Tap power from fuse box?
#1
Tap power from fuse box?
Hi guys,
I need a power source, a strong one. I don't feel like running a pair of wires to the battery so I am wondering what some thoughts are on tapping the main fuse box in the engine compartment?
I figure there must be a high current line direct from the battery to the various fuse boxes. According to the wiring diagrams (which I stink at reading), there is a 140A line running to the engine compartment (or somewhere up there) with a fusible link. It then appears to split off but I cannot find the specific fuse box in the diagram. The device needs about 10A to start and then runs at about 3.6A after that. There are two of them so 20A start, 7.2A running.
Any thoughts?
I need a power source, a strong one. I don't feel like running a pair of wires to the battery so I am wondering what some thoughts are on tapping the main fuse box in the engine compartment?
I figure there must be a high current line direct from the battery to the various fuse boxes. According to the wiring diagrams (which I stink at reading), there is a 140A line running to the engine compartment (or somewhere up there) with a fusible link. It then appears to split off but I cannot find the specific fuse box in the diagram. The device needs about 10A to start and then runs at about 3.6A after that. There are two of them so 20A start, 7.2A running.
Any thoughts?
#2
Re: Tap power from fuse box?
I can't imagine why you would prefer to mess around with circuits you don't completely understand, accepting a large power loss, and possibly system damage, rather than simply tapping the 12V battery. I'm pretty sure Toyota would tell you you'd be on your own nickle here if things went wrong. The baseline 7.2 amp (85 watt) draw alone will knock your battery down pretty quickly.
If the TAH operates like the HiHy, the 12V battery will be kept charged by the traction battery when ignition is in the "ready" position. When the traction battery voltage falls beyond a certain level, the engine starts to recharge it.
I ran a 750 watt inverter (about 60 amps max draw) about half-time like this for a couple of days during a power outage and it worked well. Because of the very small 12V battery, I coupled it with jumpers to a larger external 12V battery connected to the inverter.
Pete
If the TAH operates like the HiHy, the 12V battery will be kept charged by the traction battery when ignition is in the "ready" position. When the traction battery voltage falls beyond a certain level, the engine starts to recharge it.
I ran a 750 watt inverter (about 60 amps max draw) about half-time like this for a couple of days during a power outage and it worked well. Because of the very small 12V battery, I coupled it with jumpers to a larger external 12V battery connected to the inverter.
Pete
Last edited by PineywoodsPete; 09-01-2008 at 10:04 AM.
#3
Re: Tap power from fuse box?
Hi,
Fuses exist to protect the wires and if you 'tap' into an existing circuit you run these risks:
Looking at the loads:
GOOD LUCK!
Bob Wilson
- overloading because the new load is parallel to the design load
- on one side, blowing the fuse (fusible links are expensive)
- on bad side, the wire melts and burns up the car
- 20A * 13.5 VDC = 270 watts (1/3 hp)
- 7.2A * 13.5 VDC = 97 watts (1/8 hp)
GOOD LUCK!
Bob Wilson
#4
Re: Tap power from fuse box?
This is a headlight application. Should 12 GA stranded coper wire work? I will run a power and a ground wire to the battery and to the wiring harness. My problem is, I have no clue how to get the wire from the engine bay to the battery.
Last edited by mikieboyblue; 09-01-2008 at 05:04 PM.
#5
Re: Tap power from fuse box?
http://www.powerstream.com/Wire_Size.htm
A 12 GA wire should work fine. The initial 20 A. is well within the limits of chassis wiring and the sustained 7.2 A. gives plenty of sustained power margin. However, you won't need a ground wire to the battery. Just find a good electrical ground in the engine compartment.
Sorry but I don't know enough about the Camry wiring and chassis to offer practical advice on routing. I'd suggest looking for the repair manuals with electrical diagram. BTW, that might give you a pointer to the 12 VDC power source from the inverter. Whether or not it can be tapped, the diagram and maintenance manual would be the road map. Just make sure you put a good, inline fuse close to the source.
Bob Wilson
Last edited by bwilson4web; 09-01-2008 at 06:11 PM.
#6
Re: Tap power from fuse box?
I used the main lug, under the hood in the fuse box, for the main power feed to the relay for my fog lights. It is the feed from the battery and is about in the middle of the fuse box. I believe it has a 10 MM nut on it. I ran a 15 A fuse on that relay line also.
#8
Re: Tap power from fuse box?
Hi Ron and Jon,
Yes, it is a HID setup.
After calling Mobile HID, it turns out they modify the H11 connector on the wiring harness to fully plug into the stock H11 connector. They are sending me a modified wire which will jumper between the ballast and the stock H11 connectors making a clean and complete connection.
I then double checked that these ballasts are able to run on the stock wires and that the stock wires can handle the load. The answer was yes. After all, they are digital ballasts.
With all that said, I have received various responses as to whether I can (or should) use the stock wires or if I should run a wire to the battery.
The mere thought of running a wire to the battery is what has me a little annoyed and what prompted me to figure out if I could tap power from the fuse box. But, it sounds like I probably don't need to do that.
In any event, Jon, could you give me some of your advice?
Ron, I sent you an e-mail.
When I get this done, plan on writing up a tutorial for others.
Thanks,
Mike
Yes, it is a HID setup.
After calling Mobile HID, it turns out they modify the H11 connector on the wiring harness to fully plug into the stock H11 connector. They are sending me a modified wire which will jumper between the ballast and the stock H11 connectors making a clean and complete connection.
I then double checked that these ballasts are able to run on the stock wires and that the stock wires can handle the load. The answer was yes. After all, they are digital ballasts.
With all that said, I have received various responses as to whether I can (or should) use the stock wires or if I should run a wire to the battery.
The mere thought of running a wire to the battery is what has me a little annoyed and what prompted me to figure out if I could tap power from the fuse box. But, it sounds like I probably don't need to do that.
In any event, Jon, could you give me some of your advice?
Ron, I sent you an e-mail.
When I get this done, plan on writing up a tutorial for others.
Thanks,
Mike
#9
Re: Tap power from fuse box?
if your getting a wire harness then your good the HID is plug and play. I mounted my ballast in front of my radiator, between the grill and the radiator. I didnt drill any holes just used existing ones. My lights are made by phillips so I know the quality will be good, not worried about water, but heat is another story. remember not to touch the bulbs,because body oil will kill it, also remember when you first see the lights at night, they are not supposed to be lined up in a straight line only Acura does that. the pass side will be slightly higher and then step down. that is so you can see wide on the right.
#10
Re: Tap power from fuse box?
if your getting a wire harness then your good the HID is plug and play. I mounted my ballast in front of my radiator, between the grill and the radiator. I didnt drill any holes just used existing ones. My lights are made by phillips so I know the quality will be good, not worried about water, but heat is another story. remember not to touch the bulbs,because body oil will kill it, also remember when you first see the lights at night, they are not supposed to be lined up in a straight line only Acura does that. the pass side will be slightly higher and then step down. that is so you can see wide on the right.
The kit is suppose to be plug and play as they are digital. I just need the modified wire to allow a complete connection between the stock wiring and the ballast.
Interesting mount point. I mounted one to a ground wire mount and another to the windshield washer fluid res. I might move the one that is mounted to the res as it could be a bit studier.
Thanks for the tips.