aetoma motor and battery for my commute

[jeohearn]

Wow! I really appreciate your help. Based on your response (and some others) I think I will keep my motor. I am almost certain my motor is brushless and the controller (or motor) is without sensors. I asked about these two things because in the little research I did, those two features seemed to be important. My seller told me that only two people called him with problems and they were folks who tried 48 volts and the controller burned up. I don't think I need 48 volts but know I need more amp hours (range??) but I would like your opinion based on this info:
-I want to be able to go one way to work without minimal pedalling if I so choose, which I cannot do now with 36 volt lead acid batteries. Note: The batteries are new but I nearly drained them so they seem to last less, although they never could get me to work free wheeling without petering out.
-My 7 mile one way commute to work is on a very slight up hill grade ('very slight' means that car drivers are convinced it is flat!). There is one 10-15 degree inclined hill 50 yards long. Although this ride to work is relatively flat I do notice a difference between going to work versus coming home on my regular and electic bikes: speed is a little less and the batteries peter out much quicker.
-I don't feel I need to go faster nor have more power, although as an options minus the extra cost and weight, I would take them!
-I believe I want a lithium ion because I understand they last longer and are much lighter, but particularly because their strength is continuous whereas the lead acid batteries I have, seem to lose speed and power part way through my commute even before approaching the end of their juice.
-The main question: how many amp hours do I need? 10 or 15? I wish I could just try one out and then I would know. (I charge the battery at work so we're only talking needing to go 7 miles, but I suppose having the option of taking a detour is appealing.
-A bonus question: Is it worth considering getting 48 volts (and of course a new controller that can handle that)?
-What is the difference between a motor that draws 750 watts versus 500? Is it an advantage that I have a 750 watt motor? Is it faster?
Thank you!jeohearn
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Joined: Sun Sep 13, 2009 11:03 pm
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[ekingsting]

Welcome Jeohearn,
I have used 4 12v 12a sla batts for 9 months and 1050 mi.on my aotema brushlesss and routinely ride 15 to 20mi and 1200 to 1400ft. elevation change no problem. I do assist minimal but any assist will extend range greatly. I also run high preasure slicks which helps rolling resistance a little. Love the Aotema at 48v. but I have had an issue with controller which several people are working to solve. Even though I bought my motor from ebay, Terry at Hightekbikes has been most helpful in attempting to help with solution. Although I don't run at wot very often the extra umph from 48v is worth all 8,5 lbs of extra batt. I find the motor really likes to go up most steep hills around here ( with a little assist) at 15 to 20mph. Also you will notice that many others have controller issues with other motors as well while attempting to push the envelope to suit their own needs . This is a good thing as it results better motors, controls etc. in the future.
Always charge sla's immediatly after use with a 3 or 4 stage sla charger for maximun life and distance per charge. Keep the Aotema , I believe it is a great motor for the money. Good Luck

 

[morph999]

well, there is the cheap way and then there is the expensive way. Since you are doing only 36v. You could put 3 12v20ah batteries....that would be about 13x 3= 39 lbs of batteries.

Here are the batteries that I'm thinking about buying.

http://www.zbattery.com/CSB-EVX12200-SLA-Battery

Those would probably get you 10 mile range full throttle (20 mile range half throttle). I haven't tried them but 12v20ah even on SLA's is pretty good. Or you could go 36v10ah lifepo4 and get about the same range.

I got 45 lbs of batteries on my bike right now so it's doable. I just check all the bolts before I leave the house to make sure they are tight.

 

[dogman dan]

I'm allways willing to type the newbie stuff again. To get real specific we need to know how much you can comfortably spend but here is the basics.

The range you need is definitely doable with sla's in the 12 ah size, using 4 of them for 48v. Don't worry too much about the high voltage, few of the problems with controllers have been happening with sla's. The reason is the voltage sag you described. Though you start out with 60 volts,( yep 48v sla charges to 60v) the voltage quickly gets into the 50's and is safe for the controller. I suspect some of the controllers blaming 48v had the throttle applied while the wheel was creeping backwards. That can blow a controller sometimes. I just roll a bit forward as I put on the watts.

The next option, and good for newbies is nicads. A 48v 8 ah pack from Ebikes.ca would just have enough range. Nicads are still heavy, but ligher than lead, and they are more tolerant of deep discharge than sla's and don't need to be charged immediately like lead.

From EV Components, a 36 v 10 ah headway lifepo4 pack can be had. This is one of the best batteries avaliable at a reasonable price. Some real world testing of these is in progress by ES members who bought them recently. This is what I'd be going for if I was you. About $450 including the charger, shipping etc I think. Not sure how quick they can deliver at any given moment, they may be sold out at times.

