Yes the Victron is a useful tool. There are other brands that are less expensive. The utility comes from measuring actual current in/out of the battery.
I have Nexus instruments from 2002. The speed in the table I posted was GPS speed from my tablet, not the nexus knotmeter speed. And it is probably not so useful to have that hundredths place in the data. The torque app records speed in meters per second. I converted to knots.
I also have a data logger that I made with some Arduino bits to use with the Nexus instruments. It takes the NMEA 0183 data and logs it to a file on a micro SD card. Eventually I plan to get a data set with wind and boat speed data included. Motoring into a 7 knot head wind is a significant increase in power consumption. If I can get the data from NMEA0183 to CAN BUS maybe I can collect it with the torque app along side the controller data. That is probably a winter project at this point. But I can collect the instrument data separately for now. Both have a GPS time base to reference.
Dan Pfeiffer
Nice chart, Dan !The Victron 712 seems like a useful tool.You'll need the speed through water of course, not GPS readings.You must have a very good speed log, reading x.xx values !As I'm in need of a new one (mine is broken), it would be nice to know which type of log that you use.CarstenOn Monday, 9 August 2021, 23:22:26 GMT+8, Dan Pfeiffer <dan@pfeiffer.net> wrote:Here is some data comparing the readings from the Sevcon controller (via can bus) and the Victron 712 shunt meter. There is an anomaly in the Sevcon data where power goes down at about 900RPM while boat speed is actually increasing. I don't know what is causing this but it is consistent and repeatable. The throttle input is increasing and the boat is going faster for each step in the data but the power reported by Sevcon drops at about 900 RPM. I know that's incorrect because physics is real and the Victon shunt meter confirms the actual power draw from the battery.
This is just some quick data to compare the Sevcon data to the Victron shunt meter. I did not do two direction averaging to account for wind and current. I'll do that when I get a properly calm day. I also haven't found a way to log data on the Victon. I was just grabbing snap shots of the display screen in the app and comparing that to what was logging on the Torque app from the Sevcon can bus data. Maybe the PC version of the Victon Connect app can do data logging.
Dan Pfeiffer
On 2021-08-08 10:14 pm, Dan Pfeiffer wrote:
I have been progressing with testing and tweaking of my new electric drive system. I have some mods to the cooling system in the works.
Today I installed a shunt type battery meter (Victron 712) to get a definitive look at current flow in and out of the battery. I collected some data and I'll have that later. In the mean time I have some encouraging results from testing the regen capabilities.
I was sailing in 8-11 knots making 5 knots and I set the motor speed at about 300 RPM and was generating about 130 watts into the batteries according to the Victron meter. This is quite a bit better than I expected at this moderate wind speed and moderate boat speed. The 18" propeller probably helps with this. I estimate the regen was costing about 1/2 to 3/4 knot of boat speed. I was only flying my main and a working jib and was sailing on a close reach to beam reach. It looks like I may have a chance to try this out in wind enough for hull speed in a few days. I'll report back if I do.
I should have started out with one of these shunt type meters. The instrumentation that Thunderstruck provides through the CAN translator reading from the controller is good but the shunt meter is more definitive as to what is going in/out of the battery. The Victron unit I have has many nice features the most useful of which is probably the time to empty display.
More to come...
Dan Pfeiffer
BOAT DETAILS
Pearson 10M
33' LOA
28.33' LWL
12,500 lbs
48V 280AH LiFePo4 battery
Sevcon Gen 4 Controller
Motenergy ME1616 w/3:1 belt drive reduction
J Prop 18" 3-blade feathering prop
Victron 712 battery monitor
No comments:
Post a Comment