Watt hour/mile?

6 posts / 0 new
Last post
__Tango
Offline
Last seen: 6 years 6 months ago
Joined: Sunday, July 19, 2009 - 20:21
Points: 59
Watt hour/mile?

So, for those of you who are calculating this stuff, what kind of watt hours per mile are you getting on your zapino?

I finally dug out my WattsUp Pro and did a calculation of my ride yesterday. I rode about 10.7 miles (all flat, but with a good sized headwind for about 25% of the ride and riding full throttle ungoverned most of the way, oh yeah, i weigh just over 200lbs too), and the WattsUp shows i used 1366Wh. That works out to 127.13 Wh/mile. That seems a bit high to me, and i'm wondering if i did my math wrong, or if that's a reasonable number.

I've been researching doing conversions on other motos, and i've heard people talking about getting faster mph using 70-90Wh/mi (but those were motorcycles, though one is using a hub motor as well).

Thanks.

...tango...

PJD
PJD's picture
Offline
Last seen: 4 months 3 days ago
Joined: Wednesday, November 22, 2006 - 05:44
Points: 1416
Re: Watt hour/mile?

My modified old-version E-maxs (top speed 45 mph) are getting about 79 WH per mile (49 Wh/Km) over about 1800 miles of use so far this season.

To make it equivalent to the way fuel economy is expressed in the US, we should probably express it in miles per KWH. Or in Europe KWH per 100 Km. My scooters get about 12-13 mi per KWH, or 4.91 KWH per 100 km.

But expressed that way, the numbers look like the fuel economy of an SUV. So better yet, to drive home the energy efficiency of EV's, we should really be expressing the electrical efficiency in "equivalent mi/gallon (MPGE), or L/100 km, gasoline". Expressed this way, my scooters are getting 424 MPGE or 0.55 L/100KmE. That's better!

Assuming 32,000 Kj (Kw-second) energy content per liter of gasoline, the conversion to MPG is (Mi/KWH)*33.6, or for L/100 KM it would be 100/(Km/KWH)*8.88.

as far as your question on your numbers looking high, I recall getting similarly higher numbers (about 115 WH per mile) on my e-max's when I was still using lead-acid batteries. Lead acid batteries have poorer charge efficiency than LiFePO4's, plus, the best practice of keeping them on float-charge for a few hours after charging wastes more power.

Iccarus
Iccarus's picture
Offline
Last seen: 5 years 6 days ago
Joined: Saturday, December 20, 2008 - 08:05
Points: 347
Re: Watt hour/mile?

I'm running an Xm3500li with 28cells and a kelly KBL12251. I'm getting 22wh/mi@20mph average(in slow neighborhood driving)with up to 16% regen, 48wh/mi@40mph average (city driving)7% regen average. The worst I've seen is 68wh/mi on long high speed trips over 45mph 2% regen. I'm using a cycle analyst to collect data. I get a 45/50 mi. range at that 48wh/mi figure. So I guess doing ok with this machine. I sprayed some ACF-50 on the brake calipers and they don't drag anymore, that may be helping the range a little.Oh,and I weigh 170lbs. but I also have a pod and some supplies in it, probably another 15 lbs.

2008 XM3500li Mods/Kelly KBL12251/84v 28cell 40AH pack/ Variable regen brake trigger on left brake handle/Givi/Cycle Analyst/Homemade BMS

KMX Typhoon Home build (recumbent pedelec) with two Astro Brushless 3220motors/twin castle Phoenix ICEHV 160/ Cycl

__Tango
Offline
Last seen: 6 years 6 months ago
Joined: Sunday, July 19, 2009 - 20:21
Points: 59
Re: Watt hour/mile?

My modified old-version E-maxs (top speed 45 mph) are getting about 79 WH per mile (49 Wh/Km) over about 1800 miles of use so far this season.

...

as far as your question on your numbers looking high, I recall getting similarly higher numbers (about 115 WH per mile) on my e-max's when I was still using lead-acid batteries. Lead acid batteries have poorer charge efficiency than LiFePO4's, plus, the best practice of keeping them on float-charge for a few hours after charging wastes more power.

Thanks PJD, So, it seems my numbers aren't that far off from yours (when you were still using the lead-acid batteries). there was a big difference in going to the lithium batteries (in wh/mi). That's good to know. What type of batteries are you using now?

Also, on a tangential note, when you moved to the new batteries, did you change the controller? What about the charger? Is it the same Voltage with the lithiums vs. the SLA's? Was this a difficult mod? I'm thinking of moving to lithiums for my zapino, and am trying to gauge the effort.

Thanks!

...tango...

__Tango
Offline
Last seen: 6 years 6 months ago
Joined: Sunday, July 19, 2009 - 20:21
Points: 59
Re: Watt hour/mile?

I'm running an Xm3500li with 28cells and a kelly KBL12251. I'm getting 22wh/mi@20mph average(in slow neighborhood driving)with up to 16% regen, 48wh/mi@40mph average (city driving)7% regen average. The worst I've seen is 68wh/mi on long high speed trips over 45mph 2% regen. I'm using a cycle analyst to collect data. I get a 45/50 mi. range at that 48wh/mi figure. So I guess doing ok with this machine. I sprayed some ACF-50 on the brake calipers and they don't drag anymore, that may be helping the range a little.Oh,and I weigh 170lbs. but I also have a pod and some supplies in it, probably another 15 lbs.

Thanks iccarus. What's the top speed of your XM3500LI? On another side note, how does the regen work on your scooter...is it "always on" when you coast? Is it a back twist on the throttle? Is it attached to the brake? How do you like it?

As stated in my original post, i'm gathering data after the fact by gathering the watt hours used to recharge the battery after a day's rides. I've done 3 rides where i've gotten the data from my wattsup, and I've calculated 128, 122, and 122 Wh/mi using this method. I wonder how different it'd be with a paktrakr or cycle analyst.

Thanks again.

...tango...

PJD
PJD's picture
Offline
Last seen: 4 months 3 days ago
Joined: Wednesday, November 22, 2006 - 05:44
Points: 1416
Re: Watt hour/mile?

I think we are comparing apples an oranges when the efficiency is measured using a cycle analyist versus measuring the the actual energy usage at the wall socket. There are charger and and battery charge efficiencies which aren't included with the cycle analyist, which are fairly large.

I am using a "hybrid" setup with sixteen 40AH Thundersky's for the main pack plus two parallel connected 20AH SLA's for use in a switchable-while-riding 60 volt "boost" mode.

An upgrade to 48 volts of LiFePO4's is cheaper than it used to be, but still expensive ($1100 to $1300 counting, but once installed, they should be the last battery pack the scooter ever needs and ultimately cheaper than staying with SLA's. No upgrade to the controller is needed. The biggest job is finding cells of the dimensions and physical arrangement which will fit in the existing battery boxes. the nominal voltage under high current is 3 volts per cell, so 4 cells are used for each 12 volt battery they re replacing. The next biggest job is finding or usually making a battery management system. A do-it-yourself kit is available here:

http://www.tppacks.com/products.asp?cat=26

This BMS works with most, but not all, 48 volts SLA chargers like you are already using. I am still using my original stock chargers, which saved as good bit of money.

The cheapest source for Thundersky cells in small quantities seems to be here:

http://www.elitepowersolutions.com/products/

Log in or register to post comments

Buy Ecotric bikes, get free accessories!


Who's online

There are currently 0 users online.

Who's new

  • tomjones
  • kirkthomas7
  • Minja_Taria9
  • JVale
  • Eom bikes

Support V is for Voltage