Fuses in High Amps Setups ?

[El_Steak]

This is a continuation of the fuse discussion started in the Zippy Flightmax / Turnigy lipo testing thread. It was off-topic in that thread so I moved it here.

I want to add shorts protection to a 24s Lipo setup - 100V / 75A (Cycle Analyst-limited) and I'm not sure which way to go.

The "standard" fuses available at the hardware store seem to max out around 40 amps.

Then there are "MAXI" fuses that seen to max out around 80 amps.

Higher than that, I saw a lot of "Fusible Links". They seem to go up to 140 amps. Not sure if those are the same as fuses though.

I also saw some DC-breakers up to 150amps. Not sure if they'll like 100V though:

So what are you guys using to protect high-amps setups?

 

[gwhy!]

I use standard blade fuse in parallel . A 20A fuse should blow around 30-40A..

edit: just realised how much voltage you are talking about you might want to consider a different type of fuse One that will not explode if it sees a extreme current, blade fuses are only rated upto about 50v.

 

[methods]

Maxi fuses are expensive but you can find them at local automotive stores.
Paralleling fuses is probably wise especially considering that whatever fuse holder you use will probably be of a small wire gauge.

Dont get caught up in the exact value or type. Just pick up something that is available, affordable, and about what you think you will need.

-methods

 

[SpeedEBikes]

For easy availability and affordability I like blade fuses.

I get 30 packs of 30 amp and 40 amp blade fuses for ~$8 from a local auto parts store. Online you can get 10 packs for $1.55 plus ~$8 shipping.

However, the blade fuse holders are crap - high resistance connections that worsen over time. So mostly I just solder a bit of 10 gauge wire directly to the fuses and solder on my favorite connnectors (currently 5.5 mm bullet connectors from HobbyKing). I make up a few spares and also have a couple holders wired up for backup/troubleshooting/testing with other fuse ratings. I sand the gray scale off the terminals with emery paper and then dip them in flux before soldering.

Although these fuses are only rated for 32v I've been using them at up to 90v without incident (other than melting holders). They can detonate pretty hard at higher voltages so it is prudent to provide a little physical/mechanical separation from anything fragile or flammable.

I've never had an issue using them in parallel or series.

 

[amberwolf]

Higher than that, I saw a lot of "Fusible Links". They seem to go up to 140 amps. Not sure if those are the same as fuses though.

These are common on powerchairs and wheelchairs as primary protection. Big UPS systems for servers, like the APC 2200 I got for parts and batteries also use them. That UPS had one on each battery string. The powerchair battery boxes I've had so far use them one per battery string, or for the ones that have only one battery (group 24, usually) per box, there is also then one fuse for each battery.

I am using a breaker on mine, the same one used on some really heavy duty powerchairs. Takes a while to pop on overload, though (at least several seconds), so it's possible to blow up the controller or damage the motor while waiting for the disconnect.

 

[heathyoung]

Car audio fuses + holders are great for this...

 

[El_Steak]

Great suggestion, I hadn't looked into audio stuff.

I could protect each LiPo pack with an AGN fuse in an holder like this:

The holder is just 3$ and the fuses are dirt cheap. It accepts 8 Gauge wire.

 

[heathyoung]

Most of them have adaptors that also come out and you can use 4 gauge wire as well (and there are some that hold 0 gauge!) - easy

 

[jag]

This is a continuation of the fuse discussion started in the Zippy Flightmax / Turnigy lipo testing thread. It was off-topic in that thread so I moved it here.

I want to add shorts protection to a 24s Lipo setup - 100V / 75A (Cycle Analyst-limited) and I'm not sure which way to go.

The "standard" fuses available at the hardware store seem to max out around 40 amps.

Then there are "MAXI" fuses that seen to max out around 80 amps.

Soldering in two standard cheap blade fuses in parallel (30,35 or 40A) will likely do. Current might be slightly unequal in each due to varying resistance, hence 2x30A in parallel might blow at less than double the current of one. However this is unlikely to be a problem in practice.

For a proven high current single fuse solution you could get a glow plug fuse from am old Diesel car or truck in a junkyard. A 6 cyl with typical Bosch plugs (e.g. out of a Volvo Diesel or similar VW/Audi) will be fused at about 75A. An 8cyl will be about 100A. The fuse is really just a metal strip. The fuse holder a plastic box with screw terminals usually screwed to the firewall. Replacement fuses are a $ or so at Diesel parts stores. (A side benefit: Lacking a fuse it is possible to jam a dime into the holder... b.t.d.t.)

You could also just solder in a short piece of thinner wire, so that this wire will burn first (instead of any expensive stuff). This is usually what I do. I'm surprised methods didn't suggest this solution...

 

[magudaman]

I've heard of the cheap AGU fuse holders being really bad to the point of melting the internal solder of the fuse from so much resistance. I bought a fuse holder today that uses Midi fuses. Hadn't ever even heard of them or seen them till today and they really seem to be a perfect size for up to 150 amps. The holder was pricey at $20 and 4 fuses were $10 but it seem like a balance between weight and low resistance. Check'm out:

Extra large mouse pad ^^^

 

[amberwolf]

As an alternate to finding sockets for the "maxi" size of Littelfuse brand fuses, one could just do as APC has done in at least their rackmount version of the 1400 Smartpower UPS. I was cleaning one up today, pulling out the very very dead SLAs in it and temporarily hooking it up to some bigger ones I have as spares for my traction pack, and it used hard-plastic-shielded spade lugs to plug a 65A maxi littelfuse into.

