What alternators are you guys running with 2 and 3 battery setups?
 

I think the alternator is beginning to go in my boat. I'm running 2 marine deep cycles to power my amps.

My voltage gauge seems to only be around 12v at idle, and as soon as I throttle up, quickly jumps to the 14v range.

I lost my sub amp last week, and I think its due to my alternator being weak and not supplying my batteries with enough juice.

Looking into a higher output alt and wondering what everyone is running!


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I doubt your alternator fried your amp (assuming it wasn't putting out some damaging voltage). Many folks run dedicated batteries that they charge with shore chargers without issue.

I run two smaller AGM's for my setup and run just the stock alternator. What kind of amp draw do you have?

One thing I was told that will fry any system if to make sure your batteries are the same type. Doesnt have been the same brand but capacities have to match.

I run a solenoid setup on two matched batteries so when the boat is running they both charge, when it is shut off the stereo pulls from one battery and will crank from the other.

My sub amp is 2100w rms powering 2 DC audio 12's

And a 900w rms powering my tower and in boat 6x9's

This will be changing though because I'm upgrading to some rev8 or rev10's in a few weeks, so I will have an additional amp to power those.

Want to make sure I don't have any more issues


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As the boat came, there were the 2 batteries, daisy chained if you will with 0awg connecting them.
This is my first boat, and first time running a dual batt set up.
Is this correct?


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I agree with NOSbird, a weak or dying alt should not toast an amp. As the battery voltage drops, the amp will just power off, if the head-unit doesnt first. An over charging alt can though.

I would not trust the helm gauge to diagnose a voltage problem, you need a volt meter. You may just have a bad cable. Then again, its not uncommon to see a low reading at the dash at idle, then it jumps up once the engine is off idle.

burban89,

as long as all the batteries are 12V, they will not damage the electronics. Wiring different types of batteries together can impede the ability of the alternator or on-board charger to properly recharge the batteries, leading to a shortened life span of a battery.

Chevy? Cs144

What alternator are you using now and how many amps? I would check voltage at amp at idle with stereo on, Compare to voltage at batteries. If you have a significant drop you can improve the wiring to reduce that. If your alternator just isn't charging well at idle or lower RPM then a bigger alternator will help. Don't just throw parts at it without getting a better idea of the problem first or you may just be wasting time and money.

Personally I rcently upgraded from a 51 amp to this DB Electrical ADR0334 105 amp. I also made a new 4 gauge charge cable from alternator to starter solenoid. Existing pos and ground to batteries at 2 gauge and look alright. I get no voltage drop between alternator charge post and batteries. I'm happy with it, voltage now reads proper at idle and it will start charging without revving the engine above 2k RPM to get it started. Those are the issues I was trying to solve, I don't have any amps or high draw equipment on the boat, just wanted to know my alt works well, changes at idle, and will recharge quickly after floating for a few hours.

best way to smoke an alternator is to treat it as a battery charger. Your alt should be mroe or less a batt. maintainer. If your sitting for long periods and running down your batts expecting your alt to "re-charge" the batteries you will eventually fry it.

Wheres the post "Like" button when you need it!. :D

can anyone attest to the reliability of these? seems like a killer deal for a 100 amp alternator

A lot of times I have the engine running at idle when floating for music. But it's racking my hour meter.
I'm sure I have the capacity between my batteries to withstand a few hours no problem, but I don't want to take that chance.


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At idle, you are just burning gas. The output from the alt is too low to have any positive impact. Also, the risk of CO in and around the boat is too great to sit an idle for long IMO. Build a larger battery bank and rely on shore charging.

Since I store my boat outside during the summer at a location with no electricity, I wanted to get one of these setups but it's a little pricey
http://www.batterystuff.com/solar-chargers/BSP60WK.html
I know some people that have a houseboat out at Lake Powell and they have one of these setups and works awesome.

Like others have said don't use your alternator to charge your battery's, get a on board charger on there somehow.

Instead of getting an upgraded alternator for mine, I had my stock one rewound at a local shop to output a little over 100 amps. Been running the same alternator for 6 years with no problems, but I have an onboard to do most of the work. Depending on what you currently have this may be your cheapest option.

What do you guys mean by an onboard charger?


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A marine smart charger that gets plugged up to 110AC when the boat is back in its resting spot.

Cabela's has some on sale right now - not sure if they are good prices or not, just passing along:
http://www.cabelas.com/product/Cabel...h-All+Products

If your on a budget....just have your current one re-wound ( like Jason mentioned) up to 90-105 amps is gonna give decent output and be reliable ( and not break the bank) anyhting higher is gonna be expensive...or if it's not made with cheap parts ( liability).

if not on a budget...go with a balmar setup.

You've got to weigh the cost of a new alternator vs. the cost of the fuel burned plus the cost of depreciation from racking up hours on the meter. Assuming that you ever even have to replace the alternator, I bet the alt is much cheaper in the long run. There are some good alternative on here to using the alt as a charger instead of a maintainer but running the engine doesn't sound like one of them.

Well. I may have solved the issue to my problem.

I learned today about wiring 6v batteries in series and being able to pull many more amp hours.
So I have 2 6v golf batteries in route and we will see where that takes me.



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I hope you didnt get misleading advice. a pair of 6V batteries wired in series has the same Ah as a single 6V battery, Its that it takes two wired in parallel to get to a usable 12V.

two 12v batteries wired in parallel retains 12V, but doubles the Ah.