48V 30aH Battery location?

Hi, This is my first attempt at posting on ES so excuse any lack of proper verbiage or if my post is too long. I am in the process of building my first E-bike and am trying to decide on whether the location I have chosen for the battery will work or not. I am basically looking for any input from other members that have built their own E-Bikes already and have some constructive input that could lead me in the right direction. I have pasted a photo below of my current build with a cardboard mock-up of what I was planning for the battery enclosure. The top cardboard enclosure is actually larger than it will be, since I plan on mounting the BMS's to the top of the lower enclosure instead of inside the top enclosure like I had originally planned. I have also attached a image of a sketch-up diagram I have created based on my plan. Also placed a few facts regarding the bike and cells I am using below. I want to know if having the cells above the top frame bar would cause any problems based on center of gravity being too high. I thought this was better than trying to mount half the cells in the triangle and the rest on either side of the rack in the back of the bike which would place a lot of weight towards the back of the bike. In addition the rack on this bike sits fairly far back so most of the cells on the rear rack would be above or behind the the rear wheel. I am building this bike with the hope it will take me 19miles to work and 19miles back home.
Thanks for any input and sorry about the long post.
Bike: Rocky Mountain Reaper I "2011"
Cells: 32 Headway 40152S 3.2V 15aH/ea "Total 48V 30aH"
Motor: Crysalyte 5303 V2 "From Lyen"
Controller: Lyen Extreme ? "Not sure of Model #"
Monitor: Cycle Analyst V2

Why not panniers?

are you planning to use two individual 16s1p packs, and then parallel them together with one bms each?

you're much better off building 1 big 16s2p pack - even if it's physically split into two 8s2p packs

and just use one high power bms

the cells will stay in balance much better, balance charge out much better/easier and it'll be easier to work with too



looking at your photos/diagrams, I'd pack as many cells into the triangle as possible, then if there's any left over mount them above the triangle... as long as they clear the pedals ok ?

you might need to mount the cells 2 wide instead of having them long ways

Hi!

this high COG will cause that

-unstable when driving around corners
-it is less safe to drive, since you are unable to react properly if you try to evade
-your bike will be felt more heavy than it acutally is
-it is likely that your stock sides stand will be useless, since it was not made for such a high COG
-your bike take a lot of damage if it falls over the side stand

IMO there are only drawbacks, i would place the battery in between the downtube and the front wheel. This also leads to more pressure onto the front wheel which is good for driving around corners. If there is not enough space put the rest into the frame triangle but as low as possible.

all the best!

you gonna have to remove your legs and space them 6" wider to pedal that thing with the battery in the way like that.

plus that 48V30A of cylindricals is gonna weigh a ton. do you need that much capacity?

a 48V15Ah might fit inside the frame and just be a little too wide but still a little bowlegged possible.

there are 15Ah cylindricals available. do close packing and align them vertically.

lay out and make a box out of cardboard equivalent to the pack and see if it fits in the frame. if you can only get 13-14S inside the frame then put the last 2S-3S below it or in front of the head tube like oatnet did but he used a pelican box.

Exactly what I was thinking too. Why so much capacity? Planning on a really long ride?

I'd be inclined to make a narrower mount for as many as possible in the frame. Then carry a second 48v 15 ah bundle as a pair of 24v batteries in panniers.

48v30ah isn't that much if you want to go fast

72v10ah lasts me about 7 miles of my normal riding (all power, no pedals, mostly 30mph+)

sabongi said:

Why not panniers?

Click to expand...

I thought about panniers originally, but did not think all the weight in the back was a good idea either so I I thought I would try to mount as many in the center as possible and then decide what to do with the remaining cells. In addition I did not like the look of the panniers and was hoping I could create something a bit more custom, of course if it takes me 3 months to do it maybe the pannier bag ideas would have been the way to go.

