My unfortunate experience with Moma electric bike

[arzmikayel]

Hi everyone,

I’m sharing my experience with a fatbike from Moma Bikes Efat26. I didn’t expect top-tier quality, but what I found instead was a series of technical issues and misleading specs that I think others should be aware of.

Please not, whatever i say, is valable also for moma E-MTB 28 using the same battery and other electric parts.

Issues noticed right from the start:​

1. Battery level on the display is inaccurate — it stays full for a long time, then drops rapidly. There’s no consistent way to know how much charge is left.
2. The motor keeps pushing even after braking — when coming to a full stop, it sometimes continues to drive the wheel, causing vibrations. It’s unpleasant, and at intersections it can be dangerous.
3. Rear suspension is extremely poor quality — comparable to entry-level big-box bikes.

The real problem: the fake “48V” battery

The label says: 48V – 13Ah – 624 Wh. But after testing and some research:

• The fully charged voltage is 50.4V, which means it’s a 12s battery (12 × 4.2V), not 13s as a true 48V pack should be.
• Internally (based on teardown info from another user), the pack uses 60 × 18650 cells (2600 mAh each), in a 12s5p setup.
• The actual energy capacity is:
  3.7V×12s×13Ah=577Wh3.7V × 12s × 13Ah = 577Wh3.7V×12s×13Ah=577Wh
  That’s ~8% below the advertised 624Wh.

So the battery is not a true 48V but rather 43.2V, and the energy spec is inflated.

Controller: mismatched and potentially harmful​

The controller inside is marked 43V, with a low-voltage cutoff of 35V ±1V. That’s 2.91V per cell, which is dangerously low for lithium-ion — deep discharging like that can permanently damage the cells.

In the user notice they mention kindly: "do not fully discharge the battery, otherwise the charger may not be able to regenerate the battery". What a nice (ugly) way to put on the customer's neck the responsability for their poor conception.

One year later…​

After not using the bike for a while, I tried turning it on — nothing. The display doesn’t light up anymore. I contacted Moma’s support, and they suggested I buy a new display for €60 + €14 shipping — with no guarantee that it would solve the issue. I refused.

I checked the battery: it’s charged, voltage reaches the display and even the control buttons. So either the controller is dead, or the display is.

What I’m considering now:​

1. Replace the controller and/or display
   But the 43V controller is impossible to find. And even if I get the same one, the cutoff voltage is still unsafe for the battery. No idea if other displays would be compatible.
2. Replace the whole system
   Switch to a real 48V (13s) setup — battery, controller, and display. I don’t mind using an external battery, but the bike frame doesn’t support standard rear racks, so I’ll have to weld something custom.
3. Switch to a VESC controller
   This would let me set exact voltage limits, motor power, and even upgrade to a 13s battery later. Seems like the cleanest option, but I still need to confirm compatibility with the PAS sensor and SHENGYI DGW07 motor.

Thinking about legal action​

I’m also considering filing a legal complaint against Moma Bikes. If anyone else has had similar problems, I’d be happy to join forces.

Here are the most questionable issues:

• False advertising about battery voltage (not a real 48V)
• Inflated energy capacity (577Wh vs. 624Wh claimed)
• Dangerously low cutoff voltage, blamed on the user in the manual
• Motor doesn't cut off when braking, which violates Pedelec safety rules
• Spare parts unavailable or overpriced, with poor aftersales support

If others are interested in taking action, we’d be stronger together.

Thanks for reading — I’d love to hear if anyone else has had a similar experience.

 

[neptronix]

Tons of people who buy prebuild bikes end up in this situation with 1000's of different brands.
That's why our forum is heavy on DIY instead of buying prebuilts. Just tired of crappy designs that aren't designed to be repaired.

12s isn't the worst thing. Some cells can tolerate down to 2.5-2.8v. You'd have to find out the cell spec to find out if this is safe or not.

But overall it sounds like the way to make the bike work is to make it into a DIY bike and build it the right way.
Sounds like a controller would solve most of your problems.

 

[arzmikayel]

Tons of people who buy prebuild bikes end up in this situation with 1000's of different brands.
That's why our forum is heavy on DIY instead of buying prebuilts. Just tired of crappy designs that aren't designed to be repaired.

12s isn't the worst thing. Some cells can tolerate down to 2.5-2.8v. You'd have to find out the cell spec to find out if this is safe or not.

But overall it sounds like the way to make the bike work is to make it into a DIY bike and build it the right way.
Sounds like a controller would solve most of your problems.

Regarding the batteries indeed the ones used in Moma bike they do not survive the low voltages. I didn't write in my post but first unfortunate experience I had couple of months after I acquired the bike. Due to the non-linearity of the display of the remaining charge I almost depleted, still not fully, one stripe was remaining still, but battery died. Moma bikes are aware of this issue, otherwise they would not put in the user's notice "never discharge the battery completely". We dailyu use hundreds of devices with batteries. We discharge them, but their cut-off voltage is programmed the way not to damage the cells. Are there other bike constructors that put such an advertisement in their notice?

Anyways, now I want to keep the frame from this Moma fatbike and redo the rest (maybe also keep the hub brushless motor). What controller should I go for to solve my problems? If I go for a controller 48V, the cut-off will be far before the battery is close to depletion (safe 3V) and I will loose more than 30% of autonomy range. If I go for the controller 36V, the controller will be heavily under overtension and then the cut-off voltage will be too low risking to damage the cells. Should I opt for VESC? I heard it is difficult to make work with PAS.

 

[neptronix]

I generally like baserunner/phaserunner controllers if you want PAS because they do it well out of the box.
I'm always going for a VESC if the application has a throttle.

Google search works here, i've seen a post or two about PAS and VESCs.

 

[OlderGiantFan]

Tons of people who buy prebuild bikes end up in this situation with 1000's of different brands.
That's why our forum is heavy on DIY instead of buying prebuilts. Just tired of crappy designs that aren't designed to be repaired.

[rant]
I have no prob with DIY, but I'm old now and just want to simplify my life as I have a lot of hobbies. Why can't I buy a decent one off the shelf? One I can do my own maintenance/simple mods on... Even the high end ones selling for $7000+ are junk basically when it comes to Middrive motor/gearbox reliability

So I have to wade into the R@D swamp and mix and match bikes and motors, become a software developer (basically) so I can change a hundred program parameters just to get it to run smoothly. I seriously wonder about the future of ebiking you know. 99% of the public buy off the shelf for little joy rides around the suburb and don't care. And the manufacturers have just completely dropped the ball as far as real progress. Oh they have all the good components available, they just refuse to build them into one bike! And I can't see any reason for it, other than "built in obsolescence"? And then there are the batteries... Buying one of them is like playing roulette where the house always comes out on top. I don't usually go all Negative, I have an abundance of stuff in my life that performs flawlessly, but the business of getting an ebike up and running trouble free for thousands of miles just eludes me, that is from my readings here.

I see that Moma bikes is still selling, At the higher end €1,500 for a 250W pedal asst e-mtb hardtail, a suburb cruiser basically.
E-MTB 29” electric bicycle – Moma Bikes. Shimano Altus; Suntour fork
A replacement battery for it, €400 for 36 v with 10 ah capacity. No wonder Spain lost it's Empire lol.

"My kingdom for a horse" penned Shakespeare.
My income for a few months for a reliable e-bike say I.
/rant