The 12 volt bike to end all 12 volt bikes

[creativeadapter1990]

I already own an ebike with 25 kg (57 lb) of powersonic lead acid batts and it is perfectly fine except for being slow up hills that being due mostly to a 400 watt motor and a cheap controller. On flats I can make over 20 mph. It corners better than my (since stolen) 4 stroke scooter despite having all batteries behind the seat. I have taken it on public roads riding with cars going spending most of my time at full throttle or close to it and never came close to draining the battery. The 25 amp controller had a tiny heat sink, and it was ice cold even after charging straight up a peak that slowed me down to little more than a walking pace at full throttle.

I admit I might not get 40 mph, and that a high amp motor will be less efficient but I do not expect or need more than 30 miles range.

to make clear my earlier statements

a 1.6 or 2 c rate at full throttle only and perhaps half of that cruising is not that extreme for a lead acid system and will for the same weight of lead acid remain roughly the same for any voltage.

other vehicles already in production and with good reputations push their batteries harder. The Izip pulls 25 amps from a 10 ah lead acid pack, which is at least as bad as pulling 150 to 200 amps from a 100 ah battery.

200 amps will be the PEAK load NOT THE CONTINUOUS load.

the bike build is not meant to be the most practical or efficient system, it is meant to be a (relatively) cheap thrill that gets people talking. The project is more about building a reluctance motor and doing something fun with it than it is meant as an ideal form of transport.

I'm not going to hurt anyone or myself the worst that is likely to happen is I get a heavy, short range bike with too much wh/km.

 

[ZOMGVTEK]

If you're set on it, go ahead and build the bike how you want it. It's not like anyone on here is going to stop you. Most of the time what is said is based off experience. If you don't plan on actually using the bike, lead works fine. In the long run, its an absolute joke compared to lithium. My first bike was about 110Lbs, most of that weight was the 48V 18AH lead battery. It was heavy, hated to put out power, and the capacity was only available if you were willing to draw it stupidly slow. It would go maybe 5-10 miles at WOT (26MPH), or 20 miles at 6-10 MPH. After only a few miles, the battery hated to put out power, and the bike was SLOW. The last 5-10 miles, the bike would hit LVC under WOT, so you needed to baby the throttle. Add in the fact that the battery was dead by the end of the year, and the replacement cost was about $200, its junk.

My LiPo pack costs about $300 without a charger, gets about twice the range, and puts out power at ANY SOC, without regard to how you draw it. I can draw 8kW at 10% SOC and I won't hit LVC, its about 50lbs lighter, and I can charge it in 20 minutes.

If you want the bike to screw around and only go a few miles, lead is OK. Otherwise its absolutely worthless, and EXPENSIVE for how short its life is when used hard.

 

[REdiculous]

No offense, but I totally did this already. My 12v push trailer can handle short bursts to 2kw if my batteries and reduction were up for it. I'm saving for a reduction and lipo.....then a proper controller...and then it'll probably go on a bike instead of a trailer.

lead sucks....you'll figure it out soon enough though. :lol:

 

[SamTexas]

+1 to amberwolfes post, he explained
Best why lead acid has no place on a bicycle...
KiM

That is why most people choose a higher voltage. It usually is better to series the batteries you do have (if you have more than one of the same kind) for that higher voltage, especially for chemistries like LA, simply because of the losses to Peukert if for no other reason. Raising the voltage decreases the current necessary, which lowers the C-rate, which lowers the effect Peukert has on the total capacity, sometimes dramatically.

Not really. Let's take an example: Power requirement = 250W, batteries available = 3 x 12V - 10Ah
1) All 3 batteries paralleled = 12V - 30Ah. At 250W, the total current will be 20.8A. So the current from each battery is 6.9A.
2) Serialized = 36V - 10Ah. At 250W, the current is also 6.9A.
So it does not matter whether the batteries are serialized or paralleled, the current provided by each battery is the same. The Peukert effect is the same in both cases.

