Anyone use SLA's still? Need distance and speed.

[iwasbeingsarcastic]

I am currently running a 36 v BL-36 Hub motor by wilderness energy. I have all the original parts, and had them for 9 months with a total of about 1200 miles, My daily commute is only 10 miles, then I slap it on the charger for the next days use.

I have recently rigged an attachment to add an 18v Lithium cordless tool battery to run in my 36v series for more speed. I really only use the extra speed for a busier road where I can keep up with traffic (30 mph+). The 3 ah battery lasts a short 2.4 miles at 30 mph, then i disconnect it and run on the 36v SLA series.

What I would like to do, and would like advice on is this: I would like to have a total of 8 - 12v/12ah SLA's running two 48v packs parallel, for a total of 48v/24ah. it would be a total of 64 lbs, i believe. Has anyone done something like this? I am happy with what I have, but sometimes I need that extra speed, and I need the distance in case I need to run an errand on a work day that my be off route. I ussual save my errands for my days off because My bike wont handle the distance without a 4 hour charge. I can get 12 miles off of my current setup with little pedaling. Would I get at least 20 miles out of a 48v/24ah pack. I know the extra weight will shed some miles off, but could I run it at the top speed and get 20 miles? I run my current setup at the highest speed as much as I can (22 mph isn't very fast to me). I am just assuming if I have 36 volts at 12ah, going 12 miles at full speed (22mph), couldn't I get 12 miles out of 48 volts/12ah going full speed (30mph)?

I want to stay cheap that is why I want to use SLA's until I am confident with the setup, speed, distance, usability, etc. Then I will upgrade to a similar volt/amp hour lithium pack.

Thank you in advanced.

 

[GTA1]

My factory Schwinn e Bike with 2 factory cheapie 12V-12 batteries give me 24v, 12ah and it is getting me roughly 16km range (down 75% with 25% in reserve).

Roughly, if you double the battery capacity, you will get twice the range less a minor speed / acceleration penalty in the relevant range (65lbs total).

If you get slightly better grade SLAs, like specific motive power / deep cycle batteries, or AGM deep cycle, you do much better.

However, if you use starting batteries, you get much better acceleration / high current, and much worse life / durability.

Think of 65lbs this way.

If you weigh 180lbs, +65lbs still put you in the acceptable weight class for a bike.

If you weigh 120lbs, +65lbs gets you to mid weight for an adult bike.

 

[TylerDurden]

...if I have 36 volts at 12ah, going 12 miles at full speed (22mph), couldn't I get 12 miles out of 48 volts/12ah going full speed (30mph)?

It takes roughly 2x the power to go 30mph as 20mph, due to drag.

Considering 12ah cells:

36V = 432Wh * 2 = 864Wh

48V = 576Wh

At 30 mph, you will only get about 8mi, unless you get more capacity.

 

[TylerDurden]

PS:

300W @ 36V = 8.3A
650W @ 48V = 13.5A

So, you will have more Peukert effect (sag) losses... figure about 5mi @ 30mph.

 

[GTA1]

Lead acid cells have different capacities depending on the rate of discharge.

The best capacity (power output) is from slow discharges, at close to maximum discharge rate... very different curve.

 

[vanilla ice]

I would like to have a total of 8 - 12v/12ah SLA's running two 48v packs parallel.

Other than weight, theres no reason why that won't work. I've run 54v of sla before. What kind of bike is this? Hopefully its a heavy duty one with lots of cargo space.. I'm thinking xtracycle, mebbe a trailer setup or a tandem frame single seater.

 

[dogman dan]

The best practical option for you now is to run 4 12 ah sla's for a 48v bike. You just need one more sla, and a 48v charger. Adding more sla's, like 8 of em, just ends up getting heavy enough to slow you back down again. Lots of other options are out there, but cost $$$$. Much above 48v , your controller is taking a big risk, it was designed for 36v after all, but can be run at 48v. So running 5 12v batteries is really not so great unless you get a different controller. For your length of ride, a 72v headway pack would be just right once you are ready to pay out the money.

