wturber said:
Of course. And that's why I don't hold Anderson blameless when e-bikers purchase a PP45 connector thinking it should be appropriate making 45 amp connections. Of course, I don't hold the e-bikers blameless either.
What blame?
The PP can be used for 45A connections - as the datasheets indicate.
Remember, the datasheets don't say that they can only be used to 30A - that is a decision that Alan made based on what he feels is a good temperature rise "for his application". There are no facts that prove a 45A continuous rating is incorrect. In fact, if pushed to the safe operating limit of the plastic housing housing, the PP45s can handle 65A at room temperature or about 57A at 100degF ambient - in still air with 10ga wire.
The UL test procedure measures the temperature at the point of wire attachment. As anyone who has soldered 10ga wire is aware, the significant heat sinking effect of 10ga wire drops the temperature extremely rapidly in just a couple of inches. The rated 40 deg C temperature rise at 45A (this is less than the temperature of hot tap water) will be reduced to a merely warm wire within inches of the connector.
So - looking at the datasheet values a little differently, we see that in still air at 45A the 10ga wire temperature rise will be in the neighborhood of hot tap water and the 45A current has an operational safety margin of (65A-45A)/45A = 44% to reach the still-safe maximum capacity. Exposed to airflow, the datasheets become inapplicable, but there is little doubt that the temperatures will be further reduced.
This really calls for a little more pragmatic and less specsmanship perspective...
Although it may be true that the 15/30/45 numbers are really just 'part numbers' and not continuous power ratings, it is important to realize that these numbers did not just come out of the air. As you pointed out, looking at datasheets isn't for everyone and these products have a retail consumer market. Clearly Anderson invented these part numbers as a 'rule of thumb' for 'most' applications that gives the non-techies a suitable means to select parts that will work reliably for long periods of time. These are ballpark values based on risk, target market, and technical evaluation - but they are not specific measured facts. So - dismissing the 'part numbers' as meaningless is just silly - some considerable thought went into them for the clear reason of addressing a market audience possessing a non-engineering level of understanding.
Beyond that, it is clear that this 'misunderstanding' about the meaning of the 'part numbers' is reinforced by widespread advertising of this current rating by virtually every retail vendor of the product. If Anderson actually felt that this all-pervasive sales practice was incorrect or compromised their business they would stop it. Instead this misunderstanding is exactly what they want - that the retail vendor present the rule of thumb numbers and the bulk OEM purchasers can sic their Engineers on the datasheets. From Anderson's perspective, even though these values are generalities, the substantial safety margin (44% as noted above) make part failure extremely unlikely.
Anyhow - I use Andersons for all sorts of stuff. I find the primary problem lies with large wire gauges in the requirement of a freely rotating contact in the housing. This is a critical because if the flat blades cannot be held in alignment by the SS springs, the connector cannot achieve the rating specification. The effect will be abnormal heating from the reduced contact area with the expected nasty consequences.
That said, carefully routing, molding, and shaping heavy gauge wire runs prior to affixing the contacts can significantly reduce those specific failures. You need only be careful to align the contact just prior to the crimp to ensure that there is only an initial few degrees of rotational error in the relaxed wire in situ. Crimping an unmounted wire and subsequently routing it can require significant wire twisting to achieve alignment. With heavy gauge wire this can result in torque-loading the contact so that it cannot be aligned properly by the SS springs. IMO this may be the largest cause of failures - not over-currenting the part (or failure of the part to meet spec). Unfortunately, the resulting housing and contact damage looks very much like over-current is the cause. In other words, this failure is a fabrication/installation issue, not a crimping, soldering, or rating issue.
In any case, just another view of the same parts and the same datasheets. I believe the generic rule-of-thumb ratings are acceptable and offer a large safety margin and modest temperatures. I also believe that improper attention to required contact freedom of motion accounts for many temperature-related failures because of the wide documented safety margins when used correctly and the high temperature failure mode of the design when contacts are misaligned.
