Amp fuses and Alternator question

 

Bronze Member
Username: Chrisilver

Post Number: 11
Registered: Jul-08
If an amplifier has FIVE 30 amp fuses, does mean the alternator that its connected too can't push over the fuses combined 150 Amps, or can the alternator be any size?
 

Gold Member
Username: N2audio

Lawrence, Ks USA

Post Number: 1674
Registered: Mar-04
no, that's not how it works at all.

Don't look at it as current (amps) being "pushed" from one component to another.
Electrical components (the amplifier in this case) DRAW current from the charging system.

It sounds like you have an amp that's around 1500w.
An amp that size will, at times, max out most standard alternators and begin to draw current from the battery.

The question is how often will the alt be maxed out, and will there be enough down time to keep the battery charged.

If that's your only amp it might work ok on a fairly strong stock alt and batt, but if you have a 2nd amp of some size, or a smaller alt you may need to look into a high output alternator.
 

Bronze Member
Username: Chrisilver

Post Number: 13
Registered: Jul-08
Alright thanks, that's what I figured, but I was having a dumb moment. My stock civic alt is only 70 amps, so I will be upgrading most likely to a 160 amp unit. I just read the 150A fuse rating and thought i'd ask just to be sure. The amplifier is sundowns sae 1200
 

Gold Member
Username: N2audio

Lawrence, Ks USA

Post Number: 1676
Registered: Mar-04
A 160A should get it done w/o much trouble, and leave enough slack to add a good amp for some full range speakers.
 

Bronze Member
Username: Chrisilver

Post Number: 15
Registered: Jul-08
*A 160A should get it done w/o much trouble, and leave enough slack to add a good amp for some full range speakers.*

That is my plan, sub first then, save up for a nice component set. Would a 160 amp alternator be plenty to power a 1200 w amp as well as maybe a 400 w for speakers, along with the regular car functions a/c ect.?
 

Gold Member
Username: N2audio

Lawrence, Ks USA

Post Number: 1678
Registered: Mar-04
160A should give you TONS of headroom in a civic. 1600w should be no problem at all.
 

Bronze Member
Username: Chrisilver

Post Number: 18
Registered: Jul-08
Could you suggest me some companies the make good quality alternators? I was planning on one from alterstart, but I read some pretty bad stuff about them hardly even working at normal idle speed. There's endless reviews on subs, amps and other parts, but alternators seem to be a bit of a gray area in car audio, I can't much good information on them. Any input would be appreciated
 

Gold Member
Username: Nd4spd18

Philadelphia, PA

Post Number: 8968
Registered: Jul-06
DB Electrical

Motor City Reman


Two best HO alt companies I have dealt with.
 

Gold Member
Username: Snowball123

West Allis, WI

Post Number: 1682
Registered: Oct-07
mechman
 

Bronze Member
Username: Chrisilver

Post Number: 19
Registered: Jul-08
I have another quick question,
What determines the size of fuse you need in between the battery and the amp?
 

Gold Member
Username: Nd4spd18

Philadelphia, PA

Post Number: 8979
Registered: Jul-06
Fuse size is based on wire gauge


Wire Gauge, Current Flow, Max Total Amp Power
Class AB (60% eff), Max Total Amp Power
Class D (75% eff)

0 awg 330 amps 2731 watts 3414 watts
1 awg 262 amps 2168 watts 2710 watts
2 awg 208 amps 1720 watts 2151 watts
3 awg 165 amps 1365 watts 1707 watts
4 awg 131 amps 1084 watts 1355 watts
5 awg 104 amps 860 watts 1075 watts
6 awg 82 amps 683 watts 853 watts
7 awg 65 amps 542 watts 677 watts
8 awg 52 amps 430 watts 537 watts
9 awg 41 amps 341 watts 427 watts
10 awg 33 amps 271 watts 339 watts
11 awg 26 amps 215 watts 269 watts
12 awg 21 amps 171 watts 213 watts
13 awg 16 amps 135 watts 169 watts
14 awg 13 amps 107 watts 134 watts
 

Bronze Member
Username: Chrisilver

Post Number: 21
Registered: Jul-08
So if I have 1/0 gauge wire and a 250A alternator do I need like a 300-330 amp fuse? or around 250 amps? The wire is 17.5' long
 

Gold Member
Username: Nd4spd18

Philadelphia, PA

Post Number: 8988
Registered: Jul-06
yeah 0 gauge wire you need a 300 or 325 amp fuse
 

Gold Member
Username: N2audio

Lawrence, Ks USA

Post Number: 1690
Registered: Mar-04
If the sum of the maximum current draw of your amps don't add up to the maximum current limit of the wire I suggest fusing to only what the amps need for a little extra safety factor.
Sounds like you're looking at a total current draw of about 200A so there would be no point in fusing the wire at 300A except to give the wire more time to heat up if you ever do get a short.
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