Just how cheap are chinese electric mopeds?

[auraslip]

A guy came into the community bike shop I volunteer at hoping someone could fix his ebike. What are the odds? His charger had a bad case of "wiggle to work". I took it home and promised to bring it back to his house later tonight.

The charger. OMG what a cheap POS. A tiny 2 amp 48v sla brick with no fan and makes a sound like a tiny cat in heat or as he said "the sound of electricity working" :lol: One of the caps on the board had come unloose and was flopping around. The case had come unglued, the input plug moved up and down when you plugged it in, and the real problem was with the plug into the battery pack. I tested it and could get 53v from it when I wiggled it just right. An easy fix, but when I put it back together I made a mistake. Apparently the factory in china has a different definition of N and L from the rest of the world. So when I wired the negative to N and the positive to L on the new plug I installed, the fuse on the battery pack blew. Totally my bad as I should of tested the output of the charger for polarity, and the polarity on the battery pack.

The scooter: So we were over at his place, and we took apart the battery pack. It consists of 4 12v 15ah SLAs in a plastic casing. They are wired together with what must be 14 or 16 gauge cable All the cables on the bike are SHOCKINGLY TINY. The tiny bullet connects that you might see at an automotive store rated at like 15 amps used on the phase cables are MELTING and BURNING the plastic housings. The controller is so tiny I thought it was the DC-DC. It's rated at like 18amps. On a 120lb moped ?!

Anyways, I'm about to go back over there to rewire the + and - on the scooter to western standards. Eventually I'd like to upgrade all the wiring and connections on his moped, and maybe even talk him into getting a lithium pack. He claims he gets up to about 30 mph on sla. It's really not to bad of a deal considering he got the thing for $600. I'd just worry about the mechanics of it. They bike seems solid, but who knows how it'd handle at 72v

The scooter is a PEM Pretty and I'll take a bunch of pictures.

 

[vanilla ice]

Current limiting by 16awg!

 

[auraslip]

Well that was a quick fix!
Here are the pics as promised.

Not bad for $600 new

Battery pack disassembled. The main wires only look thick compared to the tiny charge wires. Main leads are probably 12-14gauge

48v 18amp controller is the same size as my dc-dc What's with the other mark that reads 42v? Notice the melted phase cable bullets?

This is where the battery pack plugs in.

My camera battery died at this point. Irony....

I feel kinda bad because the SLAs are already a year old, and they've been sitting discharged for over a week. I measured near or less that 12vs on all of them
I measured them at 4x4x6 inches, so a 16s pack of 10ah headways should fit nicely.
If he needs to replace the batteries soon, I'll try to talk him out of SLA. Also I'll try to get a bigger controller, and thicker wires for him

 

[amberwolf]

Realistically, the problems described sound just about like most of the cheap ebike stuff as described by people jsut starting out with problems on their bike. Also about like most of teh cheap electronics and whatnot that I have tried to fix for people, of all sorts of types and things. Some of the stuff is not even "Chinese junk", but says "Made in the USA" or other places, but it is all pretty new stuff when they bring it to me. Just really crappily made.

 

[karma]

when i first got my scooter style ebike i was all grin until the problem surfaced to name a few :|

key switch
wiring
phase wires
turn signals
lights
forks
4 sla's that would leak acid all over if tipped
removable pedals that would fall off


run 60volts and those ebikes are a hoot

 

[karma]

another part to remove would be the rear trunk. rings like a wood box when riding :wink:

 

[jmygann]

36 volts ... I call it a bicycle ... gets me to town and back .....12 miles .... 18mph

no noise except for the rear box

[youtube]lCMBZA7RmMI[/youtube]

 

[dogman dan]

Looks like the biggest problem is the bullets to me. 18 amp controller doesn't need much bigger wire, but you sure can see those connectors get warm.

 

[Jeremy Harris]

48v 18amp controller is the same size as my dc-dc What's with the other mark that reads 42v? Notice the melted phase cable bullets?

The 42V marked on the controller will be the low voltage cut-off I expect. 42V is about right for a 48V lead acid battery.

As others have said the wires are probably just about OK, it's the crappy connectors that are causing the overheating problem.

Jeremy

 

[spinningmagnets]

My son losing his car license for a year was the thing that got me researching E-scoots (and then E-bikes) over at VisforVoltage (Thanks Fechter!). My original plan was to buy a 150cc gasoline scoot with a fried 2-stroke engine for about $300, and convert to electric.

Spent a lot of time digging through E-scoot posts. Thin wires, corroded dry-crimp connections, small connectors, unlabeled or wrongly labeled spaghetti-balls of wires, intermittent mystery shorts and trickle drains (on new E-scoots, not old ones!)...seems to be pretty common. Vectrix owners seemed pretty happy on average, but very high price! (nothing in the middle?), of course price slowly came down some. Upping to 60V very common, and 72V folks sounded happy.

Each Chinese E-scoot should come from the factory with a $10 digital test-meter and a basic trouble-shooting guide.

 

[Lessss]

use foam strips(the kind you put around doors) to silence the trunk rattle.

 

[auraslip]

Looks like the biggest problem is the bullets to me. 18 amp controller doesn't need much bigger wire, but you sure can see those connectors get warm.

The 42V marked on the controller will be the low voltage cut-off I expect. 42V is about right for a 48V lead acid battery.

As others have said the wires are probably just about OK, it's the crappy connectors that are causing the overheating problem.

Derp, I should've figured that out

Anyways, this got my interested in power loss from wiring resistance.I found this spread sheet meant for pro audio


Assuming full power, and that the battery and phase cables all total 20 feet. I know phase cables are at different currents, I'm not really sure how that'd work mathematically. Also this doesn't even take into account the crappy connects that are causing the heating problem. At 2000watts and 14 gauge wiring (that's what is on 9c phase cables right?) power losses were 150watts, assuming 10 feet of length.

Another thing he said was that the 25 amp fuse would occasionally blow, so he replaced it with a larger one and that didn't blow but it did cause the housing holding the fuse to melt

On subject of power losses and fuses, what do you think of these 60amp fuses I impulse purchased off of ebay for 5 bucks

Tiny little bottleneck?

 

[vanilla ice]

I have the same charger. I'll record it for you.

 

[Alan B]

Watch the voltage ratings on those fuses. Not enough for ebikes. Is that really a 6 amp unit instead of 60?

 

[auraslip]

Watch the voltage ratings on those fuses. Not enough for ebikes. Is that really a 6 amp unit instead of 60?

Maybe that picture doesn't show how big these fuses are ~

40 amp fuse vs the 60 amp fuse

They are both rated at 32vdc - what happens if you go over that? I've been using the 40 amp fuses without a problem @ 52v for some time now....

 

[Alan B]

I have some of those type 60A fuses and holders, and I was going to use them on my ebike until I found you cannot get higher voltage fuses. They make various fuse ratings in each size, current wise.

When you exceed the voltage rating of the fuse it may not disconnect reliably. Often they disconnect and then reconnect a few times. There is not enough room for the arc to go out quickly. I found some suitable fuses at Mouser but have not bought any yet.