Thanks for the reply.

knighty said:

are you planning to use two individual 16s1p packs, and then parallel them together with one bms each?

you're much better off building 1 big 16s2p pack - even if it's physically split into two 8s2p packs

and just use one high power bms

the cells will stay in balance much better, balance charge out much better/easier and it'll be easier to work with too



looking at your photos/diagrams, I'd pack as many cells into the triangle as possible, then if there's any left over mount them above the triangle... as long as they clear the pedals ok ?

you might need to mount the cells 2 wide instead of having them long ways

Click to expand...

I was planning on using two individual 16S1p packs and then wire them in parallel. This can kind of be seen in my drawing as you can see the jumpers on one side of either battery, what you can't see is the other side, but all 16 cells on each pack are wired in series. If what you are saying about the cells staying in balance is true I will definitely change my plan. I have two BMS's I purchased from Headway Headquarters that say they are rated at 50-100A. The question is, would one of these work with a 16s2p pack? I could probably just call Jim at HH back and ask him.
Thanks for the useful information I think I need to rethink this a bit based on yours and other peoples response to this.

Why not take a couple of suggestions and combine them. Build half the pack as flat and mount it on the rear and make the other half triangle shaped and mount it in the frame?

crossbreak said:

Hi!

this high COG will cause that

-unstable when driving around corners
-it is less safe to drive, since you are unable to react properly if you try to evade
-your bike will be felt more heavy than it acutally is
-it is likely that your stock sides stand will be useless, since it was not made for such a high COG
-your bike take a lot of damage if it falls over the side stand

IMO there are only drawbacks, i would place the battery in between the downtube and the front wheel. This also leads to more pressure onto the front wheel which is good for driving around corners. If there is not enough space put the rest into the frame triangle but as low as possible.

all the best!

Click to expand...

Thanks for the information. This is what I was worried about, but without having a way to mounting them there and taking it for a spin I was basically guessing. I checked the space between the down-tube and the front wheel and 16 cells could fit there, but I was concerned that when the shocks would compress the wheel would be getting uncomfortably close to the enclosure around the cells. I think based on your input I am your input alone I am going to try and move the cells that are above the upper frame.
Thank you for the input this will help me in the end to hopefully create a bike I will enjoy riding and won't kill myself on!

dnmun said:

you gonna have to remove your legs and space them 6" wider to pedal that thing with the battery in the way like that.

plus that 48V30A of cylindricals is gonna weigh a ton. do you need that much capacity?

a 48V15Ah might fit inside the frame and just be a little too wide but still a little bowlegged possible.

there are 15Ah cylindricals available. do close packing and align them vertically.

lay out and make a box out of cardboard equivalent to the pack and see if it fits in the frame. if you can only get 13-14S inside the frame then put the last 2S-3S below it or in front of the head tube like oatnet did but he used a pelican box.

Click to expand...

I was also worried about this, but felt with almost 35lbs of cells on this system I don't plan on pedaling a whole lot and with the extra capacity hopefully I won't have to. I am looking at the pedaling as an emergency only option and possibly when I am taking off from a dead stop. I actually purchased 25mm pedal extenders from a company called http://www.kneesaver.net. hoping to avoid some of this problem. Not sure if this will help or just make it worst, but I guess there is one way to find out. I am going to look into changing the orientation based on everyones response to my post. I think you are correct the way I have it now would make for some very uncomfortable pedaling.
Thanks for the fast and informative reply.
Ed

dogman said:

Exactly what I was thinking too. Why so much capacity? Planning on a really long ride?

I'd be inclined to make a narrower mount for as many as possible in the frame. Then carry a second 48v 15 ah bundle as a pair of 24v batteries in panniers.

Click to expand...

I think I may end up doing the pair of 24v batteries in panniers which was sort of an original plan, but I just did not like the idea of panniers. More of a cosmetic thing, but I was also trying to avoid more weight over the back tire and also leave that space in case I actually wanted to carry something back there. I am planning a fairly long ride. I work about 17 miles from home and based on the Mileage from http://www.mapmyride.com it would be a 19.85 mile ride with 938 feet of climb included. The average incline is less than 3%, but this still needs to be considered too. A few months ago this was costing me between $130 to $140 a month in gas not including tires and registration and all that good stuff. So I thought this could be a good way to avoid this. In addition I live in Colorado and 1, there are a lot of hills and 2, the weather out here can change abruptly and I wanted the extra capacity to have the ability to possibly wear a heated vest to extend the days I can comfortably ride. There are over 300 hundred days of sunshine in the Denver area, but many that are not necessarily warm.

