Weak Charging System....?
 

Guys,

Data dump..... During my 496 rebuild, we retained the OEM alternator. I even took it to a local alternator/starter shop, had it tested and was told it was actually putting out more than it was rated for (don't remember the number). Not so much that the regulator would be bad, just a bit more than rated. I also replaced the entire fuel delivery system, from tank to intake, including a massive fuel pump that is undoubtedly more than I need. It is the pump that Weldon made for the Merc 1075 and 1200s. Like I said, more than I needed, but it came cheap, and I knew it wouldn't fall short. Over the course of the project, I also added an automatic charging relay, so both batteries would be charging while the engine is running but separated otherwise (I have it rigged as Batt#1 and batt#2, not start/house). And lastly, I added a second bilge blower. You know... Just in case. After all is said and done, engine back in the boat and running, I am showing significantly reduced voltage at the gage. With the engine running and the blowers on, the gauge shows ~10.5v. I've checked at the batteries, however, and they both meter at ~12.5. I haven't checked at the batteries, but with the blowers off, the gauge shows a little over 12v, so I'd assume at the batteries would likely meter at well over 13v. So far, we've put several hours on the boat (15+) since getting it back in the water, and the starter has never faltered even a little bit, even after several hours of running the stereo while anchored, but I can hear the fuel pump sag while the engine is cranking over (I've never thought to glance down and see if pressure drops, but I have to assume it does). I keep both batteries on charge when it's on the trailer, but they never show more than ~12.8v after a day's running; typically ~12.3v. I have a 29D series battery, that the Holley HP is connected directly to, as batt#1, and a 27D series battery as batt#2, which is the one I have been starting on, just to make sure to hopefully never have a low voltage situation with the Holley (that's when it will dump the tune, as I'm told). For context, I don't really have any pre-failure data on the charging system, other than we never had an issue.

So, what's going on? Am I swelling on something that isn't an issue? My biggest fear is a low voltage condition at startup and the ECM dump the tune. I've got the global file on a thumb drive, and on our laptop, but I don't carry it with us unless the tuner is going to be doing some tweaking. The tech at Weldon told me, if memory serves right, that the pump draws ~18A at 50psi, and the blowers draw 2.5a each. My presumption is that, between charging both batteries simultaneously, the massive fuel pump and the two bilge blowers, the OEM alternator is just falling a bit short. The CFO has already expressed her displeasure with the whine of the fuel pump, so I'm probably going to be replacing it over the winter with a turbine style pump that will draw less current (open to suggestions), but I'm inclined to keep the dual bilge blowers. Should I be looking for a higher output alternator? If so, what are my options that will drop right in?

Thanks. Brad.

If you checked the voltage at the batteries with an actual voltmeter and you have around 13 volts with the engine running and the blowers on then you are probably ok. I would check the voltage at the gauge with a voltmeter and see what you get. If it is 12 volts and the gauge is only showing 10 then you know that the gauge is the problem. If you get less than 12 volts at the gauge connections then you have a wiring issue.

I'm going to convert mine to Holley ECM's, is this tune dumping a thing? I have not heard of that but that could royally suck any idea of how common it is?

I have two of the Weldon's like you do and they are not particularly noisy. I also have two of the marine A1000 Aeromotive pumps in my system. Do not use those they suck and will fail. I've replaced both of them already and this last one that failed, I used the different Weldon version (similar to the Aeromotives) that is also much quieter and will not fail like those steamy piles of s%&*.

Dave,

Good to know on Aeromotive. That’s actually what I was looking to get when the Weldon kinda dropped in my lap.

The Weldon is pretty loud. The tuner tells me that’s just what gear pumps sound like. It could be because I’ve got it hard mounted to the transom and it’s using the entire hull as a soundboard. I’ve considered mounting it with rubber grommets. But, if I’m gonna replace it for other reasons, I won’t bother.

My tuner tells me the only times he’s seen a Holley ECM dump the tune is if you let the batteries get really low and try to start the engine. Essentially an extreme low voltage condition. Not sure what that number is, though. And this is the core of my concern with my battery/charge situation.

Thanks. Brad.

BillK,

I’m getting ~12.5 volts at the batteries, blowers running which I’m guessing is just barely enough to keep them from discharging while running.

I will have to check under the dash, but I’m not sure I’m going to be able to get a running value until after the season is over. I do need the change the oil again. Maybe I’ll take that opportunity.

i can tell you the volt meter jumps significantly when I switch the blowers off. It’s hard to imagine, with all the other things that draw significantly more, that those two 2.5A blowers are having that much impact on their own. Leads me to believe it’s on the low threshold otherwise.

Thanks. Brad.

Do you run your blowers continuously?

Padraig

Padraig,

No. Not intentionally, anyway. I have been known to forget to turn them off. :rolleyes:

My concern is being that close to maxing out the output of the alternator that two 2.5A motors are enough to slowly discharge the batteries while running.

Thanks. Brad.

Boat wiring to helm can cause odd measurements at the dash. There's likely one hot wire that powers everything on the dash.. If accessories (like blowers/pumps/lights/nav equip) are powered from the dash wiring, that puts a load on the main hot wire pulling the voltage down to the dash mounted volt gauge. The more stuff you power from the dash, the more the voltage drop you get on the main hot wire..

Some of this can be addressed by using relays to power high current items. That way the dash power only has to engage the relay and not actually power the accessory.

In some cases, you can run a larger wire from the batt (or batt switch) to the dash and help prevent large voltage drops. Same for the dash main ground wire since there's not return path in the chassis like most cars have.

