Full Power to Lightweight - Bosch 800Wh replaced with 400WH compact

[neiloxford]

I can't wait to test all this, I'll receive the 3D parts tomorrow.

You will need to check the lower lid - I made a tweak that removed one of the holes by accident - now corrected. I need to reprint it myself, but waiting for the parts to arrive so I know they all fit together using this new printing process.

 

[Davzell]

You will need to check the lower lid - I made a tweak that removed one of the holes by accident - now corrected. I need to reprint it myself, but waiting for the parts to arrive so I know they all fit together using this new printing process.

I had seen it on the plan, but I didn’t think to ask if it was normal… I’ll drill a hole if needed, just to check the assembly.

 

[neiloxford]

Mine also arrived today - now wish I got it dyed black. It all fits together very well. The o ring might be a bit thin in this material, so as I have to order another lid, I will make a thicker o ring at the same time - although the power adaptor and o ring will need to be glued to prevent rattling, which makes me wonder whether I need an o ring at all - I have updated the long post, and flagged that the o ring is optional, as one could simply glue the BCH3901 in place.

 

[neiloxford]

 

[Bogdan_CH]

Wondering if this could be adapted to the Mondraker Crafty systems. But since I already bought the 600wh I'm a bit hesitant if I need the 3rd battery

 

[Davzell]

Wondering if this could be adapted to the Mondraker Crafty systems. But since I already bought the 600wh I'm a bit hesitant if I need the 3rd battery

I try on my mondraker

 

[neiloxford]

Wondering if this could be adapted to the Mondraker Crafty systems. But since I already bought the 600wh I'm a bit hesitant if I need the 3rd battery

My hope is that it works on all bikes that are designed for the 600wh battery and the 800wh battery. My mounts are designed to match the 600wh battery, so if the bike comes with different mounts for the 600wh battery, those will need to purchased.

It might work on bikes that are only designed for the 600wh battery, for example the Vala, but probably not. The 600wh battery is 71mm wide, and it appears Santa Cruz have focused on making the frame as svelt as possible.

The 400wh battery is 75mm wide, and the mounts are 70mm wide.

 

[Davzell]

My hope is that it works on all bikes that are designed for the 600wh battery and the 800wh battery. My mounts are designed to match the 600wh battery, so if the bike comes with different mounts for the 600wh battery, those will need to purchased.

It might work on bikes that are only designed for the 600wh battery, for example the Vala, but I have no way of testing.

I think it’s compatible with all electric bikes that can accommodate either a 600 Wh or 800 Wh PowerTube battery that can be removed via a cover.

Since the battery is mounted to the cover, the adapters should work in each case. However, you will indeed need the 600 Wh battery adapters if the cover doesn’t support both installations directly, like on your Trek.

For e-MTBs with an internal 600 Wh battery that cannot fit an 800 Wh battery (like the Vala and Orbea Wild), I think it could still work since the lengths of the 600 Wh and 800 Wh batteries are identical. I imagine it’s the width of the 800 Wh battery that causes the issue.

Looking at the integration on the Orbea Wild, it’s similar to my setup on the Mondraker on the upper part. You’d still need to check the alignment of the mounting holes.

Where there might actually be a problem is with the locking mechanism at the bottom.

 

[Bogdan_CH]

I have the 600wh battery for my Crafty which uses different mounts than the 800wh. Just the system is different for the Crafty as the battery is screwed in the frame and the cover is connected to the battery.

 

[Davzell]

I have the 600wh battery for my Crafty which uses different mounts than the 800wh. Just the system is different for the Crafty as the battery is screwed in the frame and the cover is connected to the battery.

Different system, but the 3D-printed adapters are compatible as well.
I installed them on a Crafty R 2026.
You just need the 600W battery adapter in addition for me.

 

[Bogdan_CH]

Different system, but the 3D-printed adapters are compatible as well.
I installed them on a Crafty R 2026.
You just need the 600W battery adapter in addition for me.

So it works with the Crafty? I have the 600w battery as a secondary setup so basically I would only need the 3D printed parts and the battery?

 

[Davzell]

So it works with the Crafty? I have the 600w battery as a secondary setup so basically I would only need the 3D printed parts and the battery?

have a part that is being printed again because there was an error with the first version, but there’s no issue with the assembly on the cover. I haven’t tried installing it on the bike yet, though. But as far as I’m concerned, it should be fine.

