isolator, alternator, 98 honda civic

It doesn't show the Honda civic wirings and they r not pretty it's in black n white lol

All you should require is alternator B+ to isolator A.... Then isolator-1 to main battery +12V.... Then isolator-2 to aux battery +12V.    (And please follow the simple rule - ensure the chassis/body is doconnected from the battery(s) WHENEVER doing such electrical work. IE - the battery -ve is first off and last on.) The E is to provide excitation current which you should not require. The only cable off the Honda's alternator B or B+ terminal should be to the battery or fuse(box) to the battery and vehicle +12V. And if your Honda alternator is a Nippon Denso, it's probably the 2,3,or 4 terminal "Sensing" type (eg: S,L,I terminals) whereby S goes to the main battery terminal - therefore you don't have to worry about the isolator's voltage drop. [ Even though those Sure Powers are "the most efficient" according to their blurb. Hey, their Schottky Diode versions have ZERO voltage drop - imagine that! Geez I like taking the pss out of companies that take advantage of people's ignorance, else are so ignorant and stupid themselves....! But is is a fee market, and some have the freedom to spread bullsh... ]

This is definitely a CHMOS post. Strong advice to our poster. Don't do this at home, have it done professionally. From your line of questioning I can see very expensive damage, at least a new alternator.

Ok so I got it all wired up and it looks good with the multimeter... The only think now is my car HU is dimming when the beat hits but my head lights n lights in the car is fine they don't dim. N my amP is connected to the 2nd aux battery but my HU(deck) is connected to the main front battery. And when I play the music loud my jl audio amp resets n the low vottage lights come on... Why is that I wired everything correct Any idea why this is happening n how to fix this problem?

If its a diode type isolator, yes. You may be undercharging the system unless the alternators Sense wire is connected as I described. And you have two batteries that are independent of each other and unable to share the load. If it is a relay type isolator, the you probably need to do the Big 3 upgrade, else get a bigger alternator. And Howard - I seriously doubt that this could be considered High speed Complimentary post - it's way slow. (Sorry - I forget how to spell that C word in that post-TTL era MOS logic.) For I while I thought you wanted to CHange our MODerator - but I'll put that down to my UNIX hangover.

I don't know what I have I post the isolator name n modal on my first post n I have that the big 3 upgrade n my isoolator does show that it's charging the batteries when car is running

I don't know either. I forgot the type it was and I have no intention of reading back, but I'm certain all the info required is there. Thanks to Howard's comment I recall it's a Honda and, as I said, it should therefore be an ND alternator (usually 3-wire but with 4 terminals) and hence sensing battery voltage instead of the ~0.6V higher alternator voltage. Maybe take it to someone that knows what they are doing else can understand what I wrote etc etc. Howard's advice is the best.

well i have a 165amp high output alternator and i dont know what size fuse i need between the battery n the alternator also what size fuse would i need for my amp thats 1000 rms jl 1000/1v2 from the battery to my amp... i need 2 fuse or do i need more? i did the big 3 upgrade and i have no fuse on my alternator right now is that dangerous? all the wire including the one's on my amp are all 1/0 gauge wires

1000W RMS probably requires a 100A fuse or larger. The alternator should not need a fuse - older vehicles never had them. [ PS - other than battery end - see below... ] Newer vehicles have them for reasons I cannot ascertain... The battery end might have one in case the alternator end shorts to GND, but the heavy cables (for >160A else whatever the alternator's MAXIMUM current output is if that is higher) should be going to the amp or fusebox etc rather than the battery. And provided the alternator cable is rated for its max output, it shouldn't need a fuse (to protect the cable). In all cases, the fuse/s is/are to protect its/their downstream cable segment (to the next fuse or load). EG - if 200A cable is used to the amplifier, then the fuse must be 200A or smaller.

Good points about the alternator. For the amplifier, you can take a look at this page to see how much current a 1/0 gauge power cable can carry (350 amps). This fuse should be as close to the battery as you can, about a foot or less is ideal, and it will protect the cable from a short circuit. Rating should be equal to or less than the cable's capacity. The JL amplifier should have a fuse requirement (###? amps) in the user manual, and can be placed just before the amplifier. If the power cable goes straight to the amp, you can use a single fuse rated at the lower of the cable's capacity or the amplifier (certainly going to the be amplifier in this case). -JMalcom: "This is the captain. We have a...little problem with our engine sequence, so we may experience some slight turbulence and then...explode."

Jayne: "We're gonna explode? I don't wanna explode.