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Eek, I might have a battery issue ...


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I have a 100v Begode Nikola. I tend to ride conservatively (20-30mph), let the battery get down to 40% then recharge fully, let the charger go green then leave it there for an hour afterwards to balance. The wheels been behaving perfectly but ...

After last charging it I noticed the voltage reading on the side said 95.5V rather than 100V. The EUC app said 96.4V and said 90%. It should be reading 100V after the charger has the green light showing for an hour. I'll admit I don't normally read the charge after charging it, I just assume it's at 100% though it has read 100V (or 99.9V in the past). I do read the charge mid week just to check I'm not running low and the lowest I've ever been is about 86V (30%).

What do I do? I read that I need to check the charger is running to 100V but the pins are very close together and it worries me I'll short something. I've never taken the wheel apart but I'd probably be fine doing this. On Friday the weather is supposed to be good so I was going to leave it on charge all day and see if that alters things. The wheel normally lives in my house but I'm  a little worried now. I can put it in my garage but I have a lot of toys in there. Only other choice is leaving it outside in the garden with a cover but I live in the UK and the weather isn't great this time of year.

Thoughts?

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1 hour ago, mike_bike_kite said:

I have a 100v Begode Nikola. I tend to ride conservatively (20-30mph), let the battery get down to 40% then recharge fully, let the charger go green then leave it there for an hour afterwards to balance. The wheels been behaving perfectly but ...

After last charging it I noticed the voltage reading on the side said 95.5V rather than 100V. The EUC app said 96.4V and said 90%. It should be reading 100V after the charger has the green light showing for an hour. I'll admit I don't normally read the charge after charging it, I just assume it's at 100% though it has read 100V (or 99.9V in the past).

That sounds bad - about 4.2V missing could be a whole cell (group) gone bad...

1 hour ago, mike_bike_kite said:

I do read the charge mid week just to check I'm not running low and the lowest I've ever been is about 86V (30%).

What do I do? I read that I need to check the charger is running to 100V but the pins are very close together and it worries me I'll short something.

Measuring the charger is the first step. Get someone with a steady hand ;)

As chargers have a current limiting (first stage of charging is constant current) they should survive a short circuit - for a short time - hopefully  - but better not to burden the chargers... 

Insulating gloves should be very recommended! 100V DC are not recommendable between both hands...

1 hour ago, mike_bike_kite said:

I've never taken the wheel apart but I'd probably be fine doing this.

Then you could measure the charger voltage at some wires inside the wheel after the charge plug. With batteries disconnected to get the charger no load voltage. Additionally you can measure the battery voltages how far below this charger no load voltage their voltage is after charging - if at all. Could be just the motherboard voltage measuring off..

Also chances are high that only one of the battery packs is bad - so charging one after another will show which packs are good and which are not. (Just performing this test can show you the problem without any measuring in case it is really a bad battery pack, which i'd assume)

Do not connect packs again to the wheel if they have different voltages! Measure the voltages before connecting! (Try to get differences somewhere below 0.5V) As they are paralleled they will create huge currents to settle the voltage difference...

1 hour ago, mike_bike_kite said:

 On Friday the weather is supposed to be good so I was going to leave it on charge all day and see if that alters things.

Long charge duration do not really help with balancing. Better do take a little ride and charge again. Let the battery rest for some half hour to finish balancing and start again with a short ride, charge, rest, ...

If you see a rise in voltages over the cycles balancing helped.

1 hour ago, mike_bike_kite said:

The wheel normally lives in my house but I'm  a little worried now. I can put it in my garage but I have a lot of toys in there. Only other choice is leaving it outside in the garden with a cover but I live in the UK and the weather isn't great this time of year.

Thoughts?

Outside without shelter in UK now will kill the wheel. Condensation will corrode the battery packs...

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27 minutes ago, Chriull said:

Measuring the charger is the first step. Get someone with a steady hand ;)

As chargers have a current limiting (first stage of charging is constant current) they should survive a short circuit - for a short time - hopefully  - but better not to burden the chargers... 

It turned out the charger was the female end so testing wasn't as difficult as I thought it might be. Mine has 5 small sockets arranged in a circle with a small indent to make sure you insert it correctly. If I measure the 2 sockets either side of the indent I get 100.3V however, if I measure any other combination of sockets (I tried all combinations), I get nothing. Is that correct? 

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1 hour ago, mike_bike_kite said:

It turned out the charger was the female end so testing wasn't as difficult as I thought it might be. Mine has 5 small sockets arranged in a circle with a small indent to make sure you insert it correctly. If I measure the 2 sockets either side of the indent I get 100.3V however, if I measure any other combination of sockets (I tried all combinations), I get nothing. Is that correct? 

Ok - so the charger is fine and it's time to open the wheel and check the packs:

2 hours ago, Chriull said:

one of the battery packs is bad - so charging one after another will show which packs are good and which are not. (Just performing this test can show you the problem without any measuring in case it is really a bad battery pack, which i'd assume)

Do not connect packs again to the wheel if they have different voltages! Measure the voltages before connecting! (Try to get differences somewhere below 0.5V) As they are paralleled they will create huge currents to settle the voltage difference...

