An advantage to your suggestion on method C is that you could use smaller wires to each battery. The disadvantage it that there would be more connections. Connection failures are the most common failure in a working system. This usually comes from a failed wire terminal or lug crimp. Limiting the number of connections is a high priority in my personal opinion. But your method C would serve the same purpose. There are applications where your method C is a better choice, for example when the batteries can not be installed next to each other due to space constraints.

Option c also means any problem with a connection affects only one battery and will be easier to detect.

@offgridwanabe is spot on the way he describes is the only way to perfectly balance all the batteries traveling light is wrong

My batteries are connected with 1/8 in. x 5/8 in. copper buss bars, I think the resistance would be negligible. On the other hand, it would take very little effort to move one cable to the other battery. Good advice, thanks.👍👍

If done by a professional who can guarantee twice as many crimps will all be done perfect. For the small gain in similarity I would rather see beginners do it with less crimps. Pro do not need this video.

If you are building a lithium battery from lithium cells you need a Battery Management System (BMS) for each battery. This BMS will manage the cells contained in each battery, as a unit. This video is about batteries. All lithium batteries already have BMSs managing the current and voltage of the cells. No large lithium batteries are sold without BMSs. You can get small lithium batteries for model aircraft that do not have BMSs. The ones that do not have BMSs will have balancing leads with a JST connector. However, this video is about power system batteries.

If you have a 2 battery setup with the batteries in parallel, then the inverter should be connected the same as any charger. Use method B. Regardless of whether the battery is being charged or discharged the connections should be the same. Throughout the batteries' life it will get an equal amount of charge as it get discharge. I hope I answered your question.

I have connected as the B...I was not sure but finally is the best way.also the chargers cables are connected as the B. Thanks a lot!!!!also I don't know if you can help batteries during day are full charge 13.8v as the panels produce power.with no loads and the 12v power inverter off at next morning controler shows 12.7v.batteries are 2x 12v gell deep cycle 150ah each connected parallel.any ideas?connections are ok charger is an mppt powmr 60a maximum

@@djperfecto1 Your batteries look like they are okay. The float voltage is also higher than the resting voltage. Your solar controller is correctly bringing the batteries up to 13.8 volts. When it shuts down the battery voltage settles down to it's resting voltage. For AGM the fully charged resting voltage can be between 12.7 and 12.85. It depends on the manufacturer and also on the whether there is any voltage drop in the device you are reading the voltage from. Regardless, from all that you have told me, your system is working fine.

I do not have a definitive or data based answer for you. I can give the best science or physics based answer though. It takes the batteries a long time depending on how hard you are using them. You will not see an effect within days or weeks but over months and years. However, the harder that batteries are worked, the greater the in use difference, in each batteries discharge you will get. Let me explain that. Think of it like this, In example method A, if you pull a high current from the batteries, battery 1 has slightly less resistant than battery 2. Battery 1 will discharge slightly more than battery 2. It would be working harder to supply the load. It would essentially lose more energy and its voltage would be slightly lower than battery 2. When this high discharge current is removed, Battery 2s voltage would be slightly higher and it will charge battery 1 until they are balanced. This process happening over and over is what method B prevents. Method B just simply prevents this by the physical nature on the wiring. Each battery the same wire length as all the others. Therefore each has the same resistance in the circuit. This is because they are all in a loop, as opposed to a string with one on the end like method A. So, method A is not going to ruin your batteries but method B is better for them. If you have new lithium batteries I would recommend changing the wiring to method B as earlier a possible. They last a long time and method B will help make them last. If you are running lead acid, leave them alone. They don't last that long anyway. If you are only, ever, running very low currents, it is probably not worth changing to method B either unless it is a simple task. If you are running an inverter from your batteries, I would make the change as soon as possible. Also if you are running more than 2 of any type of batteries I would change it. I know I did not exactly answer your question but I hope I least gave you a better understanding of how battery 1 gets "exercised" more then battery 2. Oh, part 2 to your question, I kind of answered but, this is only happening during "running time" and mostly during high current loads. During "idle time" the batteries balance each other to equal loads. JT

Cheers. I think the “buzz” word is current. Less pressure on the battery and adding a fuse. @@TravelingLightReflections

Yes, you should. So many DIYers just to method A, because I do not realize there is a difference.

Yes , I would agree. That is great, short and complete summary of the idea.

