What you should know about used wheels and buying/selling them here

[Chriull]

Don't miss the battery info below.

1. This forum takes no responsibility for what is sold and bought here

This forum's purpose is solely to make it easier for potential buyers and sellers of electric unicycles (EUCs, wheels) to get in contact. Please keep in mind that this forum is no sales platform and does not guarantee anything else! You are responsible for what you buy or sell here.

The moderators are here just to look that the forum rules are respected. While we may try to assist in some situations, primarily in order to keep the forum quality and standards high, do not expect dispute resolution, legal assistance, guidance, responsibility, or any other involvement from the forum staff.

Think about securing yourself before transfering money or an electric unicycle:

• Set up and agree with your sales partner all the necessary details. Maybe even in the form of a simple purchase contract.
• Inform yourself about the legal possibilities and consequences in your/your sales partner's country.
• Inform yourself about secure payment methods and possible resulting consequences. For example, Paypal (in some modes) and many credit cards can allow a buyer to dispute the transaction if there is a problem, while a bank transfer may not offer this option. This is good for both seller and buyer to know, as disputes may be justified or not.
• Or just use an established sales platform of your trust! Often this means meeting in person. This will also save you shipping costs.
• Ask questions. Ask the seller or buyer, ask the forum members for their opinion. Being stingy or vague with information is a bad sign, openness and honesty and unambiguous answers are a good sign.
• Beware of scammers and use a reversible payment method. See here.

2. Used wheels are great - what you should know

Used wheels are usually an extremely great bang-for-the-buck option for anyone looking for a EUC - you get the exact same thing as a new one (and some scratches) for a steep discount.

EUCs are very simple machines, so there is little that can be wrong with them. In fact, there are mostly only three areas of concern you should check:

• The battery
  The most expensive/important/dangerous (if faulty) part of a EUC is the Li-Ion battery pack. The cost to replace the battery comes close to buying a new EUC and is most probably above the price of a used wheel!
  If the battery does not charge to full, that is a strong sign that something is wrong with it.
  Make sure the battery charges to the full voltage, maybe with an app screenshot from the seller. Ignore the charge percentage, as 100% may not mean full voltage. But of course notably less than 100% charge percentage means the battery does not charge to full.
  There may be other (easy to fix) reasons for a battery not charging fully, for example a bad charger, slightly misbalanced cells (which would be fixed by properly charging to full once), or simply a wrong voltage report or display.
  We personally recommend every seller to look into this before selling! First this will give a better price, and second it will prevent further trouble.
  If the battery charges to full (voltage!) however, you can expect it to be good.
• There should be no obvious, serious mechanical damage to the EUC (scratches don't count!). If the wheel looks like it has gone to hell and back and is crooked, you may have a cracked shell, bent axle, stripped screw holes, and things like that which can lead to problems further on. You can always ask a seller if they had any serious crashes. The usual tumbles and falls are no problem, any cosmetic damage is no problem! We're only talking about serious crashes.
  If the wheel looks good however, you can expect it to be rock-solid mechanically.
• Unfortunately, some first production batches of wheels had some issues, like questionable boards or suspension problems, which have been fixed in later revisions. So be aware if you buy a wheel from a "problem batch" that may need some extra attention.

Don't be afraid if not everything is perfect. Just be aware of what it could mean. We ask all sellers to disclose anything "important" about their wheel, but we take no responsibility on what is sold and bought here or how it is presented.

If a EUC works (balances as it should, etc.), the battery is fine (full voltage), and everything looks good, you can expect such a wheel to work just as good as a new one (if not better*), only for a greatly reduced price! You can trust to enjoy it for a long time, most likely with no issues at all.

EUC values also depreciate fast. A top model from one or two years ago might be had for half the original price.

Warranty

Buying/selling second hand EUCs means they are not new (obviously) and maybe also the manufacturer/reseller warranty already expired or is voided by a sale. You can often continue an existing warranty from reputable sellers.

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*EUCs tend to fail right away (from the factory), or not at all. So a used wheel in good condition has been tested and has been confirmed to be solid!

Edited August 19, 2022 by meepmeepmayer

[Chriull]

A discussion topic is set up here:

 

[RagingGrandpa]

On 4/28/2020 at 7:03 AM, Chriull said:

If the battery does not charge to full, that is a strong sign that something is wrong with it.
Make sure the battery charges to the full voltage, maybe with an app screenshot from the seller. Ignore the charge percentage, as 100% may not mean full voltage. But of course less than 100% charge percentage means the battery does not charge to full.

This idea is correct, but modern EUC's have taught us a few caveats to consider:

It is normal for different control boards, even of the same model EUC, to measure voltage (and therefore %SOC) slightly differently.

Because of this variable accuracy, one healthy Sherman may report 101V, and the next healthy Sherman report 99V, for the same battery on the same charger. This is the typical measurement accuracy for low-cost, non-calibrated voltmeters (and the similar electronics in EUC controllers), and is not indicative of a problem.

(In this example, if the voltage does not reach 95V, or 90% SOC, then a real issue is more likely.)

The best way to confirm health of a battery pack is to monitor current flow during the end of the recharging cycle.
If the electrical current falls gradually over many minutes to below 0.5 Amps, the pack is healthy; if current is cut off abruptly at a larger value, or never falls below 0.5A, the pack has an internal issue.

Monitoring it can be done in a number of ways:

• Observe the EUC-reported charging current using a bluetooth app like Darknessbot or EUC.World. (Note: Gotway/Begode EUCs do not report charging current, so this method is not possible.)
• Observe the digital display of the charger (some chargers have a built-in current display).
• Connect the AC input to the charger to a "plug meter" device.
• Connect a Charge Doctor or similar current measurement device in series with the charging cable.

Ride happy!

 

Edited May 12, 2021 by RagingGrandpa