Bear in mind also that along with being an illegal vehicle, when you go to a 72v bike, you will need the best of everything, helmet, brakes, frame, etc, and only idiots run that high a voltage on a front hub. Mo money.

 

[dogman dan]

Another thing that works well, is paralelling some nicads with sla's. But when I was doing it, it was just two sla's and a 24v nicad pack, so only about 30 pounds total. It pretty much eliminated noticable voltage sag on the slas though. But two 48v packs, uggh , just too heavy.

 

[vanilla ice]

I'm with dogman. Raise your voltage 1p and ride it at your old speed, not pinned.. just pin it for the short stretch where you need the speed.

I'm more positive about SLA than your average ES'er.. but dude, 8 12ah packs is too much for a standard bike. Well you *could* setup 8 packs good on a utility cargo-type setup..

 

[torker]

These guys are right on. Much over 20 mph and wind resistance will play a big role. I know on my 36v setup a headwind seems to slow me down alot more than a small hill. If you can live with the speed you could try maybe 17 ah sla. Four of those would still be heavy but better than 8 12ah batts.

 

[dumbass]

I am currently running a 36 v BL-36 Hub motor by wilderness energy. I have all the original parts, and had them for 9 months with a total of about 1200 miles, My daily commute is only 10 miles, then I slap it on the charger for the next days use.

I have recently rigged an attachment to add an 18v Lithium cordless tool battery to run in my 36v series for more speed. I really only use the extra speed for a busier road where I can keep up with traffic (30 mph+). The 3 ah battery lasts a short 2.4 miles at 30 mph, then i disconnect it and run on the 36v SLA series.

very fast to me). I am just assuming if I have 36 volts at 12ah, going 12 miles at full speed (22mph), couldn't I get 12 miles out of 48 volts/12ah going full speed (30mph)?

I want to stay cheap that is why I want to use SLA's until I am confident with the setup, speed, distance, usability, etc. Then I will upgrade to a similar volt/amp hour lithium pack.

Thank you in advanced.

Basiclly I started out and still run exactly this way. I have a Cyclone 360w 24v motor with a Nuvinci hub drive. The batteries are 2 pack eack containing 2 -12v 18ah batteries (4 in total). This gives me 24v 36ah. However, at 8 to 9 ah I typically start getting the yellow light on my speed controler indicating my voltage is getting low. I have run them about 20 miles on maybe 10 to 12 ah. The total weight of both packs were52 pounds. Add an additional 6.5 lbs for the Nuvinci hub and and there's quite a load. Not to mention 40 lbs for the bike and 230 lbs for my fat ass.

This week I am testing a Thunder Sky 24v 20ah pack. I was intending to buy 2 but wanted to start slow and do some testing with just one. So far the one 20 ah Lipo4 pack is putting the SLA pack to shame. They give more speed and range with 13 lmb vs 52 pounds of the SLA. I am still working out the charging issues but I am very happy.

By the way I charged up to 3 24v 18ah packs (6 batteries in total) with 1 12v lead acid charger. My pack consist of 2 batteries in a bag. And each battery is actually wired independently to the outside of the pack. Each cabble exiting the pack is 12v. Therefore, I can plug in a standard 12v charger. Or by using a "gang" cupler I can charge as many batteries as I like. As I said I normally do 4 to 6 batteries at a time. When I did the wiring on the bike I did it in a way to create the required 24v need for the motor. I installed a twin connector so I can do the same thing to both batteries at the same time. Or I can plug in just one pack at at time. But in all cases I always have 12v for charging and 24v for running.

NOw that I have the Lipo4 pack I still do exactly the same thing. In fact I am actually doing a test today using the same 12v lead acid charger to charge the LIpo4 pack. So far so good. I am not using a BMS ether. If you are happy with the idea of riding the bike for what ever you use it for then save your money and dump the SLA batteries before you spend anymore money on them. You can go futher, faster and cheaper in the long run with lipo4 batteries. Trust me I wish I had done in in the beginning.

