Alternator voltage?

[chadwick02]

I feel like the running voltage of my Malibu is lower than normal. Idle its reading about 12.2 and while running it only tops out at about 13.5 – 13.8.

I feel like I remember in years past it being up around 14.2 -14.4 while above 1000 rpm’s or so.

So far this summer on several occations we’ve had low battery voltage and had to switch on the auxiliary battery to start up after a long day on the water. I put the charger on the battery over night and its fine the next day.

We don’t do much “cruising” in the boat – its usually on for a few minutes then off between riders. It’s a small lake and we start and stop from the dock Short runs (short alternator charging times) frequent starts and large stereo and electronics draw made me think after a long weekend the alternator simply wasn’t spinning fast enough for long enough to compensate for all the loads.

But seeing the running voltage be substantially under 14 volts makes me wonder if the batteries are not getting enough charging voltage from the alternator to begin with.

Any thoughts?

- Chad

Edited July 13, 2009 by chadwick02

[Pistol Pete]

I think 13.5 V is normal running voltage. You may have answered your own question with the frequent stop/starts and not letting the engine run long enough to recharge the batts.

[Bobby Light]

I feel like the running voltage of my Malibu is lower than normal. Idle its reading about 12.2 and while running it only tops out at about 13.5 – 13.8.

I feel like I remember in years past it being up around 14.2 -14.4 while above 1000 rpm’s or so.

So far this summer on several occations we’ve had low battery voltage and had to switch on the auxiliary battery to start up after a long day on the water. I put the charger on the battery over night and its fine the next day.

We don’t do much “cruising” in the boat – its usually on for a few minutes then off between riders. It’s a small lake and we start and stop from the dock Short runs (short alternator charging times) frequent starts and large stereo and electronics draw made me think after a long weekend the alternator simply wasn’t spinning fast enough for long enough to compensate for all the loads.

But seeing the running voltage be substantially under 14 volts makes me wonder if the batteries are not getting enough charging voltage from the alternator to begin with.

Any thoughts?

- Chad

You're going to loose that battle if you're constantly relying on your alternator to charge your batteries. They should be fully charged by an external charging source after each outing.

Alternator seems to be doing fine given the task it's been subjected to.

Edited July 13, 2009 by 06vlx

[aaudii5150]

I feel like the running voltage of my Malibu is lower than normal. Idle its reading about 12.2 and while running it only tops out at about 13.5 – 13.8.

I feel like I remember in years past it being up around 14.2 -14.4 while above 1000 rpm’s or so.

So far this summer on several occations we’ve had low battery voltage and had to switch on the auxiliary battery to start up after a long day on the water. I put the charger on the battery over night and its fine the next day.

We don’t do much “cruising” in the boat – its usually on for a few minutes then off between riders. It’s a small lake and we start and stop from the dock Short runs (short alternator charging times) frequent starts and large stereo and electronics draw made me think after a long weekend the alternator simply wasn’t spinning fast enough for long enough to compensate for all the loads.

But seeing the running voltage be substantially under 14 volts makes me wonder if the batteries are not getting enough charging voltage from the alternator to begin with.

Any thoughts?

- Chad

You're going to loose that battle if you're constantly relying on your alternator to charge your batteries. They should be fully charged by an external charging source after each outing.

Alternator seems to be doing fine given the task it's been subjected to.

Spent the first month batteling this issue! Get new batts and a good charger for both batt(we ended up with a 40 amp on-board, LOVE IT!) We replaced 4 out of 5 and now we run like 14 all the time.....

[WakeGirl]

Couple of things.

~ If you drain your batteries, a trickle charger isn't going to be enough to bring them up completely. A good 3-stage onboard charger (like a Promariner) would be the trick, or taking the batteries down to a shop to have them put on an industrial charger for a few days. (With the way that you run though, I think that an onboard charger would be a slam dunk.)

