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Razor mx500 (mildly modded monster)
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Discussion Starter · #1 ·
So I'm not sure what happened as my fiancee was using the bike but within 100 yards of the house the battery (which was showing 100% charge on the pack meter) shut down completely. Couldn't get it to do anything, even the charge meter wouldn't work. I had to plug it in for a few minutes to get it to reset.

I'm a noob to the lithium ion battery pack thing and I've never had this happen to me, even with the abuse I've put it through off road, on hills, jumps, wheelies, pulling hundreds of pounds of added weight, riding in rain and through water and so on. Can you guys she'd some light on what the hell just happened so I can try to avoid a repeat and possibly being stranded on the other side of the city?
 

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It could be your motor or speed control is going out and is starting to draw too many amps.

Watts ÷ volts = amps - efficiency

Using math we know you're 30 amp BMS is capable of 1200watts MAX!!! But a realistic 1000 Watts if you have a 800 watt motor that is dying it could possibly draw that!!!

I have even seen 600 watt motors internally short and draw double the amps.

Basically your BMS saved your butt and kept your battery pack from catching on fire and exploding like a Christmas hoverboard.

It would be strongly advisable to fix the problem before attempting to ride it again.
 

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What's your poison? Mine is 40:1
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Do you have a fuse off the pack? I have blown my buddy's 30amp fuse a few times. Replaced it and back on the road. Thats the 24v 500w motor running 36v. The lithium pack has a bms as well. Two safety items. That was under heavy load up a hill
 

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Razor mx500 (mildly modded monster)
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Discussion Starter · #4 ·
I'd like to fix the problem for sure, I just need to figure out what the problem is exactly! No I do not have an inline fuse as I figured the 30a bms was designed to essentiallybe a built in circuit breaker, although I'm considering putting one in now as it's a lot easier to replace a fuse on the fly than to reset the bms board
 

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I'd like to fix the problem for sure, I just need to figure out what the problem is exactly! No I do not have an inline fuse as I figured the 30a bms was designed to essentiallybe a built in circuit breaker, although I'm considering putting one in now as it's a lot easier to replace a fuse on the fly than to reset the bms board
Go with a 25 amp breaker
Amazon.com: Resettable 25AMP Automotive Fuse ATO ATC ATS APR Breaker Type III Thermal Circuit Blade-Style Circuit Breakers: Car Electronics

Then you can reset it if it trips you want to fuse under your BMS Max you don't really want to trip the BMS it's really bad for it and after a few times the BMS will quit working.
 

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Razor mx500 (mildly modded monster)
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172 Posts
Discussion Starter · #6 ·
Yeah definitely need that to stay working, so I'll be looking into that
 

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Razor mx500 (mildly modded monster)
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Discussion Starter · #8 ·
Alright so I meant to update everyone sooner but it's been hectic here and I been blowing stuff up lol.

UPDATE: turns out I had water built up in the battery pack. Pulled a wheelie and about 8oz of water dumped out. I had ridden it about 2 miles to the store and back in the pouring rain the day before so I guess it collected in the blue casing. I'll be working on weatherproofing it.
 

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What's your poison? Mine is 40:1
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Yeah that makes sense. You have to remember these bikes are basically water-resistant but not waterproof. One of my friends had their mini chopper out I'm pretty sure they left it outside in the rain one night and it would turn on but it would not turn the rear tire. I opened everything up and we dried it out and a day later it was working again
 

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It could be your motor or speed control is going out and is starting to draw too many amps.

Watts ÷ volts = amps - efficiency

Using math we know you're 30 amp BMS is capable of 1200watts MAX!!! But a realistic 1000 Watts if you have a 800 watt motor that is dying it could possibly draw that!!!

I have even seen 600 watt motors internally short and draw double the amps.

Basically your BMS saved your butt and kept your battery pack from catching on fire and exploding like a Christmas hoverboard.

It would be strongly advisable to fix the problem before attempting to ride it again.
Haah right.
 

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if you trip your bms, i would replace it. ESPECIALKY in a cChinese pack. I had a customer that DIY'd his bike with a 1500w brushless kit and a Chinese "20ah" battery (one glance at the battery and you could tell it was no more than 10ah). He kept tripping the bms so he wired a switch to cut power completely to the controller to reset it. Well, one day he was charging his battery and this happened:
Tire Wheel Automotive lighting Automotive tire Vehicle
 

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MobCity is doing a complete rebuild right now. Here's where we"re at so far. Got a ways to go. Original frame, motor, bars, and wheels. We're calling it "The Pheonix".
Wheel Tire Crankset Bicycle tire Bicycle frame
 

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if you trip your bms, i would replace it. ESPECIALKY in a cChinese pack. I had a customer that DIY'd his bike with a 1500w brushless kit and a Chinese "20ah" battery (one glance at the battery and you could tell it was no more than 10ah). He kept tripping the bms so he wired a switch to cut power completely to the controller to reset it. Well, one day he was charging his battery and this happened: View attachment 160931
💯 Definitely if the BMS trips more then 3 times it needs to be replaced...
 
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