Tonymark said:
I chose a 25 max amp KT sine wave controller with a rated current of 12w.
Do you mean 12A? (W and A are very different, so it is important to be clear).
Running it with 48volt battery, ~15 amps seems would be in acceptable range.
What specifically do you mean? Do you mean that the system is actually drawing 15 amps under load instead of 12A, and you want to know if that's acceptable loading of the battery? For us to know this, we need details of the actual battery being used to know what it can handle. A link to the sale page for it, or details of your build if it's DIY, may help us help you determine this.
If you mean something else, you'll need to tell us exactly what you meant so we can figure out what the acceptable range for whichever part / parameter that is.
The problem is the max current setting is not as granular as I had hoped. It’s either “Max Current/1.5” of “Max Current/2.0).
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I would have more granular control of max current by either using the max/1.10 or max/1.15 settings.
Just to be sure, are the second set of settings intended to be the same as the first set? Or are they a different parameter or different choices in the settings?
With “Max Current/1.5” selected it looks like I could hit a peak power 910w on a completely full battery going up a steep hill(over the motor’s rated peak power). Is this something I should worry about?
Motors in general can handle short bursts of significantly more than their "rated" power--the limitation with most of them is heat buildup. If you don't let heat build up in it (let it cool down between this kind of usage) it'll likely work fine. With geared hubs it's a lot harder for the heat to get out of the motor than with DD hubs, so if you think you're going to create a lot of heat in the motor, often, you might want to add a thermal sensor inside it if it doesn't have one.
Even at or below rated power levels, if they're used in a way where more waste heat is generated than they can get rid of, they'll overheat. You can see how this can work using the http://ebikes.ca/tools/simulator.html using any of the motors in the list that has thermal modelling (if it shows N/A for the Overheat In field on the right below the graph, it doesn't have thermal modelling--it will show a temperature / time, or "never" if it does).
If your system can maintain sufficient speed under the high load, it won't generate as much heat inside the motor as if it slows down a lot, so overheating is less of a risk. You can make some estimate of this using that simulator, even if your specific kit parts are not listed, if you can "build" a system there similar to your own that uses thermal modelling, and put it in the same circumstances you'll be riding in.
In geared hubs, exceeding the torque capabilities of the hardware, especially with hard-starts from a stop, can break things like the internal clutch (it can slip, or actually break), but it usually takes way more than the rated power to do this.
If I had chosen a 17w controller,
Just to be sure, do you mean 17A here, vs 17w? (same as before, it's a very important difference).