Another reason is the wiring: it would have to be extremely large gauge wire to avoid significant resistive loss in the cabling itself (causing further voltage drop in the system, causing even further power losses before reaching the motor, requiring even higher current draw to achieve the same total motor power).

Agreed. There is no reason to use MUCH HEAVIER wire to achieve the same result.

 

[Samd]

get a different motor and 72v lipo

 

[amberwolf]

Not really. Let's take an example: Power requirement = 250W, batteries available = 3 x 12V - 10Ah
1) All 3 batteries paralleled = 12V - 30Ah. At 250W, the total current will be 20.8A. So the current from each battery is 6.9A.
2) Serialized = 36V - 10Ah. At 250W, the current is also 6.9A.
So it does not matter whether the batteries are serialized or paralleled, the current provided by each battery is the same. The Peukert effect is the same in both cases.

This is true, but what I was reading implied using a single 12V battery, rather than the pair he has in parallel (whcih makes a great deal of sense weight-wise), and so using two of them in series for 24V would be better than a single as 12V. I did not mention that paralleling them would also do the same thing, mostly because it has been my experience that the higher voltage systems have a lot more oomph for the same motor.

If making the motor to match the voltage, then it wouldn't matter.

 

[Sunder]

I think it's great that everyone is offering good advice here, but I think we need to bear in mind that everyone is in a different circumstance. Not everyone wants a daily driver (rider?) and not everyone has $1k+ to spend on a set up that's a dozen times better than a $300 set up.

The guy has already made it clear that he has the batteries, and he has the motor spare. Perhaps if his budget was quite sparse, and all he wants is a bike he can motor around on for short bursts at a time for fun, his plan is good?

Anyway, I'd been keen to know the answer to one of his question too - what happens when you unbalance a bike so much by putting 100 pounds of lead on the back?

I've got a project in mind coming soon, which I think many would discourage me from doing in the same way as people are discouraging the OP in this thread. I'm planning on a 200W continuous (Maybe 400W burst?) mini-motor on a carbon fibre road bike. I'm just not quite sure how I'm going to do it yet. I want it to look as close to a normal road bike as possible, and failing that, look as NSW, Australia legal as possible.

 

[ZOMGVTEK]

My first build. The main goal was cheap, which it was reasonably priced. That lead might not look THAT heavy, but that rack was about 70 lbs... It was a wheelie machine. The front end had maybe 2-5 lbs holding it down. Touch the rear rack and the front lifted...

I relocated two of the batteries up front, and it helped drastically. The bike itself was still over 100lbs. It needed to be tipped against trees and strong poles, as it was VERY top heavy.

For how heavy the bike was, it wasn't that bad. The seatpost slowly bent, and eventually snapped, even with only two batteries on the rear rack. As long as you understood the bike was nearly a motorcycle weight, it was fine. Anytime someone new rode the bike, most of them immediately dumped it from the weight. I put over a thousand hard miles on that setup. Almost all of those miles were screwing around, doing stupid stuff, and general abuse.

This was the final iteration of the lead setup before it ended up giving me near zero useable capacity. My power demands went up, and the aging lead just didn't take 60A peak discharges well. The sad part is that 60A is 'only' roughly 3C on a 18AH battery. The voltage sag and peukert effect is basically what made me ditch the lead. I was close to dropping another $150-200 on new lead to last me another year. In the end, I went LiPo for not that much more, and its vastly superior in every way aside from charging.

 

[SamTexas]

This is true, but what I was reading implied using a single 12V battery, rather than the pair he has in parallel (whcih makes a great deal of sense weight-wise), and so using two of them in series for 24V would be better than a single as 12V.

Hmm... Of course 2 batteries is better than 1. But then 4 is better than 2, and 8 is better than 4... Keep this up and he'll end up with a bicycle that weigh a ton!

 

[ZOMGVTEK]

It's always best to carry as much capacity as possible. You reduce the depth of discharge for a given trip, reduce the c-rate of discharge for a given load, often reduce voltage sag, help to negate temperature and peukert effects...

The only real issue is weight, space, and cost.