Thank you for the reply it is greatly appreciated. I will keep everyone updated as to how I finally end up mounting the cells. I just hope I can get it figured out and completed before the middle of May when the weather really starts getting nice. They are still calling for snow here tomorrow so I guess I have a bit more time.
Best Regards,
Ed

Charge at work, and 48v 15 ah will be enough, if you ride about 25 mph or less.

Save yourself about half your battery costs, and the bike will ride a lot better. This isn't blowing out my ass because I calculated it, I rode home 15 uphill miles every day on my commute for years, and live about 1000 vertical feet from the valley where work was. Never carried more than 48v 15 ah. Range was 22 miles at 25 mph, so your extra two miles won't matter enough to care about except on the coldest days. Worst case of course, is cold diminishes your capacity and then you have to buck a headwind all the way home. Days like that, slow to 20 mph and you will have plenty of range.

You don't need to carry another 15 ah of headways for that though. It's very hard to beat some RC lipo for an emergency reserve tank on days you are likely to need it. Two 6s packs for a 44v 5 ah spare is very easy to carry for emergencies. You might want the RC charger anyway, so you can balance your headway pack quickly at times.

Or, you could build a 5 ah A123 round cell pack, and carry 20 ah instead of 30. Or get ping to make you a 5ah pack, that would work fine provided you paralleled it in with the headways. I could go on and on and on about options that beat the hell out of carrying 30 ah for commuting. If you plan on riding around the mountains touring, that's another story, and the best option would likely be using a trailer or longtail to carry even more.

But carrying 30 ah just for daily commuting is just going to suck. You will feel every pound past 15 pounds of battery like it's 5 pounds instead of just one. Past 20 pounds, your bike frame will start bending like a wet noodle unless it's a very very good frame.

I was looking at my front forks, thinking about panniers of sorts. Something like a small pod on each side to hold a stick each. A 2x2x11" square section alloy tube can hold a couple of 5Ah 4s hard-packs. Nice and low, and very forward. Using round cells would have aero benefits. The steering shouldn't suffer much, as the weight would be very close to the axis it all turns about.

Certainly some space elsewhere, but I thought I would add this to the mix

Edited because I couldn't add up lol

dogman said:

Charge at work, and 48v 15 ah will be enough, if you ride about 25 mph or less.

Save yourself about half your battery costs, and the bike will ride a lot better. This isn't blowing out my ass because I calculated it, I rode home 15 uphill miles every day on my commute for years, and live about 1000 vertical feet from the valley where work was. Never carried more than 48v 15 ah. Range was 22 miles at 25 mph, so your extra two miles won't matter enough to care about except on the coldest days. Worst case of course, is cold diminishes your capacity and then you have to buck a headwind all the way home. Days like that, slow to 20 mph and you will have plenty of range.

You don't need to carry another 15 ah of headways for that though. It's very hard to beat some RC lipo for an emergency reserve tank on days you are likely to need it. Two 6s packs for a 44v 5 ah spare is very easy to carry for emergencies. You might want the RC charger anyway, so you can balance your headway pack quickly at times.

Or, you could build a 5 ah A123 round cell pack, and carry 20 ah instead of 30. Or get ping to make you a 5ah pack, that would work fine provided you paralleled it in with the headways. I could go on and on and on about options that beat the hell out of carrying 30 ah for commuting. If you plan on riding around the mountains touring, that's another story, and the best option would likely be using a trailer or longtail to carry even more.

But carrying 30 ah just for daily commuting is just going to suck. You will feel every pound past 15 pounds of battery like it's 5 pounds instead of just one. Past 20 pounds, your bike frame will start bending like a wet noodle unless it's a very very good frame.

Click to expand...

