Eric
thanks for that
4 blades no wonder your slip is low !
Andrew
On 2/29/2012 8:26 AM, Eric wrote:
Hi Andrew,
First the prop. It's a 13x15.5 four blade prop. You can see a pic of the prop in this group's photo section, here's the link (again)
http://groups.yahoo.com/group/electricboats/photos/album/1967401930/pic/1689340396/view?picmode=&mode=tn&order=ordinal&start=1&count=20&dir=asc
As far as the math, 106A x 48V works out to 5088W on my calculator, and since my observed average voltage at full throttle was 48.7V, I'm calling it 5162W, or 5.1kW in general conversations. All current measurements are from a TBS E-Xpert Pro HV monitor attached at the battery side of the contactor and controllers, so it's reading pack current. This works during charging or discharging, even if the drive system is not energized. The figures agree with input current figures supplied by the Sevcon Clearview display that "... show(s) a variety of data from the Sevcon motor controllers it is connected to..." so I believe that the E-Xpert Pro HV is both precise and accurate.
For those that weren't around when I originally posted my observed performance specs, here's an link to my first performance post (post # 17700) http://groups.yahoo.com/group/electricboats/message/17700
And here's the link to my post after my second round of testing. (post # 17974) http://groups.yahoo.com/group/electricboats/message/17974
I still haven't done the "run the batteries to empty" test to confirm the actual against predicted range, perhaps I'll get around to it this spring. Plus it will allow me to verify the Peukert's Exponent setting that I put into the E-Xpert Pro HV to make it's reading more accurate (IIRC, I used 1.03 in position F5.4)
Fair winds,
Eric
Marina del Rey, CA
--- In electricboats@yahoogroups.com, Andrew Gilchrist <andrew@...> wrote:
>
> Chris
>
> the ratio - depends
>
> Eric reports using a 48v supply the ME0913 turns 1900 rpm and draws
> 106 ampsat full throttle while spinnign a 13*15.5 prop through a 2.55
> reduction box. (Eric is it 2 or three blade - do you have a brand or
> blade style)
>
> Another way of putting it is on 48v the motor is making 16.56Nm and
> using 4.172kw at 1900 rpm.
>
> Through a 2.55:1 box the prop is being turned by 42.3Nm and 4.172 kw at
> 750 rpm with 35% slip
>
> Thats a reference point.
>
> What engine is in there now, what boix ratio is used and whats your
> prop? what do you want in terms crusing speed? is the battery size
> limited by weight (say the same as the current engine and half a tank of
> fuel) or other factors?
>
-- AJ Gilchrist Fastelectrics 0419 429 201
No comments:
Post a Comment