isolator, alternator, 98 honda civic

New to this n I cant seem to find out the right fuse I'm a noob lol it's for a 98 Honda civic n it does have a fuse box for the alternator but I'm adding a new high out put alternator n not sure of the new fuse I should put in to replace the old one , should I get a 160 amp fuse cause the alternator has that much ampage?

teenkertoy x2. [Thanks! Dare I say you make me feel Serene? (Blame GI Jayne)] The amplifier's required fuse being placed at the battery end (instead of at the amp end, and another battery-end fuse to protect the cable) is what I was trying to say in my last paragraph. Though sometimes not understood, that also reduces path resistance and increases reliability (one less fuse etc). Though I am uncertain, it could be that your Honda splits the alternator's output. One is fused to the battery, the other (maybe also fused but usually not) to the fusebox.    I suspect it has a 3-flink (fuse-link) box at the +ve battery post similar to what I am using, and an ND alternator. If it's the newer ECU type Civic, it might have the ECU interactive alternator (the ECU/EMS can cut out the alternator for better acceleration and (IMO!) probably worse fuel economy.)    If it is a split alternator cable, then the battery fuse should not require increasing as the battery is likely to limit that current, and that is not changing. (Again, that flink is only there to protect the cable - not the alternator.) Note that supply voltage (and the battery) determine the battery's charge current. Assuming the existing alternator has adequate charging capacity, increasing its size will have no effect. (Only increasing its voltage will.) And chances are that your alternator to main fusebox bussbar is unfused. (It instead relies on physical security instead if inline fusing protection, and the battery-alternator fink will blow if it's the battery that supplies any fault current to the main fusebox via that alternator path.) By main fusebox I mean the fusebox that usually has the major circuit fuses - which may include relays as well. I assumed you also did The Big 3 (or 4) in conjunction with this. Heavier grounding between engine-body-battery(-ve) will be required for the added Amps else to reduce their voltage drop. Same for the battery to amp and alternator to amp +12V paths (that's the extra #4th in the Big 3 if I recall correctly..!). Otherwise ensure adequate grounding. Burning out ground straps can be disastrous for vehicle electrics - especially if sensing the battery voltage as most Hondas do - ie, those with the older 3-wire SIL type alternators. (System voltages can go way above 15V or 16V, though ND and similar "S" type Jap alternators are often limited to around 15.5V max output in case the Sensing S connection goes faulty - or for whatever lucky reason they are limited to under 16V - the common upper design limit for 12V loads.) And inadequate grounds when cranking can cause fusing of other engine-ground paths - like throttle cables, low current harness grounds, springs - and spot welding or plating of prop-shafts, bearings etc. As to where you connect your ">1kW" amp cable, that's up to you. You want minimal resistance - but from your battery (for 1kW with engine off), or the alternator (1kW engine charging)? I'd prefer maybe the main fusebox if convenient with a "1kW" fuse to the amp (ie, 100A, 150A whatever), and similar cable from the battery and from the alternator added (capacity wise) to the existing alt to fusebox & battery to fusebox wiring... But many take it from the battery +12V, but I'm unsure how they then modify their alt-battery and fusebox-battery cabling and fusing. (IMO such heavy battery termination is for adjacent loading - ie, boot/trunk batteries for amps; winching batteries; starter motors, etc.)    Simple isn't it? (NOT!!!) (But that's why I have my methods... But even they vary with design desire.)

Ok that helps a bit thanks

well here is my problem... even with a new alternator 165amp is still giving my jl 1000/1v2 amp a low voltage light(blue), i'm running a 1000/1v2 jl audio amp with 2 12" jl w6v1 subs what have i done so far? * the big three upgrades * bigger high output alternator (165amp) (14.4 volt) * 12v blue top optima battery in the back just for the amp it self... * battery isolator well my main question is what should i do to fix my low voltage light that keeps showing up when i turn the volume up loud... i dont know much about car audio but i'm sure ihave more then enough watts and power to run the amp... so why is it still showing up the low voltage light? wel i have a yellow opt optima battery also and i was planning to add that to the mix and hope it fixs the low voltage light problem BUT cause the battery is a 12v can i connect it with the blue top and yellow top together as a series and i know that wll higher the voltage by double its normal voltage bu will that harm my amp in anyway?? or should i just do the parallel but then the parallel will not give my a higher voltage but will stay the same but is that going to fix my low voltage problem? series or parallel and why? let me know what you guys think i should do... and any advice would be great... thanks p.s. its a refurbised alternator with new parts in it and i just installed it... should it need to be break in or shouldit just work right away? idk you guys let me know what you think

bump *** does any one know how to answer my question i really need help

oldspark: Time for some thrilling heroics. bryanmc1998: I'm going to try and write this out in great detail. I hope you can learn lots, but if you are at all unsure, please ask a local car shop to examine your system. To connect two batteries together, go in parallel. If you run series, not only will the alternator not be able to charge it, but there is a great chance of something burning up due to having 24volts instead of 12volts (this includes stuff in the car unrelated to the amplifier). Adding a second battery will not fix a low-voltage problem. Do not add yet another variable (battery) into an unstable system (low voltage) before you fix the system first. You either have a broken amplifier, or a weak link in this chain: alternator positive to battery positive, battery positive to amplifier, amplifier negative to ground, ground to alternator (engine in most cases), and don't forget battery to ground (chassis in most cases). If you have a multimeter, you can troubleshoot by measuring resistance (ohms) between these points. All measurements should be at most a couple ohms. This is for a typical setup, but you also have a battery isolator. This complicates things for troubleshooting. The most solid troubleshooting step I can recommend is running everything from a single battery and remove the isolator and second battery. If you still can't get the amplifiers to work properly, you may have a bad amplifier. If you can get the amplifiers happy on one battery, then add the second battery in parallel and test. If that works, install isolator and test again. The problem should show up at some point, which will almost always be caused by the last thing that you changed (so only change one thing at a time!!!) .... If you are still having trouble please find someone local (a proper car audio shop) who can examine the setup in person. We are quickly approaching the point where it's not possible to fix over the internet. -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.

teenkertoy: - I love you. (Nothing personal of course - that's purely professional!) bryanmc1998: Your next step is to replace the isolator with a relay type - diode isolators should never be used for audio battery isolation. That should increase battery voltage by about .6V. (That assumes it is a diode type, and that all the rest have been done....) CHMOS indeed.

I love you too? Something is dragging the voltage from about 14v at the alternator down to roughly 10v (for the blue light to come on, according to JL's manual). Changing from a diode to a relay-based isolator can only account for a tiny fraction of that voltage drop, suggesting the problem lies elsewhere. I echo oldspark ... have a local shop check everything else first! -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.

bryanmc1988 - See a specialist. Unless you can measure and compare voltages to determine where the drop is, IMO it is pointless else risky continuing. You could damage components or worse.... And I agree with teenkertoy that the isolator alone should not be causing such a big voltage drop. Maybe it is, though it's probably poor or inadequate wiring to the rear, or the rear battery is faulty (that's hazardous - especially if an AGM like Optima). But unless you have a specific reason for NOT wanting the front and rear batteries interconnected whilst charging, you have the wrong isolator anyway. Most will parallel the batteries instead.