 

[GTA1]

The issue is not so much weight as much as overall balance, both static and dynamic, and suspension.

If you are hanging 70lbs of batteries on a bike without front and rear suspension, you are asking for trouble.

Need good front forks, rear suspension (not the cheap look good shock that basically is nothing...but an industrial grade damper with a high quality spring with a good progressive rate - like what you would find on a top of the line off road 125cc bike.

Striction (frictional resistance of the shocks) is a big issue when you get to a bike.

Then, the batteries need to be placed at the center of the bike and reasonably low to the ground to lower the frame center of gravity. Batteries cannot move around like the human body in response to dynamic forces, so it must be in a place that gives good all round balance.

The scooters that have the batteries in a case between the front and rear wheels has the right idea, but that makes for a pretty hard to pedal bike.... unless you are a wide stance guy like Larry Craig.

The idea is to replicate that in a conventional frame --- i.e. a custom case to put batteries between the frame and low is what I would do.

Weight transfers forward as you stop....

If the battery is high (as if on a rack on top of the rear wheel, you have the additional problem of gravity dragging it down.

That is both a problem when you park your bike (it tends to fall and break things)... and not optimal in terms of dynamic stability.

The second choice to center mounting the batteries would be to mount it low on the frame behind where it interferes with the crankset and pedaling.

However, the problem is, how to mount the batteries low (close to ground), and still have it in a sprung (not unsprung) structure.

The issue of shock, vibration really becomes a big deal as speeds pick up --- 40kph is about the maximum for a bike that is sprung with $3 forks in the front and unsprung rear wheels.

50kph (30mph) without a good suspension is getting interesting --- unless you are on a bicycle racing track.

45mph (70kph) without suspension is positively asking for trouble.

 

[dumbass]

I am currently running a 36 v BL-36 Hub motor by wilderness energy. I have all the original parts, and had them for 9 months with a total of about 1200 miles, My daily commute is only 10 miles, then I slap it on the charger for the next days use.

I want to stay cheap that is why I want to use SLA's until I am confident with the setup, speed, distance, usability, etc. Then I will upgrade to a similar volt/amp hour lithium pack.

Thank you in advanced.

Here's a pic of my bike with 4 SLA 12v 18ah batteries. Remember this setup can be used as a 24v 36ah or a 48v 18ah. The bike weight is 40lbs, batteries 52 lbs, Cyclone motor 6.5 lbs, battery mounting mayby 1.5 lbs and my fat ass 230 lbs..Total 330 lbs and I rode it about 300 miles last year this way. This year I replaced the mountain tire with some low resistance tires and a Nuvinci hum. While the tires are lighter the Nuvinci is 6.5 lbs hevier and I am not trying lipo4 battery pack. Boottom line this year is still around 295 lbs.

Believe it or not the balance is not a problem. But the weight is a pain to pick up to put on the bike carrier on the car. Of course the batteries are remover.

 

[iwasbeingsarcastic]

PS:

300W @ 36V = 8.3A
650W @ 48V = 13.5A

So, you will have more Peukert effect (sag) losses... figure about 5mi @ 30mph.

I have added an additional 18v 3ah battery to my 36v setup and got 2.4 miles out of it going 30mph. How would you figure only getting 5 miles if I add an additional 5 12v/12ah SLAs? I know the drag from the weight is going to take some miles off, however, the power of my 3 batteries is enough to move their own weight. So theoretically each additional battery should have enough energy, in itself, to more than compensate the energy required to move it.

About the weight/mounting issues. Like dumbass' photo, I will have a similar mount, in addition to 4 or 6 being startled around the rear wheel. I will make my mounting system custom, with the addition of shocks, so the majority of the weight will be free to move up down, and side to side without much problem. I already had issues with my 3 sla batts bumping around. I feel I have the mounting already solved I just want to make sure I can get the range I want, and the short bursts of speed.

Also what would be the best solution for charging? Two 48v chargers? Could I charge both 48v packs with one charger at the same time (just taking twice the amount of time)? What are my other options on charging? I charge overnight so as long as it is not more than an 8 - 10 hour charge I don't care?

