# Best fuse location in the battery pack



## Tahoe Tim (Feb 20, 2010)

Corbin,
Controller wiring schematics show the fuse as close to the positive post of the pack as possible, before the main contactor. 

With a split pack, I would put the second one at the positive post of the front pack. Some people also put a secondary contactor to remove power from the front pack. I am going with two main contactors, one at pos end of pack and one at negative end of pack.

Check the drawings in the back of the warp drive manual.


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## corbin (Apr 6, 2010)

Tahoe Tim said:


> Corbin,
> Controller wiring schematics show the fuse as close to the positive post of the pack as possible, before the main contactor.
> 
> With a split pack, I would put the second one at the positive post of the front pack. Some people also put a secondary contactor to remove power from the front pack. I am going with two main contactors, one at pos end of pack and one at negative end of pack.
> ...


Oh yeah, I forgot about the WarP manual having a recommendation -- I'll look into that! 

I am also using two contactors -- I have them outside the entire pack; one on the positive side controlled by the WarP Drive Controller and another on the negative side controlled by "key on" - basically what the WarP manual says. 

In the picture I attached my front pack is on the bottom right, and the rear pack is the top left. Doesn't it make more sense to have the second fuse right off the positive of the rear pack? (Note: I'm ignoring the 5 extra cells placed horizontally). That way, a short between the front and rear pack will blow that fuse. Attached is a new diagram showing the location I'm now thinking.

thanks!
corbin


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## Tahoe Tim (Feb 20, 2010)

The Warp manual talks about additional contactors and how to properly wire up your precharge circuit. From your drawing, I assume that your items labeled "fuse" are the contactors. The idea behind putting them as close as possible to the positive of the pack groups is to make your wire from end to end of the car not live.

try to visualize disconnecting the main lead from a group of packs - is the wire in your hand still live? The contactor does the disconnecting for you. 

I am wiring my warp with the second contactor on the negative end of the pack. Place them as close to the pack as possible. On your firewall front and read should be good.


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## corbin (Apr 6, 2010)

Hi Tim -- 



Tahoe Tim said:


> The Warp manual talks about additional contactors and how to properly wire up your precharge circuit. From your drawing, I assume that your items labeled "fuse" are the contactors. The idea behind putting them as close as possible to the positive of the pack groups is to make your wire from end to end of the car not live.


No -- I do mean fuses. I'm trying to figure out where to put the second fuse. I know for sure that the first fuse should be off the main positive side of the pack. Most wiring diagrams that I see don't include a second fuse, which is why I'm not sure.



Tahoe Tim said:


> try to visualize disconnecting the main lead from a group of packs - is the wire in your hand still live? The contactor does the disconnecting for you.
> 
> I am wiring my warp with the second contactor on the negative end of the pack. Place them as close to the pack as possible. On your firewall front and read should be good.


Yup, mine are in the same location within the pack. I think putting the second fuse right off the positive of the first half of the pack is the best location; that way if there is a short, it will separate the two packs right at the source.

On unrelated stuff: when do you think you'll have your Wombat running? I go up to Tahoe quite a few times during the summers -- mainly for mountain unicycling trips at Northstar, the Tahoe Rim trail, Mr Toads, etc. I'll have to stop by your shop and say "hi" during this summer.

corbin


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## Tahoe Tim (Feb 20, 2010)

We are waiting on the Calb cells to arrive any day. We just have to make the battery racks. I installed the car pc and wired up the headlights, flashers, etc into the touch screen software. I am shooting for March for a big expo in the casinos. I live in South Lake Tahoe. My shop (Winters Electric) is on Lake Tahoe Blvd and is easy to find. You are welcome to stop by any time.


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## ElectriCar (Jun 15, 2008)

What touch screen are you working on Tim? I'd like to have more data at my disposal but only have a PakTrakr, which isn't very reliable.


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## major (Apr 4, 2008)

corbin said:


> Where is the best location to locate the fuses?


Hi corbin,

A fuse is a circuit protection device. Like the circuit breaker panel in your house. Where is it located? As close as possible to the service entry (where the power comes into the house). In your EV, the fuse should be as close as possible to the source, which is the battery. It should be inside the battery box or directly adjacent to it for protection of the cables running from the battery to the rest of the equipment. If you have a split battery arrangement, you should have a fuse with each group of batteries.

The above describes the main fuse(s). These need to be properly sized for rated voltage and full battery current.

There is a secondary function for a fuse. That is to protect the device and wires running to it. This may be a lower power rated device like a DC/DC converter running on full battery pack voltage. Such a "branch" circuit may only require 10 amperes from the battery and use maybe #16 wire. That branch circuit should then be fused at slightly above 10A, like at 15A as near as possible to where that branch breaks out from the main battery circuit.

For your EV, and where to put the fuse, imagine an accident and you're trapped inside and the responders have the jaws of life cutting away your car to get your limp butt out of there. That big cutter goes right thru your battery cables and shorts out positive to negative. If the fuse is in your battery, it will blow and do its job and all will be fine. If that fuse is up front and the cables are cut between the fuse and the battery pack, and the pack is shorted, the fuse will not blow and the battery pack will supply full current to the short and overheat in a few seconds, catch on fire, explode and kill everyone in a 20 mile radius. Well, not quite that bad, but if it scares the EMS guy enough to stop saving you, it might be bad news for you or your family.

Put the proper fuses in the proper places.

major


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## Ziggythewiz (May 16, 2010)

major,

thanks for the explanation of the jaws shorting scenario...I suppose that's one's negated in my car as the power cables never run together (pos runs up passenger side, neg on driver's side.

What other major shorting scenarios are there to consider?


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## ElectriCar (Jun 15, 2008)

Ziggythewiz said:


> major,
> 
> ...I suppose that's one's negated in my car as the power cables never run together (pos runs up passenger side, neg on driver's side...


I did mine the same way but I'm changing it due to EMI issues. I think that may be why I'm having so much trouble with the PakTrakr also. I didn't think about EMI when I ran them.

Here's some wording from the National Electric Code, though it doesn't regulate vehicles, the practice of routing conductors together still applies. *
"Conductors of the Same Circuit. All conductors of the same circuit...shall be contained within the same raceway..."*


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## Ziggythewiz (May 16, 2010)

Interesting EMI info...I'll have to watch for any interferece with all the electronics in my '74 bug.

As for the code...*"Conductors of the Same Circuit. All conductors of the same circuit...shall be contained within the same raceway..."*
The HV lines are all inside the vehicle, which doesn't even go on the raceway...as for the 12V lines, well half of those ARE the vehicle, so not sure how to apply the code


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## major (Apr 4, 2008)

Ziggythewiz said:


> What other major shorting scenarios are there to consider?


In EV racing we have to consider rollover  And then there is always the pesky controller failure which locks you into full motor power. And especially with a series motor, you may have more wheel torque than your brakes can stop. So having a fuse which will blow slightly above your routine current requirement will protect you from the high currents you would encounter with a shorted controller and full brake pressure.

And then probably the most common short-----the dumb guy with a wrench  Hey.....been that guy myself 

Be careful out there,

major


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