Regarding what else is needed, you should check Neiloxford’s list above — it’s the same.
You need the Bosch adapters, the 3D-printed parts, screws, etc.

I also a second part number 38 for the front mount.
This way, I just need to unscrew 4 screws (number 15) to remove the entire battery + adapter assembly from the cover, if I want to swap batteries

 

[ntm95]

I'm not entirely sure the 700g savings is worth the trouble, along with the the reduction in range. Particularly considering that the mass has not been entirely removed from the highest point. A pair of 600wh batteries to hot swap seems like the best solution for most occasions.

 

[Davzell]

I'm not entirely sure the 700g savings is worth the trouble, along with the the reduction in range. Particularly considering that the mass has not been entirely removed from the highest point. A pair of 600wh batteries to hot swap seems like the best solution for most occasions.

Clearly, switching from a 600 to a 400 doesn’t make much sense, I agree. But replacing an 800 with a 400 might be more worthwhile.


Honestly, I’m waiting to try it myself before forming a real opinion.

 

[neiloxford]

A quick update - I have made some small tweaks to the designs based on the mounts being used on a different bike design, and have reordered one of the parts for my own bike. I have reordered from China, as it is much cheaper. It has been dispatched. I will update the main post when it arrives, with photos of me glueing it all together.

 

[neiloxford]

Photos of me putting each section together.

 

[Davzell]

finaly finish to adapt the 400w battery to my Mondraker Crafty. First ride this afternoon to see if there are e difference

400w battery with cover, adater, screw,... = 2.5kg
800w battery with cover, adater, screw,... = 4.3kg

Weight total for bike with 400w battery = 23.5kg

 

[Bogdan_CH]

Honestly not sure if it's really worth it that much. The 600wh is 3100 grams with the cover. Also range would be really tigbt. Most of my rides are quick laps and with the 600wh I end up with 30 to 40% left. That means with the 400 it would be alsmost full discharge each ride. Not ideal.

 

[Davzell]

Honestly not sure if it's really worth it that much. The 600wh is 3100 grams with the cover. Also range would be really tigbt. Most of my rides are quick laps and with the 600wh I end up with 30 to 40% left. That means with the 400 it would be alsmost full discharge each ride. Not ideal.

Indeed, between 600 and 400 I don’t think it makes any difference. You won’t notice it.


Compared to my 800, I can definitely feel the bike reacting differently at the front — less heavy, more responsive.


I’ll do my usual ride this weekend to really see the difference.

 

[Davzell]

So, after a first real ride, here’s the verdict.
I managed to do 24 km with 850 m of elevation gain and I still had 7% battery left, in auto mode and Tour the whole time.
I weigh 86 kg with all my gear on.

The weight reduction doesn’t radically change the bike, but there is a noticeable difference.
The front end is clearly lighter, so the bike feels more responsive in my opinion; you can really feel it in tight switchbacks and when dropping down big steps.

The front also lifts more easily, so you notice it on climbs or when hopping.

For those who do a bit of bike park riding with their bike, it can be an advantage as we

I think that to feel a more significant difference, I’d need to shed another 2 or 3 kg.

 

[Davzell]

PLEASE NOTE THAT I HAVE YET TO ASSEMBLE THIS WITH MJF PA12 PARTS. WHEN I HAVE, I WILL MAKE ANY REQUIRED CHANGES TO THE BELOW POST AND DELETE THIS MESSAGE.

THE TESTING OF THE PARTS WITH A MOONDRAKER BIKE ARE HIGHLIGHTING SMALL DIFFERENCES IN DESIGN BETWEEN BIKES, SO I HAVE CREATED A TREK RAIL VERSION OF THE LOWER BASE AND A UNIVERSAL VERSION WITH SLOTS IN THE LOWER BASE.

Weight
Battery_______2,043 grams (Plummet above)
Mounts________161 grams (Scales)
Bosch BCH3901___ 25 grams (Manufacturer)
Bosch Adaptor____21 grams (Manufacturer)
Nuts and Bolts____20 grams (Scales)
Glue___________ 2 grams (ChatGBT)

Total_________2,272 grams

Comparison
800wh___3,900g (Manufacturer)
600wh___3,000g (Manufacturer)

800wh with trek mounts and cover = 4,258 grams
400wh with my mounts, bosch parts and cover = 2,507 grams, a weight saving of 1,751 grams.


