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Switch enabled shunt mod attempt? + other small bits


andrewk

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Hi Everyone,

I shunted my generic x3 clone EUC last night using the guides from @hobby16's thread (thanks!). I decided to do go for a best of both worlds situation and add a switch to the shunt as I got paranoid about overcharging/overheating and over depleting the battery. So now when using the EUC I plan to keep the switch on to avoid another unexpected shutdown and face plant and when charging the device I'll flick the switch off to re enable the BMS protection. Is my logic right here? And does sound like a good idea or was this a waste of time?

I have also done some other small bits and bobs - had to replace the piezo speaker as during a crash the speaker stopped working and when I took the device apart I could see the solder joints had ripped off the speaker as it had rattled around inside the device (wasn't glued down properly to begin with). I have also applied a layer of hot glue to  the top of the replacement piezo speaker I installed to attempt to muffle it a bit, still a bit too loud for my liking though. 

I replaced the pads on the side with thick foam pads to replace the crappy little red rubber mats that it came with as they bruised the crap out of my shins/calves.

I lost the cap for the charger so I had to makeshift one out of a plastic cap and I've also attached velcro strips to the pedals to hold them up! Had to do this as the grubs that you can tighten to hold the pedals kept coming loose, to the point where they would be completely unscrewed and almost fell out of grooves before I noticed last second! I have since balled up some blue tac and left in the the grub slots so they can't fall out, guess it wouldn't really matter if they did since I use the Velcro straps now anyway. 

Any thoughts? particularly on the switched shunt mod. I've attached some pics.

Thanks,

Andrew

 

 

IMG_8147.JPG

IMG_8148.JPG

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Hello. You said "the solder joints had ripped off the speaker". I wanted to remove the beeper as the wheel gives plenty of signs you go too fast. So I heated the solder from below while pulling the beeper, but what happened is that the pin came out of the beeper and not off the card ! So some weakness in beeper set, probably, as you had. I understand your beeper is glued ? Not mine.

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27 minutes ago, andrewk said:

Hi Everyone,

I shunted my generic x3 clone EUC last night using the guides from @hobby16's thread (thanks!). I decided to do go for a best of both worlds situation and add a switch to the shunt as I got paranoid about overcharging/overheating and over depleting the battery. So now when using the EUC I plan to keep the switch on to avoid another unexpected shutdown and face plant and when charging the device I'll flick the switch off to re enable the BMS protection. Is my logic right here? And does sound like a good idea or was this a waste of time?

Imho this was a waste of time - at least regarding the reasons you mentioned. Overheating and over depleting the battery is not handled by the BMS. Overcharge protection is not affecting anyway by the shunting.

The MOSFETs from the BMS which are to be shunted following the guides from hobby16 are only in the "discharge" path and limiting the available current while riding the EUC. The overcharge protection  is in the "charge" path and only looks for overvoltage. 

So the overcurrent protection you shunted is not active while charging and your switch will not have any effect for this...

The only use for this switch i could think of is, that you can turn it of while you are storing your EUC and in case some wiring gets loose and would cause a short in the main battery path the overcurrent protection could become active. But for this imho the chances to happen are way to low.

You payed attention that the switch you used can handle the current?

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26 minutes ago, Chriull said:

Imho this was a waste of time - at least regarding the reasons you mentioned. Overheating and over depleting the battery is not handled by the BMS. Overcharge protection is not affecting anyway by the shunting.

The MOSFETs from the BMS which are to be shunted following the guides from hobby16 are only in the "discharge" path and limiting the available current while riding the EUC. The overcharge protection  is in the "charge" path and only looks for overvoltage. 

So the overcurrent protection you shunted is not active while charging and your switch will not have any effect for this...

The only use for this switch i could think of is, that you can turn it of while you are storing your EUC and in case some wiring gets loose and would cause a short in the main battery path the overcurrent protection could become active. But for this imho the chances to happen are way to low.

You payed attention that the switch you used can handle the current?

Lol oh dear, may have been a waste of time. I read something that someone posted in that thread that lead me to believe it could be potentially dangerous - that it could overheat at any time.

Good point about the switch, I actually didn't think to check that. The spec of switch is:

"A slim line rocker switch with a black body and black rocker. The switch is rated at 6A/250Vac and has a single pole single throw latching action. Requires a 6.8 x 19 mm cut out. Fitted with 4.8 mm faston terminals."

Will this be okay ? 

Thanks

1 hour ago, Maxime said:

Hello. You said "the solder joints had ripped off the speaker". I wanted to remove the beeper as the wheel gives plenty of signs you go too fast. So I heated the solder from below while pulling the beeper, but what happened is that the pin came out of the beeper and not off the card ! So some weakness in beeper set, probably, as you had. I understand your beeper is glued ? Not mine.

Hi Maxime,

I'm not sure I totally understand the question sorry. 

