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John Eucist

King Song 14 inch electric unicycle features review (by Kevin Lee)

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It looks like Gotway may have some competition to worry about now. Even if the source code was stolen from them.

A little surprised that they couldn't get more Wh's in the removable battery pack, it would have been nice if they had managed to squeeze 260wh in there.

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Yeah I thought that the 174wh packs are dumb.  It's over the 160wh airline limit yet too low for serious riding (voltage drop issue included).  Why not just have 340wh or 680wh internal instead of 2 or 4 packs?  Also, the lack of a practical trolley solution is a deal-breaker for me.

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Yeah I thought that the 174wh packs are dumb.  It's over the 160wh airline limit yet too low for serious riding (voltage drop issue included).  Why not just have 340wh or 680wh internal instead of 2 or 4 packs?  Also, the lack of a practical trolley solution is a deal-breaker for me.

I quite like the idea of swappable batteries as it means that with a spare your can ride out until you drain one and then swap and with care get back home.

Or for me it would mean I could put a fresh battery in for the hill climb up to my home.

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I quite like the idea of swappable batteries as it means that with a spare your can ride out until you drain one and then swap and with care get back home.

Or for me it would mean I could put a fresh battery in for the hill climb up to my home.

 

Why not just have a bigger pack in the first place?  It would suffer from less "voltage drop" on amperage demand even on a half full large battery than a completely full small battery.

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Even with a bigger battery on a long ride your actual voltage will drop and as Austin has demonstrated very well voltage equates to speed and power so putting in a fresh battery at full voltage prior to climbing a long steep hill should give you optimum performance.

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Even with a bigger battery on a long ride your actual voltage will drop and as Austin has demonstrated very well voltage equates to speed and power so putting in a fresh battery at full voltage prior to climbing a long steep hill should give you optimum performance.

 

But wouldn't the momentary voltage drop from a large current draw (say from acceleration, especially on an incline) drop the voltage of the fully charged low capacity battery to a lower voltage than a half charged much larger battery (cells wired in parallel) doing the same thing?

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But wouldn't the momentary voltage drop from a large current draw (say from acceleration, especially on an incline) drop the voltage of the fully charged low capacity battery to a lower voltage than a half charged much larger battery (cells wired in parallel) doing the same thing?

If it was low capacity it might. That's why I was a little disappointed they squeezed so few Wh into the pack. But I have to admit that when my 260Wh IPS'S are fully charged there is no discernible drop that I can detect over a 3 mile high grade high speed climb.

Edited by Gimlet

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If it was low capacity it might. That's why I was a little disappointed they squeezed so few Wh into the pack. But I have to admit that when my 260Wh IPS'S are fully charged there is no discernible drop that I can detect over a 3 mile high grade high speed climb.

 

Did you have an app or method to monitor the voltage?

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Unfortunately not. No app for IPS so it's all subjective but my son and I got a fairly good idea as we were racing the two IPS machines.

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In general, the more batteries you have in parallel the lower the internal resistance of the (combined) batteries which will guard against voltage sags under load. The Firewheel has a "battery level" readout which I assume is basically just a voltmeter. When you climb a hill there is definitely a large drop. The voltage seems to be measured at the controller board so it isn't clear how much of that drop is from the internal resistance of the battery and how much is from the relatively thin battery leads. 

 

A half-charged "big" battery will have a smaller internal resistance so the internal voltage drop will be lower at a high current draw. But the initial voltage of the "big" battery will be lower than a fully-charged "small" battery (this page shows it's about 10% lower at half charge), and the voltage drop on the battery leads is equal. So who knows, it could end up with the same voltage to the wheel. You'd have to measure everything to get a complete picture. 

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It's on sale now. You can order it from me. Please message me for details.

Technical data would be nice.

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