amps cutting off from loss of power

[ctalley44 10+ year member]

setup:

2001 honda accord

h22 engine

2 mtx 9500 12" dvc

2-81001 mtx class d mono block amps 1500 watts each

1- 7804 mtx amp 4channel 1200 watts

mtx 6x9's 6.5" 3" tweets

optima yellow top under hood and in trunk

12 farad stinger cap

1/0 wiring troughout

165 h/o alternator.

at idle has 13.9 at battery under hood and trunk

under full load runs down to 10.0 vlts and then cuts my amps off for a second then cuts them back on but keeps doing it unless i cut the music down. im watching this on my digital voltage meter my head unit. i thougt it was the alt but replaced the stoc 90 with the 165 buts its a ebay Hi-Amp Alt. and my batteries seem to be fine and all my wires are connected well to all my amps and batteries. have NOT changed the wiring from alt to battery still stock. I have a 100 amp fuse in my fuse box where the battery fuse is and wondering if this keeping my alt from juicing my batteries. any help will be appreciated and will give any further details if needed.

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[KerX 10+ year member]

did you do the big 3?

 

[ctalley44 10+ year member]

not sure havents done no rewiring from the alt to battery. what should i do?

 

[helotaxi 5,000+ posts]

Big-3 is first.

How are your amps grounded? If you're using a chassis ground, you might want to consider a dedicated ground run from the front battery to the back battery.

Check the quality of all your connections. A bad connection can cost you a big voltage drop.

The fuse would only be a problem if it was blowing. Since it isn't, then that isn't the problem.

 

[ctalley44 10+ year member]

cool i check all again and do the big 3 and see whats up

 

[Millertime1028 10+ year member]

IMO that alt is most likely your issue. Doing the Big 3 will help you out slightly but you will greatly improve your voltage stability if you stepped up to an official large case High Output alt such as a Mechman alt or DC power alts. I've personally ran alts from ebay in the past, the one's claiming that they are "High Output" but in all reality they are just rewound/remanufactured OEM alternators. If I were you I'd try to purchase a true H.O alt for your car, leave your yellow top under the hood, put a group 31 battery in the trunk, big 3, and call it day. Your voltage should hold quite well @ full tilt.

 

[helotaxi 5,000+ posts]

The alt isn't for transients. Won't do a thing for quick voltage drops like he's seeing. The only cause for drops that low is bad wiring. A connection is bad somewhere or he's using a chassis ground which is insufficient for the transient current he's demanding. The big 3 will help that to a small degree, but he really needs a more robust negative connection to the front.

 

[Millertime1028 10+ year member]

^ In the case of the OP, Considering the power he is running a better ground connection will only help the amp pull it's current from the alt more efficiently. He will intern STILL need a bigger alt. If it was a bad ground connection his amp would cut before he would see that major voltage drop up front in which that is where he is testing the voltage at. The current alt he has seems it can not support the load of the extra batt sufficiently. Once the reserve of the batts trickle down @ full tilt due to insuffient amperage his voltage can surely dip into the 10v range because of this. IMO A bad ground can be a factor but not the reason in the OP's case.

 

[ctalley44 10+ year member]

do i need an isolator too between the two batteries. i got the yellow top under the hood and a deka yellow top in the trunk with the 12 farard stinger. im doing the big 3 and gonna see what the changes are first

 

[1rockford1 5,000+ posts]

hmmm

 

[helotaxi 5,000+ posts]

^ In the case of the OP, Considering the power he is running a better ground connection will only help the amp pull it's current from the alt more efficiently. He will intern STILL need a bigger alt. If it was a bad ground connection his amp would cut before he would see that major voltage drop up front in which that is where he is testing the voltage at. The current alt he has seems it can not support the load of the extra batt sufficiently. Once the reserve of the batts trickle down @ full tilt due to insuffient amperage his voltage can surely dip into the 10v range because of this. IMO A bad ground can be a factor but not the reason in the OP's case.

If the alt was unable to sustain the average current demands of the system, the voltage would gradually drop as the batteries discharged and would stay down as long as the system is switched on. Drops to 10V only happen when there is a high resistance connection, the batteries are bad or the current draw is exceeding the CCA of the battery. Notice that the alt has nothing to do with that set of choices.

Bottom line, the alt is there to keep the average current demand satisfied. Transients are the realm of the batteries. Provided that the alt can cover the average, two batteries is no more of a load than one and there is no way that his system is drawing more, on average, than his alt can handle.

Wiring is the problem here. He's not drawing enough current to overpower the alt or the batteries. 10V would be a totally drained battery. If the drop is happening quickly, that rules out draining the batteries since that would take minutes of zero alternator input to occur. One the other hand, resistance based drops happen instantly and change with amp current demands since the current is what is actually causing the drop.

 

[ctalley44 10+ year member]

what do you suggest i do?

 

[helotaxi 5,000+ posts]

Fix your wiring. I would start with 2 runs each of positive and negative between the front and rear battery. Upgrade the connection between the battery negative and the engine block and the battery to alternator positive connection.

Wire the amps to the rear battery both positive and negative. Make sure that all your connections are solid

 

[dbeez 5,000+ posts]

i feel there is a very bad ground there man i sold you that deka if i recall.

 

[ctalley44 10+ year member]

DId the big 3 and upgraded all the wiring from frront to back in 1/0 gauge and replaced deka with kinetik 2400. still cuts out but ran good for while. whuts the deal now?