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CurtB

Add A Battery Switch And Amp Capacitor?

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CurtB

Fellow bu owners,

I'm doing some upgrades this winter. Installing an Add A Battery system (Dual circuit system from blue sea) and upgrading the audio system with new Capacitor and Amps.

? Will turning the battery switch to off and back on again (possibly a few weeks later) effect or damage the Capacitor since it needs to be charged and discharged when it leaves or enters the system? If anyone has a similar set-up and it works fine let me know. At what point in system is the Cap installed? Thanks

Curt.

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Bobby Light

Do yorself a favor and get rid of the cap you don't need it.

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Earmark Marine

As you know such a large capacitor comes equipped with a resistor for the purpose of a slow charge upon the initial installation. With a daily driven vehicle the capacitor remains charged at all times so this step does not need to be repeated every time you power up the system. However, in a boat the capacitor is automatically discharged every time you disconnect the battery via the switch when you store the boat. A violent recharge with repetition will permanently damage the capacitor and it will become a charging system liability.

A capacitor is intended to connect as close to the amplifier(s) primary terminals as possible rather than near the battery.

A stiffening capacitor can only prop up the voltage for a fraction of a second in the event of a significant short term demand in response to a music transient and cannot raise the voltage above that of your average charging system output. Its a bit of an estoteric solution that doesn't apply to the real challenges of a boat supply.

There are any number of more important remedies such as more efficient amplifiers, increased battery reserves, quality cabling and connections plus an AC shore charger to name a few.

David

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Deephaven

If you need more juice add another battery. Capacitors will do you absolutely no good.

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Brianinpdx

X3 no capacitor. It begs the question, "why are these things deemed so important in audio?". It applies far more to car audio than it does for Marine audio. The reason being, in most car's the battery is located up in the engine compartment and one needs to run power cables back to the trunk area where an amp rack is usually installed. This run can be 15-20 feet and generate voltage drops that affect the amplifier. Not a great thing. By placing that 1/2/3/4/45/50 Farad capacitor in line back physically next to the amplifier it acts as a stiffening device for the voltage feeding the amps. yes that can help with transients etc.

In the marine towboat market there is zero reason for these devices.

1 - the cable runs are typically very short (unless you own a Tige).

2 - as David mentioned, off season discharge situations create a big problem for your system as the cap actually becomes a leech to the batteries its connected to.

My advice = Leave the leech's someplace else. Don't use Caps. Ever.

-Brian

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MLA

X3 no capacitor. It begs the question, "why are these things deemed so important in audio?". It applies far more to car audio than it does for Marine audio. The reason being, in most car's the battery is located up in the engine compartment and one needs to run power cables back to the trunk area where an amp rack is usually installed. This run can be 15-20 feet and generate voltage drops that affect the amplifier. Not a great thing. By placing that 1/2/3/4/45/50 Farad capacitor in line back physically next to the amplifier it acts as a stiffening device for the voltage feeding the amps. yes that can help with transients etc.

For the benefit of the audio section, Id like to address some incorrect info. A Capacitor can not in any way, shape or form, raise the system voltage as implied above. So, to say that its place in a system is to compensate or counter, or stiffen as stated above, a voltage drop caused by long cable runs, is incorrect.

A Capacitors job is to store voltage and then rapidly flood that stored voltage into the system if the static voltage sags. But the voltage level of the Cap will only be as high as the alt/battery. or in the example given, the Cap's voltage will be what it is at the end of the long cable run with a large voltage drop.

So, if you have a long cable run (such as in a car or a Tige as pointed out) with a noticeable voltage drop, and the Cap is placed next to the amp(s), the Cap will see the same voltage drop as the amp(s) and upon discharge, the amp(s) will still see that same drop. There will be NO increase in voltage to compensate for a voltage drop caused by the long cable.

Don't sweat it Brian, you know how it is, we all make mistakes. Good thing there's always someone here to point them out and get the thread back on track. Actually I'd suggest just consulting that www.bcae1.com site. Sometimes a great visual helps in understanding how a capacitor operates.

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Steve B.

