[NVDucati]

I'm in the early stages of building my own lithium battery. By that I mean the learning and gathering stage.
I've been using them for a few years, adding them to my bikes one at a time as the old ones failed. The new ones are different from my first ones chiefly by the addition of the built-in BMS (Battery Management System). I feel comfortable stepping away from my lead/acid youth;).
The price savings is not the driving factor, but I don't hate that. I'm mostly interested in the fact that they can be built in shapes that are not rectangular or square. They also can be mounted in any orientation because there is no up or down to them. This opens up a lot of possibilities on a motorcycle where "packaging" is very tight and weight matters. Battery capacity on touring / camping bikes is always desirable and having a source which is separate from the starting system, ... priceless.

Think of a battery that is one inch thick X 3 inches wide and as long as you need it to be, say to live under the rear fender from tail light to swingarm. Or making one to line the edges of your top box. You get the picture. I have paddled though this forum and another forum looking for this discussion or folks who are currently rolling their own. It isn't really "rocket surgery" and more of an assembly process.
Building custom batteries is growing with the drone crowd and E-bike folks for reasons not the same as mine. Here is a taste of some of that:
DIY Lithium Battery Parts 1-5 https://www.youtube.com/playlist?list=PLPqn8bOJKP_nYD-BAKxJHOYovjickM3wD

Love to hear from anyone doing this ...

[axman88]

I was looking at some U-tube vids of people doing this, building grids of cells.  One benefit was that you would know you had decent quality cells. ( Samsungs were said to be good quality at reasonable price)  Inexpensive sealed purchased packs might be filled with who knows what ("satisfacton cheerful batery"), and quality both in terms of capacity and longevity varies widely between reputable product and substitutes.  I've experienced some pretty awful quality in aftermarket digital camera batteries.
 
Also having the ability to build gives one the ability to repair, which comes down to finding the weak cell(s) and replacing them.

From what I saw, building packs came down to the ability to source or make the connector buss elements from thin sheet, and the possession of a low powered spot welder.  As I recall, some people were building these from  microwave oven transformers with the secondary coil rewound to low voltage, high current.  The fancy ones had a pulse timing setup.

I'm sure I'm simplifying, it might be nice to also have some built-in charge management, maybe even a way to switch the pack into different grid configurations for different voltage and charging options.

What are you thinking of using for a housing?  A buddy of mine had a home built vac forming setup in his garage for a while, and fiberglass is nice for free form boxes.

[AzCal Retred]

Putting the Li Battery in the rear fender gets it away from the fuel tank, maybe a good thing if things go awry...? Lead-acids normally just leak or occasionally pop; Li has a reputation for burning down the house. All that said, it looks like a worthwhile project, useful weight savings and likely more ruggedness. Doesn't the total battery volume also shrink with Li vs. Pb? Aircraft Spruce sources Kevlar fiber in several forms, good for high vibration applications. They carry the specialized cutters too, as well as a bewildering variety of epoxies and "vacuum bagging" supplies.

[GlennF]

Plus Lithium is pretty easy to obtain if you have a prescription for it

On a more serious note, these home made battery would not necessarily even be contiguous and presumably could be split into several smaller packs linked by a very heavy cable, this could be handy trying to hide a battery to make your bobber or cafe racer project look like it does not have one

[NVDucati]

I was looking at some U-tube vids of people doing this, building grids of cells.  One benefit was that you would know you had decent quality cells. ( Samsungs were said to be good quality at reasonable price)  Inexpensive sealed purchased packs might be filled with who knows what ("satisfacton cheerful batery"), and quality both in terms of capacity and longevity varies widely between reputable product and substitutes.  I've experienced some pretty awful quality in aftermarket digital camera batteries.
 
Also having the ability to build gives one the ability to repair, which comes down to finding the weak cell(s) and replacing them.

From what I saw, building packs came down to the ability to source or make the connector buss elements from thin sheet, and the possession of a low powered spot welder. As I recall, some people were building these from  microwave oven transformers with the secondary coil rewound to low voltage, high current.  The fancy ones had a pulse timing setup.

I'm sure I'm simplifying, it might be nice to also have some built-in charge management, maybe even a way to switch the pack into different grid configurations for different voltage and charging options.

What are you thinking of using for a housing? A buddy of mine had a home built vac forming setup in his garage for a while, and fiberglass is nice for free form boxes.

_ You are so right about being able to specify the quality.
_ The supply houses sell nickle connecting strips of various gauge.
_ Hand held spot welders are available and not very expensive, even for the "next up" models with a digital power read out.
_ As for the housing, I luckily have a pretty extensive history of building light weight, super strong housings. I use "Foam Core Carbon Fiber" construction methods. I got my first EAA certification in 2002. I love that system and even made a two seat sports car in 2005.

