Batteries in parallel?

[nigel]

G’Day, got a new guy question here. I have just set up a 25” mono using two 11.1volt, 2200 milliamp, 3 cell LiPo’s in parallel. I a using a Y lead (with Deans connectors) between the batteries and the speedy. The question is how do I stop one battery draing more than the other?

Is it possible, any help is appreciated?

Cheers Nigel.

 

[raptor347]

Nigel,

A small difference in capacity is normal, less than 5%. If the difference is more than that you need to see if it is related to the harness going to the ESC or if it is specific to one of the battery packs. Marginal solder joints are the biggest cause (or huge differences in wire length).

 

[nigel]

Thanks for that,

Both batteries are the same type and capacity/rating (25-50C 2200milli amp) bought at the same time. The boat has only had the one test run so far and both batteries were charged before the run. As I had no idea what the draw on the batteries would be I ran the boat at full throttle for 45 seconds then checked. Both batteries were at 29 degrees C. One battery only used 450 mili amps and other used 60. Set up is a Hacker Navy 77 and Feigao 7L, prop X436/2. Like I said first electric so all help appreciated.

Nigel.

 

[Andrewg]

Nigel

It sounds to me like there could be a dry joint in the soldering in one pack In a parallel setup this can happen easily and the side that isnt working wont be in evidence until one pack is damaged or the run ends prematurely

 

[nigel]

Thanks for the help guys.

Found the problem to be in the Deans connection of one of the batteries to the ‘Y’ harness. Have fixed this up so will go and test tomorrow. Must say that I do like the way this little boat runs for a bit of fun.

Cheers Nigel.