There are two of them in there, one on each paired series 12V 7Ah battery set. Then the whole pack plugs into the UPS board cable via a 60A gray Anderson.

 

[MrKang]

i also use those car audio fuses. namely because i can fit all 6 lipo wires in it.

and i use a car automated fuse 150A which goes into the controller. never had a shortcut but to be sure it is installed for safety

 

[El_Steak]

Here's a great document outlining the differences in size, weight, capacity and response time for the major types of fuses:

http://www.pirate4x4.com/tech/billavista/PDFs/Blue_Sea_fuses_and_fuse_blocks.pdf

ANL fuses seem like a good option, they go up to 300 amps and they are pretty cheap at 10$ for 10 on ebay. They are big though, 2.5 inches long!

The mini ANL fuses (midi) as posted by megudaman are much smaller and still go up to 150amps. Couldn't find them as cheap as the full size ANL but still affordable.

 

[SniperGaulois]

THANKS FOR THIS THREAD!

ANL Fuses sound good! say if you have sustained 35amps/50v, choosing 32V or 12V doesnt matter : would 32v 100amp be recommended over 12v 200amp?

What about magnetic curcuit breakers same as they use in households? If the amps are too high, the wire heats up, the magnet flips, and the cuircuit is saved! are they only AC? I love magnetic household cuircit breakers! the feeling of flipping the switch and the electricity comes on again without fiddling with fuses. possible?

The perfect fuse would be a magnetic fuse with adjustable Amps rating, so you can turn a screw on it and gradually adjust the ampers limit from 30 to 100 volts for example, to find the perfect rating for you bike!

 

[Ricky_nz]

THANKS FOR THIS THREAD!

ANL Fuses sound good! say if you have sustained 35amps/50v, choosing 32V or 12V doesnt matter : would 32v 100amp be recommended over 12v 200amp?

Nither.

for 35A / 50V You need a 35Amp fuse. using a 100Amp or 200A fuse offers no protection for a 35A system!
You also want a fuse rated for at least the voltage you are trying to protect otherwise there is no gaurantee it will break the DC current under fault conditions.

 

[SniperGaulois]

for 35A / 50V You need a 35Amp fuse.

The 12v - 40A blade fuses blow all the time on an ebike, at 50v they are taking 3x as much energy as designed for. and the fuse holder melts too.

Any types of standard blade fuse holders that dont melt?

Would you really say that a 40A fuse is much safer than a 50A one on a 35A bike?

 

[NeilP]

Another possibility
http://export.rsdelivers.com/product/littelfuse/04980900zxt/fuseholder-bf1/5489183.aspx

or the Maxi fuses
http://www.technobotsonline.com/fuses-and-fuse-holders/automotive-fuses/maxi-automotive-fuses.html

http://www.technobotsonline.com/maxi-blade-fuse-holder-30430.html

 

[auraslip]

None of these fuses are rated above 32v. How important is that anyways?

 

[NeilP]

the ones i linked to are, they go up to 100 amps

 

[NeilP]

ooops you said volts not amps

 

[NeilP]

I found this

Voltage Rating
The voltage rating, as marked on a fuse, indicates the maximum voltage of the circuit for which the fuse is designed to operate safely in the event of an overcurrent. Basically, you don’t want any potential sparking to negate the operation of the fuse.

 

[peterperkins]

Breaking High DC currents at above ~32v or so requires specialised fuses as a self sustaining arc can develop when the fuse blows and it basically just keeps passing current until everything has melted The higher the voltage the worse the problem. High voltage DC fuses are filled with an arc quenching material and cost a fair bit more. Make sure you get a correctly rated fuse, AC rating is not the same as DC where fuses are concerned. :wink:

 

[auraslip]

Breaking High DC currents at above ~32v or so requires specialised fuses as a self sustaining arc can develop when the fuse blows and it basically just keeps passing current until everything has melted The higher the voltage the worse the problem. High voltage DC fuses are filled with an arc quenching material and cost a fair bit more. Make sure you get a correctly rated fuse, AC rating is not the same as DC where fuses are concerned. :wink:

TL;DR everyone here is using the wrong types of fuses (myself included)

Actually, one of the advantages of fusing each parallel group of lipo packs is that the voltages should be less than 32v ~

 

[parabellum]

I already use AC breaker as switch not really as fuse. I did it on 2 setups and it seems that 40A breaker is sometimes switching off at about 60A DC on 24s lipo. But I’m still unsure how DC and AC current correlate. I shot about 80A trough 50A breaker at 60V and nothing happened.
Some one know how to match them?

 

[vanilla ice]

You can score high amp DC fuses/breakers from broke/trashed UPS power supplies. Some of the larger ones are 24v or 48v.