Had one of those lightbulbs going off in my head becuase of this conversation.

The thought never dawned on me that having double the battery reserve power would affect the amp's ability to track the signal correctly, but that makes absolute sense !

I alway's run on one battery when chillin', now I may try running on both, just to see if it sounds more full or something.

Steve B.

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Brianinpdx

MLA - Mistakes do happen all the time. But I think you're a bit confused here. This would be a good link for people to take a look at. The issue is the resistance of the 'run' of the power cable in a given automotive environment. Current delivery is degraded. This is a functional issue of ohms law 101. The intended purpose is to keep that energy very close to the given amplifier to reduce /stabilize/stiffen ripple. Sorry if I wasn't clear earlier?

In general, caps of any kind are electronic witchcraft in my opinion because they can be ineffectual in many auto systems. My direct product development experience was with [power core20F] and [power grid 10F] CIRCA 1996-98. The underlaying basis for their success was using a capacitor array with extremely low ESL caps. Read expensive, but had real results for the few that could afford them. If memory serves, these where 500-700 solutions. Crazy expensive.

In short, as it applies to the OP's question, I recommend staying away from caps for all of the reasons in this thread. Pretty simple. It's wasted money. Just my oppinion.

-Brian

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Earmark Marine

We are missing the core issue here with supply cable length. MLA gets it but let me state it in different terms.

A capacitor's intended function is to stiffen the supply voltage in response to transient music demands that momentarly exceed the supply. Yes, the capacitor can deliver a short burst of current but there is no potential to deliver current unless the capacitor voltage is momentarily higher than the supply. Wire length from the battery to the capacitor plays no role in the capacitor's ability to correct a transient voltage sag. Here is why. Let's say you have a battery voltage of 12.5 volts. You have a long supply cable that introduces resistance and therefore a 0.5 volt drop. The capacitor that is at or close to the amplifier primary terminals will see no more than 12.0 volts after the voltage drop and cannot be charged above 12.0 volts. So the capacitor in no way can offset the supply cable loss whether in a short or long run. The capacitor is equally affected by the cable losses.

Can capacitors have a role? Sure, in the ideal situation. You can be sure of this because storage capacitors are used in the same manner inside every amplifier with a DC to AC to DC switching power supply which would include every Class AB, B, D and G/H amplifier that we are presently using. Zapco and Audio Mobile were one of the first two manufacturers of automotive amplifiers that used switching power supplies in the 70s. Zapco had an optional external capacitor storage bank for their amplifier and in that case it made a difference. Again, it can be an esoteric solution in the right system and in the right environment. But the challenges of a boat to maintain voltage at rest with no alternator moves a stiffening cap way down the list of priorities and I'm not sure you will ever reach the bottom of that list. The subtle sonic benefits while underway will certainly be nullified by the high level of compression caused by a very noisy and turbulent environment.

I could go into some depth about how a stiffening capacitor can impact music if anyone is intertested. But you are better served by propping up the voltage with batteries, better cables/connectors and the right shore charger.

Something I wrote above in another post was misinterpreted. I did not suggest that a capacitor would "leech" while in storage because I assumed that the battery would normally be isolated via a battery disconnect switch. Capacitors will self-discharge over time if not maintained by a constant voltage source and then must be slow-charged before re-introduction to the battery in order to avoid damaging the capacitor. Its not an issue in a daily driver but it would be an unnecessary pain in my opinion for a towboat.

David

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Bobby Light

This is getting retarded.

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martinarcher

Let's keep it on topic. The OP asked about a cap and a Perko switch, not about voltage drops, capacitor principle, current draw, etc.

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Deephaven

In 99.9% of mobile audio installations capacitors do have one positive attribute. They are capable of smoothing the voltage delivery to the headlights so that the owner doesn't realize that he has a voltage supply problem. Of course, hopefully you smell the sarcasm in my positive statement.

As for the turning of the switch, generically speaking it is safest to never do it while under load. Some of them are just fine and can be done even while you are running but to be "safe" its better to do it before you start the boat. As for how the cap will be effected by it, hopefully you've read enough to just ignore the installation of one.

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