Battery Woes
I called the battery warehouse and asked about what models might be available with a higher maximum discharge rating. I had to describe a couple times what exactly I was asking for. The gentleman on the other end of the call only knew that batteries were usually rated by a 20 hr amperage. He suggested I check out the SLA 1185/1175 and DCM0075. I did, and as expected, they are for far more A-hrs than my current battery, and cost almost twice as much too. I don't think he ever quite realized what I was asking him. I doubt I will call and ask again, because I always get that guy.
Making matters worse, I rechecked the spec sheet for the DCM0035 I bought a week ago. It shows a small table that compares discharge time to A-Hr capacity. Discharging the battery at a continuous 1.7 amps will yield 20.1 hrs of power, while a continuous draw of 17 Amps will yield only 1 hr of power. Of course, if I'm cruising at, let's say, 45 amps, I'll have about 15 minutes of that kind of power.
Seriously
Distance: My commute is 3 miles one way.
Time: It usually takes me 12 minutes (.20 hrs) to get to work.
Velocity: I usually travel at 45 mph (which might pull only 45 amps on the Lifan)
I can find my average velocity with:
Velocity = Distance / Time
My velocity is then 3 miles / .20 hrs = 15 mph.
This is my average velocity over the course of the entire commute because the time variable includes the time spent at a stop, accelerating, cruising, and decelerating.
I can find my theoretical minimum commute time with:
Time = Distance / Velocity
My minimum commute time is then 3 miles / 45 miles / hour = 3 hours / 45 = 4 minutes.
This assumes no change in velocity, though, which is why it is theoretical only.
I can find a theoretical maximum range with:
Distance = Time * Velocity
A 45 Amp draw implies a discharge time of 15 minutes = .25 hours.
My maximum range is then .25 hours * 45 miles / hour = 11.25 miles
These are just estimates. If I later find that the bike actually only draws about 38 amps at 45 mph, then the numbers instantly change. A 38 Amp draw implies 30 minutes of power for the DCM0035. Thus, I would instead have a maximum range of .5 hours * 45 mph = 22 miles! Considering it is a theoretical value, 22 miles isn't bad if you ask me.
Likewise, if I were headed up a hill, into the wind, and gained 50 pounds overnight, the motor might pull 70 amps, just to maintain the same 45 mph. This would give me a cruise-time of 10 minutes, and therefore an estimated minimum range of 7.5 miles. This means I could make it to work and back fairly easily, I think. Maybe there isn't anything wrong with this battery after all. Later on, I'll be able to charge my batteries at work, so that will help in extending their life and my actual range.
The point:
One simple formula can tell you a lot about the performance you can expect from such a machine. Even if some results are theoretical, it doesn't hurt to know absolute minimums and maximums because at least it can't get any worse than that. =) No matter what you're trying to calculate, it's important to treat the values correctly and consider closely what each variable you've specified really includes or excludes.
Question:
I wonder how much regenerative breaking really does help. I mean, how much can it really "re-charge" the batteries, based on speed and regenerative efficiency? I wonder if exceeding the maximum charge rate of your battery pack when using regenerative breaking is analogous to over-revving your manual transmission when down-shifting. =0
-Colby
Thursday, February 5, 2009
Tuesday, February 3, 2009
Planning
I spent the 3 hours or so last night and another 2 tonight, measuring, recording, plotting and drawing points on graph paper with a pencil, measuring compass, ruler and trusty tape measure.
Practice makes perfect:
This isn't the first time I tried to translate the bike's dimensions onto paper, but all my previous attempts eventually had discrepancies, where one point no longer lined up when measured from 2 or 3 other points of reference. However, this time, before I started, I put small pieces of masking tape at all the important intersections of the frame and a single dot of blue ink on it to indicate the point I should measure to each time. Given that the bike is 3-dimensional, ignoring one of those dimensions and measuring straight from one point to another repeatedly will always yield a small amount of error, but I'm still very pleased with my results this evening. I ended up with a 1/4th scale nice side view of the bike that will allow me to plan for component placement, ground clearance, and even center of gravity if I feel so inclined later. It was a lot of work, but I would seriously recommend it if you tend to like things to be done as efficiently as possible - meaning well done on the first try. I'm going to make some copies at work on legal paper so that I can loosely sketch battery trays without messing up the original, a product of 5 hours' work.
