View Full Version : Battery Space

02 September 2013, 2028
Hello everyone.

So this bike is almost "done" (if such a thing is possible) but (and I am sure that some of the folks who have been around here for a while have heard my somewhat tired story before) I have a welder friend who said that he was going to make battery mounts for me. I've been bugging the crap out of him for about a year and a half and I am starting to suspect that he's too busy to handle my bike and I think that I am starting to bother him. For one reason or another, I just don't think that it's going to happen. That's why this bike has been on hold FOREVER.

So I am pretty much suspecting that I am going to have to do this myself. Now how the heck do I fit four of the batteries (pictured in the frame) on here? I've thought of a couple of things...

-I could remove the tank and annex some of that space building partially vertically and partially horizontally.

-I could build sort of a 'cage' out of steel edging and bolt it together.

-Solider up, buy a welder... there's no time to start like the present.


(BTW, electrically this works, I've even ridden it with smaller batteries just to test it.)


03 September 2013, 0807
I'm doing my first bike as well and wedging 9KW worth of LiPo into a Interceptor frame. I chose an older model for the steel frame which I feel more comfortable welding and knowing it is strong. I can weld Aluminum with my TIG but not confident enough to be riding down the road at 70 MPH holding it together for my safety and those on the road around me. I'm assuming your frame is steel and if you have never welded steel, practice a lot before you do it or take a class at a community college. It will save you time and headache in the long run but give you the satisfaction you did it yourself. Another suggestion if you don't have a welder is take a class at TechShop http://www.techshop.ws/
and then you can use the welders there to finish your work without the cost of buying a welder plus you'll get some great support from those folks. I'm sure you have thought about cutting out the bottom of the gas tank for space and doing the old trick of cutting Styrofoam blocks the size of your batteries to figure out how to pack them in. Skip the cage and punched angle iron frame, do it in some square tube and make it look professional.

03 September 2013, 0845
A suggestion, Lionstrike, would be to utilize some CAD (cardboard assisted design) for this. Just make up four cardboard boxes matching the dimensions of your batteries. Possible make them a little taller than the batteries to account for clearances been cells.


03 September 2013, 1639
So here's something interesting... ironically enough, I got a phone call today from my welder friend. His email was not working. He told me the list of stuff that was keeping him from getting to my bike. I felt bad for asking. Holy crap! I swear married folks with kids have a never-ending "to do" list. He physically did not have space in his shop for my bike. Seriously. He did say that he'd come by in get in in a couple of weeks.

O.k., but still I like your suggestions. I'll get some cardboard.

Also, check this out:

That's from one of Tony Coiro's videos on Youtube. I have those same mounts on my bike. I'll bet I can go that way and probably could get away with it without a welder.

04 September 2013, 0441
Lionstrike, Cardboard Aided Design is the way to go to at least sort out how you're going to fit the cells into your bike. It's how I did it with my ThunderSky cells and I fitted all of them in with a bit of room to spare, thanks to some creative thinking.

Please, I beg of you, consider buying new Lithium Iron Phosphate or Lithium Iron cells. You get heaps more range out of them, they're massively lighter, they last longer, and they deliver more current. They also come in a (bewilderingly) wide variety of shapes and sizes, so you'll find something that you can fit easily into your frame.

(Quick plug: look up my Battery Comparison website on El Moto for assistance with choosing :D )

Either way, I'd suggest finding another person who can do the welding for you. If possible, ask your welding friend who he'd recommend. You'll probably get someone who can do it quicker, and for a case of beer rather than stupid amounts of money. No offence to your friend, but you want it done this year, not this century :)

Hope this helps,


04 September 2013, 0509
+1 on lithium iron phosphate. You don't need a bms and will probably be happier in the long run. My first conversion was 36 volt of lead and it sucked big time compared to my current ride which uses 72 volts of Thundersky 100AH cells.

Sent from my Nexus 7 using Tapatalk 2

04 September 2013, 0547
Agreed Frank and Paul, the investment into some type of lithium over lead acid is well worth the money. I built my first EV with lead because at the time Lithium was considered "exotic" and out of my price range. I would never consider lead acid again even if they gave me the lead batteries because the lower cost and performance of lithium far out weighs lead acid. There is many different Lithium chemistry types out there and get educated before you leap. Some require a BMS, others with careful use and monitoring do not. Paulway has an excellent Battery comparison link that explains it all (sorry Paul for blowing your horn) http://www.elmoto.net/showthread.php?3085-Shameless-plug-battery-comparison-website The cardboard box idea is great, I did my with real CAD (computer aided design) because I'm a geek but the other CAD version works just as well.

04 September 2013, 0719
Thanks everyone for the great responses. Believe me, it's going to lifepo4 eventually. The thing is, I have a functioning Vectrix VX-1 now. Despite it's quirks (periodic overheat, overamping on extended hills and causing motor cut-out) it's a damned fine machine.

