Two 18650's in parallel

[plumber105]

Hi all was wondering if it's normal for 1 battery in a dual setup to discharge more than the other in a parallel config as when I charge both together 1 always finishes before the other (I remove and charge in an i4 intellicharger ) seem to remember reading somewhere about 'lead batterys discharging more' batts are 2x efest 35amp and 2x sony vtc5's would it be an idea to label the batts 1 & 2 and the holders 1 & 2 and rotate positions to get a more even usage from both bats any help or links to previous posts would be most appreciated.
Thanks in advance

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[Switched]

In series the battery closest to the load will always discharge faster. In parallel they share the load equally. That being said if the batteries internal resistances are different you will get what you are describing. Best way to check is to take a voltage reading prior to charging them. Give them a rotation it wont hurt anything. Were these batteries always used as pairs?

Now I do not know about batteries perse, but in a parallel generator set up there was always a lead generator, the switchboard was set up that way, not by much mind you perhaps 50KW but there definitely was a lead and lag generator.

 

[plumber105]

Thanks for the reply.
Both pairs of batteries were bought together as pairs and have only been used in their pairs the sonys are around 1 week old but seem to be the worst affected as when put on charge one finished pretty much 45mins before the other. On another note the battery holder needed to be made parallel by soldering a wire across the positives and across the negatives. And on the positive side I soldered two fuses (parallel) inline to the dna board but they only come off one terminal ie battery 1 connected to battery 2 pos to pos neg to neg and from the pos of batt 2 to one side of ptc fuses and then to board. I was wondering if this is causing the unbalanced drain? Would it be better to take a separate wire from each positive up to the board?
Thanks for your advice

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