 

[Hillhater]

- what happens when you unbalance a bike so much by putting 100 pounds of lead on the back? .

.. It makes it a difficult , unstable , heavy , horrible pig to ride..and close to un-rideable when the power dies !
It isn't a big deal to load a couple of bags of sand onto a bike rack for a quick test. Most average people wouldn't be able to even hold the bike up to get on, and probably not be able to pick it up if dropped !!

 

[Sunder]

- what happens when you unbalance a bike so much by putting 100 pounds of lead on the back? .

.. It makes it a difficult , unstable , heavy , horrible pig to ride..and close to un-rideable when the power dies !
It isn't a big deal to load a couple of bags of sand onto a bike rack for a quick test. Most average people wouldn't be able to even hold the bike up to get on, and probably not be able to pick it up if dropped !!

Based on ZOMGVTEk's photos... Wow. I would not like to be riding that thing around. I thought my 35kg bike was heavy...

 

[ZOMGVTEK]

My bike is around 70 lbs with LiPo. It's a very heavy bike, with very heavy slime filled tubes, and quite a bit of steel. It really feels stupid light compared to the bike when it had lead. It holds itself up on a kickstand and everything!

A 100+lb bike is really quite different. It's a little difficult to pick up after it falls, and it was always a concern that it would fall over. It's something you need to learn how to use. All that weight that high up makes it react more like a motorcycle than a bicycle. If you manage to grab a little bit too much throttle going up a hill or something, you jump off the bike and run out of the way to avoid getting hit by it. I did not pedal this bike, ever. It was easier to get off and push. The DD motor, combined with the mass, made it feel like a brick. Riding it was more of an 'experience', and in some ways, more fun. However, I could only get about 3kW out of the thing. 10kW is a lot more fun.

 

[Pure]

- what happens when you unbalance a bike so much by putting 100 pounds of lead on the back? .

.. It makes it a difficult , unstable , heavy , horrible pig to ride..and close to un-rideable when the power dies !
It isn't a big deal to load a couple of bags of sand onto a bike rack for a quick test. Most average people wouldn't be able to even hold the bike up to get on, and probably not be able to pick it up if dropped !!

IMO the best way to haul this kind of battery the OP is looking at building, would be with the use of a small trailer. That way it would make the bike at least manageable.

 

[Sunder]

My bike is around 70 lbs with LiPo. It's a very heavy bike, with very heavy slime filled tubes, and quite a bit of steel. It really feels stupid light compared to the bike when it had lead. It holds itself up on a kickstand and everything!

A 100+lb bike is really quite different. It's a little difficult to pick up after it falls, and it was always a concern that it would fall over. It's something you need to learn how to use. All that weight that high up makes it react more like a motorcycle than a bicycle. If you manage to grab a little bit too much throttle going up a hill or something, you jump off the bike and run out of the way to avoid getting hit by it. I did not pedal this bike, ever. It was easier to get off and push. The DD motor, combined with the mass, made it feel like a brick. Riding it was more of an 'experience', and in some ways, more fun. However, I could only get about 3kW out of the thing. 10kW is a lot more fun.

Yeah, my Bike would be around 70lbs with Lipo as well. It's a 15 year old steel framed mountain bike with a few things added on to it.

My main gripe is that I feel that for short bursts, I can get my human powered road bike to go faster than a 1kw mountain bike + pedaling... I'm pretty sure that shouldn't be the case.

It wouldnt' say my bike handled like my 160kg or so CBR250RR, but it feels closer to that than my 9kg road bike. When the road bike dips one way, a tiny nudge with the knee will bring it back in line. When the mountain bike does that, I need to actually catch it.

Step one is to change my 12S battery pack into a 14S battery pack, but if that doesn't solve a fair few issues, my aim is build a bike on a sub 10kg frame, with 4kg of motor, 4kg of battery, and 1kg of controller, for a sub 20kg road bike with deep v rims, very narrow tyres, and high quality hubs, chains and gears, to let me put a fair bit of my own power in.

I fear I may be derailing the OP's thread, but I guess part of his question is to do with overly heavy bikes, so maybe not.