The problem is, it's just complicated enough to be tough to work on and expensive to repair. I understand that the charger goes for a cool grand, and if the controller goes for any reason, I hear it's 2K. People have built entire e-moto projects for that.

And there is something cool about looking at it and saying "I built that" isn't there?

I've got just about 4,000 miles on that Vectrix and you know what? I'll be damned if I give up my EV-commuting. I love this. But if it's going to be anywhere between $2000 -$4000 for replacement batteries when these things go one day (I've heard different figures), I am going to have to take a pass. No way. 2,000 I would consider. 4? ... Forget it. I'll do something else.

So my thought process is that the lead is something of a placeholder. Once that battery tray is built, I can put whatever in it and as you've said, lifepo4 is a magnitude smaller and lighter. Lead is in a way overengineering for the worst case scenario isn't it?

I like that link... but I can't seem to find which lifepo4 does NOT require a BMS. That would definitely pique my interest.

Thanks again for the responses. Early next year, this thing makes my commute to work.

04 September 2013, 1244
I'll add my $0.02. Building with lead will be a good experience, but you will be disappointed in the end. For one thing, 48V is just too low for anything but a toy, but even a 72V lead pack will disappoint. When you do v2.0 with lithium, your batteries will be in a completely different configuration and you will most likely not be able to reuse you battery trays anyway. Of course starting with lithium will be a learning experience as well. Many (most?) people on this board ruined their first lithium pack. I can't say which battery chemistry I think you should start with, but it will probably take you 2-3 tries to build something you're happy with. As for cost, I spent $3500 on a lead acid conversion using used components and doing all of the labor myself. I don't mean to discourage you, but in the end I think you'll be happier with more realistic expectations. Good luck.

04 September 2013, 1600
I am not discouraged at all, in fact I appreciate the perspectives. This is a costly hobby. It's powered exclusively by my overtime hours at work.

The advantage is that I have no other bad habits. I do not drink, smoke, or have other expensive hobbies. I am just addicted to electrons.

I am kind of disappointed that 72v doesn't work well though... that was kind of the plan for 2.0.

04 September 2013, 1714
Higher voltage means more speed AND lower current for a given power. Both of these are good things. But higher voltage components cost more. How well 72V works depends on your definition of "well". The main point I want to make is that I think you will be disappointed with the performance of any lead pack if you expect it to be more than a learning experience.

04 September 2013, 2043
I think that I get where you're coming from. Thanks.

Right now, a learning experience is fine for me. I will definitely want to expand later though. If I gather this correctly, that's not an uncommon experience among builders. I've read a few threads from folks who said "I'D NEVER DO THAT AGAIN!!"

There will probably be a MK II e-moto. I think that a Ninja frame would work well.

05 September 2013, 0734
One thing you haven't mentioned (or maybe I missed it) is how far to you drive your Vectrix now? The type of batteries you buy has a HUGE impact on your range. If you are building something to drive say a couple miles to work and back, lead could be an option. I'm not promoting lead, but just as others have said, many ruin their first battery pack no matter the chemistry until they figure it out. Lead is more forgiving and cheaper to learn on, but you have to look at the range you need or are building for. As I said earlier, my first build was a Lead sled in an S10 but I over sized my battery boxes knowing someday when the priced dropped I would replace my "learner pack" with some form of Lithium. Of course it still has lead (Optima Yellow tops) and I quickly lost interest in it since I'm building a faster longer range motorcycle...:) With Lithium also comes the cost of a good BMS but worth it to protect my investment in LiPo.

05 September 2013, 1724
I've probably neglected that detail. I've been so on and off with this project, it almost certainly slipped my attention to mention this time around. All in all, I've probably been at this thing for 5 or 6 years or so. I've managed my time by building electric bicycles in the meantime.

I commute about 13 miles to work one way on the Vectrix. If you can believe the battery gauge (and from what I've read, there are very good reasons NOT to) it drains the battery meter just above 50% on a one way commute. It uses 125v 30ah Nimh cells.

This thing that I've built, whatever you want to call this conversion literally sits in the back of my kitchen. I am somewhat hesitant to have that much energy density sitting idle in my kitchen while I still have a totally functioning, running Vectrix.

08 September 2013, 0725
Just keep the terminals covered well. I have a spare set of Optima yellow tops (12) with pieces of rubber hose over all of the terminals and then covered with a sheet of plywood. My set of LiPo have all the terminals covered at all times unless I'm working with connections and testing. I freak about the same thing and know you what you mean.

I don't know much about the Vectrix but I'm sure you can pack more power in a motorcycle frame than one of those.

09 September 2013, 1601
Good point. I was thinking about that too. 48v short across the terminals to the frame... yikes... not good. Gotta watch the bumps.

09 September 2013, 1637
The two fundamental equations here are watts = volts * amps and loss is proportional to resistance * amps squared (forgive me for not being technical enough there, I'm trying to keep it simple for non-electricians).

