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Rockford amps cutting out due to inadequate battery supply?


Brodie

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I just redid my stereo system by going from two 4-channel amps(running about 800+ watts RMS) to one 4-channel and two Rockford P500-2s, pushing about 1400 total RMS. Everything is wired with 4 gauge power and ground. With the motor off (it's still winter here) when I crank it up, the rockford amps cut out. The protection lights don't come on on either amp. When I isolate just the tower speaker amp-(P500-2)via the WS 420 they still cut out at high volume.

My question is:

Do Rockford amps cut out if you don't have enough voltage/amperage?

When I ran my 800 watt system last year, it never once cut out, even when parked for 2-3 hours at high volume. Now, the rockfords cut out almost instantly when driven hard, especially the one hooked to the tower speakers (2ohm stereo load).

I have avoided Rockford amps for 20 years due to my opinion that they just don't perform under high volume or low impedance loads. I thought I would give them another chance, but they seem to be what I remember.

None of my other systems have cut out like this (unless they got hot, which isn't the case here). Do I simply need to add another stereo battery? Right now I have 1 Optima for the audio, and separate cranking battery hooked to a Solenoid to isolate while the engine is off.

Fwiw, battery is charged and I even tried it with the charger on. When I turn the key on (thereby connecting the second battery) it gets better, but still cuts out some.

Not impressed with the Rockfords. Anyone else experiencing this with other amps?

I realize I will probably need a second battery for the audio in order to play music while parked, but I'm really surprised the Rockfords cut out instead of just putting out less wattage? What am I missing?

Sent from my iPhone using Tapatalk

Edited by Brodie
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Could be any number of things. At this point I am not convinced that the amplifier(s) are to blame.

Even though the batteries appear to be fully charged, that could just be a surface charge. To be sure, check the voltage at the amplifier primary terminals with a multimeter while the amplifier is under load and right up until (just before) the time the amplifier shuts down.

I like Optima but if the single Optima is a group 34 that is a smaller battery than standard. And then you have the age and condition to consider.

Isolate your issue to one amplifier temporarily just for the purpose of diagnostics. Start with the tower. Disconnect both channels at the amplifier terminals and try only one speaker on one channel at a time. If it shuts down this eliminates a low load impedance and moves the focus to voltage. I suspect voltage in one form or another.

A voltage issue could manifest in several ways. Low voltage is one possible cause. But another possible cause is a potential inequity between audio components. Like when two components in the audio chain are supplied by two different battery sources. The difference in voltage potential seeks to circumvent the isolation and to correct the inequity by flowing in unwanted places, like an RCA shield for example. Or, a bad ground on one component can have it seeking a completed circuit via an unwanted path thereby lowering the operating voltage to one component enough to shut it down.

So triple check every ground of every component in the signal path plus both battery grounds.

Make absolutely certain that ALL audio components share the same physical grounding point and share the same B+ point. No exceptions.

Isolate the tower amplifier from the remaining system with only an iphone/pod as a direct input and see how it does.

Step by step isolation, substitution or measurement until you narrow the cause. No short cuts. Time to roll up your sleeves.

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I had trouble with my kicker ix1000.1 going into protect mode and cutting out after install. Double checked everything and all was good. Decided to put charger on for a day and let both batteries charge to full and tried it and no more cutting out/protect more. I ran system for over an hr today in the shop and no problems at all. Good luck.

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FWIW, I had just the 4 Channel (about 100 x4 at 2.7 ohm load) and one P500-2 (on sub) hooked up for about a month and tested many times without a hitch. I then hooked up the tower amp and now the problems surface. I am running a fuse block on power and a dist. block on ground(same as before). The tower amp is seeing a 2 ohm stereo load as I verified this with a DMM. Voltage at battery was ~12 volts at rest, but dropped under 11 under load. I will check voltage at the amp and try isolating via an Ipod. My gains are set at about 1/3. My 4 channel amp never skips a beat, just the Rockfords, and the tower amp more than the sub amp. If I isolate the tower amp with the 420, is cuts out at about 2/3 volume, and returns if I go down to half.

BTW, my optima is a series 34. I will recheck everything again. I'm just surprised that it cuts out like it does. It really acts like its an issue with the Rockford amp due to low voltage. Are these amps designed to shut below a certain voltage? None of my other amps have done this, Soundstream, Alpine, Kicker, Profile, etc.

