Gas Tank style battery thoughts

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Dec 1, 2015
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Me Tarzan, Eugene
Most of my bikes are suspension designs with shocks that get in the way for mounting a triangle pack.
I've been looking for one and I guess now planning to build in the absence of anything similar.
The dolphin packs are cute, but awkward and low amp...so my thought is a gas tank that straddles the top tube.
My initial idea is to use 1.5" and 4" pvc pipe...made into a double walled tube.
Then the side cut out so it fits around the top tube in a long upside down U shape.
Guesses many cells I could fit in there?...say 20" long...to get up to a 52v20a pack?
Maybe I would need a second one on the down tube...but it would still protrude lass than other designs.
i like the idea of keeping things tubular to preserve the bicycle shape.
Anyone seen or thought of anything similar?
Someone should make these...would mount to more frames easier.

Equally...I havn't been able to find a good source for a top tube pannier...pleanty for back racks though.
 
Whatever few pounds an empty tank weighs, add 6 pounds a gallon for gas. How much are the batteries you'll put in place of that gonna weigh? That's my first thought. I remember someone responded to my warning about 'Build a cheap one first' with his tale of woe at an expensive motorcycle build that handled miserably. Without seeing that bike, I wonder just where the batteries were situated.
 
Have you looked at either of these threads?

https://endless-sphere.com/forums/viewtopic.php?f=6&t=235

https://endless-sphere.com/forums/viewtopic.php?f=3&t=12847

There are a lot of different ways of mounting stuff in those two threads. ;)
 
For full suspension bikes, some type of home made boxes that straddle the top tube is a common solution for carrying RC lipo packs.

Just don't tape em to the bike, then go and crash dinging up the packs. Some attach to the bottom tube, but I have always been fearful that a big bump, or jump would make the front tire contact the battery housing.

I have found that though it definitely affects the handling, if you can have a rear rack mounted battery weigh less than 8 pounds, it can be tolerated even for pretty hard off road riding. But it would not do for any kind of competitive, or high performance riding. Just the kind of riding I do. I ride hard, but I'm not 25 no more.
 
Have you seen the thread on Additive Bike bag?

2586759_orig.jpg
 
Any decent sized battery pack is going to be a significant part of the total weight of the bicycle and putting it up high in the frame is exactly the WRONG place. The early motorcycle makers that are being copied had a heavy iron engine mounted as low as possible in the frame to lower the CG to a reasonable level. The board track racers that seem to be so popular to copy as eBikes had an even lower CG given that their fuel tanks were very small capacity.

Better to build a fake engine for a battery box, add some fins for "cooling" and save the gas tank area for personal storage of gloves and sunglasses.
 
Well, yeah,,, if your frame has room for the battery in the middle, put it there. But when it does not, attaching it to the side of the frame is the place. FWIW, 80% of many motorcycles tank capacity is below the top bar, and soon as you ride a bit, all of the weight is below the bar.

Here's how I did the battery carry on a cheap Y frame. Most of the weight is centered, and I would have mounted it lower except my feet would hit the box pedaling if I did.
 
Thoughts? What is commonly the gas tank area on a motorcycle is not the appropriate place for a battery. It is too high and impacts stability when parked, and when riding having the weight there makes the bike feel heavier. Forget gasser designs and come up with something sleek cool and different.
 
Awesome responses everyone, thank you for the links.
That Additive bag is sick, really close to what I want!
I understand the weight will be high on the bike...but with suspension bikes the options are limited.
For most riding I plan to use a 12lb 52v20a battery from Luna in my backpack...but want to make something for long exploration days to double my range.
My fiancé is good with a sewing machine, we'll try some designs and see what we can share...untill I can make what i really want.
 
Hey mate, as u saw on my bike I run 10ah 76v up on the top bar as well. I take these off for shorter trips and use the same size pack down low. What I can say is the bike is totally different to ride when the battery pack is down low, but still very usable up top.
 
This is my frame I bought off of E bay for $200 two yrs ago you can find these still every now and then there was a whole bike for $700 just a few weeks ago its a 2000 intense tracer it has worked out perfectly a 12.5 ah battery rides low and snug making a great handling trail bike with a low power geared BMC hub motor it is a pleasure to ride on tight twisty MT bike trails . I am now trying to put a 24 in rear wheel and a set of Boxxer forks on it for this summer . Have a look give me your thoughts on this frame I know Chaol would deem it unridable
 

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Much depends on the frame of course, and you may be stuck with using a frame that is not ideal, such as the y frames I have. Somehow, my budget is always blown on more batteries, rather than new DH frames. Or, having learned to weld, I make my own no suspension frames for street.

But assuming you just want to ride now and don't have any space in the frame, then the best thing you can do is mount the battery more on the sides of the top tube, than on top of the top tube. Get them as low as you can, without actually snagging your foot on them pedaling. In that old pic of my dirt bike, I got about 75% of the weight below the top tube. This is low enough to handle ok in the dirt. Bear in mind, on FS dirt bikes, that top tube is not so high anyway. Not like a cruiser top tube.
 
Leebolectric said:
Guesses many cells I could fit in there?...say 20" long...to get up to a 52v20a pack?
Maybe I would need a second one on the down tube...but it would still protrude lass than other designs.

+1 for the Additive bag. I really like mine. It does not get in the way of the dual crown forks and mounts quickly and very securely to the bike with only three straps and an adjustable velcro strap that only has to be tweaked the first time you fit it. It is very thick and well built. When I got caught in a heavy downpour it did not appear to let any water in either.