Lifepo4 from Pingbattery, or High Tech Bikes Terry. Both similar , I'd get a 36v 15 ah or better still 20 ah. These cells are lower discharge rate so the pack needs to be bigger for the best reliablilty. This is the choice for those with longer range needs that want a big battery anyway.

I suggest 36v if you go for lifepo4 since the lithium charges to a higher voltage than sla and keeps a higher voltage longer, so it's more likely to cause a 36v controller at 48v problem than lead or nicad. The caps in the controller are 63v, and 48v lithium charges to 62v. Pretty thin margin. Since the aotema has no sensors, controller choices are more limited. 72v pedal first controllers are avaliable, but not cheap.

On the other questions, do some reading in the tech reference section to fully understand amps, volts, amp hours etc.

Here is some of it though. Volts x amps = watts. So for a 36v battery, which is actually about 42v, using a 20 amp controller puts out 840 watts. The aotema controller is 22 amps, so your motor is actually about 900 watts, but you seldom use all of it. 900 watts would be seen on a start while going up a steep hill. On flat ground, cruising full throttle, your motor will pull about 16 amps if you weigh 180 pounds. So most of the time you are running around 700 watts or so.

Motor wattage specs are very confusing, but most motors listed at 500 watts can handle up to 1200 or so easy. Motors listed under 500 watts, the motor may handle it, but have thin wires leading into it that would melt if high wattage was run through them. The low watt motors have low amp controllers that keep the watts less, and may run on less volts too. Your aotema is perfectly happy to run at wattages from 300 to 1000 with the stock wiring. Want to use less watts? just use half throttle. Ranges dramaticlally increase at half throttle, riding about 14 mph.

 

[jeohearn]

OK, so Lifepo4 36v is the way to go. From EV Components a 10ah BUT from Ping or High Tech (about an hour and a half from where I live) a 15ah. After draining my lead acids and cutting their duration in half I don't want to be worried about that again. I also don't want 40 pounds on the back of my bike. By going this route I don't have to deal with getting a different controller and possibly wires. I can keep my Aetoma which I'm learning is a good motor. I can still keep my cruising speed of close to 25mph. I have less weight. Good!

What about a partially used Lifepo4 at a lower price?? Is there a source for that?

Now I need a bike. The bike that the motor is on now is a Magna (I believe from Target). It's cheap: front shocks are weak and wobbly, brakes are weak, I have to lean way forward, there is no gear with which I can pedal at 25mph etc.
My ideal bike:
-front fork shocks (I understand I may not get that)
-sit upright (so most of my weigt is on the seat and not on the handle bars)
-shocks on the seat post with comfort style seat
-a gear that I can go up steep hills with and one I can pedal along with at 25mph
-change gears while powering the motor
-stop efficiently

Any suggestions?

Thanks very much!
Jeff

 

[fabiograssi]

From EV Components, a 36 v 10 ah headway lifepo4 pack can be had. This is one of the best batteries avaliable at a reasonable price. Some real world testing of these is in progress by ES members who bought them recently. This is what I'd be going for if I was you. About $450 including the charger, shipping etc I think. Not sure how quick they can deliver at any given moment, they may be sold out at times.

Dear Dogman, evcomponents comes with charger?

Look at this:

http://www.evcomponents.com/ProductDetails.asp?ProductCode=H4810

 

[dogman dan]

You have to get the charger seperate. As I understand it, the web site currently shows only big chargers for larger EV's but some chargers for the 48v 10 ah packs are or are going to be avaliable . Those that have a pack may know more about this, many of them in the group buy are the type that simply make thier own chargers. ( must be nice to have that skill set).

Other places do have suitable chargers, 80 bucks or so. So figure $450 for everything?

With Terry in the same town as me, I'd buy from him for sure. Don't we all wish Ping lived in our town?

As for the bike, to keep suspension and run a front hub you have to stick with bikes that have the cheap all steel front shocks. Don't even consider running a front hub on alloy shocks. Some do, with torque arms, but really, just don't do it!

The issues you have with the current bike can be fixed or lived with. Freaky as it may look, the floppy fork is not dangerous. I cut one apart once to be sure, but believe me, there is no way in hell that fork is falling apart. The part attached to the top, is actually the inner layer of the pinched tube dropout. So even though floppy and not so great, the fork will stay together for sure. Bmx handlebars cost about 10-15 bucks and some new cables another 20 or so. Viola, lame straight bar mtb becomes a great comfort bike. New seat for sure too. The last cheap item on the bike is the crank, and I bet Terry can help you with that, or get something used but high quality from fleabay or the local flea market. I buy old junk bikes just to get quality stuff off em, better v brakes, cranks, seatposts, etc.