FWIW, I have run my batteries down many times over the years with different systems and never had any of my amps cut out due to this.

Maybe I just need to add another battery to power the additional wattage?

Edited by Brodie
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12 at rest is only a 50% charge. A sealed lead acid battery should hold more like 12.5-6 if really charged.

Unfortunately it is the regular 34m battery which has a lower resting voltage. Yes, I agree that it should be higher, but why have I never had an issue before when it was under 12+ volts? I get that I now have additional demand, but shouldn't that just reduce the actual output of the amps due to lower voltage rather than it cutting out?

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easy to test. Take the battery out of your car/truck and substitute it and see what happens.

When I connect both boat batteries via the solenoid it gets better but still doesn't eliminate the cutting out.

The cranking battery is newer than the Optima, so I could try switching them?

Edited by Brodie
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Sure is beginning to sound more like a voltage issue due to one cause or another.

Different amplifiers shut down at different voltage thresholds. The lower the load impedance, the more current flows, the more voltage sags.

A meter can only check DC resistance. AC impedance can be another story.

I may be mistaken, but I thought that a new fully charged AGM rested a little higher, at perhaps 12.8V, although an aged battery won't hold that after the surface charge has dissipated. I would get that battery load tested, or after a full recharge, let it sit in isolation for several days and check the amount of self-discharge. For example, if it drops from 12.5V to 12.0V on its own in two or three days, you have a battery issue.

Btw, your batteries will not last very long if you are repetitively discharging them below 12.0 volts. I would set 11.8V as the minimum. Of course, they will bounce lower with music & heavy bass. If you can't hold close to 12.0V then you need more capacity.

Don't mix an aged battery with a new battery, particularly on the same bank.

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I believe I usually get a resting voltage after a full charge of about 12.45 on my optima. I have it on a 2 amp charge today and will turn off tonight and retest in a couple of days. I will try swapping the 2 batteries, as the starting battery is actually newer and larger capacity. Regardless, I'm not impressed with the amps, as my others in the past would operate at lower voltage. I will probably end up buying a new SRM-29 to replace my Optima, as it doesn't appear to be enough anyways with the additional amp.

Edited by Brodie
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Brodie if it were my boat I swap out the batteries and get a better charger than a 2amp trickle charger. Do them both - not just one of them

You should be able to find group 31 wet cells for $115 to $130 each and I;'d would not stray outside of the East Penn Deka line on the Interstate line. Really would benefit you to look into a pro mariner smart charner as well....might be the most important thing you can do.

Here is how crazed I am about my battery charging routine. We recently moved to some boat storage that does not have electricity. It it 10 miles from the house and has a private ramp and marina with all the amenities. I pull both my 31's at the end of the day and them home to throw them on a the charger...It add's 3 minutes to my routine when leaving and coming and we use the boat once a week....I'd never think of leaving the batteries uncharged for a week and them coming back next week to fire up the boat with depleted batteries.

I know - Im a nut!

Edited by Murphy8166
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Murphy,

My charger is a 50/10/2 amp automatic charger. I usually charge it it at 10 amps for a 3-4 hours and then switch it to 2 amps for 8-10 hours. During the summer, my boat sits on a lift and I have never had an issue with a dead battery (unless I left a switch on), and I didn't need to shore charge them once last year.

The batteries you are referring to, does that include the SRM-29?

Sent from my iPhone using Tapatalk

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Murphy,

My charger is a 50/10/2 amp automatic charger. I usually charge it it at 10 amps for a 3-4 hours and then switch it to 2 amps for 8-10 hours. During the summer, my boat sits on a lift and I have never had an issue with a dead battery (unless I left a switch on), and I didn't need to shore charge them once last year.

The batteries you are referring to, does that include the SRM-29?

Sent from my iPhone using Tapatalk

Yeah - SRM 29 might as well be a group 31.

I'd still consider a smart charger so that you dont have to flip the switch. To each their own

Edited by Murphy8166
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It might not be a voltage issue. It could be a impedance problem.

Make sure the total load on the amp is within specs. I know I just replaced my tower speakers with new speakers, I didn't realize the new speaker was 2ohm. This is causing my Rockford amp to shut down when pushed. My batteries and voltage is fine but the amp can not handle two pair of 2 ohm speakers. it is seeing a 1ohm nominal load per channel and when being pushed the load decreases and the amp goes into protection.