Battery tray:
I've looked at a lot of bikes and other vehicles on evAlbum and elsewhere. For vehicles like cars and trucks, it's a little more important and common, it seems, to fit all the components under the existing panels, doors and frame. For motorcycles, it appears to be far less common. Tons have wires, plugs, and components hanging on for dear life, by the looks of it. Some builders at least took their time and bundled up, organized, or custom cut their wires to make the end result look nice. Then there are the few who get everything to fit under the original fairing, or even make their own fairing and actually have a great looking bike in the end - not that a bike needs full fairing to look good. I mention all of this because as much as I'd like the bike to be low maintenance, it is a vehicle and it's only a matter of time before I have to check, replace, or fix something on it. I don't want it to require 3 hours of dissasembly just to get to the part that needs attention. For this reason, I'm hoping to design a battery tray can be completely removed from the bike in roughly 10 minutes, after removing only a few bolts and disconnecting a couple easily reached plugs. I'd like it to feel really modular when finished, almost like the battery pack for a toy truck. Now that I can begin to decide on the potential placement of multiple batteries, I can start planning for how I might be able to do this.
To do:
Here's what I need to accomplish in the near future:
I'll try to upload a copy of the rendering soon.
-Colby
Practice makes perfect:
This isn't the first time I tried to translate the bike's dimensions onto paper, but all my previous attempts eventually had discrepancies, where one point no longer lined up when measured from 2 or 3 other points of reference. However, this time, before I started, I put small pieces of masking tape at all the important intersections of the frame and a single dot of blue ink on it to indicate the point I should measure to each time. Given that the bike is 3-dimensional, ignoring one of those dimensions and measuring straight from one point to another repeatedly will always yield a small amount of error, but I'm still very pleased with my results this evening. I ended up with a 1/4th scale nice side view of the bike that will allow me to plan for component placement, ground clearance, and even center of gravity if I feel so inclined later. It was a lot of work, but I would seriously recommend it if you tend to like things to be done as efficiently as possible - meaning well done on the first try. I'm going to make some copies at work on legal paper so that I can loosely sketch battery trays without messing up the original, a product of 5 hours' work.
Battery tray:
I've looked at a lot of bikes and other vehicles on evAlbum and elsewhere. For vehicles like cars and trucks, it's a little more important and common, it seems, to fit all the components under the existing panels, doors and frame. For motorcycles, it appears to be far less common. Tons have wires, plugs, and components hanging on for dear life, by the looks of it. Some builders at least took their time and bundled up, organized, or custom cut their wires to make the end result look nice. Then there are the few who get everything to fit under the original fairing, or even make their own fairing and actually have a great looking bike in the end - not that a bike needs full fairing to look good. I mention all of this because as much as I'd like the bike to be low maintenance, it is a vehicle and it's only a matter of time before I have to check, replace, or fix something on it. I don't want it to require 3 hours of dissasembly just to get to the part that needs attention. For this reason, I'm hoping to design a battery tray can be completely removed from the bike in roughly 10 minutes, after removing only a few bolts and disconnecting a couple easily reached plugs. I'd like it to feel really modular when finished, almost like the battery pack for a toy truck. Now that I can begin to decide on the potential placement of multiple batteries, I can start planning for how I might be able to do this.
To do:
Here's what I need to accomplish in the near future:
- I have yet too verify my choice of battery. This is priority #1 for this week, since the battery warehouse is only open from 8-5 during the work week.
- Use my 2D, quarter scale diagram to place the components and do some calculations and more measurements.
- Design a battery pack tray to be fabricated.
- Take a step back before I buy more or build anything to see what problems others encountered or solutions they figured out that I haven't even considered yet.
I'll try to upload a copy of the rendering soon.
-Colby
Sunday, February 1, 2009
State to Date
The current state of my project:
I now own a 2006 Lifan 150-25.
I have roughly 97% of the original motorcycle. The missing 3% is the camshaft and piston from the internal combustion engine (I.C.E). I purchased the bike and after 5 months, have resolved ownership issues which I should have verified before purchasing the vehicle in the first place.
Lesson #1: Never purchase any vehicle in any condition without being provided an accurate title of ownership.
Where I began:
In an EV conversion, the batteries play a huge role in the ultimate performance of the vehicle. The motor and motor controller do the application and processing of power, of course, but how that power is provided is pivotal.
This is where I started with my research. After looking at the types of batteries others used and their price tags, I purchased a battery from the local Interstate Battery store/warehouse. It was a PowerPatrol 1116 Sealed Lead Acid (SLA) maintenance free battery. I had run some numbers on a spreadsheet and figured that these batteries could probably get me to and from work alright. I used the battery for planning how I might fit several on the bike chassis, and to verify their size, weight, cost, etc.