~ You're going to fry your alternator by continuing to put that kind of load on it. You need to get the batteries up to snuff. Furthermore, if they are at unequal levels (sounds like a high probability) then they definitely won't come up properly.

~ Extended periods of high output from your stereo with very little run time in between will drain them. The fewer that you have, the less off key time that you'll have. You may have found the point that you need more batteries if you're going to make it a habit. What are the specs for your stereo? What is typical in terms of when you're in listening mode? Do you run it loud & hard?

On all of my inboards, 14.2-14.5 has been the standard above idle. At idle, it was always at around 13.9-14.0. If things went below those benchmarks, then I knew that I had a problem somewhere.

[rustie]

With these power sucking stereo's (especially those running during "parked" times), anybody ever thought of replacing the standard alternator with a high output unit?

If so, what has been the most reliable uprated alternator??? (been thinking of this solution myself)

[rustie]

These are what I was considering:

http://www.summitracing.com/parts/SUM-810350/

http://www.jegs.com/i/Tuff-Stuff/908/7140B/10002/-1

[rustie]

Or even THIS version. Probably the best choice overall:

http://www.alternatorparts.com/Extreme%20D...-144%20type.htm

[WakeGirl]

You can, but depending on what you get it may run a lot hotter than what you want (= much shorter lifespan). I can't remember all of the specifics from when I was looking, but it wasn't as simple as you would think. From '04 on, Indmar runs 90 amp alternators & as long as everything else is in balance (enough batteries to handle the off-key load, & properly charged batteries), the stock alternator works just fine. Off-key time is generally the real issue here anyway, & a higher output alternator won't help you not drain them just as quickly if you don't have enough to start with.

FWIW, I ran 2 blue top Optimas with my last boat & never had any issues at all after I put the Promariner in. As long as your charging system is working correctly, starting with properly topped-off batteries and of course having enough of them to support your off-key time are the 2 big keys to the equation.

[rustie]

Off-key time is generally the real issue here anyway, & a higher output alternator won't help you not drain them just as quickly if you don't have enough to start with.

Yes, the "off-key" time is soooo true....and a drained batt is just that (you're screwed!) Although, a higher amp alternator will bring them back faster...as long as you can still start. To that end, I just put two brand new Concorde AGM high capacity batts in my LSV, and STILL ran the volts down to 11.9 while running the sound system "off-key" while eating lunch (and general lounging too of course...LOL!)

It barely started the engine, but there was still enough amps to JUST do that...and then during the next few pulls, I watched the voltage climb back up towards 13.6 before shutdown for the day. Of course, if needed, I would put a charger on it over night...but then again, sometimes I feel that should still be plenty for the next day's run (it's a coin toss at that point).

With a higher amp output alternator, I would probably have seen 14+ volts before shutting down....making me feel MUCH better for the following day's runs (without attaching an external charger). And with that last brand of alternators at....

http://www.alternatorparts.com/Extreme%20D...-144%20type.htm

.....a 140, 170 or even a 200 amp unit would easily keep everything topped, even after a couple short pulls before shutting down (and probably enough for a little cranked night time sound too). With their double bridge HD rectifier circuits, THOSE alternators wouldn't even draw a sweat topping BOTH Concorde (or Optima) batts...and would never overheat with the loads we would need. They even have a 350 amp, which is waaaaay overkill....but then again, I like overkill! Naw....I'll stop with the 200amp!

BTW...even a 200amp unit won't cause any noticeable power loss at the prop. It would have the batts topped off in less than half the time the 90amp unit would...and then the load would be backed off as the batt voltage climbed to max (these Concorde's will top out at an amazing 15+ volts on their proprietary charger...but I like to see around 14.4 or so normally).

Another BTW.....just got the key fobs. Verrrry cool WG!!!!

