BIG amp install maximun current draw for the dc/dc converter?

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patatewz

Member
Joined
Dec 1, 2015
Messages
18
can i use a 150 amp fuse on the 12v+ with a 0 gauge wire to power a big sub amp or i will fry my dc/dc converter?

i read somewhere the dc/dc converter can provide 135 amp... so if i draw more than that whats happen?

thanks a lot and sorry for my english im french.
 
Yes you should fuse it at 150 amps and when you say converter, do you mean inverter? Is it sine wave or mod- sine wave? What kind of sub are you trying to power that pulls 1000+ watts continuous?
 
very big 18 inch sub... i talk about the dc/dccconverter from the leaf to feed the 12v current... i think it can handle only 135 amp so if i use a audio amplifier of 150 amp maybe i will blow my dc/dc leaf converter?
 
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I would have a separate battery to power the amp so as to absorb the surge power.
LEAF DC-DC converter can keep the extra battery topped off when you are not busting your eardrums.
Lots of people use Optima batteries as a buffer in these stereo systems.
 
yea i have a yellow top primary batterie but how i connect a second batterie? and how the seconde battery will protect my dcdc converter?
 
The resistance in the wire will prevent surging overload from being transmitted to the DC-DC converter. When running at max power the second battery will be basically powering the amp and the DC-DC converter providing a steady charge without overload.

Use a smaller wire such as #6 and maybe an 80 amp fuse. This will create a voltage drop during excessive load and restrict power to the second battery to a safe level. Still plenty of power to keep the second battery charged on a daily basis. I assume the second Optima would be in the rear of the vehicle or close to the amp.
 
just to be clear the second battery in my trunk with a 80amp fuse between the mainbattery and the second? and i plug my amp at the rear? and when a big surge will come, the 80 amp fuse will blow to protect my dcdc converter?
 
In the end yes the fuse will protect the Leaf's DC-DC, but what is really protecting it is the battery up front, the lines running to the back and then primarily the rear battery. All these will reduce surge on the DC-DC converter. I honestly doubt that sub will pull more than 100w continuous unless your pumping white noise through it, sure it might surge to close to 1000w but in short bursts for milliseconds.

One way to think of it is the main DC-DC converter is a supply or hose of running water (water being power) and the first battery is a tank and the "hose" leading to the second battery as another tank. All the main DC-DC has to do is re-fill those tanks, the instant surge will be pulled from the closest battery or "tank" to the amp and will then slowly refill.

I am not sure what size you will run from the front to the back, but even at 4 gauge, unless you dead short it (that's what the fuse is for) you shouldn't hurt the car. Just remember to leave the car on, if you manage to run the 12v dead you won't be able to restart it.
 
wow your helping me a lot!

ok i will run 0 gauge wire from 12v+ and 12v- from the feont to the rear. with a fuse at 100 amp in front.

i will plug my amplier at the rear 12v+ and 12v- at on the body of the leaf.

do i need to ground the 12v- in the back to the body of the leaf?

and i will use a 5000w rms amp the sub is a special sub y can handle 10 000w burst.... so you tell me i can run a very big amp in the back and its only the rear batt it will suffer and no big urge draw in the front and on the dc dc converter thats correct?

thanks for your help its amazing!
 
Actually running 4 gauge from the front to the back will actually protect the cars converter better as it won't allow the amp to pull as much from the front, sort of limiting the power, but only under very high draw situations.

Yes I would ground the battery at the rear, neg to ground as well.

Is the amp 12 vdc?
 
yes 12v dc can accept 14.4v to.

ok only 4 gauge in beetween my the batterie. and 0 gauge in the back for the amp to the rear battery.

i will post some other pics tomorow im making the box now.
 
patatewz said:
just to be clear the second battery in my trunk with a 80amp fuse between the mainbattery and the second? and i plug my amp at the rear? and when a big surge will come, the 80 amp fuse will blow to protect my dcdc converter?
No. When a large demand hits the extra battery the extra battery provides the power. The fuse will not open.
 
Hopefully never. You would likely need a short leading to the back battery or maybe past the back battery to blow the fuse.

Speaking of fuses you should have one on the positive side leaving the front battery and one on the positive side of the back battery leading to the front. Then a last one as it leaves the back battery for the amp itself. So three fuses, the reason being if the line from the front battery shorted to ground, it would blow the front fuse, but the back battery would still be shorted to ground, and that is bad, so there needs to be a fuse on each end of that line.
 
patatewz said:
ok but when the fuse will blow? never?
Probably never. The primary purpose for the fuse is to protect the wire not any other component. Actually as you have a power source at each end you should have a fuse at each end. The fuse is for a wiring fault such as short to ground.
 
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Where its safe to connect my 12V+ 4 gauge wire for my amplifier? At the #1 or #2. I know we have a sensor at the 12v+ to see curent draw... but i dont know where its best to connect to not mess with that sensor...

thanks.
 
i just find in a other post, the hall sensor is on the neg terminal of the batery. So its important to not connect anything on the neg pole of the battery.
 
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