Bosch 400wh battery + one of the screws included with the mounts

https://www.alltricks.co.uk/F-17439...128146-bosch_compacttube_400_battery__bbp3242

OR

https://www.alltricks.com/F-174393-composants-electriques/P-3128146-bosch_compacttube_400_battery__bbp3242

Bosch BCH3901 - 100mm version

Bosch BCH3901 Charging Socket Cable

Keeping eBike components up to date is key to your safety. Buy your Bosch BCH3901 Charging Socket Cable from All Terrain Cycles today.

www.allterraincycles.co.uk

Bosch Battery Adapter 2 Smart System

Bosch Battery Adapter 2 Smart System - Batteries - E-Bike - Parts | The Trailhead Bicycle Company

www.thetrailhead.co.uk

M4 Steel Hex Nuts

https://www.diy.com/departments/diall-m4-steel-hex-nut-pack-of-20/3663602744535_BQ.prd

M4 12mm Hex Steel Bolts
https://www.ebay.co.uk/itm/166098821085?var=465613598768

Nylon Glue - I went with Loctite HY4070 due to this article

3D Printing Glue Strength Guide

Curious about what strength you could get gluing dissimilar 3D printed materials together? Check out our 3D Printing Glue Strength Guide.

forerunner3d.com

Upper Mount - please read the disclaimer

https://www.thingiverse.com/thing:7153386

Lower Mount - please read the disclaimer

EMTB Lower by BoschParts123

⚠️ DisclaimerUSE AT YOUR OWN RISKThis 3D model is provided as-is without any guarantees or warranties of any kind, express or implied. The design is intended for experimental use only.By downloading, printing, or using this model, you agree to the following:You assume full responsibility for any...

www.thingiverse.com

Printing - SLS PA6-CF or PA6-GF or MJF PA12
SLS PA6-CF or PA6-GF

Plastic 3D Printing Service, Custom Parts | Wenext

Professional online plastic 3D Printing services, SLA,SLS,MJF to fulfill your 3D Printing projects. Get affordable 3D Printing price in seconds.

www.wenext.com

MJF PA12:

MJF PA12 Nylon - 3DPRINTUK

MJF PA12 Nylon offers an excellent balance between performance and reusability, making it ideal for manufacturing final parts and functional prototypes with fine detail and dimensional accuracy.

www.3dprint-uk.co.uk

Online 3D Printing Service | Custom 3D Printed Parts

Custom 3D Printed Parts from $0.30. Professional 3D printing service with SLA(Resin), MJF(Nylon), SLM(Metal), FDM(Plastics), SLS(Nylon), BJ(Metal) and WJP.

jlc3dp.com

Tensile Strength
SLS PA6-CF___110Mpa
SLS PA6-GF___77Mpa
MJF PA12_____48Mpa

Flexural strength
SLS PA6-CF___135Mpa
SLS PA6-GF___130Mpa
MJF PA12_____46Mpa

Note: I went with MJF PA12 - I do not know if this will be strong enough. If I get anxious using it, I will be printing with SLS PA6-CF/GF which is more expensive. I decided not to use FDM printing, as it is weak in the Z axis.

Estimated Cost
Battery_____£260 to £330
Bosch Parts__£35
Printing MJF__£60
Glue_______£25
Nuts & Bolts__£5

Total_______£385 to £455

As a comparison, Bosch 600WH BBP3860 is £725 on ebay

Trek parts with cost
Trek RIB 2.0 Downtube Battery Cover - W5318794 - £20
Trek RIB 2.0 Upper Battery End Cap - W5322238 - £15
Trek M4 Button Head Screw - 10mm - W1052364 - £4

Total £39

Assembly Instructions

I highly recommend doing one or two practise assemblies without glue first, so that you understand how the components fit together, and how the new battery fits into your bike. Obviously do not cycle the bike at this point.

The screenshots below illustrates how the base and lid go together.

Step 1 - attach the lids to the 400 wh battery at both ends, using the M4 12mm bolts and one screw from the mount that came with the 400wh battery (which lid and hole requires this screw will be obvious, hint: the hole you can't see in the photo below). I recommend using threadlocker because the bases will be glued together, so you will not be able to retighten them at a later date.

P.S. The lids are not symmetrical, so orientate them correctly, so that the battery is horizontal when placed on a flat table. See screenshot 1, that shows how the lid is flush on one side of the battery, and protrodes on the other side of the battery. I have the lids protruding on the flat side of the battery.

