Confused about fuses.

[Bgt2u]

I have 4-48v batpacks, two 48a controllers (moving up to 2-55a controllers soon), and two 1800w 48v Boma motors. Each batpack has it's own fuse holder. I currently am using one 25A fuse in each. The fuses are 12v automotive blade type. Being that thay are rated at 12v, does that create a problem? I am thinking about bypassing all four fuses, and using a single 48v fuse. Is that a better idea? Also if the single fuse is a better option, what size would be the best for my application?

 

[PullHorse]

I got you thinking about it!

 

[Bgt2u]

Yes, you did.....Thanks to you, l am questioning my own work.....lol

 

[PullHorse]

I got a 10awg in line holder and then a few 50s, a 60 and an 80 in case. I'll start with 50 unless someone says otherwise.

Not to go off topic but where did you mount your shunt on your cart for the meter? I think I ordered the same one and this might be a stupid question but does it have to be out of harms way? Do you mount it near the controller and run wire to the front?

 

[Bgt2u]

I have not received it yet. I ordered the 300a version. I am going to mount it under my (phone) speedometer, and run the needed wires down the steering mount/shaft. The actual shunt will be mounted very close to my controllers. I beleive you can mount it wherever you want to, however do not let it get wet. I also am using 10awg wire. I have enclosed a photoshopped picture of what l am intending to do.

 

[PullHorse]

Looks good. I must of been mistaken maybe I got the same meter as the OP of the previous thread we were in. Thanks for info on shunt. I'll mount it in box holding controller and run wires. I also recently found brake sensors! That's what I'll need to install to get the controller and physical brakes synced I think.

 

[Bgt2u]

I'm glad you got the sensors, you should be all set now. What shunt/meter did you get....post a pic if you can.

 

[PullHorse]

 

[Bgt2u]

Thanks for the pic. I almost purchased that same one. I didn't, because of the max shunt amp rating, as l am using two controllers with double amps. I ordered the 300a just to be extra safe. I did like the display on yours better, as it is less confusing, and easier on the eyes to see.

 

[itsid]

voltage rating is actually important..
not as important as a current rating of course, but you shouldn't rely on a 12V fuse being accurate for a 48V system.

it'll trip too early (say on 20Amsp than the rated 25 Amps or so)
how early is not exactly clear without testing the exact style of fuse from the exact manufacturer..

So check littelfuse.com for properly voltage rated fuses instead...

'sid

 

[Bgt2u]

Will do, thanks for the link. Should l go for the single fuse option, and ifso, what approx amps?

 

[itsid]

Uhm.. I'd say I'd go for two fuses one per controller and motor

as I said before I wouldn't parallel the two batpacks at all I'd keep them fully seperated.

that way two fuses suffice to keep controller and battery safe (amperage depends on the lower value of either battery or controller)
I think you too have a 32A controller, right? 35A then (unless the battery can't handle that much)

if you insist on merging the batteries into one splitting that back up again,
two 35A (one per controller)
and another that can handle the max load of the batpack but no more than 70A;
(say a 65A?) to protect the battery from shorting or overheating.

'sid

 

[Bgt2u]

Sid, l am taking your advice, and wiring the controllers seperately. It still will have 2 batpacks wired parallel to each controller, (as l have a total of 4 batpacks). I am currently using the two poorly designed, crappy 48a controllers. Yes, and one of those is the one of the one that hadthe mysterious green wire issue. I have attached the specs of the 4 batpacks that l have. I was reviewing the specs for my batpacks, and it has four discharge rates. They are as follows:

Peak discharge current 50a
Rated discharge current 20a
Continuous charge/discharge rate 40a
Maximum continuous discharge rate 20a

https://ibb.co/JBbbgP9

From what l can figure, each motor and controller would need a single 100a fuse, connected to two parallel batpacks, connected to single 50a fuse, wired diectly to the 48a controller. Does this seem at all correct?

 

[itsid]

Oh..
so you should stick with ~20A per battery
in parallel that's 40 Amps for a set of two ...

Frankly, if your toying with the idea of exceeding those 40 Amps for prolonged periods of time, I'd spend the vehicle another two sets of batteries to up the battery amps to hopefully perfectly save 60A.

I don't trust chinese ratings no longer (for obvious reasons I think)
So the lowest is what I'd stick with not to blow anything up.
assuming the 40A as a one minute peak and the 50A as a ten second peak (can't tell for sure)

I'm still not sure I'd fuse it higher than 50Amps per pack of two.

the joy of cheap lithium cells are endless.. that is if you enjoy a good campfire
else they're very much limited (as we already discussed )

IDK man.. please stay safe!
rather blow a fuse than your kart or worse your behind.

IMO still way more fun to go 20mph in a kart than
60mph in an ambulance with 3rd grade burns

'sid

 

[Bgt2u]

Sid, I agree about the ambulance ride...lol. Wow, this (what should be) fairly simple stuff, can get confusing. Okay then, let me get this straight, so l can stop bothering you, and avoid any unnecessary hospital stays.....l should be fine, if l use just ONE single 50a fuse (due to controller's needs, and while protecting the batpacks also), that comes off of the two parallel batpacks, connected directly to the controller. Totalling TWO 50a fuses for the entire cart. Please tell me I've finally got it correct this time! I will definantly upgrade with two more batpacks, once l get the Kelly controllers. Thank you for your patience with me.

