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48v sla's is a lot for the back rack. If you have a hole in the frame triangle big enough, hang two batteries there.
Be the pack leader.
36 volt sla schwinn beach cruiser
36 volt lifepo4 mongoose mtb
24 volt sla + nicad EV Global
I have a full-suspension MTB, so not much space in the frame. Problem is that the pack is sliding side to side. The rack that came with the kit seems plenty strong even with the added weight. It's supposed to be rated for 40 pounds, and this 48v pack weighed about 35 pounds on my bathroom scale. The tool bag has some plastic skids on the bottom that run across the width of the bag. I think if I cut some grooves in the skids where they contact the rack, that should fix the problem.
Gasoline? No thanks.
Well just live with it then I guess, or build a box to fit the battery pack and fasten it to the rack. Later on when this pack gives out, a Lifepo4 will weigh so little you'll forget its even there.
I think I'm finally finished with the bike, at least for a while. I cut some notches in the skids of the tool bag where they go over the rack, and strapped it on with a ratchet strap. That thing won't budge now. I put some silicone on some of the components for waterproofing, and put some fenders on front and back. The kids got me a headlight for my birthday earlier this week, so put that on. I put on a speedo to see what it would do at 48v -- 53mph with the front wheel off the ground, 30mph on flat (thought it would do a little more), 18mph up the steepest hill on the way to work with some light peddling. I have about 15 miles at 48v so far, no problems yet.
After a few hundred miles of riding and getting in better shape, put a mondo front crank on the bike. I put a 48 tooth on instead of a 44 and my speed went from 25 to 29 since I can now actually push on the peadles. For you, you would need about a 52 to get more speed though. At about 28 mph peadling gets to be a joke with the 48 tooth. Every time I think I'm done, I find another cool part and start tinkering again. Pretty soon I'm going to be in the bike buisness with all the garage sale finds I keep bringing home.
I've taken the bike to work about five times at 48v. I can go without peddling most of the way (4 miles one way), but the motor gets very hot. On a slight downhill I got it up to 35mph. Motor does not get very hot if I stay at about 20mph and peddle some.
Update on motor heat. I can do the trip to and from work with very little peddling, and the motor won't get very hot as long as I keep speed in the low 20s. The motor only gets hot if run full throttle much of the way.
yeah that's why I fry mine. full speed all the time. Now that it is cool, 80's today, heat is no problem anymore.
Full speed all the time not so good with SLAs, you must be lovin' the LiFePo4.
With 14.5 uphill miles from work to home, 3 sla's didn't work. 4 slas, didn't work, and when I tried 4 sla's and 6 24v dirill nicad packs, I was so heavy I ran out of battery even further from home than before. Without the battery from Li Ping, the bike would still be just a toy. Unfortunately, my climate might be able to kill any motor ridden uphill for an hour in summer. eventually I want to build a small motorcycle with a motor I can cool better. Or even a car if lifepo4 gets really cheap. It's too bad the current cells need a big sise pack to power an ebike. A 10 ah pack that could still put out 40 amp bursts without damage and run 20 amps continuous is about all many bikes need. And it might prevent the kind of problem I had with riding too far for the motor. But to get that for around $300 is dreaming now. More like $800. The price of the A123's at this time has to be jacked up. The perfect cell for an ebike would be a 5ah A123 cell. That way you could have two little 5ah packs to split between panniers, or tuck into frame space without a jillion cells to connect.
With so many uphill miles, perhaps you'd need to modify one of those foldable commuter bikes with a smaller (20"?)wheel diameter. I'd guess a large part of the heat is from the torque required to turn a 26" wheel.