Thanks for all your answers.

 

[gerhardt]

I disagree with Dogman's comment that only idiots use a 72 volt front hub. I use a 72 volt two speed front hub in a 20 inch wheel on my Delta Safety E-Trike. I can safely keep up with traffic at 35 mph and carry 100 lbs of groceries. I use a Redline heavy duty BMX fork. The trike has a roll bar, side impact bars and a 4 point racing harness. I am testing the trike with various batteries including (6) 12 ahr lead acid batteries. I keep the center of gravity low. The bottom of the batteries is six inches above the ground. Operating hub motors at higher voltages increases their versatility. I have used a Wilderness Energy motor at 48 volts, however the 72 volt two speed hub motor is better.
Don Gerhardt

 

[swbluto]

I belive Dogman was thinking of a bike, as the original poster possessed, not a trike.

 

[TylerDurden]

I have added an additional 18v 3ah battery to my 36v setup and got 2.4 miles out of it going 30mph. How would you figure only getting 5 miles if I add an additional 5 12v/12ah SLAs?

First: Adding a 18V lithium is more like adding a 24V SLA, when you're drawing 13A... since the voltage drop on SLA is significant under load.

Second: I answered the question in your first post:

couldn't I get 12 miles out of 48 volts/12ah going full speed (30mph)?

Okay, now... you might want to know about SLA 48V/24Ah @ 30mph?...

• Energy required >650W @ 30mph
  Typical system efficiency at moderate load <70%, so figure you need another 200W... call it 850W draw from the pack... at about 18A
  SLA ratings are typically based on .05C (20hr) discharge rate. Pack has 24ah and the draw is at least 18A, or .75C (25x the rating discharge), so the capacity of the pack will be significantly less than the specs.
  The SLA voltage sag will require compensation to maintain speed, so add more current-draw which consumes the total capacity faster.
  At 1C loading, the pack voltage might be ~43V, dropping to ~36V at LVC, in >30min.

I rekon it might go ten miles @ 30mph a few times. After that, it will need to go slower to make it that far. It might last 100 cycles, since the pack will go 100% DOD each time.

 

[iwasbeingsarcastic]

Assuming you had the know-how and materials. Anyone ever consider removing the hub motor from the wheel, adding a sprocket, mounting it in the middle of the frame, and tapping it in to your chain drive (with a freewheel modification of course). I just thought of it, took measurements, and planned it out, I think it will work, but is there a reason I shouldn't? It's quiet, powerful, eliminates drag if I want to pedal, and I wouldn't have to buy a cyclone, or similar kit. I am going to do some math to figure rpm's and speed, and I may not need more rpm/volts form the batteries, just a few gear changes, maybe?

"There are many things that we can point to that proof that the human being is not smart. The helmet is my personal favorite. The fact that we had to invent the helmet. Now why did we invent the helmet? Well, because we were participating in many activities that were cracking our heads. We looked at the situation. We chose not to avoid these activities, but to just make little plastic hats so that we can continue our head-cracking lifestyles.

The only thing dumber than the helmet is the helmet law, the point of which is to protect a brain that is functioning so poorly, it's not even trying to stop the cracking of the head that it's in..." - Jerry Seinfeld

 

[GTA1]

Now why did we invent the helmet? Well, because we were participating in many activities that were cracking our heads. We looked at the situation. We chose not to avoid these activities, but to just make little plastic hats so that we can continue our head-cracking lifestyles.

For a little trouble, you can surgically relocate your brain to a better protected place, like the lower abdomen.

The cranium case can be retained to build a much harder casing, and perhaps some secondary neural functions can be maintained in the former location, kind of like an "auxiliary control".

 

[TylerDurden]

Anyone ever consider removing the hub motor from the wheel, adding a sprocket, mounting it in the middle of the frame, and tapping it in to your chain drive (with a freewheel modification of course).

Google "stokemonkey"... they do it.

 

[vanilla ice]

I've thought about it, be neato with a 5speed freewheel and derailer. Would be alot of shifting between that and the gears for your legs, but you could always keep the motor in its happy range.