P.S. I added a picture for some fuses/breakers, that l am considering. Are they any good for my application?
https://ibb.co/3yNhPS7

 

[Functional Artist]

You probably already know
...but, I'ma gonna throw this in the discussion anyways

The fuse is supposed to be the "weakest link" in the system
..if sized "too big" the next weakest link, whatever that may be (a part in the controller, a wire, a connection etc.) in the system "becomes" your fuse

So, I usually try a fuse on the "smaller side" & work my way up (if necessary)

FYI:
My !Arriba! kart has (2) 48V, 1,000W MY-1020 clone's on it, powered by (4) 12V 12AH SLA's
...& I've run it with (1) 12V 50A circuit breaker (never once tripped it)
…& now I'm runnin' it with just (1) 12V 40A fuse without any issues
...& that's while poppin' wheelies
(I used the 50A circuit breaker on Damien)

https://www.youtube.com/watch?v=DEJQl4b-8Ow

* When in doubt, always listen to Sid, he knows his stuff

 

[Bgt2u]

Yes, l am very aware of your Arriba. I watched (and studied) all of your videos on YouTube. Chains popping off, dual throttle set up, you crashing, your daughter's test drives...etc. As a matter of fact, your Arriba is actually what inspired me to build my EV. Because of yours, l have mine. That is also why l use the two motors in the back. So, thank you! As far as the fuses go, yes, l am aware of what you mentioned, however, l do like the way that you laid it out. I do have a question for you though. Is it better to put a (4 pole) switch before, or after the fuses, or does it not make a difference? I am using a 4 pole switch, so that l can shut off all of the batpacks at once, but still can charge them individually, because each has it's own BMS. Oh, and yes, l always listen to Sid, he definitely knows his stuff. I do however take any input from any other member, as that is why we are all here, to share ideas, information, and knowledge, isn't it?

 

[Functional Artist]

Yes, l am very aware of your Arriba. I watched (and studied) all of your videos on YouTube. Chains popping off, dual throttle set up, you crashing, your daughter's test drives...etc. As a matter of fact, your Arriba is actually what inspired me to build my EV. Because of yours, l have mine. That is also why l use the two motors in the back. So, thank you! As far as the fuses go, yes, l am aware of what you mentioned, however, l do like the way that you laid it out. I do have a question for you though. Is it better to put a (4 pole) switch before, or after the fuses, or does it not make a difference? I am using a 4 pole switch, so that l can shut off all of the batpacks at once, but still can charge them individually, because each has it's own BMS. Oh, and yes, l always listen to Sid, he definitely knows his stuff. I do however take any input from any other member, as that is why we are all here, to share ideas, information, and knowledge, isn't it?

Wow!, that's so kool!
...glad I could help/inspire ya

From what I understand, it's usually best to have the fuse located as close to the power source (battery) as possible.
...that way, if something goes wrong, the power gets chopped/disconnected, right there at the source

A (4) pole switch?
...is it rated to/can it handle the amperage that your system can apply/draw thru it?

Yup, sharin' knowledge is what it's all about.

 

[Bgt2u]

"Help inspire ya", is an understatement. I just happened across your videos, while looking for something interesting to watch on YouTube, and said.."That's soo cool". I had never even considered the elecrtic route before, but it looked so cool, and fun, that l figured I'd give it a shot, and build something along those same lines as you.
I am a retired Electro/Mechanical/Structural Engineer, and an A.S.E certified technician. l however, had absolutely no knowledge of what anyone used for parts, or where to start on a little project like this. The Arriba is even why l decided to go with a 48v system, and that particular brand of motors. I did not realize that you, on here, were the creator of it? So, take all of the credit...You and your Arriba alone, were my only motivation to take on a little EV project.....
Okay, back to the discussion (l got side tracked). Ya, the switch is only rated at 32a at 12v, so, it will probably end up frying, but that's all l could come up with so far. I do have four of them on hand, so l could use two of them, (or all four of them for that matter), one for two batteries, splitting the amps. If it fails, l suppose l could use 4 automotive type cut off switches, or l could use 4 fuse/breaker combo's (maybe 20-30a, instead of two 50a) like l posted earlier in this thread...IDK..
l simlpy need to find a way to be able to charge all the batpacks seperately, and am trying to figure out a simple way to do it, without constantly plugging and unplugging wires. Do you have any suggestions? Some of my methods are questionable at best, because, I try to use stuff that l have available around the shop as much as possible, due to my wife......oops, l mean budget...lol.

P.S. l have included some pictures of a few of my other creations (there are many others). I do realize that this forum, is not dedicated to these types of projects, however, l just felt you might be interested. https://ibb.co/4NQjCqs
https://ibb.co/mtvFRbN
https://ibb.co/PmZhgYD
https://ibb.co/SwXbjSF
https://ibb.co/56Rjk1y
https://ibb.co/SNVqGdJ
https://ibb.co/nwhC9Xj
https://ibb.co/2yCXjRq
https://ibb.co/DCnhz2k

 

[itsid]

love the bike (that a Honda fat cat or Yamaha BW?)
a tr7 is cool..
and that white-thing.. am I hallucinating or are those E36 doors?
(you need to sand that rough spot down a bit on the front )
rough like that it looks like papier-mâché (and being white doesn't help with that LOOL)

'sid