Edited July 14, 2009 by rustie

[WakeGirl]

You need to be sure that it's a marine-rated alternator with a spark arrestor. Also, the voltage regulator may or may not need to be changed, and I would be sure that your wiring harness can handle the extra power. Another important thing to keep in mind is how you are going to spin the alternator. Larger alternators put a larger load on the belt. There is a limit to how much energy you can transfer from the belt and trying for too much will make belt life short and wear out bearings (because you have to make the belt really, really tight!).

100 to 120 amps is probably about the most you can reliably get out of a single V-belt. To go above that you most likely need to change pulleys and have double belts. I am not sure what the limits are on a serpentine belt, which wouldn't apply to your boat. You can opt to have your stock unit re-wound, but often-times that decreases the life since it typically will run hotter.

Couple of sites if you want to pursue it that are reputable for marine grade alternators:

www.balmar.net

www.db-starter-alternator.com

[aaudii5150]

I can run 1600 watts for several hours HARD on one good charge(not from the alternator). I've even thought about taking the stereo bank out of the charging loop so I don't toast my alternator! We were out running the stereo for like 6-7 hours on the 4th without starting the boat and had no issues. If it were me I'd save the money on the big alternator and get another batt or 4 and an on-board charger....

Just my .02

Edited July 14, 2009 by aaudii5150

[chadwick02]

Wow, tons of info guys, thanks!

Here’s some more info on my situation.

Running 2 optima blue tops, less than 2 years old. A hellroaring automatic isolator keeps Battery one isolated at all times (except when charging) and keeps battery 2 connected as the main battery.

The sound system is pretty intense – 3 soundstream 800w RMS amps, alpine deck, JL sub and wetsounds tower speakers. BUT, we hardly ever crank the system since it’s a small lake everyone will hear it – don’t want to be too obnoxious. And we never sit with the system on for more than 5 or 10 minutes – just long enough to change riders…etc.

Even while pulling a rider we don’t blast it. I ran the stereo for hours at similar volumes last year on only a single battery and was still able to start afterward – never had a problem. I added the second battery and isolator as a precaution part way through last summer, and the whole thing has worked flawlessly.

Several weeks ago when I first noticed a problem (when the main battery was to weak to start the boat and I had to use the back battery after a weekend on the water) I put both batteries on automatic battery chargers and brought them up to 100% charge during the week. The next weekend up there I kept my eye on voltage.

Had 12.2 – 12.5 or so when I first connected the battery with the boat off and about the same with the boat running on idle. And only ended up in the low to mid 13’s while underway. This seemed too low for me, especially with fully charged batteries, but I cant remember what the voltage was or should be. I don’t mind investing in an on board charger if I need one, but I want to make sure I’m not covering up a bigger problem by adding one to my system.

- Chad

Edited July 14, 2009 by chadwick02

[WakeGirl]

It is too low. By coincidence, I had a very similar setup, right down to dual Optimas with the HR Isolator. I also had a similar issue start up, just out of the blue. One battery wasn't getting a proper charge, or at first I just thought that it was low. I tried taking both out, getting a good deep charge put on them. Same thing showed up a few weeks later, one was way down. It turned out that the isolator had gone bad on me. So I replaced it with a Perko, bought a Promariner, got everything hooked up/charged up, & never had a problem after that.

I've learned a little bit about isolators, combiners & switches out of all of that. I would never put an isolator in a boat again & here's why. A diode-type battery isolator makes you pay a price for the automatic operation. A diode will drop your charging voltage by .7 volts. If your alternator is putting out 14 volts, your batteries will "see" 13.3 volts. The biggest problem with diode based isolators is this very fact, your batteries never receive the full charging voltage that your alternator can deliver. After learning this, I verified it on the good battery with a volt meter - it was receiving 13.7 volts instead of the full 14.4 that the alternator was actually delivering.

An Automatic Charging Relay, (ACR or combiner) is wired basically the same way as an isolator, but uses voltage sensing to detect a charge. When it knows for sure a charge voltage is present, it closes a switch (relay) that allows both batteries to charge at the full charging voltage. There's a little more to it than that, but I can pull up more info on that if you like. It's probably the way that I'll go in my next boat if I don't just stay with a Perko.