Step 2 - slot the cable of the BCH3901 through the big hole in the solid end of the lower base, and hold it in place with the printed o ring. (you could add a dab of glue to hold it in place to stop it rattling) (The o ring is optional as the BCH3901 will need to be glued in place to prevent rattling)

Step 3 - glue the bosch adaptor to the lower lid, as per the 2nd screenshot below.

Step 4 - put the nuts into the lower and upper bases, and attach to the external fittings - in my situation, with the Trek W1052364 screws, attach the Trek W5318794 and Trek W5322238.

Step 5 - place the battery with the lids already attached, into the battery cover with the bases attached, and glue the base and lids together.

P.S Steps 4 & 5 are going to be a bit challenging, and will vary by battery cover design - I am not an engineer, but it should work if you're patient, and think about what you're doing.

View attachment 169955 View attachment 169956

I'm completing the Neiloxford information regarding what is specific to Mondraker
And thanks to him for designing the 3D parts — a huge amount of work was done!

I added parts that I got from LVR-Cycle (French website), but they are available on other sites or directly from Mondraker.

Rear 600Wh battery mount for Mondraker Crafty Carbon – 099.25085
Reference: 099.25085
Necessary because the setup uses the hole pattern for the 600Wh battery, not the 800Wh one.

Upper battery mount for Mondraker Level / Crafty 2025 – 099.25049
Reference: 099.25049
I got an additional upper battery mount on top of the original one. This allows me to have a fully removable block (400Wh battery, Bosch adapter, 3D-printed parts, 600Wh adapter, etc.), so I only need to remove the 4 screws of the battery cover to switch back to the 800Wh battery.

4 x Battery protection foam for Mondraker Crafty Carbon – 099.25089
Reference: 099.25089
The battery protection foam helped me fill the 8 mm gap between the 400Wh battery and the battery cover. The battery doesn’t rest directly against the cover like the 600/800Wh ones do.
This can also be done with other materials such as foam or a plastic piece.

M4X6L screws Mondraker (sold individually) – 099.25052
Reference: 099.25052
I also got extra screws because I think they can be easily lost.

 

[ntm95]

finaly finish to adapt the 400w battery to my Mondraker Crafty. First ride this afternoon to see if there are e difference

400w battery with cover, adater, screw,... = 2.5kg
800w battery with cover, adater, screw,... = 4.3kg

Weight total for bike with 400w battery = 23.5kg

Odd, my size large crafty with a coil shock, dh tires, heavy alloy wheels, 223mm rotors, and a 600wh weighs 22.5 kg/49.5 pounds.

 

[Davzell]

Odd, my size large crafty with a coil shock, dh tires, heavy alloy wheels, 223mm rotors, and a 600wh weighs 22.5 kg/49.5 pounds.View attachment 171238

Yes, strange. The weight announced by Mondraker is 24.4 for the RR 2025
Minus 1 kg because you’re using the 600 battery, so it should be 23.4
Maybe you changed other parts? And that: did you weigh it yourself?

 

[ntm95]

Yes, strange. The weight announced by Mondraker is 24.4 for the RR 2025
Minus 1 kg because you’re using the 600 battery, so it should be 23.4
Maybe you changed other parts? And that: did you weigh it yourself?

Yup, calibrated luggage scale. It tracks with my other bikes, same weights as on friends scales.
Only thing I can think of is that the ohlins 38 is lighter than a fox or zeb, carbon cranks, carbon bars, wolf tooth dropper, etc.
As for the mondraker advertised weights, it is 22.9kg/50.5 pounds for a crafty xr with the heavy (and not so great) onoff dropper/stem/bars/grips.

 

[Davzell]

Yup, calibrated luggage scale. It tracks with my other bikes, same weights as on friends scales.
Only thing I can think of is that the ohlins 38 is lighter than a fox or zeb, carbon cranks, carbon bars, wolf tooth dropper, etc.
As for the mondraker advertised weights, it is 22.9kg/50.5 pounds for a crafty xr with the heavy (and not so great) onoff dropper/stem/bars/grips.

Oh, but it’s an XR. I was thinking of a modified RR.
Yes, the XR is much lighter, but also €3/4,000 more expensive than the CRAFTY R
I had compared the RR SL and R, and indeed it gains 100–200 grams on each component (crankset, handlebar, wheels, etc.) to end up losing a few more kilos.

