What causes the fuse to blow?

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Lionstrike
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Joined: 12/19/2011
Points: 74

So I am hearing mixed reviews about the Vectrix fuse. From what I understand, the 125a littlelite fuse is by some people's account a bad idea, and horribly underrated. Others seem to have went several thousand miles without ever having any problems with the stock fuse. EVERYBODY agrees that it is a pain in the rear to change.

And I fall somewhere in between I think.... and that is to say nervous. I don't have range anxiety about my commute anymore, but I have something of a fuse anxiety. How hard can I push this thing without a "POP!!!!" and having to glide to someplace safe before the traffic behind me makes me a speed bump?

Now normally, 50mph is fine for my commute. I do however have a three mile or so stretch where that is about 10mph under speed. This creates a line of rather impatient cars behind me.

I am capable without wind resistance using the stock firmware (which I have never had a problem with in any way) of 62 mph. GOLDEN... but then there's that fuse...

I would have thought that not only the circuitry would be designed for a 125 amp limitation, but the motor controller would be set to limit amperage to less than 125a. So then... what causes this thing to blow? Defective fuses?

And then there's a post I read a while ago about someone's fuse blowing while he was doing 30mph with regen. That shouldn't be much amperage there, I've used regen from 50mph to coast to a stop without issue.

If this is true, me being ginger on the throttle does me little good. Something else causes the main fuse to blow. I am nervous about replacing it because I do not understand fully how to design a proper ICL (I think I kind of get it) and it looks extremely involved.

But the worst thing that I am doing in hopes of avoiding an unpleasant disaster is not riding my Vectrix... which I am sure is far worse for it than anything else.

Any opinions?

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HarryS
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Joined: 10/08/2008
Points: 341
Re: What causes the fuse to blow?

Sounds like you are anxious enough that you should just change it. It takes about 2h to do, disconnect batteries, lift out the rear, get to the controller, disconnect and reinstall the 200 amp fuse and put her back together. Really no big deal if you know how to work around the battery. It's just very heavy to get the battery out.
On the positive, you learn something about your bike.

aima
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Joined: 11/27/2008
Points: 58
Re: What causes the fuse to blow?

because your scooter an not afford so big current.it's nothing to do with your fuse,if you change a 200a or 300a fuse,the you have to change your battery,motor or controller.
But fortunately,most supplier exaggerate the discharge current to meet customers for high speed,security regardless of the performance and inherent limitations of motor,controller and battery.
Endless sympathy for you!

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antiscab
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Joined: 07/07/2007
Points: 1599
Re: What causes the fuse to blow?

Lionstrike wrote:

I am capable without wind resistance using the stock firmware (which I have never had a problem with in any way) of 62 mph. GOLDEN... but then there's that fuse...

I would have thought that not only the circuitry would be designed for a 125 amp limitation, but the motor controller would be set to limit amperage to less than 125a. So then... what causes this thing to blow? Defective fuses?

And then there's a post I read a while ago about someone's fuse blowing while he was doing 30mph with regen. That shouldn't be much amperage there, I've used regen from 50mph to coast to a stop without issue.

Battery current limit on the controller is ~230A

A 125A fuse won't blow straight away at 230A, it takes ~20-30sec IIRC

repeated current above 125A actually lowers the current rating on the fuse, so it eventually blows (mine blew after 7'000km)

The fuse is sized to stop the battery wires from catching fire in the event of a short circuit.
It is only supposed to blow after your MC has failed.

The fuse is undersized, but then again so is the battery wires and battery itself.

To be honest, it takes the same amount of time to change a good fuse as a bad one
I'd just ride it till it fails, and keep a spare fuse, socket set and screwdriver.

Matt

__________________

Daily Ride:
2007 Vectrix, modified with 42 x Thundersky 60Ah
Vectrix 60Ah Lithium Tyres Fuel Registration Insurance cycle analyst replacement TC Charger
conversion
Spent so far: $5800 + $7000 + $1720 + $960 + $320 + $720 + $140 + $600
Cost to do it again: $2500 + $5600 + $1720 + $960 + $320 + $720 + $140 + $600
Cost for a Petrol bike:$6000 + + $1440 + $6000 + $800 + $1400 + $3200 servicing
Total spent: $17260
Total to do again: $12560
Total to have used a petrol bike: $18840
Total distance travelled so far: 79'120km

Lionstrike
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Joined: 12/19/2011
Points: 74
Re: What causes the fuse to blow?

Thanks for the responses all. I appreciate your time.

So if it is true that a 125 amp fuse can withstand brief periods of 230 amps, then is it also true that a 200 amp fuse wouldn't blow immediately at > 230 amps? Does it then follow that a 200 amp fuse might not provide sufficient protection to that controller?

If the main fuse blows... can I still charge the pack to keep the pack healthy while I work on the fuse?

I was also thinking (which is also dangerous) I have the stock Vectrix firmware. Despite a bunch of warnings to change that firmware NOW I have had no performance related problems with it at all. It's top speed is 62 mph. 62 mph seems less likely to pop a fuse than the 68 mph firmware. Perhaps I have that going for me at least.

Perhaps my main concern is that I do not understand inrush current limiting exactly. I really wish I could buy an ICL for the Vectrix that was plug and play so that I could make sure that I protect the $2000 motor controller inside. It would be nice to have some kind of plug and play device.

Thanks humoring a new guy, I appreciate your patience.

antiscab
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Points: 1599
Re: What causes the fuse to blow?

