Originally Posted by
Jeff Crosson
Danny - I just got two top wire exit Traxxas Connector 5000 SMCs and noticed the number on the back are much lower than the side wire exit ones.
My side wire exit one has
7.47 ave. voltage
4.0 int. resistance
~5200 mah
My new TRA conn. top wire exit ones both have
7.37 ave. voltage
7.0 int. resistance
~5000 mah
The numbers were low like this when you guys didn't measure directly from the power leads, and then when you did, they were much higher. Did you guys go back to not measuring it directly from the power leads? Or is it just like that because they have Traxxas connectors?
As with any batteries there can be fluctuations in batches. We did get one freak batch that had very low IR and higher average voltage but we were also seeing more cells with internal shorting. In our pack cycling method we discovered that going through the Deans connectors was creating erratic readings so we decided to change the way we measure the packs. Since the packs come with shrink on the 12 gauge wires where they are soldered to the connector we need to find a way to measure the voltage wihtout removing the shrink. So we decided to tap into the balance connector. We did this on 200 packs that came in and the IR and voltage looked really good which made me wonder why. So I took a packs and cycled it a few times then removed the shrink on the 12 gauge wire and cycled it a few more times. The results was 1 milliohm higher in IR and .03 lower in voltage. So since that batch of 200 packs we now adjust the numbers to compensate for the difference.
Your side exit pack was surely from that batch of 200 so you lucked in and got a low IR pack with high average voltage. We have asked our supplier why that batch was like that and he can't figure it out as he tells us he uses the same materials and same way of building the cells. I know they have to buy materials and maybe it can fluctuate from batch to batch. Hope all of this makes sense.