Properly Rated Fuses for an eBike

[Gionnirocket]

In my other thread on my first build I asked if anyone was fusing their motor... Since then, I've been doing a little research.
I still haven't decided on whether or not to fuse the motor, but add ons such as lights probably should be.

Seems that finding a DC fuse rated above 32V is not as common as one would think. In my research I've come across several that say a standard 32v automotive fuse is what is being used...
Having an electrical background, I have to disagree. It may work most of the time, but using an electrical component above its rated limit is flirting with disaster. Since adding protection is the goal, I don't understand taking the risk.

So far Littlefuse FKS ATO® STYLE BLADE FUSE RATED 80V seems to be the most practical solution... Though they don't seem to be readily available, especially in the smaller sizes.

https://www.mouser.com/Circuit-Protection/Fuses/Automotive-Fuses/_/N-ba8b5?P=1yocc0hZ1yx4attZ1yth2yu&gclid=EAIaIQobChMI3df2v_Cw6QIVFGKGCh35BwZQEAAYAiAAEgLtTfD_BwE

So I'll ask the question again... Anybody fusing? And if so what and how?
Danke

 

[Gionnirocket]

Another option... Maybe even more suitable for motor protection due to the time delay characteristics. They didn't show up in a search on the Littlefuse website but I did get the spec sheet via online request.

Again not readily available.

 

[Gionnirocket]

... and lower ampere ratings for accouterments such as lights

 

[harryS]

Not fusing. The first three batteries I owned had rubber gaskets covering openings in the cases for fuses, but there were no fuse holders inside.

Accidental shorts from exposed prongs on XT connectors touching screws and rivets are the only shorts I've seen, and that was Luna's fault for wiring male XT's to the battery. I changed them.

 

[Gionnirocket]

I guess fuses aren't for everyone.
My thoughts are if a <$10 investment can possibly save part of a $1000 in hardware, I'll give them a try. If anything it'll keep me out of trouble for a few more hours while I cut them in.
I've been living in my house for 25 years now and have never tripped a circuit breaker... but I'm still glad that they're there

 

[Gionnirocket]

I ended up going with the FKS ATO 80V BLADE FUSES and so far with about 200 miles traveled since installed I haven't had any problems.
I added a 20a for the motor and a 4a for a future light/horn accessory tap. While riding I have spiked it once to 20a and a few times to 18a without it blowing... But as I get the feel of things and experiment less I'm thinking that should happen less as well.
I'm keeping a pair of spare fuses on board... and just in case I've cut them in using XT60 connectors so I can easily pop them out of the series in an emergency to get home.

 

[curt]

What is the proper amp for Rad Rover, 30 or 40?

 

[tomjasz]

Save your money. If you're running 1500-8000W motos, learn about fusing. However I do buy controllers, 750-100W, with the ability to use a key switch, I use a rocker switch and I do fuse it.

 

[Gionnirocket]

What is the proper amp for Rad Rover, 30 or 40?

You'd have to be more specific about which one you have.
A quick google yields a hub motor @750w/48v. In this case I would suggest starting with 20a and moving up to 25a or 30a if you get nuisance trips.

Note that the purpose of this thread was to highlight using the proper voltage rating. Choose a fuse with a minimum rating of 48v and make sure that it is a DC voltage rating.

 

[curt]

I have a 750w/48v.

 

[Gionnirocket]

I have a 750w/48v.

Then as stated above. There are a few variables to consider when fusing which is how the motor is used and how hard you intend to push it... But the general rule for the best protection is to use the smallest fuse that doesn't present a nuisance.
Using a 30a or 40a fuse will basically protect against short circuit and not much protection from overload.
I'm using a FKS ATO 20a (80V) on my 750w/48v mid_drive and have yet to have it blow. I do not ride the motor hard in general.

 

[curt]

Then as stated above. There are a few variables to consider when fusing which is how the motor is used and how hard you intend to push it... But the general rule for the best protection is to use the smallest fuse that doesn't present a nuisance.
Using a 30a or 40a fuse will basically protect against short circuit and not much protection from overload.
I'm using a FKS ATO 20a (80V) on my 750w/48v mid_drive and have yet to have it blow. I do not ride the motor hard in general.

I intend to use the bike for casual riding, sometime commute to work (12 miles round trip). Paved asphalt trail. I do not intend to push the motor hard at all. Thanks.

 

[AHicks]

Curt, the issue is that you can "cheat" on the electrical ratings, going to a draw that's WAY higher than the rating (safely!), but you can only do that until things start getting warm.....

I have 3 bikes with 500w motors, all using aftermarket KT controllers that will basically pass anything available from the battery right on through to the motor. All 3 will show 1000w or better at wide open throttle. This makes for a pretty awesome bike for getting across a busy road, climbing a short hill, or catching up to a riding buddy. So that in mind, getting back to your question, how would you fuse these bikes? Remember, the connections right at the fuse need to be able to handle some pretty serious power, or you'll just introduce potential for ANOTHER place for the electrical system to fail.....

The reason I bring this up is I'll bet if you look at your display, on occasion betting you'll see readings much higher than 750w. If you have your system fused for just 750w, you're going to be blowing that fuse constantly - especially when the motor really starts working. Like when climbing a hill, trudging across soggy grass, etc.

To each their own, but I'd just as soon make sure that the wires are properly sized for their expected loads, have been installed and secured in a manner that insures no possibility of shorting, and leave it at that - like the manf's do. That's me though, FWIW. -Al

 

[gromike]

Maybe on my next build I'll use one of these.

 

[Gionnirocket]

Maybe on my next build I'll use one of these.
View attachment 152777

I'd mount it in place of my rear shock

 

[6zfshdb]

I often use 48 & 52V batteries with no built in switch. I use this circuit breaker which acts as both a fuse and a disconnect point.

https://www.amazon.com/gp/product/B08V8K4F4N/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1

This also solves the potential problem of fuse arcing.

 

[Gionnirocket]

I often use 48 & 52V batteries with no built in switch. I use this circuit breaker which acts as both a fuse and a disconnect point.

https://www.amazon.com/gp/product/B08V8K4F4N/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1

View attachment 152812

This also solves the potential problem of fuse arcing.

Very nice... I'll have to keep this in mind for the future.
I installed a separate switch (low current via the BMS) for ease of access and appearance so fuse arching isn't an issue.
I find having a shut off without having to unplug anything invaluable