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Battery relocation.

TwistedSmoke

Well-known member
Joined
Nov 19, 2016
Location
Milford ,Pa
TDI
03 Jetta tdi
Ok i relocated my battery the trunk. I ran 0 gauge positive wire to the front, and 0 gauge to the ground. But now i was thinking about adding a fuse next to the battery as a just in case. what amp fuse would i add in? I was think 250 or 300 amp but i am not sure any ideas would be great.
 

KrashDH

Veteran Member
Joined
Dec 22, 2013
Location
Washington
TDI
2002 Golf
1/0 seems way overkill for these cars, but I guess that's not a bad thing.
I built cables for my 04 Cummins. All the main cables I made from 2/0.
The alternator cable I ran 1 AWG and protected it with a 250A slow blow fuse. I would think 250 would suit you just fine for that wire. Just remember the larger the fuse (especially on those big guys) the longer they take to fail. So you could have the wiring subjected to HIGH amperage for a period of time.

I'll usually analyze the load rating for the circuit, see what the wire can handle, choose basically a good middle ground where I don't have to worry about popping the fuse when the circuit is loaded, yet it's de-rated from the wire capabilities so you're not dancing on the hairy edge of melting any wiring. Remember too, adding length of wire increases resistance therefore lowers the current rating. There are tables out there that can give you a good idea of load capacity per foot length.

Interesting mod though, would definitely clear up some space under the hood!!
 

TwistedSmoke

Well-known member
Joined
Nov 19, 2016
Location
Milford ,Pa
TDI
03 Jetta tdi
Well i used a 150 amp alternator fuse which is what the stock one ran on. I was just adding a fuse to in the trunk to protect the the main line that runs threw the car
 

KrashDH

Veteran Member
Joined
Dec 22, 2013
Location
Washington
TDI
2002 Golf
Well i used a 150 amp alternator fuse which is what the stock one ran on. I was just adding a fuse to in the trunk to protect the the main line that runs threw the car
Fuses are made to protect wiring from melting. Nothing more, nothing less. I was giving my suggestion based on wiring size. My alternator wire in my truck was used as an example because it's close to the one you're running.
 

KrashDH

Veteran Member
Joined
Dec 22, 2013
Location
Washington
TDI
2002 Golf
The starter can draw 300-500 amps... might need to factor that in depending on how you've re-wired the car.
That seems really high to me... These starters, the specs are around 1800kw...so 1800/12-ish = 150 A.

If you're drawing in the range you've listed, something isn't right.

But it depends on the starter, connections, etc.
 

Nero Morg

Veteran Member
Joined
Oct 19, 2017
Location
OR
TDI
2003 Jetta wagon, 2001 Jetta TDI, 2014 Passat TDI
Realistically I'd set it at 150a just because that's the max I've ever seen any battery fuse on any car/truck. If your starter pulls more than that, you have other issues.
 

KrashDH

Veteran Member
Joined
Dec 22, 2013
Location
Washington
TDI
2002 Golf
Realistically I'd set it at 150a just because that's the max I've ever seen any battery fuse on any car/truck. If your starter pulls more than that, you have other issues.
If you use a 150A you're likely to pop it when you try to start the car... Based on the power rating of these starters you'd be on that "fine line". With things like starters and alternators, there can be amp spikes as well, which generally exceed the fuse rating, but they're quick and don't harm the fuse

You're likely going to want to use a "slow-blow" fuse like the Mega... They're used in GM applications (a quick spike won't take the fuse out like it could a "standard" fuse)

Remember, you're protecting the wiring from overloading, not designing one to be "just a bit higher" than the load.

Ok i will add a 200 amp one as a just in case
I'd look for a 250 Mega

 

TwistedSmoke

Well-known member
Joined
Nov 19, 2016
Location
Milford ,Pa
TDI
03 Jetta tdi
Would you happen to know if these fit an ANL fuse holder. Cause i have a single large ANL fuse holder from an old project car.
 

KrashDH

Veteran Member
Joined
Dec 22, 2013
Location
Washington
TDI
2002 Golf
Would you happen to know if these fit an ANL fuse holder. Cause i have a single large ANL fuse holder from an old project car.
No, they have different hole/connection spacing. You'll need a holder specific for the mega.

That being said, I've bolted one of those mega fuses in-line in a prior application with no I'll effect, you just have to keep it from touching anything else.

I've also seen one side bolted to the battery post clamp and the other side bolted to he cable. There's a few ways to go about it.
 

Vince Waldon

Top Post Dawg
Joined
Apr 25, 2009
Location
Edmonton AB Canada
TDI
2001 ALH Jetta, 2005 BEW Wagon
With things like starters and alternators, there can be amp spikes as well
Yup, that's my point. The hp rating is a good start for figuring out typical current draw but on a cold winter morning the spikes will be higher and last multiple seconds... long enough to melt an inline fuse.

In this case the fuse the OP is proposing also has to supply 50A to the glow plugs, other electrical loads not on the X circuit, *and* the starter.
 

KrashDH

Veteran Member
Joined
Dec 22, 2013
Location
Washington
TDI
2002 Golf
Yup, that's my point. The hp rating is a good start for figuring out typical current draw but on a cold winter morning the spikes will be higher and last multiple seconds... long enough to melt an inline fuse.