Lionstrike wrote:

So if it is true that a 125 amp fuse can withstand brief periods of 230 amps, then is it also true that a 200 amp fuse wouldn't blow immediately at > 230 amps? Does it then follow that a 200 amp fuse might not provide sufficient protection to that controller?

Neither fuse offers *any* protection to the controller

The job of the fuse is to stop the controller setting fire to the bike after it has failed

You can't charge without the fuse there, but there is also no self discharge, so it doesn't matter as much.

Matt

__________________

Daily Ride:
2007 Vectrix, modified with 42 x Thundersky 60Ah
Vectrix 60Ah Lithium Tyres Fuel Registration Insurance cycle analyst replacement TC Charger
conversion
Spent so far: $5800 + $7000 + $1720 + $960 + $320 + $720 + $140 + $600
Cost to do it again: $2500 + $5600 + $1720 + $960 + $320 + $720 + $140 + $600
Cost for a Petrol bike:$6000 + + $1440 + $6000 + $800 + $1400 + $3200 servicing
Total spent: $17260
Total to do again: $12560
Total to have used a petrol bike: $18840
Total distance travelled so far: 79'120km

myvectrix2008
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Joined: 09/28/2008
Points: 177
Re: What causes the fuse to blow?

I purchased my Vectrix new in September 2008 and the 125A fuse blew in April 2009 whilst riding steady at around 35mph. I think I had done around 4,500 miles.

It was changed under warranty for the 200A fuse and after reading the stories about it back then, I'm glad I have the uprated fuse fitted.

Jasper
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Joined: 08/18/2009
Points: 9
Re: What causes the fuse to blow?

My advice to anyone who still has the standard 125A fuse is to replace it with the uprated 200A fuse as soon as possible to avoid being stranded in the middle of nowhere with a dead scooter!

My fuse blew last week on my commute to work cruising steadily at 50mph; scooter just died and came to a stop, no electrics and speedo stuck on 50mph.

I’ve owned my scooter for three and half years and covering 18,000 miles. I thought it hasn’t blown yet and thought it neither would!

We all live and learn but the most important thing is to learn from others!

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Mik
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Points: 3727
Re: What causes the fuse to blow?

I think that a lot of the damage might have been caused during the "Battery recall" in 2008.

I guess that during this "Battery recall" inexperienced dealers, without access to inrush current limiters (ICL) and sometimes little support from Vectrix Corp., were taking battery packs apart and putting them back together again.

After that, they would reconnect the battery pack without using an ICL, or a broken ICL. They might also have followed the incorrect instructions that came with one of the three original Vectrix ICL designs that I have been shown (pictures of) over the years. Reconnecting the battery without using an ICL causes a very high current spike (a "transient") that can destroy the capacitors on the MC and does incremental damage to the fuses. The fuse then fails later on at a random time, usually (in my experience = three failed fuses) under insignificant load conditions.
See http://visforvoltage.org/forum/2977-open-letter-vectrix-corp#comment-45926
and
http://visforvoltage.org/forum/2977-open-letter-vectrix-corp#comment-17982

I replaced the fuse in the "Vectux" with a 150A fuse long before the official upgrade to a 200A fuse was recommended. This 150A fuse has never been subjected to inrush current and has lasted over 10000km and 3 or 4 years by now. As I lack practically all knowledge needed to determine what fuse is required for this application, I just upped it by one step (125A to 150A rating).

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Lionstrike
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Joined: 12/19/2011
Points: 74
Re: What causes the fuse to blow?

So then it is reasonable to assume that me being hard on the throttle is something of a non issue. It probably has more to do with the factory installation and ICL usage. That is going to be hit and miss I guess, but my insurance does come with roadside assisstance.
Is there danger of fire with that 200a fuse?

Jasper
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Joined: 08/18/2009
Points: 9
Re: What causes the fuse to blow?

When I replaced my blown fuse last week I bought my new fuse from my local Vectrix dealer. The 200A fuse is the recommended replacement for 125A version; part number Littelfuse L25S200.

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I will just keep riding till it goes bang!

antiscab
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Joined: 07/07/2007
Points: 1599
Re: What causes the fuse to blow?

Jasper wrote:

The 200A fuse is the recommended replacement for 125A version; part number Littelfuse L25S200.

I generally use the Bussman FWX-200, they're essentially the same

Make sure you get the new version (250vdc/vac, not the old 250vac only)

Matt

__________________

Daily Ride:
2007 Vectrix, modified with 42 x Thundersky 60Ah
Vectrix 60Ah Lithium Tyres Fuel Registration Insurance cycle analyst replacement TC Charger
conversion
Spent so far: $5800 + $7000 + $1720 + $960 + $320 + $720 + $140 + $600
Cost to do it again: $2500 + $5600 + $1720 + $960 + $320 + $720 + $140 + $600
Cost for a Petrol bike:$6000 + + $1440 + $6000 + $800 + $1400 + $3200 servicing
Total spent: $17260
Total to do again: $12560
Total to have used a petrol bike: $18840
Total distance travelled so far: 79'120km

Lionstrike
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Joined: 12/19/2011
Points: 74
Re: What causes the fuse to blow?

Thanks all.

I just got this one right here:
http://www.ebay.com/itm/NEW-Buss-Semiconductor-Fuse-FWX-200A-FWX-200-FWX200-/360208553766?pt=BI_Electrical_Equipment_Tools&hash=...

For $40 USD

:)

I can live with that. Now I am going to ride this thing until it quits, and if it does I am good to go on the replacement.

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