The eVFR:
During my research I had stumbled several times, upon the eVFR, Travis Gintz's converted motorcycle. In his photo gallery, I found an image of batteries, exactly like the P.P. SLA1116 I had purchased, and I got excited. I figured I'd done my homework and chosen on my first try, a battery that would get the job done. I emailed Travis about the performance of those batteries and he provided me with important feedback about them. Even considering the batteries he used were not purchased new, he still encouraged me to look at other options. Six of those 17 or 18Ah batteries were probably not going to be up to the job, and Travis mentioned how much of a pain it was to wire all 12 together in pairs. He recomended I find batteries with at least a 20 hour rating of 25 Amp-Hours.
The Gambermoto 1:
I later contacted Tim Gamber and asked similar questions about his 35 Amp-Hour PowerPatrol batteries. Once again, I recieved priceless feedback. Tim told me that even though his batteries may not have been properly balanced early on and he tended to be rough on them in terms of voltage sag during acceleration, they had worn well. This was encouraging, so I started looking at those type and size batteries myself.
Another battery:
Today, I purchased a battery from my local Interstate Batteries warehouse.
It's a DCM0035. That is to say, Deep Cycle Mobility, 12 V, 35 Ah, Sealed Lead Acid. This battery or model never showed up in any of my extensive searches on the internet for 35 Amp-Hour deep cycle batteries. The guys at the warehouse called it a wheelchair battery. So far, this battery meets all the requirements I've set for my bike, so it's definitely a candidate.
The only drawback of this battery is it's maximum discharge rating of 175 Amps for 5 seconds. The motor and motor controller I've been looking at are both rated for 300 Amps for around 30 seconds, so in this regard, the DCM0035 would be the limiting factor for the bike's performance. [This information is incorrect, as I've since learned more about how the batteries and controller interact. See my January 2010 posts.]
On the other hand, part of my correspondence with Mr. Gamber suggests that I shouldn't actually need more than what the batteries are rated for. He mentioned that he could rarely pull 200 amps from his batteries when accelerating. One difference between our bikes however, is that he was using an Advanced DC motor. I don't know much about Advanced DC motors, or how they differ from your standard Permanent Magnet DC motor, but it seems possible the "advanced" part of his motor might allow him to pull fewer amps from his pack.
Conclusions:
I'm going to see if there is a similar battery with a higher discharge rating available at the battery store. I should find out whether or not Tim Gamber's reported amperage measurements don't line up with mine mainly because of his motor, or if I can expect similar values, allowing for the differences in our bikes' properties and our estimated driving habits.
Question:
Why is the series-wired battery pack called a Traction pack?
I've heard the term, but never a definition.
-Colby
I now own a 2006 Lifan 150-25.
I have roughly 97% of the original motorcycle. The missing 3% is the camshaft and piston from the internal combustion engine (I.C.E). I purchased the bike and after 5 months, have resolved ownership issues which I should have verified before purchasing the vehicle in the first place.
Lesson #1: Never purchase any vehicle in any condition without being provided an accurate title of ownership.
Where I began:
In an EV conversion, the batteries play a huge role in the ultimate performance of the vehicle. The motor and motor controller do the application and processing of power, of course, but how that power is provided is pivotal.
This is where I started with my research. After looking at the types of batteries others used and their price tags, I purchased a battery from the local Interstate Battery store/warehouse. It was a PowerPatrol 1116 Sealed Lead Acid (SLA) maintenance free battery. I had run some numbers on a spreadsheet and figured that these batteries could probably get me to and from work alright. I used the battery for planning how I might fit several on the bike chassis, and to verify their size, weight, cost, etc.
The eVFR:
During my research I had stumbled several times, upon the eVFR, Travis Gintz's converted motorcycle. In his photo gallery, I found an image of batteries, exactly like the P.P. SLA1116 I had purchased, and I got excited. I figured I'd done my homework and chosen on my first try, a battery that would get the job done. I emailed Travis about the performance of those batteries and he provided me with important feedback about them. Even considering the batteries he used were not purchased new, he still encouraged me to look at other options. Six of those 17 or 18Ah batteries were probably not going to be up to the job, and Travis mentioned how much of a pain it was to wire all 12 together in pairs. He recomended I find batteries with at least a 20 hour rating of 25 Amp-Hours.
The Gambermoto 1:
I later contacted Tim Gamber and asked similar questions about his 35 Amp-Hour PowerPatrol batteries. Once again, I recieved priceless feedback. Tim told me that even though his batteries may not have been properly balanced early on and he tended to be rough on them in terms of voltage sag during acceleration, they had worn well. This was encouraging, so I started looking at those type and size batteries myself.
