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bangood chinese cheap EUC issue


Pingouin

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Hi,

I bought a new wheel, just a cheap chinese wheel from an individual who couldn't manage to go on it. There is an issue, it shuts down and doesn't start without the charger if the battery level indicator is at 2 of 4 lights. It's under charge, at top speed or acceleration, if I leave it still it stays on forever.

I took a picture of the maiboard, there is a loose connector and I don't know if it's supposed to go somewhere, it's voltage is the same as the battery. When the EUC shutsoff, if I take the voltage of the battery, it indicates 62.2V.

What do you think, is the battery dead ? Or is it a cell that is not balanced ?

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1 hour ago, Pingouin said:

. It's under charge, at top speed or acceleration, if I leave it still it stays on forever.

@Pingouin I have absolutely no idea what you are saying in the above sentence?  Are you saying the charger light never goes off? I can't see where top speed and acceleration fit in the same sentence or work out what happens at top speed or during acceleration?

If a wheel shuts down and will only recover after it is connected to the charger, when this has been reported in the past this seems to indicate that the BMS protection circuit has activated.

if, as I think you are saying, the charger stays on all the time but the voltage gets no higher than 62.2V then that is pretty much equal to 15 cells fully charged. Assuming you have actually checked this is a 16 cell wheel then you may indeed have one completely failed cell. You would need to check that the charger is actually capable of reaching 67.2V to confirm it is not a charger fault, but if the BMS is kicking into protection and the charger never goes to its fully charged indication that would also suggest a possible cell fault.

As for the floating wire, I've seen pictures like that before, you might want to see if you can find some shots of the TG-T3 control board as I think it may be very similar? What is on the other end of that pair of wires? As a minimum connecting to the control board you should have:

5 wires going to the Hall effect sensors in the wheel.

3 thicker power wires to the wheel

2 wires going to the on/off switch

a bunch of wires going to the LED battery level indicator

2 thick wires going back to the battery/BMS.

2 wires from battery/BMS to charger socket.

Anyhting else is likely to be optional (speakers, lights, buzzer, etc.)

 

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Hi,

I mean that the wheel shuts off under acceleratio and speed, but if I let it rest powered on against a bench for example, it won't shut off.

No I mean that the wheel shuts off when voltage drops below 62.2V with the wheel resting, but it hoes up to it's max voltage.

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9 minutes ago, Keith said:

Anyhting else is likely to be optional (speakers, lights, buzzer, etc.)

A TG T3 was my first wheel, the least expensive wheel I found to start on.  I don't think there any options on a 270 dollar wheel:(  Mine had very little range and power, it was said to be 132wh, but the time to go from 4 leds to 2 leds was so fast that I also suspected a bad battery.  @Pingouin  you may have got a faulty wheel, please if you can get a different wheel, I've heard good things about the TG F3 which has twice the battery, and costs not that much more.  A big name wheel like Ninebot Solowheel Gotway Kingsong Inmotion Ips would be best.  Check the number of posts in all the different brands on this forum homepage for an idea which ones seem to be the most popular.  I think TG T3 is okay, but not for heavy person like me.

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I can't get it changed because I bought it second hand from an individual. Thing is it seems to work fine until the batteries capacity is half empty.

This was supposed to be my training wheel but it seems I don't have any luck with EUC...

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Well it's really a ridiculous range, I need to measure, but 4-5km at 10kph is ridiculous. I would like it to work normaly..

It's my training wheel, for learning stunts...that's why I bought it.

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@Pingouin, OK that makes more sense. In all probability the battery is a low capacity 16S1P setup and, in fact, I suspect 62.2V is a red herring. It is not the powered down voltage that is important - it is the powered up and under load voltage. I.e. The BMS is seeing the voltage under load drop too low and is protecting the battery by shutting down.

I am now not at all sure you have any faulty cells, I suspect the battery is only a single set of 16 mediocre cells in which case sagging down low enough to trip the BMS in use after around 5Km is probably correct.

Really the issue here is probably a very old and very well documented problem - the BMS dangerously being in control of the power output. see this thread below on how to fix it: if you do open up the battery pack to fix the BMS then check the voltage across each cell is close to the same, if one or two cells are failing they should be noticably different voltages to the others.

 

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7 minutes ago, Pingouin said:

Ok, I've shunted the middle mosfet, it works ! now the wheel doesnt' shut off, however, I only get about 5km range at slow speed, the battery must be dying..

Thanks for your help

Just be careful with a possible dead cell! Noone wants to get burning EUCs in the media :( or in the own house...

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It doesn't seem like a dead cell considering that the voltage is normal, I think it's the electrolyse that doesn't go well inside the cells, probably because of a bad storage and use by the previous owner, but I'm happy I just needed it to learn new stunts, not for commuting I have another one for that.

