ElectricMotorcycleForum.com
General Category => General Discussion => Topic started by: DrumminStewey on June 30, 2008, 09:47:24 AM
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I am trying to convert an old moped i have to an electric motorcycle. so far ive looked around at www.evalbum.com and found a few motorcycles made http://www.evalbum.com/1817 is the person i figured to base my bike on. he picked out a fairly decent motor http://www.electricmotorsport.com/store/ems_ev_parts_motors_etek-r.php the E-tek-RT 72 Volt Motor Drive Kit which Includes: E-tek-RT Motor, Alltrax AXE 7234, Magura twist grip throttle or Curtis PB6 style pot box, Contactor, Wire kit, Fuse and holder.
this needs a 72 volts of battery correct? and should give me a speed of 50+ mph (right?)
so i looked around for batteries and explanations on what to get and all it did was confuse the hell out of me. http://www.planetbattery.com/details.asp?id=894 is a battery that i found it is decently priced 12 volt i would have to link them together to obtain the full voltage. i would need a DC-DC converter too for this correct?
also are there any other parts i would need for this please tell me now. i tried to give as much info as i can so please help if you can.
i am just kinda guessing now i have read different forums trying to explain battery needs but i dont get it at all. I hope someone can help and tell me if my thinking is wrong if my ideas are wrong or watever. i am open to criticism because i am no pro at this i just need help (majorly) so any comments would be nice thank you in advance
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No DC converted needed to link batteries, just connect the the positive of one battery to the negative of the next, the voltages will add. DO NOT connect the terminals of the last battery to the first as this will complete the loop and very bad things will happen. Typically DC-DC converters are used in EV's to bring the system voltage down from 72V to 12V, to power lights etc, which is probably the only other part you need.
With your controller limiting the maximum current output, the amount of voltage only changes the motors max RPM, which increases the top speed or the acceleration depending on your gearing.
So first you need to decide on the speed you want, whether its a round town commuter or open road cruiser, as this will affect how many batterys you need and what gearing is the best. The actual electrical/mechanical pricipals are kind of complex so i wont go into them unless anyone wants me to.
But basicaly you have a trade off between top speed and acceleration, with the battery voltage increasing the amount you can increase each. If its top speed only you want then 48V will get you 8hp, the recomended power output, however this will not allow you to overcurrent the motor at high speeds so the acceleration will be not so good. If its a town commuter, 36V is probably sufficient, this is what i plan to run mine at for round town testing.
I would recomend finding a good battery (that can deliver 330A, the ones you posted would collapse internally or worse at those sort of currents i suspect), buy 48 volts worth, select the best gearing for your top speed, chuck them in, then buy more and re-adjust the gearing if you want more acceleration.
Post what sort of range/top speed/acceleration you want to get out of it and ill probly be able to give you better advice
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alright well top speed is like 50 if i want to get it around town because the speed limit is 50 on the main road in my town. i am trying to do that it will only be for around town going to the mall or over to a friends house small stuff. i dont want to be constantly charging it though so if i could travel around a day or two on a charge thatd be nice but thats negotiable. i tried to go for inexpensive items due to the fact i dont have a great deal of funds at my disposal. you actually helped more than any other person i have tried to find.
So top speed = 50-60 be perfect
range = around town 20- 30 miles would be stupendous i think
acceleration = i have some hilly terrain around here so it needs some push
anything other than that i dont really know. if i missed something or have more questions please ask i will respond promptly i refresh this page quite constantly. I am eager to start my project!
thank you for your help
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o something else i wanted to inquire about. wat do you mean by 330A battery is that 330 amps? and is that combined of a batteries?? i didnt really understand that sorry.
thanks again
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yeh thats 330 amps, for big lead acid batteries that is required of each battery, not combined. For smaller batterys which are arranged in both series and parralell it is partially added, but unless you can afford lithium ion or something fancy you wont need to worry about that.
If we say 20 miles at 50mph, you can go faster but milage will decrase, and likewise if half you ride is at 30mph you will probably get about 30miles before charge.
At 50mph, 20miles will take 0.4 hrs, estimating 4.5kw for that speed gives a total of 1800Whr. With hilly riding 60 or 72 volts would be good options.
for a 72 volt system you would need 25 amp-hour batteries (25=1800/72).
for a 60 volt system you would need 30 amp-hour batteries (30=1800/60).
The amp hour capacitys are like the maximum current, will not add together in this application.
Both of these capacities are readily available, but you have to watch for the maximum current output, as high amp-hour batteries generally have low current output. Deep-cycle flooded lead acid batteries are the exception to this rule, but they are bloody big and heavy.
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alright thats a huge help. So i would probably need about 6 12 volt batteries at 25 ah correct? unless i can find a big 72 volt isnt that possible ????
and the motor i found with all the parts would that be a sufficient motor? it looked like a good deal but then again i dont really know much. the motor comes with pretty much everything u need to run the motorcycle right.
and i would like to get LED turn signals and lights on it are those really expensive or just a little more? because i know mine really dont work.
thank you for your help you really made it better for me to understand.