I have 100 18650 cells on each side... yes, 200 total and there is PLENTY of room to spare. Trying to decide if I want to go the distance and fill them up all the way to get more range or speed. I haven't added to the pack yet because I feel the need for neither so far, haha.
 
A wide thing at the front of the top tube really gets in the way of out of the saddle climbing pedal strokes. I wouldn't put anything wider than about 50mm up there. Try it with a couple of foam blocks (yoga blocks or the like) before getting too far into your prototyping.

I do have a 1kg battery (10s2p) mounted under my top tube in a small Jandd bag. That works well if you don't need a large battery. I've tried a 10s4p battery in the same bag (so twice as wide) and it really got in the way.
 
Awesome Ecycler, 200 cells should be more than enough for my plans, as I don't want "too" much weight.
I'm thinking something similar to a small triangle pack, 52vx12ah or 52vx20ah on each side...at the top/front of the front triangle.

Soft bag like the Additive could work great till I figure out a hard case of sorts, which seems like the "best" route.

Here's the bike in question...no room in the triangle, but 83mm wide cranks do give me a lil leg room for battery width.....
..and video of me crashing horribly on the way down from taking this picture...
https://vimeo.com/46772629

DSC04298 (1).jpg
 
I have no problem with my legs hitting the additive bag even when standing. How did you crash in the vid? Did your left pedal strike that log? It was hard to tell what happened before you went ass over tea kettle! hahaha
 
Here's one:

https://www.electricbike.com/matt-parks-basman/

1000wBasman20.png


I'm curious to see how you go about yours as my cruiser may end up with a tank style battery (I like the "faux motor" look personally, but tanks can look really nice too ..) and want to try some different looks before deciding on the best for both form and function.
 
John in CR said:
Thoughts? What is commonly the gas tank area on a motorcycle is not the appropriate place for a battery. It is too high and impacts stability when parked, and when riding having the weight there makes the bike feel heavier. Forget gasser designs and come up with something sleek cool and different.

+1

I like the weight low and forward, limited options with that frame for sure.

I'm a little concerned how your're going to fit 2x 52V 12AH triangle batteries on each side of that frame unless you're making a custom pack that would be very narrow and probably have to have a lot that sits on the top or hangs below the bottom of that frame?

I personally don't like anything too square and "boxy" but I understand you're trying to save space and weight, I think if you want anywhere near that kind of dense power, in such a small area, you'd be hard pressed to beat LiPo for the ability to pack it tight to the frame (hard packs maybe?) and then you could round out the corners with pieces of ABS pipe so it looks more appealing?

Here is a rough drawing of my idea (excuse the ghetto ms paint)

 
i meant one 52v20a on each side which are around 3" thick triangles...at 12lbs each.
Two of these... http://lunacycle.com/batteries/packs/triangle-52v-samsung-inr18650-25r-20ah-high-power/

Total of 52v40ah once paralleled...or maybe a custom setup for two 36v20ah linked in series to make a 72v20ah. (beyond my experience so taking it slow.)
...so total width would be around 8", and battery weight around 25lbs

No...not ideal placement...but trying to figure out options.
I love the way this bike rides, I don't want to have to buy a less functional frame just for battery space..but I may have to.

The goal is similar to my Tangent/Intense...but with twice the power.
The standard Tangent kit is rad as is...but I wanna see how burly I can go.
Maybe two Astro3210 motors, running at 72v...maybe just one Astro3220 at max voltage...I need to learn more...

...might just need to get a custom frame built...or, UnitedBicycleInstitute is less than 200 miles away and offers frame building classes.
 
Yep, that is the type of batteries I guessed you meant, and yes absolutely, depending on your set-up, you might benefit from volting up to 72V and 20AH as this might actually be more efficient for your motor than 2 of those packs totaling 48V 20AH.

Are you using a hub motor? If so, what controller at what amps and how fast do you plan on going?

If we guess that your top tube is around 32mm 1 1/4" in diameter, that is going to be one WIDE pack with 3 inches added to each side, so around 7 - 8 inches thick?

Sounds pretty un-weildy to me, better to have some of that in smaller pieces hanging under or just sides and top of the top tube, but YMMV :) .

I am under the impression that you might want to as much travel as possible from the fork, but if you're doing more "single track" style, maybe that isn't as important and you can allow it to hang down a bit?

Either way, let us know what you decide and discover along the way!
 
I built my 18650 packs to taper thinner in the area where my knees go. Probably not something for everyone, but it works perfectly for me.
 
I am dead set against gas tank style batteries, so why, oh why, am I seriously contemplating doing exactly what you just did: run two Luna triangles? I am looking long and hard at sewing together a couple of Luna bags and working out a mounting. My 17" Fatbike frame is a perfect fit for the Luna Batteries and Bags and my comical tests with dummy double wide bags convinces me it could be perfectly rideable. What I haven't done is load up another 12lbs to the bike and see how it feels on the trail.

Still, the range possibilities are tempting. Yesterday I rode 16.1 miles in the mountains with a 900 ft elevation gain on only 419wh as per my inline wattmeter and GPS. Since I have at least 1000wh in a single 20ah pack a pair will give perhaps 60mi range on mountain trails! This makes my eBike competitive with an ICE trailbike for long distance rides, if much slower. On the other hand, when I go up to our favorite camping and exploring site, we are above 7000ft and ICE bikes get reduced range and power from the thin air. Not a problem for an electric motor!
 
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