I'm fitting my battery in front of the engine, so I have a long run of cable from battery to electric reverse on rear joint of prop to diff.
So I'm fitting a Mega fuse in the battery box for protection.
Question is what size fuse is required?
Do you take into account battery amps, or rating of cable that's going from battery?
you cant fuse the starter its self .depending on model and the hill size could be 200 to 600 amps
just double insulate the cable.. run next size up cable as well for volt dropage.
ps: battery amps are in theory unlimited. just limitted by internal resistance of battery.
could be 800 + amps
thats why if you short a spanner over the terminals it will melt !
This suggests 150 or 250A, But I suppose it depends on your motor, and of
course, your wiring, there's no point putting a 500A fuse in there if it's hooked up with speaker wire.
You can calculate how much power is required to reverse your car.
Calculate the torque needed then multiply that by the maximum speed you want the car to move at.
Allow for the worst case; maximum vehicle weight reversing UP a 33% hill.
If you divide that number (in Watts) by the voltage available it will tell you the current draw.
Make sure that your wire size is bigger than necessary for this current draw.
Then select your fuse to be the same size as the maximum expected current draw.
If you want to go the scrappy route then I guess something like a 5 or 7 series Beemer that has the battery in the boot might be able to supply cable
and parts to match.
HTH,
James
^^^^^^
Or MX5
Be aware that BMWs may well have pyrotechnic battery terminals.
Not a joke
they are fired in an accident to disconnect the battery.
Check this thread and have a look at my pictures a bit down.
250A for the starter post.
http://locostbuilders.co.uk/viewthread.php?tid=194619
Thanks all,I'll fit a 250amp as it's 40inches old reverse system I bought
quote:
Originally posted by JAG
You can calculate how much power is required to reverse your car.
Calculate the torque needed then multiply that by the maximum speed you want the car to move at.
Allow for the worst case; maximum vehicle weight reversing UP a 33% hill.
If you divide that number (in Watts) by the voltage available it will tell you the current draw.
Make sure that your wire size is bigger than necessary for this current draw.
Then select your fuse to be the same size as the maximum expected current draw.