[NVDucati]

Putting the Li Battery in the rear fender gets it away from the fuel tank, maybe a good thing if things go awry...? Lead-acids normally just leak or occasionally pop; Li has a reputation for burning down the house. All that said, it looks like a worthwhile project, useful weight savings and likely more ruggedness. Doesn't the total battery volume also shrink with Li vs. Pb? Aircraft Spruce sources Kevlar fiber in several forms, good for high vibration applications. They carry the specialized cutters too, as well as a bewildering variety of epoxies and "vacuum bagging" supplies.

Yeah, the BMS (battery management system) of today are have pretty much eliminated the early problems and my plan is to actually build in a second one as a backup. Like everything now they are small, light and affordable. I'm willing to believe that my battery housing will out survive me in a crash . Over the years, I have settled on only using WEST epoxies which as you point out can accommodate vibration, heat etc.

[NVDucati]

Plus Lithium is pretty easy to obtain if you have a prescription for it

On a more serious note, these home made battery would not necessarily even be contiguous and presumably could be split into several smaller packs linked by a very heavy cable, this could be handy trying to hide a battery to make your bobber or cafe racer project look like it does not have one

Very perceptive. The plan, at this point is to make my first one not for my Interceptor but for a ST-1300 (retired CHP bike). It has a "radio box" that I'll splash a CF copy of and make the battery housing as a perimeter affair with the center open for luggage and gear.  But for the RE, Yes, it might very well be in two sections. I like the way you think.

[gizzo]

Oh man. I watched a mate build a 48v lipo pack  for his Ebike, years ago. He disassembled a pile of 3S toy model aeroplane packs and soldered them back together into one big one. It seemed like a sketchy thing to do back then but he got away with it. I guess what he made was a 16S2P pack.

If you build your battery box the way you describe, maybe you could use the internal cavity as a pie warming space.

Also, if you haven't seen it, have a look at Kinetix R246 low viscosity epoxy. It's thinner than West Systems and wets out carbon really easily. Great for moulding and vac bagging projects. Araldite LC3600 is great too but I can't find anywhere to buy it from in Aus. The homebuild crowd in the US love it, I think.

[NVDucati]

Oh man. I watched a mate build a 48v lipo pack  for his Ebike, years ago. He disassembled a pile of 3S toy model aeroplane packs and soldered them back together into one big one. It seemed like a sketchy thing to do back then but he got away with it. I guess what he made was a 16S2P pack.

If you build your battery box the way you describe, maybe you could use the internal cavity as a pie warming space.

Also, if you haven't seen it, have a look at Kinetix R246 low viscosity epoxy. It's thinner than West Systems and wets out carbon really easily. Great for moulding and vac bagging projects. Araldite LC3600 is great too but I can't find anywhere to buy it from in Aus. The homebuild crowd in the US love it, I think.

Yeah or maybe dry my laundry on the third day of a trip ...
I've still got a ton to learn as regards heat and how the number of cells doing the same work effects it. That plus the BMS strategy leaves me trying to first identify the questions.
_ I've made a note of the epoxy brands you've called out. Thanks.

[Adrian II]

I saw a video about somebody building a Lithium battery in an old case, he was careful to use lithium cells which would vent in case of gas build up. A little safety valve for each cell sounds like a good idea.

What crippled Apollo 13, again?

Mission control, we have a problem.

A.

[NVDucati]

I saw a video about somebody building a Lithium battery in an old case, he was careful to use lithium cells which would vent in case of gas build up. A little safety valve for each cell sounds like a good idea.

I did pass that video but haven't yet watched it. Venting for heat is a check box for sure. Not yet aware of a gas build up, but it is early days. Maybe a louvered tail lamp for exhausting it ... Thanks

[gizzo]

What crippled Apollo 13, again?

A.

Cheap Chinese lipo packs bought online from Hobbyking?

[NVDucati]

As I continue to learn about Lithium batteries it has become clear that there is no single “best” battery out there. As you’d expect, the answer is based on what exactly you want to accomplish and what you most want to avoid.

There are two main categories of design / chemistry. Lithium Ion and Lithium Iron Phosphate (LiFePO4). Make sure to take note of the letter “R” in Iron and its absence in Ion. A big difference is the life span and stability between the two.

This article seems to be a pretty even handed and informative comparison.
https://www.lithiumguys.com/lithium-ion-vs-lifepo4/

The other development for me is that I’ve come across wholesaler who has just about anything I’ll need in multiple brands and better yet they have a certified testing lab and they  they deal with custom prototype shops.  And as it turns out, They are located in Richmond California which is within an hour’s drive.
https://www.batteryspace.com/whatsnew.aspx