Another battery:
Today, I purchased a battery from my local Interstate Batteries warehouse.
It's a DCM0035. That is to say, Deep Cycle Mobility, 12 V, 35 Ah, Sealed Lead Acid. This battery or model never showed up in any of my extensive searches on the internet for 35 Amp-Hour deep cycle batteries. The guys at the warehouse called it a wheelchair battery. So far, this battery meets all the requirements I've set for my bike, so it's definitely a candidate.
The only drawback of this battery is it's maximum discharge rating of 175 Amps for 5 seconds. The motor and motor controller I've been looking at are both rated for 300 Amps for around 30 seconds, so in this regard, the DCM0035 would be the limiting factor for the bike's performance. [This information is incorrect, as I've since learned more about how the batteries and controller interact. See my January 2010 posts.]
On the other hand, part of my correspondence with Mr. Gamber suggests that I shouldn't actually need more than what the batteries are rated for. He mentioned that he could rarely pull 200 amps from his batteries when accelerating. One difference between our bikes however, is that he was using an Advanced DC motor. I don't know much about Advanced DC motors, or how they differ from your standard Permanent Magnet DC motor, but it seems possible the "advanced" part of his motor might allow him to pull fewer amps from his pack.
Conclusions:
I'm going to see if there is a similar battery with a higher discharge rating available at the battery store. I should find out whether or not Tim Gamber's reported amperage measurements don't line up with mine mainly because of his motor, or if I can expect similar values, allowing for the differences in our bikes' properties and our estimated driving habits.
Question:
Why is the series-wired battery pack called a Traction pack?
I've heard the term, but never a definition.
-Colby
First things first
I'm starting this blog specifically for my electric motorcycle project.
I hope it will serve as a good record of the amount of time and effort invested.
So far, I've been concentrating on researching other electric vehicles (EVs), specifically motorcycles (eMotos). I read whatever I come across concerning EVs at least once. I browse the EVAlbum and EV part suppliers. I investigate how each individual component works and also how they inter-operate.
The basic goals of my project are:
Goal #2 is a personal accomplishment thing. I want to prove I can plan, figure out, build, complete, and operate daily an EV.
Goal #3 is how I hope to accomplish goal #1 and #2. You see, someone already did what I am trying to do, so I'm definitely taking some cues from his project and how it turned out. It doesn't hurt that that guy has a mechanical engineering degree from MIT and has made public his well documented project. I'm not trying to 1-up him by making a better bike, and I'm not trying to steal anything from him either.
The EV community as I understand it is all about sharing ideas, techniques, lessons, technical information, and even expensive components, so as to further the interest and awareness of the field. The field is not new, however, as some of the first vehicles were electric, back in the early 1900s, so I suppose I would have to say the field has simply seen a large growth in interest in the last 10 to 15 years.
I will try to keep a running tab of my efforts, document my findings, explain my decisions, and publish my experience for the education, assistance, and general interest of others and myself.
-Colby
I hope it will serve as a good record of the amount of time and effort invested.
So far, I've been concentrating on researching other electric vehicles (EVs), specifically motorcycles (eMotos). I read whatever I come across concerning EVs at least once. I browse the EVAlbum and EV part suppliers. I investigate how each individual component works and also how they inter-operate.
The basic goals of my project are:
- Produce a relatively simple and cheap vechicle for commuting to work on any acceptable day.
- Complete a reliably working EV
- Duplicate (and perhaps improve upon) an already proven platform.
Goal #2 is a personal accomplishment thing. I want to prove I can plan, figure out, build, complete, and operate daily an EV.
Goal #3 is how I hope to accomplish goal #1 and #2. You see, someone already did what I am trying to do, so I'm definitely taking some cues from his project and how it turned out. It doesn't hurt that that guy has a mechanical engineering degree from MIT and has made public his well documented project. I'm not trying to 1-up him by making a better bike, and I'm not trying to steal anything from him either.
The EV community as I understand it is all about sharing ideas, techniques, lessons, technical information, and even expensive components, so as to further the interest and awareness of the field. The field is not new, however, as some of the first vehicles were electric, back in the early 1900s, so I suppose I would have to say the field has simply seen a large growth in interest in the last 10 to 15 years.
I will try to keep a running tab of my efforts, document my findings, explain my decisions, and publish my experience for the education, assistance, and general interest of others and myself.
-Colby
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