 

[ntm95]

Oh, but it’s an XR. I was thinking of a modified RR.
Yes, the XR is much lighter, but also €3/4,000 more expensive than the CRAFTY R
I had compared the RR SL and R, and indeed it gains 100–200 grams on each component (crankset, handlebar, wheels, etc.) to end up losing a few more kilos.

I hadn't realized there was that much difference between them. I wasn't seeking out an xr when I purchased this, it was a lightly used demo selling for $9k cad/5.5k euros. That's about what the crafty's all sell for around here in the fall, new or used.
Certainly an argument there for switching to the carbon rear triangle and rocker link to lose weight first rather than going straight to the 400wh battery.
I guess if I want to get crazy, I could drop another 1.5 kg off with the 400wh and some carbon wheels.
46.2 pound full power with decent suspension... that 400wh battery is growing on me .
My primary use of this crafty xr is bike park self shuttling, and I could have one battery charging at the van while I'm riding the other .

 

[Davzell]

I hadn't realized there was that much difference between them. I wasn't seeking out an xr when I purchased this, it was a lightly used demo selling for $9k cad/5.5k euros. That's about what the crafty's all sell for around here in the fall, new or used.
Certainly an argument there for switching to the carbon rear triangle and rocker link to lose weight first rather than going straight to the 400wh battery.
I guess if I want to get crazy, I could drop another 1.5 kg off with the 400wh and some carbon wheels.
46.2 pound full power with decent suspension... that 400wh battery is growing on me .
My primary use of this crafty xr is bike park self shuttling, and I could have one battery charging at the van while I'm riding the other .

Good price for a 2025 XR! I actually hadn’t thought about the rear triangle, but as soon as you switch to a carbon rear triangle, you lose 600–700g.

I don’t know if you can buy that separately, but I think it must be quite expensive. Carbon wheels might be a better option to improve the riding feel, save some weight, and especially because you can keep them for your next bike

 

[Bogdan_CH]

Odd, my size large crafty with a coil shock, dh tires, heavy alloy wheels, 223mm rotors, and a 600wh weighs 22.5 kg/49.5 pounds.View attachment 171238

I guess 22.5 is without pedals right?

My R has been quite well on a diet ( Carbon bars & cranks, carbon wheels, full X0 trasmision light, One Up dropper & lightrr saddle, Alloy chainring) not with intention but still there.

With the 600wh, mine is 22.6 kg without pedals. The rear triangle and link is 550 grams acconding to Mondraker but unfortunately they cannot be purchased, but theoretically going full carbon with a few other small bits ( lighter discs?!?) I could reach 22 kg in full enduro setup.

The 400 could be Intersting but I have other bikes for park so not sure if it's worth the hassle.

By the way how's the Galfer Shark discs combined with the Mavens? What pads your using in this combo?

View attachment IMG_6488.jpeg

 

[Davzell]

I guess 22.5 is without pedals right?

My R has been quite well on a diet ( Carbon bars & cranks, carbon wheels, full X0 trasmision light, One Up dropper & lightrr saddle, Alloy chainring) not with intention but still there.

With the 600wh, mine is 22.6 kg without pedals. The rear triangle and link is 550 grams acconding to Mondraker but unfortunately they cannot be purchased, but theoretically going full carbon with a few other small bits ( lighter discs?!?) I could reach 22 kg in full enduro setup.

The 400 could be Intersting but I have other bikes for park so not sure if it's worth the hassle.

By the way how's the Galfer Shark discs combined with the Mavens? What pads your using in this combo?

View attachment 171282

Could you give the exact names of the parts you chose
I’ve looked quite a lot at carbon wheels but not yet at the other parts.

 

[ntm95]

I guess 22.5 is without pedals right?

My R has been quite well on a diet ( Carbon bars & cranks, carbon wheels, full X0 trasmision light, One Up dropper & lightrr saddle, Alloy chainring) not with intention but still there.

With the 600wh, mine is 22.6 kg without pedals. The rear triangle and link is 550 grams acconding to Mondraker but unfortunately they cannot be purchased, but theoretically going full carbon with a few other small bits ( lighter discs?!?) I could reach 22 kg in full enduro setup.

The 400 could be Intersting but I have other bikes for park so not sure if it's worth the hassle.

By the way how's the Galfer Shark discs combined with the Mavens? What pads your using in this combo?

View attachment 171282

That's with raceface atlas v2 pedals.
I like the galfers, they resist warping very well.
Not a huge fan of the maven's, but it seems like every new bike I've purchased comes with them.