Help..........new battery and alternator and now I'm blowing fuses like crazy

[Paradigmonds]

Hey guys,

This is probably something simple, but while I know a good bit about sound and the back end of an audio system, I know very little about the front end.

So, I have a 98 Jeep Grand Cherokee. I had two amps running in it initially ( a RF 600-4 and a Punch 801S ) I was having some problems with battery and alternator keeping up, dimming headlights, etc, so I decided to replace alternator and battery.

Let me be clear. I did not add a 2nd alternator or a second battery. I simply replaced my stock 90 amp alternator and replaced my stock battery

OK, so I got a 200 amp alternator. I did not think that would be a problem. My wife and I have some land outside of town where we are going to build and I often use a power converter, so I thought the extra amperage might be helpful

The battery is an XS 3400, which is the model that is correct for my vehicle.

So, I installed the battery and alternator........pain in the ***, but essentially no problem. Afterwards, vehicle is running fine and stereo is playing fine. Played radio with vehicle turned off for about 30 minutes. Then, start car and drive 15 minutes home. No problem, except for a little squealing of the new serpentine belt.

Then, right when I get home, radio suddenly starts crackling and goes out. I had blown the 100 amp fuse coming off the battery. Tried another, blew it.

So, then I go look at my fused distro block, which has 60 amp fuses in it. They seem to be fine. The only two amps I have running right now are a Rockford Fosgate 150x4 and a Kicker 100x4, ( the 801s is in the closet right now ) so there shouldn't be any reason that I can think of that it would be overloaded.

I checked everything out, loosened and re-tightened, put in a new fuse. Radio comes on for a sec and then blows fuse again.

Can anyone tell me what they think the problem is? The wire is 2 gauge high quality cable. I'm going to upgrade to 1/0 Rockford Fosgate. In fact, have it in the vehicle, just not hooked up yet.

Do I need bigger fuses than 100amp? I think I can get 150's from the local audio shop.

What else could it be?

Thanks for any help!

W

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[gstokes]

I suspect a problem with the 200 amp alternator, remove it and reinstall the 90 amp unit, see if it's still blowing fuses ?

Since you replaced 2 components (battery & alternator) we need to do a little process of elimination..

 

[Paradigmonds]

If there was something wrong with the alternator, wouldn't it also affect some other aspect of my vehicles electrical system besides just the power wire fuse going to my amplifiers?

I'm not trying to be a ******** at all by asking that, but the problem is that 1. no longer have the old alternator, and 2. I spent a long hot day today replacing it, so I would hate to have to go backwards through the process only to find out that the problem is elsewhere.

I was looking at it a moment ago before it got dark. I think one thing I am going to try tomorrow or Tuesday after work is replacing the cabling. I thought that the power cable was 2ga, but I'm pretty sure its 4ga, and after I took measurements, not even full size 4 ga. The new cable that I have is rockford fosgate 1/0 cable and it looks like a **** python. It may not make a bit of difference, but I've heard that smaller cabling can excessively boost the amperage and blow fuses. In fact, I did notice that the cable and fuse box was hot when the fuses were blowing. I thought it was just the heat of the day and the heat under the hood from driving, but it could be that the cable couldn't handle the new alt and new battery.

Also, if this helps anyone, my headunit shows voltage and throughout this whole time my voltage has stayed between 12.4 and 13.2. No jumping up or dropping low.

thanks!

 

[gstokes]

all good and i never take a reply out of context but something is amiss, you mentioned it's not blowing the 60's in the distro so how many 60 amp fuses are in the distro ?

the alternator belt squealing indicated a heavy load on the alternator, now that there is more current available for the amplifiers they will draw the max amount required to make the power.

when the load resistance remains the same but the voltage drops the current increases (inversely proportional) and a voltage drop between the source (battery)and the load (amplifier) will cause it to happen, depending on how much the voltage drops during the sustained load will indicate hows much extra current is being pushed through the circuit, 1/0 gauge wire is the best you can do.

have you thought about adding as hybrid capacitor ?

a properly sized and mounted capacitor will fill the voids in the line voltage when the bass hits and if you keep the line voltage stabilized you won't have spikes in the current large enough to blow the 100 amp fuse.

so, i think the problem is a substantial voltage drop causing a spike in the available current in excess of 100 amps (obviously).

Edit: once you upgrade the cabling you should also solder the connections, use a torch and flow some solder into the connectors, crimping 1/0 gauge is fine if you have the right tools but soldering it will increase conductivity and minimize any voltage drop.