You should prepare yourself to get a new battery pack. ;(

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I'm probably going to wait till the weekend before taking the Nik apart but I have a few questions: Why did only 2 of the wires from the charger carry a voltage when there's 5 connections? Where do you buy a replacement battery pack (mine's a 1800W Nik+ so I assume I'm looking for a 900W)?

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1 hour ago, mike_bike_kite said:

Why did only 2 of the wires from the charger carry a voltage when there's 5 connections?

EUC power connectors often have pins unused - I think it's more about providing a connector unique to that series of wheels so it can't easily be mis-plugged into any other.

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They change the charge port when the voltage changes. They don't necessarily use all the pins. 

The other pins can be used for DIY beefing up the charge port to take a quick charge. 

Use a multimeter on the charge port (carefully) and measure the voltage. Compare the value with what is being reported by the app (check at the same time). Inform us here both values.

Don't worry too much about the wheel bursting into flames. That happens after continued riding with a dead cell group.

The best thing you can do (IMO) is to attach balance leads. Long term, that would allow you to keep riding for a several years even with a problematic pack. However, that is a bit time consuming and DIY. What you could do instead is to charge the packs individually. If you can identify which pack doesn't take the full charge you can swap it out or service it. In the meantime, the other pack is good and you could ride the wheel with a single pack, as long as you limit the current draw to about half. 

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22 minutes ago, alcatraz said:

They change the charge port when the voltage changes. They don't necessarily use all the pins. 

The other pins can be used for DIY beefing up the charge port to take a quick charge. 

Use a multimeter on the charge port (carefully) and measure the voltage. Compare the value with what is being reported by the app (check at the same time). Inform us here both values.

You don't mean the charge port of the wheel?

Measuring there is either useless or dangerous?!

If it's protected (against short circuit or wrong polarity/votage) measuring will show some meaningless value. If not a short circuit will insta-melt the probe tips and send glowing metal blobs flying around...

With the pins and the port chassis around it's not unlikely to short it by accident during measurement...

22 minutes ago, alcatraz said:

What you could do instead is to charge the packs individually. If you can identify which pack doesn't take the full charge you can swap it out or service it. In the meantime, the other pack is good and you could ride the wheel with a single pack, as long as you limit the current draw to about half. 

Yes, more carefull riding should be possible. Especially at lower battery percentages.

59 minutes ago, mike_bike_kite said:

mine's a 1800W Nik+ so I assume I'm looking for a 900W)?

Yes.

59 minutes ago, mike_bike_kite said:

Where do you buy a replacement battery pack

Just looked at speedyfeet as he's the only uk shop i heard off - seems to offer this pack for a reasonable price.

There should be a number of european online shops - don't know if ordering there is still feasable from uk taxwise?

Using this problem to upgrade to some pack with some smarter bms could be nice. But don't know anyone offering such.

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Just now, Chriull said:

You don't mean the charge port of the wheel?

Measuring there is either useless or dangerous?!

If it's protected (against short circuit or wrong polarity/votage) measuring will show some meaningless value. If not a short circuit will insta-melt the probe tips and send glowing metal blobs flying around...

With the pins and the port chassis around it's not unlikely to short it by accident during measurement...

I wanted to check the accuracy of the internal volt meter. 

I recently repaired my MSX control board and now it only charges to 82.7v. The charge port shows the full voltage of 84v. 

I wish I had checked the charge port first before tearing the heatshrink off my packs, only to discover that they're fine. 

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@mike_bike_kite  You did a good thing by checking resting voltages on battery packs.  We need to spread-the-word, everybody needs to do what you did; check full-charge voltages, compare between packs where possible, never over-ride a safety-flag for 'needs repair' or 'cannot charge,' etc.  The down-side is paying for new EUC batteries.  The up-side is that your wheel rolls-on because you took an interest in maintenance  . :D  :)  :D 

Edited by Cress
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Another thing is that we don't 100% know that those 100.4/100.7 volts come from 4.2v cell groups. 

If overcharge protection has failed it is probable that we've got uneven groups.

That's where balance leads come in to provide an assurance against that.

Another thing is that we don't 100% know that those 100.4/100.7 volts come from 4.2v cell groups. 

If overcharge protection has failed it is probable that we've got uneven groups.

That's where balance leads come in to provide an assurance against that.

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20 hours ago, mike_bike_kite said:

I can test this bit now as I have 2 multimeters. One fluctuates around 100.4V and the other fluctuates around 100.7V

 

 

5 hours ago, alcatraz said:

Nice work! Happy ending.

I'd guess @mike_bike_kite just mentioned he has two multimeters and wrote their  charger voltage measurement results.

Imho no durect battery pack voltage measurement happened till now!