It cost me 166$, I kind of expected a bad battery, but not it making me fall ^^

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54 minutes ago, Pingouin said:

Ok, I've shunted the middle mosfet, it works ! now the wheel doesnt' shut off, however, I only get about 5km range at slow speed, the battery must be dying..

5 Km range is nothing unusual with cheap EUC with such low capacity battery. It depends greatly on your weight so of course lighter riders will get further.

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2 hours ago, Pingouin said:

Well I'm 60kg, and it's a 67V 2200mah = 132Wh, I should get a little more of a new battery no ?

Depending on riding conditions and speed I'd expect 6 to 7 Km with your weight at least. However keep in mind that nominal capacity of the battery is not what you can actually pull out of it during ride. That would be closer to about 100Wh only. Basically all those low budget wheels are good as initial trainer wheel but you'll outgrow those pretty fast and will start looking for something faster and with larger range. You can also try to add second battery pack to this wheel which will more then double distance if it's worth the hassle for you.

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2 hours ago, Pingouin said:

Well I'm 60kg, and it's a 67V 2200mah = 132Wh, I should get a little more of a new battery no ?

@HEC, above is spot on, there is a good discussion on range at the forum link below. It does also really depend how you are using it as well as your weight. For example, I joined a rollerblading ride through London that lasted 2 hours, we only did 8 miles (13Km) and my 340Wh battery was completely flat. There was a lot of idling at traffic lights, crossroads, etc, lots of accelerating and braking and it all took big chunks out of the capacity. Greatest range will only occur on the flat with no wind and cruising at a constant fairly low speed.

Ironically, if you added a second 132Wh battery in parallel you would get more than twice the range as each battery would be working less hard so would have more usable capacity and lose less as heat in the battery as total internal resistance would also be halved. Top speed is probably set in the firmware though so you may not go any faster, unless it is just the drop in battery output voltage that is keeping you slow.

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After testing it, going for stops and goes, backward riding but mostly cruising around 10kph, I get 7km range without the wheel beeping for the low battery, maybe it's got some range back because of the charge/discharge cycle ?

7km seems to be pretty reasonable for this kind of wheel what do you think ?

For adding another battery pack, where could I fit it ? I do have several batteries from my broken F528 (4 132Wh packs), however I don't know how to solder them either.

For the driving, It feels alot like the F528 in it's smoothness but with less punch, and in the turns, like the MCM4.

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@Pingouin Yes 7Km seems reasonable enough.

You do not need to do any soldering to add a second pack in parallel, you will need (obviously) a physical space to put it. Wheels like the KingSong KS-14 have the control board on top just under the handle that gives both side panels for batteries but it looks like your control board is in the way in one side panel and you will not be able to change its orientation.

if you can find a space all you need is something like the parallel XT-60 connector I found here:http://www.hobbyking.com/hobbyking/store/__10265__XT60_Harness_for_2_Packs_in_Parallel_1pc_.html and pictured below you could also parallel the charging with a parallel Dean's connector like this: http://www.hobbyking.com/hobbyking/store/__23131__T_Connector_Harness_for_2_Packs_in_Parallel_1pc_.html.

There is only one thing to be absolutely careful about: You must ensure both packs are at the same voltage when you connect them together.  If one is more charged than the other very high currents will flow between the two.

image.jpeg

image.jpeg

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You will not have (cannot have) a battery without a BMS unless all 17 balance wires are fed out of the battery to an external balancing circuit, or one of the other pack's balancing circuit in exactly the same way your drone batteries balance lead is fed out seperately. One make of wheel (I have forgotten which) does have the BMS as part of e main board so all 17 balance leads plug into the main board but it is fairly unusual.

in the event you really do have a battery back with no BMS and no external balancing leads I would throw it away as after a while the imbalance would be enough to have destroyed several cells.

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It looked like the balance wires where going from the batteries to the main battery BMS but I'm not sure because my F528 at a friends place and I don't remember exaclty..

I'll look what I can do when I get it back, but still wonder where I could put an extra battery ^^

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2 hours ago, Pingouin said:

I have one of these for my drone, but I wonder, the F528 has 4 batteries linked together, should I choose one of the batteries without the BMS or with it ?

Do not separate the batteries of the Firewheel, unless you know what you're doing! Firewheels use a very different setup than pretty much any other wheel:

F132:  132Wh - single 16S1P-pack with BMS
F264: Two 132Wh's in series; 8S2P per pack, one pack has the BMS
F528/F779:  Four packs in series, 132Wh per pack for F528, 174Wh per pack for F779  (F779 is not really 779Wh! Only 696!), 4S4P per pack, one pack has the BMS

That makes it very difficult to use the packs separately, as you need to remove the balancing wires, get a 16S BMS and rewire the entire pack (including the connections between cells!) yourself!

I plan on dismantling my F264 packs at some point, but I use the cells separately for other projects.

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