 

[gerhardt]

I attached a photo of my electric recumbent bike with a 72 volt two speed hub motor in the front wheel. The bike has six 7ahr lead acid batteries. I recommend a recumbent bike or a safety trike with high quality components if you are going over 20 mph. The bike has a Maxxis Hookworm 20x1.95" tire in the front and a Maxxis Hookworm 26x2.50 downhill tire in the rear.
Don Gerhardt

 

[iwasbeingsarcastic]

I've thought about it, be neato with a 5speed freewheel and derailer. Would be alot of shifting between that and the gears for your legs, but you could always keep the motor in its happy range.

If you think about it, using the hub motor to power the chain would be the same load on the motor if the gearing was made to match the rpm of the wheel with the rpm of the motor. So I wouldn't have to shift if I left it in a 1:1 gear config. However if I wanted more speed/more power, I could adjust it. And the shifting would be less of a pain than just using pedal power. I shift constantly when I pedal to get the most effecient work load from my legs. After nine months I am pretty in tune with the capabilities of my motor, so I could safley assume I would know when to ease up on my throttle or change gears.

 

[dumbass]

I've thought about it, be neato with a 5speed freewheel and derailer. Would be alot of shifting between that and the gears for your legs, but you could always keep the motor in its happy range.

If you think about it, using the hub motor to power the chain would be the same load on the motor if the gearing was made to match the rpm of the wheel with the rpm of the motor. So I wouldn't have to shift if I left it in a 1:1 gear config. However if I wanted more speed/more power, I could adjust it. And the shifting would be less of a pain than just using pedal power. I shift constantly when I pedal to get the most effecient work load from my legs. After nine months I am pretty in tune with the capabilities of my motor, so I could safley assume I would know when to ease up on my throttle or change gears.

Of course this would work. But unless you already own the motor why would you go though all this work when you can buy a system already design for this? I use the Cyclone motor system and they come in several motor horse powers to choose from. And the kit include everthing you need including mounting brackets and freewheel.

 

[iwasbeingsarcastic]

Of course this would work. But unless you already own the motor why would you go though all this work when you can buy a system already design for this? I use the Cyclone motor system and they come in several motor horse powers to choose from. And the kit include everthing you need including mounting brackets and freewheel.

I am comfortable enough to design and build a mounting bracket for my hub motor, and I like building things. This will be another thing to pass the time with, right now I just got done making a small copper tube with a salt water solution sealed inside. I am using it as a reusable "ice cube" to chill my occasional glass of whiskey. Anyways, I have done some testing and some math. My hub rotates at around 300 rpm (22 mph). I think all I will have to do is add a 32 tooth gear to the left side of the crank, a free wheel crank (saving the need to pedal with the motor), and a freewheel that I would mount to the hub motor (to negate the friction of the motor when I pedal). I have come to figure, if I have the 11 tooth driving the 32 tooth (2.9:1 ratio) on the left side of the crank, that will rotate my 42 tooth on the right (1:1.3), from there I have a 7 speed cassette 28 on the big one and 13 on the little one. My motor rotates at 300 rpm @ 36v, today I tested 48v and I got up to 30 mph, that is 400 rpm. With the gear ratios, I can accomplish 20 mph - 43 mph (with the throttle pinned) by adjusting the rear gears. I will have to figure a slightly different gear ratio to tone the speed down a little, I doubt it will get up to 40, maybe down hill. Whatever I do, with the motor powering a left side crank gear, that leaves me with the front 3 gears and de-railer, so I will have a very wide range of power and speed. I do want the quietness of this motor and the power of it, plus the durability of it, I took it apart once, there is nothing but magnets and some heavy duty copper wiring, and no hall sensors, so I dont have to worry about it breaking on me.

I am going to start this project when I have a couple days off, if it doesn't work, I will have plenty of time to think about how to fix my mistakes while I am putting all the spokes back on and adjusting them. I really hope it will work.

By the way I have a cheap $200 Schwinn Mtn bike.