The lower the voltage, the more current you need to move to get the same amount of power. But the more current, the thicker your wire has to be and the more you lose to resistance.

So in general it's better to go higher voltage, because you can get away with longer lengths of thinner wire and you lose less in internal resistance.

I suppose that's my opinion there, but backed up with some kind of engineering :D

I think it's better to start by asking how much power you want. Look at motors that will give you that much power, and look at the different voltage ranges. Then decide what voltage you want, and then use my pack calculator (thanks glassblower! :D) to work out what cells suit your needs.

Hope this helps,


09 September 2013, 2212
Thanks for the response. I get it a lot better now.

Right now man, honestly I want to take this thing from scrap metal at the back of my kitchen to something that rolls down the street at the twist of a throttle, faster than the 15 mph I've had it at using smaller, more compact SLA UPS batteries.

In other words, right now I am cool with it being a glorified go-kart. Eventually I am going to want it to 60mph continuous. But for the sake of next year's electric vehicle competition, I am plenty satisfied with 35mph continuous. That's all I will need.

10 September 2013, 0151
One advantage of using smaller cells, like the Headways and other pouch cells, is that you can construct your pack gradually.

For example, Tony here (SplinterOz) has a 50AH pack at 72V, with five strings of 22 10AH cells in parallel. If he was to get just one string, that'd be 22 cells, and maybe cost him $400. He wouldn't go very far or accelerate very fast, but it'd work. The controller would still work, the charger would still work, and the BMS would still work - it'd be a good proof of concept. Then he could buy more cells as he could afford them. He'd still have to have designed his battery storage to fit all the cells, but with CAD (cardboard or computer) that wouldn't be difficult, and it wouldn't be that much more expensive than fitting a smaller pack.

The main annoyance would be to have to take the pack apart in order to add the new cells. Now, Tony's battery is designed so five cells are grouped together, connected to the next five cells, and so forth. An alternate way of doing this would be to keep each string separate, so a new string of cells would be added without disturbing the existing strings. It'd mean a more complex battery management system, since effectively each individual cell is being monitored. But it could be done that way.

And the main tricky bit is that cells do gradually degrade over time, both in terms of physical time elapsed and in number of charge cycles. The limiting factor in each group will be the old cell, because it discharges quicker and charges slower. Adding new cells to an existing battery isn't usually recommended, although it does happen (Tony and I have both done it and I bet a number of other people have too). Adding new strings beside old strings and keeping them separate will avoid some of these problems.

So that's an option for you if you don't want to spend a lot of money up front and don't want to have to re-engineer everything or throw the cells away.

Hope this helps,


10 September 2013, 0315
I've got to chime in here as well. My experience with lead - AGM - was actually great, for what they are. It got my first bike running, cost very little compared to lithium, and lasted a summer. I learned a lot with them, and am now using them in my lawn tractor conversion. :D

Because I had started with the idea of trying to design some sort of universal mount, I could then use other chemistries on that bike, and use that mount, modified a little, when I moved everything to a different frame (the R5). That mount evolved into a removable rack, or module, that allowed me to use several different packs (different capacities as well as chemistries) by simply swapping out the pack. When I got the CALB cells I needed more space, so I simply added and modified a module for the belly. It's not strictly the same, and won't interchange with other modules I have, but still, it uses the same mounting hardware. Here's what that looks like:


My whole system is based on a 40V module. I use one on the dirt bike, one on the tractor, and two on the street bike, in series for 80V. By setting them up in series or in parallel you can easily modify the capacity or the voltage, whatever you want for the application.

So I learned two lessons. First, not much I've bought for this madness is wasted. (The dirt bike project is code name: Spare Parts.) Even my first batteries are being used in other projects now. Second, it's a work in progress, and if you look at it like that it takes a lot of the pressure off. Sure, you're not going to nail it first shot, but the fun is in refining it. My advice would be to think in terms of the most flexible battery mounting you can work out, and see where it takes you. (It sounds like that's where you're headed anyway... :D)

10 September 2013, 0558
I am thinking along the lines of what Ted is thinking. What I need to get at is a "battery tray" or some kind of enclosure that maximizes the use of the internal space. Then I could just swap out chemistries at my discretion.

I'd totally be o.k. if this thing did not last more than a few months really. It's just to take around the track a few times at 35 mph for the range event in the local EV competition. Then, when my EV grin becomes a full out wicked, evil laugh (that possibly echoes a little in unison with a lightening strike), I can bring it back to my kitchen... and start the fun all over again with better gear.

Sounds plausible yeah?

10 September 2013, 0907
Totally plausible. Have some fun with it and learn some cool stuff!

10 September 2013, 1541
Thanks everyone. I appreciate the support.

13 September 2013, 0102
Say, along this idea of using Headway cells and building modularly limiting the current output to 100a.... would a cycle analyst stand alone work since I have a non programmable controller?

20 September 2013, 2139
You know, I could just bolt this on like so couldn't I?