 

[johnrobholmes]

A reliable electric vehicle just can't have much power on 12 volts. The copper losses for any sort of power go through the roof. I fought with a rich man about this for three months while he built his concept vehicle and paid an "engineer" good money to ignore my suggestions. A year later and $7000 spent on unusable parts (and god knows how much on the idiot of a helper), guess what voltage he used to hit 30mph? 48v, just like I had pushed for in the first place.


Volt up.

 

[dogman dan]

What I was thinking too. Even with fat wire, pulling much watts at 12v is going to be heating a lot of wire. Thats why you need to use such fat wire. Thats why golf carts went from 36v to 48v.

So since it wont cost more to run his two batteries at 24v, DO IT. The 12v motor can hack it. You'll get more speed, and need less fat wire. For a tractor type bike intended for lower speed 24v may not be so bad if it's geared right. I was amazed at the hill ability of my 24v heinsmann motor. Geared right, it really climbed. And had a top speed of 12 mph. At 12v it would have topped out at 6 mph.

Where do you see 12v used in an EV ever? In a kids toy car where the parent wants top speed to be about 3 mph. Perfect for that. No good for a fast e bike.

 

[SamTexas]

A 100+lb bike is really quite different.

Agreed. But that's mainly because of the higher center of gravity. If all the batteries reside inside the triangle it wouldn't be bad at all.

 

[Hillhater]

A 100+lb bike is really quite different.

Agreed. But that's mainly because of the higher center of gravity. If all the batteries reside inside the triangle it wouldn't be bad at all.

i doubt there are many bikes with a triangle big enough for that much lead !
100lbs is like having a 2nd person on the bike who wont pedal !

 

[SamTexas]

I'm quite sure he meant 100lbs total (bike+motor+batteries). Anyway, the taller you are, the bigger the triangle. Here's one:

 

[sk8norcal]

barstool racers are 12V

top speed 58mph


http://endless-sphere.com/forums/viewtopic.php?f=35&t=30746&p=444220&hilit=barstool+racer#p444220

 

[Hillhater]

I'm quite sure he meant 100lbs total (bike+motor+batteries).

The OP stated that he had 2 Group 31 battery's , each weighing 27kg ( 60 lbs )..
... and the proposal was that he should use both of them, preferably in series for 24v

..but the question was..

...what happens when you unbalance a bike so much by putting 100 pounds of lead on the back?

And i still dont believe you can get 100lbs of lead even in that triangle !

 

[SamTexas]

I never said you could fit 100lbs of lead acid battery in that triangle, did I? And I was not talking about the OP either. You could go back and see who I quoted when I made the comment.

 

[Hillhater]

A 100+lb bike is really quite different.

Agreed. But that's mainly because of the higher center of gravity. If all the batteries reside inside the triangle it wouldn't be bad at all.

100lbs + ... note the "+" sam ! ... because the thread was following the question..

...what happens when you unbalance a bike so much by putting 100 pounds of lead on the back?

 

[REdiculous]

A reliable electric vehicle just can't have much power on 12 volts. The copper losses for any sort of power go through the roof. I fought with a rich man about this for three months while he built his concept vehicle and paid an "engineer" good money to ignore my suggestions. A year later and $7000 spent on unusable parts (and god knows how much on the idiot of a helper), guess what voltage he used to hit 30mph? 48v, just like I had pushed for in the first place.

If he couldn't get to 30mph on 12v with $7000 then he was stupid. I've spent *maybe* $500, I've got just 12v 38ah in SLAs to draw from and I can hit 21mph for sure (I bet 25mph is possible but I chickened out). Load me up a couple more SLAs (lol), get me some armor, and I'm sure I'd get 40+.

The trick is not to run a 12v motor. I'm using a high-rpm 130v treadmill motor. My battery is 12v, but the fat cables end at the inverter and from there on I use cords from old power-tools (rated plenty high enough + extra abrasion resistance = peace of mind).

It's a no-brainer....volt up....at some point, at least.