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jefros

Replacement alternator

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I have a 2000 Sunesta 233 with a 350 mag. The factory alternator is a 70 amp unit. I want to replace it with a higher output unit to satisfy some increased demands due to a stereo upgrade. I was curious if anybody has had any experience with doing this? A quick google search only has me more confused. You can get a 140 amp alternator for 100 deer or for 800 deer! Im not sure why such a discrepancy. Thanks for any info.

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I have a 2000 Sunesta 233 with a 350 mag. The factory alternator is a 70 amp unit. I want to replace it with a higher output unit to satisfy some increased demands due to a stereo upgrade. I was curious if anybody has had any experience with doing this? A quick google search only has me more confused. You can get a 140 amp alternator for 100 deer or for 800 deer! Im not sure why such a discrepancy. Thanks for any info.

A couple of things:

A higher output alternator will not really help to power a high power output stereo system. Your best bet is to install another battery dedicated to running the stereo system, and use a 2nd battery kit to integrate the factory alternator to be able to automatically charge and isolate the batteries.

If you are dead set on adding a larger alternator, it MUST be marine certified and designed for marine use. Marine designed alternators will always be more expensive than an auto based one due to the special spark suppression design. Using a standard auto alternator is an invitation for disaster, as they are not spark suppressed. You are just setting your boat up to be a floating time bomb.

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I have a two battery setup. I also just ordered a Pro-mariner 20 to charge them back at the dock. I was thinking a higher output alternator would slow down the eventual discharge of whichever battery I am running while I am cruising and blasting the stereo. The alternators I was looking at were both marine grade but the Delco model was substantially less then any of the higher end models. I was hoping someone may have had some experience with changing theirs out. Thanks again.

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Seems like this was discussed last year with links. Might search here. ;)

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What purpose do engine room blowers serve if not to remove possible explosive vapors? If the blower is working using an auto grade alt or starter should be of no issue other than not lasting as long in a salt water environment due to corrossion. Fresh water boats won't even have that issue.

I worked several different commercial fishing boats over the years and they always went with automotive grade parts like that for 2 reasons, easily obtained at the drop of a hat and cheap, when your working a boat you don't want to spend a lot on it, the boat is there to make us money. :Twocents:

Oh and I agree adding another battery is key here, the alt is only designed to replace what is taken out of them.

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I think they have flame arrestors built into them. Not that they don't spark but contain it better.

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jefros,

We do all that we can to initially avoid changing out the alternator. A 70 amp alternator should be fine for an 'honest' 1000 watt system running at 50 percent amplifier efficiency if you run it very hard. A Class D system of 1600 watts wouldn't demand any more current. To extend the fuctionality of what you have you can add more battery reserve capacity and add an ACR/VSR to protect the alternator and then become more dependent on AC shore charging for full restoration. An AC shore charger is a great investment in any case.

When an audio system passes a certain power threshold then you do have to upgrade the alternator to a size that corresponds with your power demands. Once you get up to a 150 amp alternator then you really have to consider switching over to serpentine belts and pulleys. When the audio system is playing hard and your batteries are depleted creating a liability for the charging system, the larger capacity alternator is going to extract another 10 horsepower or so. You also want to make sure that an upgrade alternator will produce decently at a reasonable rpm and not just at maximum rpm levels. And, stay away from the cheap Asian imports.

When considering where all the dominoes fall and all the trickle down expenses of a large audio system, it really pays to focus on system efficiency from the get go. You can't beat fullrange Class D topology. Also system component selection and tuning (crossovers, gains, other settings) can be easily responsible for a 6 dB loss or gain in system eficiency. Its never cost-effective to try and make up that loss in extra batteries and larger alternators.