Using the alternator to charge up low batteries is the fastest way to kill it, whether it's the stock alternator or a high output. If the stereo bank of batteries is so low that it's below 13 volts, you need to switch to the starting battery & leave the other bank alone to charge at home. With a Perko you can do this manually & a combiner will do it automatically (it opens the relay on one side if voltage drops below a certain point), an isolator will not allow you to do this.

[chadwick02]

It is too low. By coincidence, I had a very similar setup, right down to dual Optimas with the HR Isolator. I also had a similar issue start up, just out of the blue. One battery wasn't getting a proper charge, or at first I just thought that it was low. I tried taking both out, getting a good deep charge put on them. Same thing showed up a few weeks later, one was way down. It turned out that the isolator had gone bad on me. So I replaced it with a Perko, bought a Promariner, got everything hooked up/charged up, & never had a problem after that.

I've learned a little bit about isolators, combiners & switches out of all of that. I would never put an isolator in a boat again & here's why. A diode-type battery isolator makes you pay a price for the automatic operation. A diode will drop your charging voltage by .7 volts. If your alternator is putting out 14 volts, your batteries will "see" 13.3 volts. The biggest problem with diode based isolators is this very fact, your batteries never receive the full charging voltage that your alternator can deliver. After learning this, I verified it on the good battery with a volt meter - it was receiving 13.7 volts instead of the full 14.4 that the alternator was actually delivering.

An Automatic Charging Relay, (ACR or combiner) is wired basically the same way as an isolator, but uses voltage sensing to detect a charge. When it knows for sure a charge voltage is present, it closes a switch (relay) that allows both batteries to charge at the full charging voltage. There's a little more to it than that, but I can pull up more info on that if you like. It's probably the way that I'll go in my next boat if I don't just stay with a Perko.

Using the alternator to charge up low batteries is the fastest way to kill it, whether it's the stock alternator or a high output. If the stereo bank of batteries is so low that it's below 13 volts, you need to switch to the starting battery & leave the other bank alone to charge at home. With a Perko you can do this manually & a combiner will do it automatically (it opens the relay on one side if voltage drops below a certain point), an isolator will not allow you to do this.

Wow. Interesting info there. You were the first person to put me onto the HR automatic isolators and combiners, too bad you've had a tough time with the product and since changed.

I emailed Mike - a tech at HellRoaring - asking him about my situation and what to do, and also mentioned your situation and compared it to mine. I've attached his response below. According to him the HR products do NOT create a voltage drop. I'm going to poke around up there this evening. I'll disconnect all but one battery and then measure the voltage right at alternator.

I'll report back.

Thanks everyone for your responses. Tons of info as always here!

- Chad

_________

It could be a bad alternator, or it could be a bad or low main battery. Depending on the alternator output capability, and rpms being operated, the demand to charge the main battery could be sufficiently high to consume all of the alternator output. When that occurs, the voltage at the output will drop and be lower than normal. That can be fine for a little while. But, if it never comes up to the normal voltage range, then there is a chronic undercharging problem. Short operation time can result in gradually depleting battery charge. Depending on the time you typically operate, and allowing for recharge, a higher output alternator may be needed, or if it already has sufficient output, then supplemental charge should be applied when in not in use. Another characteristic with some batteries is if it is depleted to zero and held there for a while, it can take a long time after a normal charge voltage is applied before it begins accepting a reasonable charge rate again. Typically a 2 amp charger for 24 to 48 hours can bring a battery from this condition back to a normally operating one. Obviously, this time of operating does not occur in a typical boating outing. So, this kind of supplemental charge is usually good to do at least at the beginning of the season. An occasional supplemental charge for less duration, may be suitable during the season depending on your typical operation and usage.

