the mystery is resolved! :)
 
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Cheap 4-life

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Nice youtube - pictures really help discussions.

My guess (from the youtube) is that you're seeing the inaccuracy of a loop/amp meter. I know it doesn't seem like that could be an explanation, but I've experienced similar 'strange' readings.

When I measure solar panel purchases I
- check voltage - which is very close such as 42v to 44v for panels of the same batch. And then...
- short the leads (connect the MC4 connectors together) and measure amps with a loop/amp meter over the panel wires
I notice the amp readings vary wildly by a full amp (e.g. 6.4 -> 7.4) by simply sliding the loop up closer to the diode box and down further the cable and/or twisting it around and/or preclamping it. Doesn't make sense to me that it would change so wildly... and seem consistently higher closer to the diode box... but I've observed this over several different sessions over the years and you may be experiencing something similar.

Using a different approach to test, such as inline meters (more accurate?), might shed some light on this.

In any case, just offering my suspicions about loop/amp meter testing as an anecdotal piece of info.

Looking forward to see if the mystery is
I’d accept that it’s inaccuracies of the meter if the amp discrepancies between polarities didn’t get greater with the lower the capacity the battery is.
 
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Cheap 4-life

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Soo... just noticed when I flip the clamp meter to read the same wire in the opposite direction I’m getting up to 2.2amps difference. This sucks for trying to figure this out... but the lower capacity battery (#4) is showing the 2.2amp difference on its positive wire when I flip the clamp. On its negative it’s a 1.6amp difference when flipping the clamp. All the rest of the batteries are showing less than 1 amp difference on each wire when flipping the clamp.
This is all getting to confusing for me. The highest and lowest amps seen on the clamp meter are on the lower capacities batteries negative, when the clamp shows positive amps it’s 5.3 on that negative. That’s the lowest amp reading from any battery with the clamp in either direction. When the clamp is flipped on that negative (now showing negative on the meter) it’s 7.5amps which is the highest amp reading from any battery with the clamp in either direction. There’s still something fishy going on with the lower capacity battery
I give up
 

ajw22

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It's a bit hard to follow with the camera being so close, but it looks to me like the clamp meter reads very different values, depending on which way you clamp the cable.
At 0:20 you measure -7.0Amps on the negative side
At 0:23 you measure +4.7Amps on the positive side
At 0:32, after flipping the clamp, you measure -5.9Amps on the positive side

At 0:47 you flip it multiple times, because you notice something is wrong.

So now, to rule out one source of inaccuracy, you need to use this badly calibrated clamp meter in only one direction, so that the Amp reading is either consistently (+) or consistently (-).
 
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