# Where to find Headway 38105 (8Ah) cells?



## Little-Acorn (Jan 12, 2010)

Does anyone know where I can find Headway LiFePO4 cells, number 38105? These are a cylindrical cell, 38mm diameter, 105mm long (nominal), 8Ah capacity.

I need a cell that is 5" long or less, and these are about the only ones I've seen that qualify. The 38120 is supposedly slightly less than 5" long, but that's without connectors. When you add in the dimensions of the connectors (especially screw-type connectors), that cell is too long for my application. Only the 38105 has a chance.

But every dealer I've talked to, says they are out of the 38105, though they have other Headway cells.

Anyone know where I can find any?

Lorraine, do you know of any?

Thanx all!


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## frodus (Apr 12, 2008)

we've got 8Ah screw terminal cells (same size as the 38120) that set sail this week/last week. Its still a 38120 cell.

whats it for?


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## Little-Acorn (Jan 12, 2010)

frodus said:


> we've got 8Ah screw terminal cells (same size as the 38120) that set sail this week/last week. Its still a 38120 cell.
> 
> whats it for?


A triangle-shaped battery that goes inside the frame triangle of an electric bike. 48V, 10Ah or 20Ah. Or, if I use the 38105, 8Ah or 16Ah.

I want the cells to lie on their side, parallel to the bike's axles if you will. On every medium-sized adult "Men's frame" bike I've measured so far, the minimum pedal clearance is 5-3/4" or more. Meaning, if the battery (many cells in a plastic box) were exactly 5-3/4" wide, the pedals would slightly scrape the battery box with each revolution. So the battery must be no more than 5-1/2 inches wide (including battery box), and that's calling it very closely - I might find I actually need a little more clearance than that. If the battery box is made of, say, 1/4" plastic, then the cells must be no longer than 5" long, including connections.

38120s are 4-3/4" long without ANY connectors. Even solder tabs add a little thickness, as do the 12AWG wires I will solder to them. Murphy's law says that it I use 38120s, I will come out with negative clearance - either the cells , tabs, and wires won't fit in the box, or the box will be too wide to clear the pedals.

I can't see any way to do this other than to use a shorter cell - and the 38105 is the only candidate that has adequate capacity (8Ah), adequate max dischare rate (10C), and is short enough to allow even a breath of leeway. They are exactly 4 inches long without connectors. With solder tabs done right, they might get up to 4-1/4" in total length. This will allow a LITTLE bit of padding inside the battery box so they won't rattle, and still keep the pedals 1/4" away from the box if everything is aligned just right.

Even that "aligned just right" requirement makes me nervous - let the ebike fall over one time, and suddenly the pedal on one side jams against the battery box.

I could chop off the bottom of the triangle and let the pedals go by just under the box, but that will reduce the number of cells I can put in the box. It might turn out that such a chopped 48V battery, can only be 10Ah max, I'm hoping for 20Ah. Still, I am keeping this possibility in mind.

Also wondering if I can make the box out of 3/16" or 1/8" plastic (PVC). Would it still be sturdy enough to take the abuse a clumsy bicyclist will eventually dish out? Perhaps an internal partition would make it stronger, as the cost of a little space for cells inside.

Jury is still out on a lot of this. I just don't want a 30# battery perched on top of the back rack if I can avoid it. Putting it lower, and amidships, would help balance a lot.


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## lorraine (Feb 11, 2009)

Hello Little-Acorn,
Thank you for your question.

Sorry, we stopped producing 38105 cells for a long time.
Our main models are: 38120L(3.2V10AH, with no screw); 38120S(3.2V10AH with screw), 38120PS(3.2V8AH, powerful cell); 40152S(3.2V15AH) and 40160S(3.2V16AH).


Lorraine
email: [email protected]
MSN: [email protected]
Skype: lorainy0





Little-Acorn said:


> Does anyone know where I can find Headway LiFePO4 cells, number 38105? These are a cylindrical cell, 38mm diameter, 105mm long (nominal), 8Ah capacity.
> 
> I need a cell that is 5" long or less, and these are about the only ones I've seen that qualify. The 38120 is supposedly slightly less than 5" long, but that's without connectors. When you add in the dimensions of the connectors (especially screw-type connectors), that cell is too long for my application. Only the 38105 has a chance.
> 
> ...


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## piotrsko (Dec 9, 2007)

gonna have to ask a stoopid question: why not just widen the pedal cranks?

if you are using an american 1 pc style, it would take heat treatment or a splice in the center, but a european style just needs a new center piece fabricated.


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## dtbaker (Jan 5, 2008)

Little-Acorn said:


> I want the cells to lie on their side, parallel to the bike's axles if you will. On every medium-sized adult "Men's frame" bike I've measured so far, the minimum pedal clearance is 5-3/4" or more.


why don't you want to stack them with battery axis aligned front to back? seems like if you make your 'parallel packs' and stack them in line with the tubes instead of crossways you'll have no problems with width.


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