Just something else to look at before you replace everything.

Mike

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Yeah - SRM 29 might as well be a group 31.

I'd still consider a smart charger so that you dont have to flip the switch. To each their own

To clarify, I don't have a Perko switch. I have an ignition activated solenoid isolator between the stereo bank and the engine bank. When the key is off, the batteries are separate. When the motor is running, they are combined. The switch I meant being left on was the occasional dash switch left on in the boat while away. I am open to other battery options. The cranking battery (which is actually a deep cycle) is a group 29, and is only a couple years old, so I will swap the two and go from there. Most of my music listening in the boat is while surfing/boarding, but we do occasionally park for 2-3 hours as well.

Impedance isn't the issue. My tower speakers are 4 ohm running in parallel, (2 ohm stereo load) and I verified this with my DMM. My sub is a 2 OHM DVC sub wired in series so amp is seeing a 4 ohm bridged load, also verified with my DMM. In-boats each have there own channel and that amp never cuts out.

I think the bottom line is that my Rockford amps require a higher minimum voltage than other amps i've used, and I just need to upgrade my battery to at least 1(or 2) group 29 or better.

Edited by Brodie
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To clarify, I don't have a Perko switch. I have an ignition activated solenoid isolator between the stereo bank and the engine bank. When the key is off, the batteries are separate. When the motor is running, they are combined. The switch I meant being left on was the occasional dash switch left on in the boat while away. I am open to other battery options. The cranking battery (which is actually a deep cycle) is a group 29, and is only a couple years old, so I will swap the two and go from there. Most of my music listening in the boat is while surfing/boarding, but we do occasionally park for 2-3 hours as well.

Impedance isn't the issue. My tower speakers are 4 ohm running in parallel, (2 ohm stereo load) and I verified this with my DMM. My sub is a 2 OHM DVC sub wired in series so amp is seeing a 4 ohm bridged load, also verified with my DMM. In-boats each have there own channel and that amp never cuts out.

I think the bottom line is that my Rockford amps require a higher minimum voltage than other amps i've used, and I just need to upgrade my battery to at least 1(or 2) group 29 or better.

The solenoids are French to me. Never used b/c I'd rather flip the switch and always know that it is doing what I want it to. Had a boat for 12 years now / never once forgot to hit da switches.

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Brodie- lots of feedback here.... but I have ran several fosgates over the years and ran batteries very low. IIRC, they did not cut out till they got down to 9.5V or so....

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The solenoids are French to me. Never used b/c I'd rather flip the switch and always know that it is doing what I want it to. Had a boat for 12 years now / never once forgot to hit da switches.

I guess you must be smarter than me, because in 30 years of boating, and 20 years of boat ownership it has happenend a few times for me. I've had perko switches in 2 of my boats, and now I have the Solenoid. I like the solenoid a lot better. IMO, since you want the stereo bank isolated whenever the motor is off, and combined when the motor is running, it is great not having to monkey with the Perko switch multiple times per day. With the current solenoid, I have never had a dead starting battery, since all stereo equipment is isolated while the motor is off. Obviously if I left the key on or left lights on, that would kill the starting battery, but that has never been an issue.

BTW, thanks for all of the advice/suggestions. I will be rechecking and retesting everything, along with probably making some battery changes.

Edited by Brodie
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When I had my system all installed they put in a breaker. I got in the boat and they cranked it up and it kept cutting out, the guy was stumped because he just listened to it for an hour blasting away. So I left the boat with him and he figured out the breaker was set off giving the amps only a little juice (not sure why or how it all works). Once he switched the breaker back on the stereo system worked perfectly.

Maybe something similar in your case? i don't know.

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I charged both batteries and let them sit for 2 days and tested voltage. My group 24 Optima battery from 2009 had 12.39 volts and my Everstart group 27 battery from early 2013 had 12.65 volts. I am guessing that my Optima definitely wasn't fully charged when I had the issues, but I still switched and put the Everstart deep cycle on the Stereo. I haven't had a good chance to crank it up yet, but I'm guessing it was low voltage. When the Optima dies, I will buy a group 29/31 for the Stereo and put the 27 back on the motor. Thanks for the help guys.

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Edited by Brodie
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