Hi Dogman,
Probably should have posted here before I purchased the cells, but I have already received my cells just under a month ago. I guess I could build a second bike with the extra cells for my wife or kids, but I like a good challenge and I think if I could get the extra cells mounted, "and not too high" it would give me some piece of mind. Additionally in my original planning I was thinking if I could make it one way with enough capacity remaining I may only need to charge it at work and not at home. I have had no time to work on it over the last two weeks, but should have sometime this coming week. I will try one more time with different positioning to see if I can some how get the majority of the cells low and centered if not maybe I will go with your idea of a smaller secondary pack.

I greatly appreciate the ideas and the fast responses. I will repost once I determine how I plan to build and position the pack.
Best Regards,
Ed

I don't think you can have too many batteries

I've killed 72v10ah on a 5mile ride into work before (wot @2.5kw 90% of the time)

72v10ah = same kwh as 48v20ah

Yes, I too have drained an 800wh pack in a very short ride. Definitely doable, and fun enough to repeat. But lugging 30 ah just to avoid a fairly easy to do charge, just makes zero sense. No problem if the bike is designed to lug a load. Do it on a trike, cargo bike, etc, no problem. It just won't be worth it to lug all that on a normal bike frame.

Dig up an old thread by Oatnet. He did a very nice fork mounted battery box for one of his bikes. I don't recall if it was headways, but he's done a lot with the headway cells. Good ideas to imitate on all of Oatnets build threads.

Mount 15 ah more or less permanent on the bike, in the frame, on the forks etc. Make it as narrow as you can, so dump the idea of loading the cells crosswise. 5-6inches wide can be pedaled around comfy enough. 7-8 inches is too wide unless you give up pedaling. ( I have at least one bike like that)

Then make the remaining 15 ah into a split pack to be carried in panniers when you need it. You'll see what I mean instantly, as soon as you compare riding the bike with 15 ah, vs riding with 30. Use the larger size pack for long adventure rides on the weekends. Or even power a second bike later with it.

dogman said:

Yes, I too have drained an 800wh pack in a very short ride. Definitely doable, and fun enough to repeat. But lugging 30 ah just to avoid a fairly easy to do charge, just makes zero sense. No problem if the bike is designed to lug a load. Do it on a trike, cargo bike, etc, no problem. It just won't be worth it to lug all that on a normal bike frame.

Dig up an old thread by Oatnet. He did a very nice fork mounted battery box for one of his bikes. I don't recall if it was headways, but he's done a lot with the headway cells. Good ideas to imitate on all of Oatnets build threads.

Mount 15 ah more or less permanent on the bike, in the frame, on the forks etc. Make it as narrow as you can, so dump the idea of loading the cells crosswise. 5-6inches wide can be pedaled around comfy enough. 7-8 inches is too wide unless you give up pedaling. ( I have at least one bike like that)

Then make the remaining 15 ah into a split pack to be carried in panniers when you need it. You'll see what I mean instantly, as soon as you compare riding the bike with 15 ah, vs riding with 30. Use the larger size pack for long adventure rides on the weekends. Or even power a second bike later with it.

Click to expand...

Hi Dogman,

I installed my pedal extenders tonight and then brought the bike outside to take for a spin, "non electric" with the cardboard enclosure in the triangle only. If I am sitting there is no problem, but if I stand you are correct it is not very comfortable and the inside of my legs hit the enclosure unless I place my feet in an odd position. The one good part was the gearing is plenty low enough so even sitting I had no problem going up my driveway which is a pretty steep incline. I am building this bike so I don't have to pedal, and only want the ability to pedal if something majorly malfunctions and when taking off from dead stops. As long as I am sitting this should not be a problem, not ideal, but I think it could work. I tried turning the pack so it was vertical, but the problem is the triangle on this bike is too small to fit all 16 cells that way so I would need to turn the last 4 closer to the front of the bike horizontal. This would make building an enclosure and wiring of the cells more difficult. I don't have any space on my forks to place a pelican case like Oatnets did, but that was a pretty clean build he did. Thanks for bringing it to my attention. I think I may have just picked the wrong frame to do this build on, but am stuck with it now and need to make it work. I am thinking now about going the Panniers route like some others and you had mentioned for the additional 16 cells and sticking with the horizontal enclosure in the triangle like you strongly recommended against. I tried a couple other possibilities but none of them seemed feasible especially since now I have installed a front fender and that completely takes away any possibility of mounting the cells under the front down tube. Even without the fender it was tight, but now it is impossible. I attached some photos of the fender installation and the pedal extenders in case anyone is interested.