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Alright i looked around for some batteries could you tell me if they are okay???
http://www.renewablestore.com.au/catalog/index.php?main_page=product_info&products_id=701
or
http://www.bfmbatterysales.com/index.asp?PageAction=VIEWPROD&ProdID=289
or
http://www.batterymart.com/p-12v-26ah-sealed-lead-acid-battery.html ( idk about this one its 26AH but its cheap that confuses me???)
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Yip thats correct. Um, the most common ones (lead acid) are 6V or 12V, although there may be companyies selling ready made stacks, and non lead acid batteries also have different voltage ranges, but as long as the voltage adds up to 72, and the ahr is 25 for each battery ull be sorted.
Yeh motor/controller combination is all good, just add batteries and all should go.
For the lights/horn/indicators LED ones are probably a good idea (no idea of the cost though), especially as you will need to rewire the loom anyway. Im not sure on the voltage (ill assume they need the standard 12) but i would expect you would need to connect them to a 72V to 12V dc-dc converter. Another option is to connect the lights to just one of the batteries, but that puts more drain on one than the others and if you use headlights it will significantly reduce the performance and battery life.
Not sure on those batteries, none give current ratings, although judging by the terminal sizes the first one looks to be the only one capable of high currents. From the datasheet on that site it can generate 225 CCA, which is cold cranking amps, which refers to the current it can generate for around 10 seconds. So you will not be able to run the motor at full overload current. More importantly the discharge time for running it at 75 Amps is 6min. 75 amps is about what you would need to do 50mph, and 6min would only give you a range of 5miles. Lead acids have the disadvantage that the current you draw the less overall capacity they have.
For my project i ran into this same problem (though i thought it was partialy caused by New Zealand having not a lot to do with EVs), and ended up getting 3x 12V38Ahr batteries, and registering it as a scooter, so i can only do 50kmhr anyway. With some calculations and custom gearing i should be able to equal the acceleration of a 60V system up to 50kmhr .Then if that goes well ill save up for some good lithium ions, then just plonk them in to instantly increase range and top speed.
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Alright so when i am researching for batteries to use wat CCA rating should i look for? i honestly didnt know there was so much to batteries the only ones i really use are AA's.
And would You know of any places that would sell used ones at a local place. Im not saying just in my area but like a common place they could be found. i am trying to do this to be as eco friendly as possible and shipping some batteries from china or something really defies that purpose even though id probably make it up within a few months anyway.
If there is anything else i really need to know about batteries just jot it down you have been a phenomenal help honestly. Without you i would still be lost. thank you so much.
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CCA of at least 330 would get the maximum performance from your motor, and higher values probably mean you would get a better lifetime, and more useable Ahrs.
Nah no idea where to get used ones, i would expect (hope anyway) that used batterys would get recycled into brand new ones. Try and find someon in the same country who has done a conversion already and ask them, otherwise "google is your friend"!
Um, only other thing i can think of is the extra weight (there will probably be a lot of it) so make sure it doesnt exced the original weight by too much (they use 1.4x as the maximum increase for cars i think). Id also recomend when you choose the battery ask the supplier if it is suitable, they probly know more about the chemical side of things than i do. Always happy to help, gotta start the EB revolution somehow :P . Also please post pics and results as you go along
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alright will definitely try to do that thanks again for all your help I will be back if i run into more problems but for now i think u really helped out.
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Alright I have been looking at batteries for a few hours/ days now. and BB batteries have come up in a few cases. i looked on their site for generic ones like another guy used( http://www.evalbum.com/1777)
When looking i found a 12 V 26 AH battery but it uses a lot of fancy words it does not say anywhere CCA so if theres a way to figure it out could you tell me so i dont have to keep bothering you.
This is the Battery: http://www.bb-battery.com/productpages/BP/BP26-12.pdf (its a PDF file)
The regular battery page is http://www.bb-battery.com/productsbp.asp its the BP26-12 Battery.
It does not list a price either so i assume id have to call and ask?
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I also found this battery?
http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=3505 its cheap (on sale) and looks okay?
Some people used Marine batteries also and Sears has them :http://www.sears.com/shc/s/s_10153_12605_Automotive_Batteries+%26+Chargers_Marine+Batteries?keyword=battery&viewItems=21&pageNum=1&sortOption=ORIGINAL_SORT_ORDER
so idk if they are any good or not but those are some with a great deal of CCA and they are 12 volt and relatively inexpensive.
This is another Sear's battery it has only a little over the CCA rating you suggested and is 12 Volt but it doesnt list an AH rating:
http://www.sears.com/shc/s/p_10153_12605_02827185000P?vName=Automotive&cName=Batteries+%26+Chargers&sName=Lawn+%26+Garden+Batteries
And could i get a solar powered trickle charger to charge all the batteries??? would that work?
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Yeh solar charging would work, dunno whether the panel size you could fit on a bike would provide any significant amount of current though.