David

Earmark Marine

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in a marine setting unless you are adding 10 subs you do not need a bigger alt. if you have one or 2 subs then a dual battery set up is what you need. most of the time a stereo is playing is stopping taking a cold beverage break with friends so that is where you need the power...lol I put a 140 amp alt on my truck cause all the other computers and electronics running under way. on boats you dont have to worry about that to that extreme

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I appreciate all the good info (especially David). Let me explain exactly what I have and then what my exact concerns were. I recently installed a complete system in the boat myself. The head unit is an Alpine cda-118m. I put 4 pairs of the Alpine m700's in the boat and a pair of Exile XM-7's on the Tower. I have two Alpine pdx-150.4 (one for the in-boat speakers and the other bridged for the Exile's). The sub is a dual 10" bandpass from Toby Subwoofers that I ported out from the storage compartment in front of the driver seat. I have a JL g1700 pushing it. Thus, I have about 1900 watts but they are all class D. (coincidently- I purchased most of the equipment from Earmark -thanks David!). I am extremely happy with the output and the clarity.

I have used it for about two weeks without any issues until this last weekend. While cruising in the low 20's, the stereo turns off and will not turn back on. After about 15 minutes, it suddenly turns back on. The up trim function was also intermittently not working. I was kind of thinking that maybe the batteries were low and the radio turned off because of low voltage? I also thought that maybe that explained the trim not working? When I got back to the dock, I checked all the wiring and charged the batteries. The main power wire coming into the fuse panel was ever so slightly loose so I tightened it (I think this was just to confuse my diagnosis of the issue because only the radio and trim were acting up?) Anyways, the stereo and trim are now back working but I am not sure if it was the wire or the charging of the batteries. Any thoughts would be appreciated.

I have ordered a Promariner 20 for dock charging. I have a perko dual battery switch with two marine batteries (not sure size). Do I need a acr/vcr (combiner?) in the system. Would a 140a Delco alternator help? Thanks...Jim

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R.W.L, I think there would be issues with the Coast Guard when using non-marine parts, especially Alternators and Starters that are not spark protected. There would also be issues with insurance. If your boat explodes and people get injured or worse, your insurance would be well within their rights to deny coverage if you are using non Coast Guard, marine parts. Most commercial fishing boats that I know are Diesel and the chance of explosion is much less. Just my 2cents.

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Only one of the commercial vessels I worked on was diesel, the other 2 both had 455 Olds big blocks in them, they were both wooden boats and no one will insure them.

We'd slap an auto zone part on it and keep pushing the channel, never had any trouble with either and as far as C.G. goes so long as your engine room is ventilated properly and you have required safety equip on board they could care less.

Leaking fuel lines will have been found during inspection which was every time we would load up for the day or night's work.

Maybe state laws vary but you open the hood on any Shrimp boat/Lafitte Skiff down here and that's usually what you will find on the bayou.

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Aside from the marine versus car debate, I was wondering if anyone else had any more advice? David @ Earmark..any input? Thanks in advance

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With your setup, I still think you will be fine using the factory alternator, and by adding the on-board charger, you will be able to maintain full charge on the batteries between outings.

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again since you tighten it up is it working fine now? loose connections can be a pain in the arse...... I had one on the back of my alt. it was corroded an about to break. replaced the ring connector and was fine. so how is it now you tightened it? what is you volt gauge doing when cruise at 20, is it going down with the system is hitting and cranked hard?

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jefros,

I think your system is fine as it stands. An ACR/VSR is certainly convenient and can serve to protect your alternator but depending on your usage habits can increase your dependency on AC shore charging. Also, without the right scheme an ACR/VSR can circumvent the dual battery isolation during shore charging and maintenance.

I'm guessing that the loose connection was your only issue other than you could use a shore charger.

Invest in a $10 to $20 multimeter. It is an essential diagnostic tool for confirming or eliminating a low voltage problem. It will give you the ability to check voltage at the precise moment of the problem and pinpoint the location of the voltage drop whether at the battery(s), at the connections or at the amplifier terminals and most importantly when under load rather than under static conditions which may not reveal much.

As your system grows and as your boat ages don't overlook the status of the main ground and power cables running from the batteries to the engine block and alternator/starter. Sometimes these are not adequate and are prone to corrosion or failing terminations due to shock and vibration. Do a battery check (fluids and resting voltage over 24 hours) and hard physical check on all main power connections every spring. This way you should have confidence through the entire boating season with little maintenance.

David

Earmark Marine

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