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So I decided to go for a 52v upgrade on my Sondors Thin using the Luna Cycles 52V TRIANGLE PANASONIC GA 18650 14AH HIGH POWER AND LONG RANGE battery. I carefully measured and I thought I could just barely get it in to my Sondors Thin if I took out the bumpers for the stock battery and some of the cable guides. I got the battery and even after looking it I thought it would work (see attached photos). I used a Dremel to take out the bumpers that were in there and most of the cable guides in the top right. The battery looks like it was made for the box, dimensionally it fits like a glove, but (and I knew this was going to be the tough part) the hard box on the Thin just won't quite close even after my modes. I don't think I'm close enough to quite get it there either.

I really like the look of the hard box case on the Thin, so I'm trying to figure out it:

  1.  Is there some alternative idea to getting this thing to work in the stock box. I'd thought maybe there's some way to modify the hinges... or even cutting off the outer rubber on the battery might save a few mm. Any ideas folks? That's why I'm posting on the forum.
  2. Is there another form of hard box, maybe from the non-Thin Sondors, that might fit in it?
  3. Is there something dumb I'm just not thinking of here?
  4. I guess the final option is just remove the box and put in a soft triangle bag (such as the Luna Cycles one). Does anyone have any experience putts one of those on the Thin? And once I do that I might as well get an even bigger 52v battery, right?

I've also got photos of it compared to the ElctroBikeWorld LT48.

Appreciate any input anyone has. Thanks!

@Reddy Kilowatt? :)









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@Chad Lauterbach, I just measured both my EBW L3 52v 20.3ah battery and my Luna 52v 17ah long range / high power battery and they both measure zackly 2.75” width. And I reviewed the drawing of the Luna 52v 14ah long range / high power and it shows 2.75”.  You did say 2.75” would fit, right?

I can only guess that if your 52v 14ah is wider, that there are stiffeners on the sides of your pack that make it wider than what’s published or the stencil between cells to improve sturdiness adds width to the pack. They may have changed their building methodology. 

  • Uses composite stencils in between the cells to make the pack more rigid and more reliable.


Although scrutinizing their drawing shows a 3” pack width on the top right image.... while 2.75”is specified elsewhere. Not sure what’s going on with their drafting. 

The 18650 individual cells measure 2.559” in length (width of the pack) and the metal lattice, should only measure 1mm (.04”) per side or so.  I do remember reading somewhere, not sure it was on Luna ,that “Now using thicker pack rap” or some such statement but a few extra layers of Heat Shrink, shouldn’t be responsible for the difference in your packs







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Yeah, you can definitely see how far I'm pushing the box. 2.75" might just be too tight at the end of the day. I've thought of loosing all the case fasteners to see if I can get a little more flex out of them.

I attached a couple more photos. Makes me think with just a little more sanding down work and removing the outer rubber casing I could just bared get it in there... What do you think? Luna said I could return the battery with a 10% restocking fee if I couldn't get it to fit, but my guess is if I take the external heat shrink off they won't take it. Luckily they are right near me in El Segundo so maybe I'll go down and chat with them at some point this week. It does look like the battery is a hair longer than 2.75" and my box is 2.875" by my count, but that doesn't include the thickness of the plastic itself, so maybe I could only get 2.6" or so in there. The LT48 is 2.5" though and it does have a little bit of play, so I think the box could take something bigger. The question is just how much.

What would you do @Reddy Kilowatt?



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Well, two things. If that battery is wider than 2.75”, it doesn’t match Luna’s drawing. It’s not as represented and doesn’t fit and it’s their fault. Of course, there’s not much you can do besides a court case to try and force them to accept responsibility, if they won’t. They are masters at denying responsibility.  I know, I’ve had problems with the Rack Battery I bought from them in 2015.


Other small items that were not as represented also. The barrel charging dongle they supplied with this battery  was the wrong diameter, fit but was loose and could caused intermittent contact. That situation fried the BMS. They stated that their batteries didn’t come with any warranty and since that rack battery was no longer manufactured .... there was nothing they could do.  

I can’t figure out how EBW can produce a 48v Battery Pack that is 2.5” since 18650 flat top cells are 2.559” without the metal lattice on both sides, plus heat shrink. My EBW L3 52v measures 2.75. I certainly wouldn't remove any of the wrap.  Make sure the edges of the pack are not contacting the inside radius of the Sondors battery box which would further limit width. 

You could always still keep your EBW 48v in the Sondors box (or not) and carry the Luna in a side pannier. I know that’s not the design element you desired for your bike but it’s what I do when camping or when I travel to a friends house on the other side of the MetroStool. I can’t imagine riding without panniers  but that’s just a personal choice and I carry a lot of stuff, besides everything, EVERYTHING I grocery shop. I even have this larger volume set for bigger loads ( I could deliver pizzas in the top trunk of this one ?)


That was when it was pretty Stock. Before building,  better double wall rimmed wheels without holes and 12g Sapim spokes, 750Watt, 7 Speed Bafang .... and well everything else on the Original. The only Sondors parts left are the frame, battery box and bottom bracket. 


Oh,  just remembered a third option. I’m building another Fat eBike based on my Dolomite.  Although I have a Luna battery bag it doesn’t fit the frame triangle exactly and instead of Scrubbing Off or Painting Over the Luna Logo  and modifying the Velcro straps, I plan on building a battery box. It’s really a pretty simple project and I love this kinda stuff, and since width is your issue you could make it as wide as you’d like. 






