Friday, May 22, 2020

[electricboats] Measured Performance #2 (03/28/2011)

This was 2 weeks later, without residual tsunami surge...

03/28/11   

Hi everybody,

I did another set of performance trials yesterday. I started at 12:00 noon, after the last rain shower passed. The process took about 90 minutes and I covered 6.35nm during the tests. I ran the same process as before, 1 pass in either direction at a particular throttle setting, progressively climbing through 6 settings and then repeat the process descending through the same settings until done. There was some wind by the end of the trials, but that should be offset through the pass in each direction. The results were more consistent than the last trials which had apparent tsunami surge that skewed some of the numbers.

Here's this weeks results:
495W = 3.0kts
1000W = 3.9kts
1500W = 4.5kts
2450W = 5.0kts
3905W = 5.7kts
5165W = 5.9kts

Slightly better at the low end and a little worse at the top end, but fairly close (+/- 0.2kts) to the previous tests.

Because we had a conversation in the interim about motor temperatures, I recorded winding temps during the second half of the trials to see how quickly the motor would recover during the lower power settings. With a max observed winding temp of 74C at the end of the fourth pass at full throttle, the motor dropped to 52C by the end of the last 500W pass.

Right after the trials, I set the throttle to about 2500W and headed out of the marina, around the detached breakwater in open seas and then back in. 45 minutes later, at a constant power setting, the motor was stable at 60C and I had covered an additional 3.85nm. Apparently, the speed boost downwind is greater than the penalty going upwind resulting in an average speed of just over 5.1kts.

After messing about for 30 minutes or so at slower speeds, I brought her back to the slip. The entire day was 10.9nm with a 4.0kt average. The battery meter showed 107.7Ah consumed. After 15 minutes rest, the battery bank was resting at 52.35V. 4 hours on the charger, and she was fully recharged.

In a couple of weeks, I'm going to try a range run on the open ocean at about 1400-1500W to see how the batteries match up against their specs. I'm predicting about 18nm at 4.3kts out of 6.4kWh of usable capacity, that should take a little more than 4 hours.

I know that all this info is more interesting to me, so thank you for your time...

Fair winds,
Eric
Marina del Rey, CA
_._,_._,_

Groups.io Links:

You receive all messages sent to this group.

View/Reply Online (#30485) | Reply To Group | Reply To Sender | Mute This Topic | New Topic

Your Subscription | Contact Group Owner | Unsubscribe [newarmyguitar24@gmail.com]

_._,_._,_

No comments:

Post a Comment