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1 hour ago, Chriull said:

 

I'd guess @mike_bike_kite just mentioned he has two multimeters and wrote their  charger voltage measurement results.

Imho no durect battery pack voltage measurement happened till now!

Yes that's correct. I should of explained myself better. I thought all EUCs with multiple packs would try and balance themselves (or die trying). 

I'm going to try and take the packs out today. Should I remove one pack, then record the voltage (as the wheel shows it and as my 2 multimeters show it)? Do the packs just have a simple 2 lead connection to test against or is it more complicated? Should I then use the charger, with one pack attached to see if I can reach 100V? Then disconnect that pack and reconnect the other pack and do the same tests.  

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3 minutes ago, mike_bike_kite said:

I thought all EUCs with multiple packs would try and balance themselves (or die trying). 

No - they have a synchronization wire, so the bad pack stops all packs from charging.

Otherwise it would die and we'd likely have more fire reports...

3 minutes ago, mike_bike_kite said:

I'm going to try and take the packs out today. Should I remove one pack, then record the voltage (as the wheel shows it and as my 2 multimeters show it)?

Yes, as (unlikely but possible) both packs could be ok and charge to full 100V but the mainboard reports way too low voltage.

If the motherboard is more or less accurate, it is important that you charge both packs separately with the wheel and measure the packs or note the reported voltage then.

Never connect both packs to the wheel again once they have different voltages! So disconnect the single charged pack first and only then connect the other uncharged pack!

After the second one is charged measure or note the reported voltage again.

Likely (hopefully) one charges (almost) up to the 100.4/100.7V - this is the good one.

The one just charging to ~95.5V is the bad one to be discarded/replaced/repaired.

3 minutes ago, mike_bike_kite said:

Do the packs just have a simple 2 lead connection to test against or is it more complicated?

There seem to exist different versions:

https://www.speedyfeet.co.uk/products/begode-100v-873-6wh-battery

vs

https://www.euco.us/products/gotway-100v-battery-900wh

But no matter which version voltage can be measured between the two thickest red and black wires. The thinner one(s) is/are for syncronisation (and charging).

As voltage measurement is here in no way harmful one can just measure between each black and red wire until one found some with a voltage in the right range, anyhow.

(Safety) goggles could be nice as precautionary measure.

3 minutes ago, mike_bike_kite said:

Should I then use the charger, with one pack attached to see if I can reach 100V? Then disconnect that pack and reconnect the other pack and do the same tests.  

Exactly.

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The wife is away so I have the wheel on the kitchen table. One of the pedal rods came out without a hitch. I was wondering why people used to complain about the Gotway rods. Then I tried removing the other rod - it turned out one allen keyed retainer was only just attached (one turn and it came off) then I found out the other end had long gone. The rod seems completely stuck in place (which might be a safety feature in this situation).

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1 hour ago, mike_bike_kite said:

I was wondering why people used to complain about the Gotway rods.

Yes they can cause all sorts of problems. I have an MS3 where a stone has dinged the pedal hole and slightly deformed it such that the screw stopper isn't going anywhere ever again, which is annoying as it is on the side I need to open to change tyres etc... hence a lot of holding the wheel at the right angle and twatting it until it falls out !

But you can solve your problem with 1 new hex grub and a spot of blue threadlock ! Little bit of grease on the pedal bar helps keep it all slipping about nicely and more easily extractable later.

 

Edited by Cerbera
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Posts between @Chriull and @mike_bike_kitein this thread should be saved for reference because a large number of EUCs from all Manufacturers in this and earlier generations will have battery failures as the LiIon battery ages.  Everybody needs to take advantage of safety measurements and warnings from current BMS technology and promote every effort to MAKE LiIon TECHNOLOGY BETTER until LiIon technology is retired.

If/when anybody complains about a 'false positive' BMS warning they can reference pictures of battery fires.  :wub:

@supercurio is promoting the EUCIA (Electric Unicycle Industry Association) as a vehicle to promote technological advancement in EUC design + production.  We can all wish @supercurio well with that project.  :)

Edited by Cress
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5 hours ago, Cress said:

Posts between @Chriull and @mike_bike_kitein this thread should be saved for reference because a large number of

This is hopefully already covered in the sticky topic 

With new bms showing single cell group voltages like the s22 it could need some update.

Edit: maybe also from "readability" and comprehensibility. I'm neither native english speaker nor especially gifted in sharing knowledge publicly. Seems to work much better in personal case to case support.

Edited by Chriull
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It turned out the pedal rods etc were fine, it was just that one grub screw retainer was completely hidden under hardened mud. Everything came apart really easily once I realised this. Do I have to remove both battery packs or do I just disconnect one, then see if the remaining one charges to 100V, then do the opposite. 

The battery packs are marked LG M50T 900Wh. My aim is to replace the bad pack with a new one. Is this the correct pack?

I'm off on holiday at the end of the week and was going to disconnect both packs before going - is this a good precaution all things considered?

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