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@Chad Lauterbach Looks to me like you are screwed here, in the sense that you aren't going to get that battery to fit... and the LAST thing you want to be doing is stripping off that heatshrink.  Inside my custom electrobikeworld battery is essentially a cardboard box by the way, thats how they can get so much smaller I assume).  I added heatshrink layers to it like you are thinking of removing.  they do a VERY important job for pack stability.

Luna can't do much - not anything, really - insofar as battery dimensions are concerned.  Those packs come in from a premium vendor in China and while they are more or less top-tier, they are Chinese and that means all you expect it would insofar as enforcing liability for unapproved/capricious deviations.  This has gotten a lot of attention from Eric Hicks of Luna on Facebook recently and factors in as the primary reason they are going entirely to in-house battery manufacture (notice, if you will, the mass-availability of the Wolf packs, which are the first in a slow wave ).

So... what about moving forward?  It so happens I am locked in the middle of spec'ing a custom battery bag for my new AWD build.  Check this pic out:  This single bag holds both my Luna 17.5ah battery and my two parallel'd (12ah total) mini cube batteries.  So 29.5ah in this bag (its an XL frame so thats a deceptively big triangle).


The bag is the very well-known Falcon EV bag (google it) which is the gold standard from battery bag manufacturers.  Its purpose built and needs a big triangle... which you happen to have.  I suggest you make that your first stop.  

I am doing bags exclusively after I spent a fair amount of time working with custom battery box builders.   Notice I am using a bag?  Well, a box was my first choice too.  Because Sondors, right?  Here's the rub:  Turns out you lose a hell of a lot of space due to fittings to hold the box together.  So much so I wasn't willing to proceed with a box and - two bikes built since that decision and #3 in progress - I have no regrets on that front.

As you can see though, that Falcon bag is not perfect.  For starters I don't like how I had to fit the batteries inside.  Next, I have more room in that triangle and I can better lay out my batteries inside if the bag is about 19.75" to 20" long and has about another 1" of height.  So I am talking to custom bikepacking bag manufacturers.  Still trying to find someone who will be able to work with my to-do list.  One vendor who is absolutely *perfect* is tied up until Spring, I heard this morning.  I have feelers out to another maker and have a third lined up if #2 doesn't pan out... Here's the bad news:  Figure $300+ for the bag.  But its a perfect edge to edge fit without any loss of space for hardware.

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Thanks @Reddy Kilowatt and @MattRobertson for your detailed replies. You guys are both so thorough and knowledgable. Interesting to think about a bag vs. a box. While I do like the aesthetic of the box, my ultimate goal is to build my ultimate commute bike (and have fun while I do it). Building a box myself is probably beyond my handy level (and the amount of time I have). I would be worried outsourcing the construction too without knowing exactly what I would be getting back. It's less about the cost and more about it actually fitting and working. I'm kind of surprised given the numbers of Sondors out there, and their affordability, there aren't more folks making pre-fabricated Sondors specific upgrade parts.

@MattRobertson How well does that Flacon EV bag fit in a Sondors/Sondors Thin frame? I know Luna Cycles makes their own bags as well, any experience with those? I'm not home right now, but I'll try and measure the triangle to find the best fitting bag soon and will report back on this post once I figure something out. Really appreciate your insight.

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On 9/24/2018 at 10:40 AM, Chad Lauterbach said:

How well does the bag fit in a Sondors/Sondors Thin frame? I know Luna Cycles makes their own bags as well, any experience with those? I'm not home right now, but I'll try and measure the triangle to find the best fitting bag soon and will report back on this post once I figure something out. Really appreciate your insight.

@Chad Lauterbach In terms of fitment I have no idea.  The FalconEV  web site does show a pic with dimensions you can use to take your best guess on that.  I actually have two Luna bags on my other two bikes and have found them to be of good quality.  I used them when I couldn't fit the very large FalconEV bag... which I have actually had sitting around for over a year waiting for a frame it would fit into.  So the Luna bags have been my go-to's for quite some time.  They hold up well. 

But in terms of sturdy construction the Falcon bag is the champ of non-custom ebike battery bags ... its only drawback being its large size.  based on what I have seen of them,  FalconEV is making them smaller generation-after generation.  The picture on the home page is the 3rd gen and thats mine.  If you root around in their site you will find a pic of the 2nd gen and the measurements in that pic are larger.  I have seen the 1st gen measured out elsewhere and it was larger still.

Here's one of my bikes with the Luna bag on it.  This bike only uses that bag for storage (my traveling Satiator charger which is no lightweight) and as a rats nest (wires) so its not quite stuffed full.  Note I did not use the rear straps around the frame but they are used to hold onto the motor cables running up the seat tube.  Looking at this pic, I am thinking the triangle of the Thin is too big for this bag given the already tight fit and the plunging top tube.


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I think it's going to be a little small compared to the triangle it looks likes. They state 16(L) x 3(D) x 11.5(H) x 13 (Bevel) inches on their site, but it seems like it will be worth it.

I'll report back with images once I receive it and get it installed as well as a ride report on the 52v battery. :)

Photo from their site:


My Thin:


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