My piezo speaker wasn't glued properly so when I crashed, it moved about a lot inside the casing and one of the solder joints disconnected from the speaker board and ripped the  solder point from the speaker board too. In the end I picked up a replacement speaker from Amazon and re installed it. I then tried to muffle the speaker as much as I could by applying a layer of hot glue to it, covering the speaker holes etc. there are probably better ways to achieve this effect so maybe don't do it as once your speaker it covered in glue there's no going back ?

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3 hours ago, andrewk said:

f switch is:

"A slim line rocker switch with a black body and black rocker. The switch is rated at 6A/250Vac and has a single pole single throw latching action. Requires a 6.8 x 19 mm cut out. Fitted with 4.8 mm faston terminals."

Will this be okay ? 

If it's rated for 6A then it is dangerous as the BMS cuts off at 60A :o

Edit: Still, you've done a nice clean job on the switch! I'd keep it and re-purpose it for something else like hook it up to the speaker so you can disable that, or set up another battery pack inside there and use it to power some LEDs. :D 

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1 hour ago, andrewk said:

Lol oh dear, may have been a waste of time. I read something that someone posted in that thread that lead me to believe it could be potentially dangerous - that it could overheat at any time.

Good point about the switch, I actually didn't think to check that. The spec of switch is:

"A slim line rocker switch with a black body and black rocker. The switch is rated at 6A/250Vac and has a single pole single throw latching action. Requires a 6.8 x 19 mm cut out. Fitted with 4.8 mm faston terminals."

Will this be okay ? 

 

As @Tom wrote that's dangerous! 

As long as the the BMS is not cutting off, you could have good luck and the main current flows over the MOSFETS and not over the switch. But once the BMS cuts off in because of overcurrent the whole current has to go over your switch! If he then goes up in smoke you face plant again... ;(

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Haha, thanks for advice guys, oh well - left the switch in place but removed the cabling for now and directly shunted the device instead. Good idea with the LED's @Tom, that might be a winner! My generic EUC doesn't have speakers so couldn't use it for that lol. It's a shame as I was also pleased with how it looked:)

@Chriull thank you for picking up on this and saving me from another fall!

Edit: just a thought - is there anyway to confirm a shunt mod has definitely worked other than using myself as a test subject ?

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7 hours ago, andrewk said:

Haha, thanks for advice guys, oh well - left the switch in place but removed the cabling for now and directly shunted the device instead. Good idea with the LED's @Tom, that might be a winner! My generic EUC doesn't have speakers so couldn't use it for that lol. It's a shame as I was also pleased with how it looked:)

@Chriull thank you for picking up on this and saving me from another fall!

Edit: just a thought - is there anyway to confirm a shunt mod has definitely worked other than using myself as a test subject ?

You would need a test circuit that would draw above the 30A or 60A or at which current the BMS would normally cutoff for a short period of time, so you could test that your shunt "holds" and everything works, without stressing the batteries too much. Imho not really worth the effort...

Just make optical double check that you really shunted at the right place and have nice soldering joints.( See here for some good and bad examples: https://learn.adafruit.com/adafruit-guide-excellent-soldering/common-problems ) Also, like suggested in another thread, making the shunt with a small piece of copper thread helps you to prevent bulky soldering joints...

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51 minutes ago, Chriull said:

You would need a test circuit that would draw above the 30A or 60A or at which current the BMS would normally cutoff for a short period of time, so you could test that your shunt "holds" and everything works, without stressing the batteries too much. Imho not really worth the effort...

Just make optical double check that you really shunted at the right place and have nice soldering joints.( See here for some good and bad examples: https://learn.adafruit.com/adafruit-guide-excellent-soldering/common-problems ) Also, like suggested in another thread, making the shunt with a small piece of copper thread helps you to prevent bulky soldering joints...

 Thanks for the link. I probably used a little too much solder but I am confident it's a good joint. If I have time tonight when I get home I'll take a pic. 

My particular generic EUC battery matched this pic so I did the shunt in the same way. 

BMS.jpg.af9134a4b53494a5f14010e8842e130c

I think my 2 unexpected shutdowns have scarred me lol. I'm now feeing anxious when riding in case it was to happen again. 

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  • 10 months later...

Hi,

I had 4 faceplants in the last month since I've my generic x3 (clone)

The first 2 were at low speed and I keep standing up, going 2 meters ahead. These faceplants or unexpected shutdowns were riding in a square, so no climbing.

The 3rd was this monday or tuesday and I was returning home from that square. It's a little hill and I put my hands on the floor. no injuries but almost :)

And yesterday I started climbing that mini hill (is a street, not a hill) and after 3 meters it stopped suddenly (NO BEEPS) and I put my hands and my knees on the floor, and this time I have a little pain on it :(

I'm waiting for a new battery because mine is a second hand unit and maybe the battery is defective, because I can't do more than 2 km of range.

I hope the new BATT will give me more range and less faceplants.

But reading your posts....I think it's normal :( 

the best solution is doing the mod ? I'm scared about explosions or fire if I do it :(

thanks

 

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