In a new bike, just look for something that doesn't have quick release hubs on the front wheel, and lotsa steel on the front forks. If you can't find that, you can get strong cromoly forks for MTB and Bmx bikes to replace the ones you have. Generally in a full retail place like the bike shop, you don't get into very nice stuff untill you get to $250-300. Above that, it's too light, and you get into dropouts that can't handle motors, usually quick release.

Look for Dogmans .... bike in the pix section to see what I've done with some pretty cheap bikes. I now have 4000 miles on the commuter, a bike that began life as a $120 mongoose mountain bike. The original brakes are still on it, even the pads , and now on the 3rd set of tires. A 48 tooth front sprocket is what you need to pedal at 25 mph. That size on a mtb triple is not so hard to find. The big sprocket is overkill but nice since i lucked out and found one.

 

[jeohearn]

OK. My aim was a little high regarding batteries. For now the LiFePO4 is too expensive. I think I'll go for the sla at 36 volts. Based on what you (Dogman) say and others 12ah is OK for my commute if I'm using 48 volts. So, with only 36 volts what would I need? I'm guessing 20ah...or would 15ah be OK?
Again, I want to go 7 miles on very light upgrade (looks flat in a car) with little to no pedaling, plus one 100 yard hill of 10-20 degree incline, add a mile or so for a detour if I need to. I don't want to come close to draining the batteries as I understand they will die a quick death as my sla 36 volt 8ah seem to be undergoing at the moment.
Where can I buy these? I live in the Bay area in California. I understand there is a shop in San Jose. Can I just go to a motorcycle shop??
Thanks again!
Jeff

 

[morph999]

OK. My aim was a little high regarding batteries. For now the LiFePO4 is too expensive. I think I'll go for the sla at 36 volts. Based on what you (Dogman) say and others 12ah is OK for my commute if I'm using 48 volts. So, with only 36 volts what would I need? I'm guessing 20ah...or would 15ah be OK?
Again, I want to go 7 miles on very light upgrade (looks flat in a car) with little to no pedaling, plus one 100 yard hill of 10-20 degree incline, add a mile or so for a detour if I need to. I don't want to come close to draining the batteries as I understand they will die a quick death as my sla 36 volt 8ah seem to be undergoing at the moment.
Where can I buy these? I live in the Bay area in California. I understand there is a shop in San Jose. Can I just go to a motorcycle shop??
Thanks again!
Jeff

if I were you, I'd go straight for the 18ah or over SLA's...cuz, if you are anything like me, and you'll be joyriding, you'll want the 18ah SLA's eventually. The 12ah and 18ah aren't much difference in price. I got 45 lbs of batteries on my bike. Some say it's horrible but I don't see anything wrong with it. It's not that bad if you have a strong rack and you don't go crazy on the bike. I got 9ah SLA's and I get 5 miles out and I have to come home. It's annoying. I wish I would have went straight for the 20ah.

 

[dogman dan]

The 18 ah batteries you need will be at a place that sells or services wheelchairs, or look online for similar places. You can't use ordinary sla's like the ones for an emergency light. An easy source of 12 ah sla's for EV's is wallmart, in the toy dept. Toy cars use the same sla's. $200 for four. Don't hesitate to go to 48v using sla's. As soon as you ride a half mile the voltage will drop a lot. That's why a 13.5v sla is called a 12 volt battery.

Before you pull the plug on more sla's look at 8 ah nicads from ebikes. ca. I'm really happy with mine, and they are a lot more durable than any sla's. They are a bit pricy, but less than lifepo4. 8 ah will be enough for the ride you speak of, and nicads aren't nearly as sensitive to overdischarge as sla's. Lighter too, since you can use a smaller pack. 8 ah nicads may cost close to the same as 18 ah sla's. You would though, need a nicad charger too.

Looking at the site, 36v 8ah would be about 300 including a charger, and I bet 18 ah sla's are close to 100 each local retail, or with shipping if bought online.

 

[pkcheng55]

I have the same cost savings thought as you a few weeks ago about the SLA vs LifePO4. However, my conculsion is that SLA is a little too heavy. It is losing the fun for biking since pedaling become harder. Eventally, I will not pedal any more if I get a SLA. In this case, I told myself if I get a SLA, why don't I buy a cheap chinese made moped which may cost the same money.

As a result, I end up to get Hightekbikes AOTEMA brushless motor with their 36v 15ah LifePO4 battery. Overall, the hightekbikes motor and 36v 15ah sever me very well and I have already put over 150 miles on it. I ended up pedaling along with the motor without sweating to go uphill (got 9-10% grade hills in my area) but I still keep enjoy the fun for riding "bicycle".

 

[dogman dan]

Cost per mile is lower on the lifepo4 if you do get 1000 cycles, but no consolation if you simply don't have the money. 12 ah sla's and shorter rides is about the only cheap way. But it sucks to have to stay with that very long unless you have a short commute.