I do not have a video recording of this but if you do not believe this watch this video. He recorded the currents for each battery. Ohms Law, V=IR or I=V/R. At a constant voltage, current is inversely proportional to resistance. ukposts.info/have/v-deo/l6CCZI2hp4l2wmQ.htmlsi=VJ-nIWsvUDvWNpU5

It is more about voltage drop, from load vs cable length, don’t forget contact resistance as well… When two identical batteries are connected together, the shortest path has the least resistance, coupled with voltage drop and load drop, the closest short cable battery drains faster than the further ones. Forcing round trip through both batteries equally, the batteries experience equal resistance, and equal voltage drop, resulting in more even discharge.

@@whochecksthis voltage drop is the result of resistance. Not sure what connectors you are using but those also should not have any relevant resistance

@@Ed19601 … everything except a superconductor has resistance, and when you connect to the closest side of the closest battery, the further lengths have resistance. It adds up, resulting in uneven discharge.

Many people suggest using a bus bar. If you can make every cable the same length and insure every connector is crimped perfectly then a bus bar is a good choice. To contradict this though, using a bus bar means 2 times as many connector to crimp and more chance of a failure. Also with today lithium batteries the BMS's also regulate charge so it become near impossible to get all cells and all batteries perfect. So, for beginners doing the work themselves and making your own crimps, I would put the 3 batteries in parallel and not use bus bars. If you are a pro you probably not interested in my input but if you can get excellent crimps then go with bus bars. Of course bad crimps are dangerous in all cases. I am just suggesting using as few as possible. Also, I always put the system under a high current load and use an infrared thermometer to look for hot spots that need to be repaired.

I knew there was a difference under load that would balance out as the batteries recharge. I have had a lot of people's comments telling me I am wrong. I went looking for other videos and found this. I was shocked at the difference. I created this video based on theory. This video shows actual tests in action. Even though the resistance is low, it still follows that if the cable length is doubled, so is the resistance. I learned from the links video too. I am curious how the quality of a crimp affects the performance. I originally made my video to help people see that they could easily use method B. Here is the other link. ukposts.info/have/v-deo/l6CCZI2hp4l2wmQ.html

You may be right.

It is not actually equal but closer with a bus bar and only if the crimps are done perfectly. Plus with the bus bar you have 2X as many crimps. I removed that section of the video because I made the video to stop DIY people from doing Method A.

Thanks, Not sure what to say but....

MY.. not MINE. or are you making LANDMINES.

Mine do to!

See my other responses.

It is much greater too, at high currents.

Care to elaborate?

This is correct!💯

To expand on that you are correct with load using method B but add to it the charge circuit should also use method B bur reverse the + and the -

It does. It actually makes a big difference. That is why I made the video.

As an auto elec, yes, it does make a difference.

You should do some scientific test before you call this BS. There is an incredible difference between the load on battery 1 and 2 in method A when you piggy back and pull off the same battery.

@@TravelingLightReflections No there is not. And your electrical engineering masters degree is from?

@@TravelingLightReflections If the cable cross section is correctly dimensioned for the current going through the cables it does not matter how you connect the wires to the load/charger. When charging the batteries, they will all get up to the same voltage as the charger is topping off / trickle charging

@@nixxonnor What you are saying is true only if a low current is being trickled into or out of the battery. As the current gets higher, is when this becomes more extreme. Electricity always takes the path of least resistance. In Method A you can have a huge difference in the current coming out of battery 1 compared to battery 2. Some other critics here are correct that for more than three batteries a bus bar is better. With the bus bar the currents in and out of each battery is closer than my Method B. However, This way doubles the # of connections. A failed terminal/lug crimp is the most common failure. Making good high amp connections takes practice. This video was made for DIYer, not professionals with lots of experience. I made it because I see too many people parallel batteries like Method A. I also made it short so people would watch it. If I was to remake this video I would add the bus bar method too. Even with the bus bar, under heavy loads, there is still a current difference within the batteries. The difference is slightly better and ONLY if the crimps are perfect and the wire lengths are exactly the same.

@@kschildt1 You apparently forgot your first year high school electronics. Draw the equivalent circuit with the resistance of each cable segment and battery ESR. Maybe capture the schematic in LTSpice and run the simulation with a 200 amp load. Look at the difference in current from each battery. Some engineers graduate with a 2.0 grade average and others with a 4.0 average. So you barely got an engineering degree ten years ago, that isn't the same as being correct. You apparently didn't study logic.

Thank you for your well thought out and detailed expert response about this.

Peace