The BB battery you would probably only get 8-10 Ahrs out of it becuase you will need a lot more current than is used in normal use, but otherwise that battery would be fine. The second one sounds like much the same as the first, with standard discharge current at 26A, and 5sec max at 260, your required current (around 70) falls in between which may mean it should only be run at that current for a few minutes. The third one seems to be like a car battery, but smaller for use in small vehicles, so it would have a quite poor Ahr rating
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alright so i stink at picking out batteries. How do you know so much about batteries??? and how could i pick out a decent one? thats the only part ( besides paying for everything) that i need.
And with that lowered Ahrs how would that affect the bike? would it shorten its range or speed or what?
Well the solar panel would be a normal solar panel used for charging not exactly located on the bike due to space issues. i was just curious if it wasnt able to work.
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Yeh it is very hard to pick the right battery, simply because it doesnt exist i think! The properties electric vehicals need are, lightweight, high current, high capacity, and cheap. I think you probably need to increase your budget a bit, and try looking at deep cycle flooded lead acid batteries. I know lots bout batteries and electronics cos i finished my robotics engineering degree last year!
Lower Ahrs mean less range, Ahrs are like a cars fuel tank, less is less distance.
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alright then. so i shouold google deep cycle flooded lead acid batteries and find ones with 25 AH ratings but some say 80 AH @ 20 hr should i divide by 20 then to find wat it is at one hour??
http://www.rollsbattery.com/pdf/pdf_rolls/24ht80m.pdf that is an expensive one almost 200 dollars but looking at its specs i thought it looked good but wat do i kno (it was kinda big and heavy though) i dont know if that will pass at all.
that degree probably helps a bit in this area haha.
i hate to keep bothering you but most of the things have big graphs and use words i dont know wat they mean and i just get really confused.
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No you cant work out the ahr rate for you application, some give lists like the battery you posted which show the ahr ratings for diffenrent discharge times, the only problem being is you discharge time will be 20min, and not many datasheets have that time.
http://www.electricmotorsport.com/PARTS/parts.htm
has quite few batteries on there, which look pretty good, i checked the specs on the EB50-12 and it looks like it would do the job very well.
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i like that idea and if i purchase it all together i can save on the carbon footprint of shipping it to my house score one for the environment (kinda)
Im sorry it got to the point of you just giving me a battery i didnt mean to take up so much of your time. You are a very good friend hope your motorcycle turns out better than you hoped. I know mine will with your help. Thank you.
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one final thing is the battery charger what should i know in buying one??
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No trouble at all, most of my replies were done in boring bits of watching tv anyway :P
Charger, again depends on your needs. Standard car ones will do the job, if you can be bothered with the hassel of 6 sets of clips (you may also have to remove the battery wiring but im not sure about that), and waiting hours for them to be charged. On the other end of the scale is an automatic 3-stage charger which is probably slightly better for the batteries, charges a lot quicker, has only two points to connect, and is probably small enough to fit on you bike so you can charge it almost anywhere, but has the obvious downside of being very expensive.
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yeah true. ill look into it as long its not to far out of my price range. i already have a trickle charger because i leave my lights on a lot soo yeah. but will still look into that kind of a charger thank you again.
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I found one charger its 200 but its still looks nice simple small
http://www.oksolar.com/n_cart/product_details.asp?ProductID=35915&cat=Lighting&subcat=Battery+Chargers
you said i might have to remove the connections to each of the batteries? would i find if i should from the charger or battery supplier?
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http://marine-products.com/boat_parts/accessories/battery_charges_and_guages/minn_kota_battery_charger_portable_10amp.jsp
theres that one too but its mad cheaper so idk if its good enough its for boat batteries but marine batteries are similar to mind right?? they are deep cycle and such
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That would only be the case if you had to charge them with a bunch of 12V chargers, even then most should still be alright, unless the manufacturer has used a common earth which they shouldnt, the worst that will happen is you can blow the charges fuse anyway which is no biggie to replace.
Both chargers do not specify what voltage they charge at, so would assume it is 12v, which means you need to buy 6 of them, or go out and change the clips 6 times to charge(taking 6x as long). Another option is to get a 72V charger which charges all at once, and only requires two clips to be attached.
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I am new to the Forum and looks like this thread has a battery expert..so maybe you can provide me some guidance.
My e-Bike uses 4 x 12V 20ah SLA batteries in series to provide 48V to a 500 watt motor. Charging is with one 48V charger. Some of us were looking at (and have done some testing) on adding an additional battery pack of 4 x 12V 9ah batteries. (We have physical room for these under the seat) connected in parallel with the larger 20ah pack. Preliminary testing indicates a more stable delivery of amps to the motor plus longer range before recharging.
One of our group thinks that:
•When the bike is not being used (and the batts are partly discharged), the 2 packs should not remain inter-connected as the larger one will discharge into the smaller one at an uncontrolled rate, potentially damaging the smaller pack. For this reason, he is planning to install some 25A diodes between the two packs to prevent this.
•The two packs need to be disconnected from each other and charged (using the 48V charger) separately and independently as charging through the main pack with both connected will cause the charger to prematurely detect full voltage and shut down early, or perhaps overcharge the smaller pack.
I personally am not convinced either of these concerns is valid, but don't want to destroy any SLA battery packs testing it. Would anyone have an opinion/experience on this?