In this case the fuse the OP is proposing also has to supply 50A to the glow plugs, other electrical loads not on the X circuit, *and* the starter.
100% agree, which is why I suggested the 250 for that setup, and it has to be a slow blow fuse which isn't effected by those amp spikes. If there are other things turned on as well, those count as load on the system. Another reason why when you're load testing a battery, it's good to turn on as many accessories as possible while turning the car over (ie headlights, fans, radio/sound system, etc).
 

TwistedSmoke

Well-known member
Joined
Nov 19, 2016
Location
Milford ,Pa
TDI
03 Jetta tdi
well i found a shop near me that carries ANL fuses and i tried out the Fuse box i had here with a 250 amp fuse and it worked last night and turned on the car. But for some reason today went to start it today and after the 2nd time cranking the car over the fuse popped. So what do you guys think might have cause this is maybe 250 not enough for everything in the car?
 

BobnOH

not-a-mechanic
Joined
May 29, 2004
Location
central Ohio
TDI
New Beetle 2003 manual
Well fuses also protect devices (like the ECU) from damage. Since all the devices in the car are protected and the battery is essentially always "on" I see no benefit of fusing it. A shut-off (disconnect) might be handy.
 

KrashDH

Veteran Member
Joined
Dec 22, 2013
Location
Washington
TDI
2002 Golf
well i found a shop near me that carries ANL fuses and i tried out the Fuse box i had here with a 250 amp fuse and it worked last night and turned on the car. But for some reason today went to start it today and after the 2nd time cranking the car over the fuse popped. So what do you guys think might have cause this is maybe 250 not enough for everything in the car?
I thought I mentioned this in my earlier post but maybe not...I may have just thought it.
You cannot use an ANL fuse in this application.
As Vince mentioned (as well as myself) even though the starter may have constant draw of 150A, there are/could be very high spikes in the current. ANL fuses are not meant to handle any spikes at all.
You need a Mega fuse like I suggested because they are a "slow blow" fuse that resist the high current spikes.

I'm pretty sure most parts stores should carry those mega fuses although I'm not sure if they will carry 250A ones.

Well fuses also protect devices (like the ECU) from damage. Since all the devices in the car are protected and the battery is essentially always "on" I see no benefit of fusing it. A shut-off (disconnect) might be handy.
This is a good point too. With 1/0 wire I wouldn't see the need to fuse it from the battery. In my situation I was protecting the alternator wire from overcurrent. Instead of putting a fuseable link on my alt wire (they don't make an appropriate fuseable link for 1AWG) I had to use a slow blow fuse. Instead of making my cable more complicated (something in-ine) since the alt cable connects to the battery directly, I just fused that wire alone. They make a battery terminal post mount slow blow fuse that worked perfect for my application.

OP, are you running the 1/0 to your starter too?
 
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Vince Waldon

Top Post Dawg
Joined
Apr 25, 2009
Location
Edmonton AB Canada
TDI
2001 ALH Jetta, 2005 BEW Wagon
250 amp fuse and it worked last night and turned on the car. But for some reason today went to start it today and after the 2nd time cranking the car over the fuse popped.

The starter can draw 300-500 amps... might need to factor that in depending on how you've re-wired the car.
The hp rating is a good start for figuring out typical current draw but on a cold winter morning the spikes will be higher and last multiple seconds... long enough to melt an inline fuse.
There is no fuse to the starter on the factory wiring... of this or any other car I'm aware of... and I'm thinking you're finding out why. :) :)
 

oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis (where it's safe)
TDI
There are just too many to list....
FWIW, the cars that have the battery mounted far away from the engine (like the gasoline fuel Vanagons, for instance) have a MASSIVE wire (with the insulation and covering, it is near garden hose size) to the starter. Not sure why you relocated your battery in the first place, but you really cannot use "too big" of a wire in this instance (within reason, of course).
 

wonneber

Top Post Dawg
Joined
Oct 12, 2011
Location
Monroe, NY, USA
TDI
2014 Jetta Sportwagen, 2014 Tiguan,2003 Jetta 261K Sold but not forgotten
Has anyone thought about winter when the motor oil gets heavier and the starter needs more amps to crank it?

I was also wondering why relocating the battery other that maybe it seemed like good idea at the time.

I would want the extra weight in front for traction.
 

TwistedSmoke

Well-known member
Joined
Nov 19, 2016
Location
Milford ,Pa
TDI
03 Jetta tdi
i am relocating the battery first to give me more space up front when i need to work on the car. Also i have some mods i plan on doing that might add weight up front so the battery not being there should be fine.
 

Andyinchville1

Veteran Member
Joined
Apr 7, 2016
Location
Virginia
TDI
2003 Jetta TDI wagon, 5 sp, 226K miles
HI,

By chance do you have pics of how / where you routed the wires and how you secured the battery to the floor.

I am looking to relocate my battery but since I have a wagon , my plan is to put it in the passenger side rear floorboard area.

Thanks

Andrew
 

TwistedSmoke

Well-known member
Joined
Nov 19, 2016
Location
Milford ,Pa
TDI
03 Jetta tdi
I ran the wire threw the grommet that is location to the right of the brake reservoir behind the wire tunnel. i then ran it down the driver side of the car near the other wires that go to the rear of the car under the plastic door sill. If you need pics i will try to get them when i get home
 
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