I currently have a Crystalyte 409 Brushed motor. Pretty much identical to the WE motor. A little bit slower and prob a litle more torque. Ive had multiple failures of a WE motor and a Cystalyte controller at various voltages and amperages. The common thing with all of them was they were running in a 26" wheel. Link of Hyrule runs a BMX bike at 72v and 20" wheels. Smaller wheel equals more torque and less speed. Higher voltage can compensate for that. Also less amps are consume and reduction in energy wasted as heat. My thing is although this works for Link because he is average build. Im a bit heavier prob double his weight. By no means that out of shape. I can cycle 20+ miles unassisted but a big guy on a bmx bike with 56v to 72v in dewalt/or milwaulkee pack would be an intresting sight. Due to prob no leg extension at it would be uncomfortable to pedal unless you have a very high seat. So even if i did the conversion i would have to make sure i have enough AH in the packs under all conditions to make sure i can get to my desitnation without pedaling. I have selected the bike and have a local source for spokes. Link is proof of concept that it would work. The torque generated in an already stout motor for its kind... take off acceleration would be sweet. If i could do 72v and find a folding 16" to 20" folder and 8 dewalt packs i could easily do 5 miles under hilly terrain virtually no assitance. I have a 35A 4310 mosfet ecrazyman modded controller with 100v caps probably good up to 84v... 84v fully charged would put the mosfets in the failure zone more likely. But it would be an intresting build indeed. I think the motor would hold up better at lower voltages in smaller wheel sizes. Prob would be virtually indestructable but once you get a taste of speed. Overvolted WE to 60v 68v+ charged in a 26 inch wheel got me up to 37mph... pulls alotta amps and it takes alot to sustain that speed which is death to a brushed motor.I know this all to well.I think i can accomplish my dream by dropping down to 20" or 16" without having to replace warped and melted brush holders and sanding commutater plates. I feel sorry for dogman who recently had to rebuild his motor to reglue magnets. And glued them wrong... but fixed it. I swear my old we axel caught hell. Charred and blackened. But when my Crystalyte axel magnets fell ofter after two or 3 runs I poped my WE axel in the motor and abused it some more at even high voltages and speeds... they are still holding up fine. Guess we mine were a different years batch. But ive blabed on enough. This is just my two cents on lower wheel sizes.
True true true on the wheel size. I do suspect it might not matter once it's 105 and 5% humidity. Air cooling is not air cooling. The water in the air does the cooling. All us old hippie vw driving desert dogs know that well. A lot of vw's would just get parked for June when the humidity is lowest.
I'm on the hunt for a mongoose MTB with a 24" tire. It looks to me like the swingarms will interchange and bolt right on to the 26" frame, and then get a 24" rear hubmotor, maybe even geared, and try that for a summerbike, and run the 26" rear wheel in the winter. Just have to find the bike at garage sale cheap. Should look kinda cool too with the front end jacked up a bit. Anyway today the high is 74, wow get a jacket, so I have 9 months to figure out something. Might be a moot point now anyway, my wife bought a 150 cc scooter today at a garage sale. If she wants AC in the summer it can be mine for those months.
Can you point me to a thread that discusses modding the BD36 controller?
You have to switch out mosfets and caps, right?
I have some hot powertrench mosfets that might work.
this is a build i was working on. It shows my struggled with controllers and such. It should give you an idea on where to start from. The BD36 is a very compact controller and modding it is not for the faint of heart. The BD36 is good up to slightly over 48v any higher you risk blowing fets. But you dont want to go any higher than 48v in a 26 inch wheel. If you wanna go to a higher voltage reduce the wheel size to 24 or perhaps 20. A nice combow would be a 24 front and a BD36 20" back. With no pedals 60-72v a lotta torque and respectable speed of around 30+ mph good for 5-10 miles unassisted. Any longer overheating can occur and u dont wanna go down that road. My posts in endless phere will discuss the horros of going to higher voltages on the BD36
Hmm sounds like 48v is the max I want to go since I need a reliable bike to commute to work.
Might be fun to build a second bike for mad scientist experiments.
I was asked what connector I used to replace the RCA connectors on my charger and my pack. The connector is a Hopkins 47965 trailer-light connector pictured here:
I cut the wires giving me two connectors with ample wire for each.
Unlike the RCA connector, you can't accidently short the poles and arc-weld everything in the immediate vicinity. Just pay attention to your polarities since in order for these connectors to "mate", one set of wires/colors will swap positions.
Where did you order your 72V controller? I have a Phoenix motor running at 72V on a trike and it is amazing!
And for all you folks fretting about a good battery mount config... go buy yourself a nice heavy duty rear basket, then tape your two sets of 12V batteries together and with a couple of large hose clamps, mount them to the BOTTOM of the basket. This gets the weight down low and gives you heeps of storage. I also zip tie (or mini hose clamps) the basket to the bike's rear frame members to stiffen it all up. I have three bikes set up this way now and it works perfect.
I moddeed a 36v controller with 4310 fets and 100v caps. But I suggest you not go to 72v unless you have a big heavy motor that can dump the heat. Link got away with it because his is in a smaller wheel therefore less amps but his motor still suffered damage.