Resistance in the circuit between the amplifier/s and the battery is what's causing the voltage drop, it's either insufficient conductor and\or connection..

more voltage that is available at the load = less amount of current flowing through the circuit = less heat in the fuse block and the distro //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[Paradigmonds]

Thanks for all the help gstokes.

OK, so you have a rundown of how things were setup when it started going haywire.

Alternator --> Battery --> 4 ga cable ( soon to be replaced with 0 ga ) --> fuse block with 100 amp fuse --------> 4 ga cable to Distro Block --->

 

---> Distro Block Fuse 1 - 60 amp fuse ---> 4 ga cable ---> RF 600-4 amp @ 4 Ohms per channel 100 RMS watts x 4 ---> 4 ga cable grounded to chassis

---> Distro Block Fuse 2 - 60 amp fuse ---> 4 ga cable ---> Kicker 400.4 @ 2 Ohms per channel 150 RMS watts x 4 ---> 4 ga cable grounded to chassis

.........and like I said, it was blowing the 100 amp fuse close to the battery, but wasn't blowing the fuses on the distribution block that were 10 feet down the power cable. With the engine turned off, putting a 100 amp fuse into the fuse holder, it was instantly frying it like a piece of bacon, even began melting the holder and one of the fuses. So, even if I didn't have 20 feet of 0 gauge cable, it would still definitely need to be replaced.

At this point, though, I don't even have any large amp or any subs hooked up that would be making a large current draw when the bass hits. Total of only about 1000 watts RMS. That will jump up to about 2200 when I hook up additional amp and subs, but right now it doesn't seem like the amps would be drawing too much power, but I guess maybe its too much power for that cable and that battery. I just don't know.

You might be able to give me some more suggestions, but here's where I'm going to start. The squealing of the belt is unbearable. It doesn't squeal at idle, but in drive it is continuous and gets worse as I accelerate. I didn't even drive my car today its so bad. I think that the tension on this new belt is not correct. So, I'm either going to call the dealership and get a new tensioning bolt and pulley, or I'm going to order a new automatic belt tensioning pulley. The stock tensioning pulley has a sliding bolt that you first loosen and then a second bolt that you use to add tension to it, before tightening it back up. Yesterday when I was removing the belt, I saw that the previous owner had broken the tensioning bolt and was apparently just pulling up the tension pulley wheel and tightening it in place ( and hoping for the right tension ) I went to Home Depot and got a 5/16" x 6" hex bolt to replace the broken one ( once I got it out ), but I think the threads in the little bracket behind the pulley are chewed up and its not able to get enough tension. i read this morning that the belt on the 98 Grand Cherokee requires 180 lbs of pressure, which is likely significantly more than is on it at this point. So, apparently the last owner was able to get the old belt to sufficient tension to keep it from squealing, but I need to go ahead and replace the part.

Following that, I'm going to replace my power cable with the high quality 0 ga cable and install a 150 amp breaker switch under the hood. That will give me a little more protection than the 100 amp fuses and also keep me from burning through expensive fuses. Then, I'm going to sand down a spot to bare metal and attach my 0 ga ground terminal bracket. and run 0 ga cable to my ground distribution block.

Besides that, I wouldn't know what else to do. You suggested a cap. What size do you think would be helpful? 1 farad? 3 farads? I see quite a few 1 farad caps that are fairly inexpensive, so if it would provide some overload protection and let me get my system back up and running, I'm definitely willing to give it a try.

So, lets say the battery and the alternator are both perfectly fine, what would be the order of things that you would check and corrections you would make?

Cable size? Better Grounds? Larger fuses? Capacitor?

Thanks again for all your help.

Have a great Monday!

W

 

[gstokes]

okay, the RF 600 requires 4 gauge cables just for itself, the RF 800 also requires a minimum 4 gauge power cable, you need 2 gauge at the minimum to the distro, then 4 gauge to each amplifier, another option would be to hook up both amps to chassis ground then use one 4 gauge cable to power the 600 and use the other cable (which was a ground) to power the 800. Don't forget to run a strap from battery negative to chassis ground. Chassis ground has been shown to be just as effective if not more so then dedicated 1/0 ground cable.

This will help explain why the 100 amp fuse is blowing..

600W + 800W = 1400W / 13.8V = 101 amps

600 + 800 = 1400 / 12.8 = 109 amps

600 + 800 = 1400 / 11.8 = 118 amps

600 + 800 = 1400 / 10.8 = 129 amps

That's being generous and giving the amplifier/s a 100% efficiency rating, once you adjust the efficiency to a more realistic 70% the current flow climbs even higher, the RF 801 is pretty old and could be losing efficiency causing it to draw more current than you expect.. You might want to think about replacing it with a modern class D design that is much more efficient than Class A/B.