Yes, building to not pedal makes a huge difference. You can pedal quite bowlegged if you are not going to use them often.

I was definitely thinking in terms of at least faux pedaling the 15 miles. That's because for me, my ass goes numb and gets very uncomfortable on a bike seat after 4-5 miles if I don't pedal. So I was just assuming you intended to at least spin, or pedal at an easy 70w effort.

On the bike I don't pedal, it's dirt riding. This means I typically stand for as much as 80% of the ride, riding "trials style". That bikes battery box is 7" wide, and can be pedaled around. It's set forward, so when I stand over the bike, my legs clear it completely. Pedaling, I just need my knees to clear it. No need for pedal extenders.

Do look at everything you will do. At stop lights, you will have to stand straddling the bike, so make sure you have crotch clearance, and won't rub holes in your pants with sharp box edges. If possible make yourself a narrower box for the portion directly above the pedals. This issue of being able to straddle the bike is the main reason I don't like the second box on top of the top bar. You can put something there closer to the bars, but not near the seat.

Trailer?
otherDoc

Trailer works good for many. One thing I like about my frankenbike longtail is it can easily carry 50 pounds. My other commuter bike can also pack 50 pounds, but not easily. It starts to handle worse at about 20 pounds, and no more than about 30 pounds is the max that is very comfortable.

Well this is what I am now contemplating after looking at many possibilities. I am really worried if I place the battery in the triangle completely horizontal that I will have the problems that Dogman pointed out and it will end up being a very uncomfortable 20 mile trip to work. This current revision would leave more room for my legs, but I still worry I may be hitting my knees on the part of the enclosure that is wider toward the front. This frame is just too damn small for this many cells, but I am still determined to make it work. I may build another cardboard enclosure based on this design and again pedal it around to see how everything fits and whether my knees are hitting anything. May is almost here and I want to start riding!!!! :x

instead of having the cells side by side, put them out in a line two wide (with the joiner plates on the ends)

instead of putting screws in the end of each cell, you can use small bits of stud, so you can screw one battery straight into the next one

so you make them into long lengths

run them parallel to the top bar of your frame, just under it

see how many you can fit in a line... then put another line underneath... might need to be a bit shorter here, you'll have to use some wire to join between the cells here... then keep working your way down like that


if you have room for 3 wide, you can run another line along side the first line (but on it's side) or however fits best for you

knighty said:

instead of having the cells side by side, put them out in a line two wide (with the joiner plates on the ends)

instead of putting screws in the end of each cell, you can use small bits of stud, so you can screw one battery straight into the next one

so you make them into long lengths

run them parallel to the top bar of your frame, just under it

see how many you can fit in a line... then put another line underneath... might need to be a bit shorter here, you'll have to use some wire to join between the cells here... then keep working your way down like that


if you have room for 3 wide, you can run another line along side the first line (but on it's side) or however fits best for you

Click to expand...

Hi Knighty,

I did not consider your idea, but I have seen cells attached like this. It does seem like it would be more difficult to wire a BMS with that type of setup but it would definitely be a more efficient use of the triangle space. I only had enough time at lunch to put one possible configuration together, but I think some of the cells would extremely difficult to wire this way and would come dangerously close to the bicycle frame. I am thinking of possibly moving the lowest ones to the left and right and try this 3 wide which I think would still be more narrow than the cell mounted horizontally. The only thin I don't like about this setup, it would make it difficult to service especially if it is 3 wide, but if it fits this may be the way to go. I will need to look at it again later this evening, but thanks for the idea.

Regards,
Ed