Here's my tip for battery mounting of a 48V system: I buy the old fashioned heavy duty wire baskets (rear style) and mount them securely to the back of the bike. Then I use cable ties to stiffen it up by running them between the basket, basket mounting legs, and bike frame wherever possible. Now here's the trick no one has previously mentioned:
I use gorilla tape to secure the two batteries together (X2), then using 6" hose clamps I strap them to the BOTTOM side of the basket. This gets the CG down low and leaves full cargo capacity of the baskets. Then I finish the setup by mounting the controller to the lower outside portion of the right side of the basket. I've duplicated this setup on several bikes and it works awesome. It's very stable and with the low CG doesn't seem heavy at all.
Will running at 48 or 60 v damage the commutator? I going to put 48v lifepo4 on my BD-36
48v will not severely damage the commutator, but brush wear will be faster, and the motor will heat up a bit faster, if that is an issue for you.
OK running at 48V will not severely damage commutator. But it will damage it a little?
heating up motor should not be an issue as I bought this 48v Lifepo4 primarily for my Aotema. I just want to put the 48 v on the BD-36 for occasional use/trial without regrets. I guess commutator wear is inevitable at any voltage with a brushed motor. All you can do is "true" the commutator. Dogman, I spoke to you about Ping and Lipo last week. I just bought 48 v 15ah f/ ebay vendor names olympics2000888. I suspect he is using prismatic cells as the weight and dimensions back it up 8.5 kg & approx 8.5x5.5x5.5 inches. It's hard to communicate with the vendors as their English is broken
etc. The 18650 round cells would weigh more and take more space. I was tempted to buy f/ Ping. He has a newer and even better, lighter version.
Here are some pictures of my bike, alternate throttle, and battery pannier arrangement that go with the earlier discussion.
rhfritz. you have a nice bike there. still looks a bit top heavy to me. anyhow i have just ordered two li ping lifepo4 48v 20ah batts for my trikes. now i want the best controllers and throttles i can find. any suggestions? any thing you have tried? brushed seems to be a thing of the past and i dont want to get something wrong when i order. i like brushed as we are in a hilly enviroment. most of my travel to work is flat but the last 1/2 mile of hill just kills the 36v li-ion. and the fact i am in Alaska is reason enough to get the lifepo4 as they handle the temps. trikes in the winter are so much fun i would advise anyone living in a cold clime to try it. Bob
I don't think the wear on bd36 commutators is very signifigant untill you get to higher than 48v. Link is the one who actually ran one above 48v. I wouldn't sweat it. Link saw little difference with 48v and minor commutator wear at 60v. When the battery comes, if it is a pouch type cell, let us know. Allways good to know who is a good vendor.
Well I can't say he is a good or bad vendor on round or pouched cells because he never answered that question. vendor stated that he was going over to factory to inquire etc.
I'm assuming it can't be round cells based on weight, dim & a higher price than most of the round cell packs. I paid $445 total for all necessaries. The vendor has a 99.5%
approval, but this is based various products. His only negative and neutral were not battery related. The jury will have to wait and see.
The better vendors, like ping and cammycc will answer questions and help if a repair is needed. Of course they do have a day off now and then like we do, so responses aren't always immediate.
It's a little top heavy. The 4 SLA's are split 2 + 2 in the panniers with their bottoms almost even with the rear axle. The trunk bag carries my charger and my lunch bag. The trunk bag also has its own zip-down panniers where I put my jacket, etc. when the afternoon is much warmer than the morning.
With Dogman's e-assistance I finally re-glued my magnets to my rotor last night (more on that in a subsequent post). I hope to start riding again next week. My brushes were fine. But if this repair works, I'll start looking more seriously at a new ping pack.
I have tried 48 v 12 ah SLA on the rear rack for experimental purposes only, and it's hard to turn with batteries high up. You made the right choice. I just got a 48v lifepo4 pack and as I reported on another thread,
the battery pack shuts down on 48 v lifepo. This is the BMS at work, so I can't use it reasonably on my BD-36. I am using it on my Brushless motor ok for.
I did hit 32 mph+ on BD36 with some wind assist. Every time I accelerate the BD36, the pack shuts off. Only way to accelerate is very gradually such that fewer amps are drawn.
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