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[GoneToPlaid]

I just bought a 2021 DSR 14.4, with a dealer-installed 3.6 Power Tank extra battery.  I've taken it out for a couple rides, and noticed a discrepancy between the % of battery used on a trip, and the Wh/mi reported for the trip.  If I use 100% charge = 15.8 kWh nominal capacity (main battery + power tank), the math doesn't work out.  But if I use 100% charge = 12.6 kWh (just the main battery), the calculations all make sense.

I used the Zero Android app to connect to the bike, and opened the Firmware Manager.  It shows MBB v31, and BMS v38.  See screenshot.  Shouldn't it also show the power tank's BMS version?

I removed the seat, and verified the connections.  The power cabling runs to the motor controller, and the communication connector looks correctly seated and has no bent or loose pins.  Also, on the left side of the extra battery, there is a small round window to view what appear to be 4 status LEDs.  With the bike turned on, the left-most LED is Red, and the other three are Green.  See picture.  Any idea what these lights mean?

When I turn on the keyswitch, I hear the main contactor close, followed closely by the power tank contactor.  So that much is working.

So, I'm suspicious that the Power Tank is not working to add range to the bike, or at least that the MBB isn't configured correctly.  Is there a procedure to verify that it is working?

And yes - it's under warranty so I could just take it back and let the dealer sort it out.  But the dealer is a long way away (4 hours one way), and if it's something simple I can fix that would be a lot faster.

Thanks!

[TheRan]

The 4 lights are on the BMS, the main battery also has one under the round plug in the front behind the front wheel. If I remember correctly by default they show the state of charge unless any of the buttons (located under the lights) are pressed. So, 4 out of 4 would indicated that the power tank is full charged or close to it.

Someone said in another thread that the number of flashes of the green light on the dash when you key the bike on indicates the number of batteries, so you should see two flashes.

[GoneToPlaid]

OK, so 4/4 lights on the BMS means full charge.  I can use that by running the bike down below 50% charge, and see if some lights turn off.

When I turn on the bike, the green charging light does flash twice, quickly.

Another possibility - the bike is garaged at about 45°F, and yesterday's ride was at 32°F air temp.   I expect less range when it's cold, but not sure how much.  Is there a capacity derating curve for these batteries, vs. temperature?

Thanks!

[TheRan]

The range estimation on my dash goes from about 80 miles in summer (20-30°C) to 70 miles or less in winter (0-10°C), and as well as the temperature I'll also be riding slower during most of the winter compared to when the weather is nicer. I'd estimate a 10-12% fluctuation in range is typical.

[Richard230]

My 2018 S had its Power Tank installed at the factory when the bike was built. I noticed that the SOC calculator was not very accurate when I first rode it home from the dealership. It used 25% on the SOC to go the 15 miles home.  A couple of months later I was able to ride 150 miles before I hit "00" on the display. After that the SOC seemed to become very accurate.  Now when I start off in the morning with a fully charged battery pack I typically see a 160 mile estimated range on the display, which of course goes down depending upon the ambient temperature and the speed that I am riding. But I can tell you that riding around freezing will definitely take the wind out of your battery pack, PT or no PT.   

[GoneToPlaid]

This chart shows 20% capacity loss at 0° C (32°F), relative to a more comfortable 25°C. I'm not sure which Li-ion chemistry it's talking about though.

Aside: Aerostich added a heated blanket to their winter-testing Zero FX: https://www.aerostich.com/blog/zero-winter-test-bike-preparation/

Richard, that is interesting about the range estimation changing over time as the BMS adjusts its SOC calcs.  Maybe I just need to be patient!

Thanks to you both.

[Crissa]

Yeah, batteries do not perform as well in the cold!  This isn't something Zero can really fix.

Glad you figured it out - your bike can run like it's significantly cold than ambient so,e days, too.  I had one day last year where it was warm out, but everywhere I parked and rode it it never got over 60F and so it acted like it was 40F out.  Man, that was annoying!

Sometimes you gotta park in the shade, sometimes you want a good sun beam.

-Crissa

[GoneToPlaid]

Crissa, thanks for your comment.  I'm not sure that low temperature is enough to explain what I'm seeing.

I've put 400 miles on the bike now, and the bike is still acting like it has no more than 12 kWh capacity.  Today, it was 65F out, and I sat the bike in full sun for 3 hours before riding.  Riding 110 miles at 50-55 mph took the SOC from 100 to 0%, with 3 miles range remaining.  The bike dash reported efficiency of 102.4 Wh/mi.  113 * 102.4 / 1000 = 11.6 kWh total battery capacity.  At 65F I would expect something like 13.5 or 14 kWh to be available.

I looked at the Zero App today, and there is new Firmware for the MBB (v32) and BMS (v39).  Only one BMS is shown - should there be two BMS listed (main battery and power tank)?  Also, is using the app to update firmware a good idea?

Thanks!

[Crissa]

The dash's Wh/mi reads low.  This is a known issue that I guess Zero doesn't care about, because my bike has it, too.

A DSR with a power tank should go about 20% further than a plain one, or 122 miles at 55, according to the website.

So 110 miles isn't entirely unreasonable.  You're just going to have to get a log and decode it to find out if the Power Tank is syncing properly, if you don't believe the blink codes.

The app is how your bike updates firmware.  2014 and earlier don't have the download space to do it.

-Crissa

[GoneToPlaid]

Crissa, thanks.  The Wh/mi reading low would explain what I'm seeing, and I had not heard of that issue.  Yesterday I rode it 131 miles and had 5% left.  I then charged it through a Kill-a-Watt meter, which recorded 16.17 kW required to fill it back up.  If I assume 85% charging efficiency (charger and batteries combined), then the true usable battery capacity is 14.5 kWh, which is as expected.  As for range being a little lower than advertised, both cold temps and me being tall and catching more wind than the average rider would explain it.

[Richard230]

Crissa, thanks.  The Wh/mi reading low would explain what I'm seeing, and I had not heard of that issue.  Yesterday I rode it 131 miles and had 5% left.  I then charged it through a Kill-a-Watt meter, which recorded 16.17 kW required to fill it back up.  If I assume 85% charging efficiency (charger and batteries combined), then the true usable battery capacity is 14.5 kWh, which is as expected.  As for range being a little lower than advertised, both cold temps and me being tall and catching more wind than the average rider would explain it.

Also don't forget that Zero's range numbers are the result of running their bikes on a rolling wheel dyno, which likely is done at a nice warm interior temperature and without any wind resistance.  However, I am not sure if there is any correction about the lack of wind. 

[GoneToPlaid]

Richard, I think they must take wind resistance into account with their range numbers.  By my reckoning, at 55mph the aero drag will be something like 2/3 of the total drag, with rolling resistance making up the rest.  Hence Terry Hershner with his Craig Vetter fairing.