The rule of thumb is 1 Farad per 1000 watts but a capacitor that is too small has been shown to actually reduce amplifier power so bigger is always better, the Stinger 5 Farad Hybrid Capacitor can be found for less than $125 and most people will say it should be connected to the amplifier using less than 8" of cable.

idea:, use chassis grounds for both amplifiers, use one 4 gauge cable to power each amplifier, amp clamp the 801 and replace if it's drawing excessive current.

 

[fly_marlin]

I had to intervene. This is getting too convoluted. Paradigmonds, please take a look at the chart below:

Recommended Power and Ground Cable Sizes & Speaker Wire Size and Length

For 2 awg power wire, its max current capacity is 225 amps. Your alternator can provide up to 200 amps, which without a doubt will blow the 100 amp fuse. You have to make sure you understand what each fuse is protecting. The fuse close to the battery is to protect the wire. That can be up to a 225a fuse. I think both of your amps are internally fused and you do not need the fused distribution blocks - you can get rid of those. You probably don't need to upgrade the power wire at this point.

1. Put in a 200a fuse to replace the 100a one.

2. Get a non fused dist block or put in 150a fuses in them. Those don't need to blow. If anything goes wrong, fuses in your amps will blow.

 

[gstokes]

I had to intervene. This is getting too convoluted. Paradigmonds, please take a look at the chart below:
Recommended Power and Ground Cable Sizes & Speaker Wire Size and Length

For 2 awg power wire, its max current capacity is 225 amps. Your alternator can provide up to 200 amps, which without a doubt will blow the 100 amp fuse. You have to make sure you understand what each fuse is protecting. The fuse close to the battery is to protect the wire. That can be up to a 225a fuse. I think both of your amps are internally fused and you do not need the fused distribution blocks - you can get rid of those. You probably don't need to upgrade the power wire at this point.

1. Put in a 200a fuse to replace the 100a one.

2. Get a non fused dist block or put in 150a fuses in them. Those don't need to blow. If anything goes wrong, fuses in your amps will blow.

excellent point, i was overlooking the purpose for the fuses at the distro, each connection in the circuit adds to the voltage drop so the distro itself is contributing to the problem, minimize the connections and the voltage drop between the amp/s and the battery.

 

[fly_marlin]

excellent point, i was overlooking the purpose for the fuses at the distro, each connection in the circuit adds to the voltage drop so the distro itself is contributing to the voltage drop, minimize the connections and the voltage drop between the amp/s and the battery.

I think the voltage drop from the distribution block is minimal, unless this thing is just terrible. The only problem I see here (besides the alternator noise) is lack of understanding of fusing. I think once the fuse with the correct rating is installed, all should be well. Get that noise thing looked at as well.

 

[gstokes]

I had to intervene. This is getting too convoluted.

you are so right, i have trouble keeping it simple //content.invisioncic.com/y282845/emoticons/frown.gif.a3531fa0534503350665a1e957861287.gif

 

[fly_marlin]

you are so right, i have trouble keeping it simple //content.invisioncic.com/y282845/emoticons/frown.gif.a3531fa0534503350665a1e957861287.gif

All good. We are all just here trying to help.

 

[gstokes]

He should really have a fuse for each amplifier (at the battery) and not combine them on the same fuse, positive battery clamp with 2 cables and 2 fuses..

 

[fly_marlin]

He should really have a fuse for each amplifier (at the battery) and not combine them on the same fuse, positive battery clamp with 2 cables and 2 fuses..

No, he shouldn't. That's why many amplifiers come with fuses. The fuse by the battery is not for the amps. I've explained above.

 

[trumpet 5,000+ posts]

It seems to me that your fuse is blowing instantly because the power wire is shorted. Since it's not blowing after your fused distribution block, check for a short in the 2 ga wire between the distribution block and the fuse holder at the battery.

You can get your alternator tested for free at some auto parts stores. First, make sure you do not have a short to ground.

 

[fly_marlin]

It seems to me that your fuse is blowing instantly because the power wire is shorted. Since it's not blowing after your fused distribution block, check for a short in the 2 ga wire between the distribution block and the fuse holder at the battery.
You can get your alternator tested for free at some auto parts stores. First, make sure you do not have a short to ground.

I'd be curious to find out the culprit. Paradigmonds, if you get to the bottom of this...please let us know.