I think she was referring to a diode type isolator. Ours is not a diode type and doesn't have that .7V drop. You can verify this by checking the voltage at each BIC terminal when it is ON (LED illuminated steady). Typically, there is more drop across the charge wire than across the BIC. Also, some loss across the wire can be beneficial by limiting the peak current demand from the alternator, thereby applying less peak stress. We typically recommend a minimum length of wire for an Auxiliary battery setup for this limiting factor. For a Backup battery setup, the wiring approach is different with larger and shorter wire. But, since the Backup battery is normally near full charge, it will demand very little charge rate anyway.

Digital meters provide the most beneficial readings. But, then it is also important to know between which points they are measuring. The built-in analog panel meters provide a general indication, but are typically not accurate enough to provide the detail needed for this level of diagnostics.

- Mike

[nuttyskier2002]

This is what I did for my sound setup in my '95 Echelon. First of all I left my stock alternator in place to charge the main battery. I added a second alternator using a mounting bracket for the GM 10 or 12SI. My second alternator is a 120 Amp Delco 12SI obtained from here: http://www.cpgenerator.com/highampalternat...evroletgmc.html. Now this alternator is not marine certified. So I obtained the parts to convert it. Here are the parts you need: 9150M - Slip Ring End Replacement and 9151M - Drive End Replacement Screens. They can be purchased from here: http://www.mesmarine.com/alternatorparts.html. You'll have to do some disassembly/re-assembly to get the drive end screens in place but for the coinage you save I think it's well worth it. The screens only cost about $20.00 for everything you need. My 2nd alternator charges the 2nd battery and only the second battery. My main battery is only used for starting/original accessories. Also my head unit is powered by it. My Optima (2nd) battery powers just my audio amps. At the present time I am only using one Optima battery for the sound system. I have run it for 2+ hours at a time and it still has enough power for the amps. I have 3 amps with a combined total of 1400+ watts RMS. The two batteries and their charging systems are isolated from each other except for the grounds. That way I always have a charged battery for starting no matter what. This system is on its 3rd season in this configuration with no problems what so ever. From time to time I do charge my Optima overnight after coming home but that’s only when we finished the day jamming to tunes for 2+ hours with a short ride back to the ramp. From time to time I lift the doghouse and give the aux alternator a once over and lay my hand on it to check temp. I’ve never seen it even get close to overheating. If anyone wants more details about this setup let me now. I’ll be glad to help. //Brian

[meb885]

While were talking about voltages....

Anyone Framilier with the "Battery Option 3" system on the new Malibus?

the 09 VTX i'm getting has "Battery Option 3" (2 800CCA Exide Nautilus Batteries) instead of a 1&2 switch it just says "combined" from how the dealer explained it it does the switching for you... so if you run your stereo and kill the battery as soon as you turn the key to start the boat it will realize this and switch batteries so u have a foolproof way to guarantee your boat starts....

I wasn't looking at the voltage on the dash when we were underway during the demo HOWEVER when we were just floating and talking about features i noticed the voltage at 12.9V (it matched the Hour Meter) that was with the engine running and NO accessories turned on (unless you count the MUX switches and Maliview as accessories)

Is this an OK voltage with the Battery Option 3 system? is it because we just filled and dumped 4 ballast tanks in a 10 minute period?

I mean come on the boat is BRAND NEW

[WakeGirl]

Interesting Chad. I had assumed that the HR was a diode type based on what I found with mine, although truth be told it could just be that in my case the isolator was bad & that removing it from the system is what cured the problem. Based on the info that Mike gave you, I have to assume that that was the case.

[chadwick02]

meb885 - 12.9v sounds good to me with the boat off (and alternator off). Just under 13 volts is what a good healthy fully charged 12v battery should be putting out. When the system is charging (motor running), then you should be higher than that, in the 14's if I recall, but thats the whole thing I am questioning.

I was too busy playing this weekend to tinker around and check voltages..etc. Busy weekend! I'll try to get it tonight or tomorrow and report back.

Thanks everyone!

Chad