I would check voltage at the batt with eng running and all accessories that you would normally run powered-up. If it's low there, you may have more power going out than coming in. Also remember that most alternators don't produce full output at idle.

On one of my prev boats, I couldn't get the spotlight to power up from the cig lighter outlet even though I measured 12V with my handheld meter. Discovered someone had made some wiring mods before I got the boat. Cig lighter was being powered from the clock which was fed by a 22ga wire! Ran dedicated (and fused) 10ga wires (hot and gnd) from the batt to the cig lighter outlet. Spotlight worked great and dash lights didn't dim down nearly as much.

Fuel Pump hard mounted to the hull is likely your megaphone issue.

Sounds to me like you have the perfect setup. CFO is complaining about the fuel pump...and not the thru-hull exhaust....

Having a voltmeter directly connected to the batts is the way to go. Even digital would be goo. One for each batt.

Your blowers are not taking up a lot of current...no different than running headlights...heater fan, wipers etc. What isnthe Holley drawing?

18A fuel pump​
5A Blowers
?? HOLLEY

Not a lot of draw.

The thing to do is test the current output of the Alt while in use. Inductive meter. Otherwise, you're just guessing.

I may have missed it, but have you checked voltage directly at the alternator while running?

Tartilla,

I have no idea what the alternator is actually putting out. Like I said, I had it tested, while the engine was out, and it was over performing at the time. Don't remember the number. It's been a hot minute. What's the spec output of the OWM 496 alternator? I'll try and check it again this weekend.

I would agree that we are not drawing that much. But the overall feeling is that the alternator is barely keeping up. My main wonder is around the fact that we are now charging both batteries simultaneously, whereas before, it was only the one the battery selector switch was set to.

If memory serves, there's a 10A fuse on the power input wire going to the ECM, but there is also a fuse at the relay for the injectors.

It was suggested that I run the two blowers through a relay when I installed the second blower, and I elected to draw straight from the switch. I even bumped up the breaker to 10A (replacing a 5A). Maybe I need to address that over the winter, too.

The thru-transom exhaust sound is normal. The fuel pump whine is new, and, to be fair, it IS an annoying sound. And it's fairly prominent at idle. She said it can be heard as she's walking down the ramp after parking the truck.

Thanks. Brad.

Its not a free diagnosis.. but this is a good piece of kit to have on a boat anyways..

I believe the stock 496 alternator is 65A.
You can measure DC current with a clamp meter like this so you can get actual amperage output from your alternator..

One thing I'm wondering is if your checking your voltage levels at idle? Most alternators, except special built ones, are barely putting out anything at idle RPM. Most won't output full capacity until at least 2000 RPM, so unless you're checking voltage levels at higher rpms, it won't really be accurate unless you're rev'ed up a bit. But again, checking voltage levels isn't really telling you the full story.. You need to be able to measure current output to see if its actually keeping up with the charging needs.

You also mentioned you are using a battery isolator.. These are essentially diodes, which have a nominal voltage drop of 0.6 to 0.7 volts.. So the output of your battery isolator will never be higher than your alternator voltage output minus 0.6 volts.. So if you spend a lot of time idling around the lake, your isolator voltage will be too low to charge.. You should check the voltage at the input and output of the isolator and verify this voltage drop.

I think step one is to actually measure your alternator output voltage and current at 2000ish RPM.

Have you individually load tested both batteries? You could have bad cell(s) in a battery causing the issue. I've seen it before, even on a Optima Blue Top in my 37AT.

Sydwayz,

I have not. But one of them is brand new and they both meter about the same. It's certainly worth looking into.

Thanks. Brad.

AShipShow,

Thanks for the spec on the alternator. I was thinking 70A but didn't really know.

It's the idle speed output I'm most worried about. But, I'll admit, I don't recall actually looking at the volt gauge on the dash while running down the lake. I'll have to do that.

BlueSea Systems calls it an ACR; Automatic Charging Relay. It's just a switch. I don't believe it has diodes. I believe its default is open circuit, isolating the batteries whenever it sees a load (starting, radio, bad battery, etc) or no current, and closes when it sees a charge. It doesn't really have an "output". It is just a switched bridge between the two output lugs of the selector switch. I guess with this said, it would stand to reason that we are seeing a positive charge, over that of demand, or the ECM battery would be down significantly by the end of the day' Logic being, if there were no charge above demand, the ACR would open, and a charge would only go to the battery the selector switch was set on, which has been #2. Am I reasoning that out correctly?

https://cimg7.ibsrv.net/gimg/www.off...679bd59b9.jpeg
There is a ground wire that has since been connected to the ACR that allows it to be an active circuit, detecting current.

Thanks. Brad.

We all know manufacturing QC has gone to shlt since Covid. I can attest as I had a brutal wreck in my racecar due to a simple failed brake component. And we've all at one time or another pulled a brand new broken product out of the box.

Ah, gotcha.. yea, ACRs have basically no voltage drop, so thats a way better system. It might not be working though, you should verify that the contacts are closing when the boat is running.. I believe it has to see over 13 volts for over 30 seconds or a minute or something to close and charge the battery..

Some good advise here, I am a dual engine but isolate and use dual blowers. You should not have low voltage issues, pretty much anything over 1200 rpm and I hover right around 14v. (13.8).

The bilge blower could be put on a relay, amazing how much that helps, I also did it with my hatch ram.

Check the current and voltage out right at the alternator first, then go from there. Who know you may have a bad connection on the main alternator feed. Sometimes even the crimp gets bad.


I use these relays in my little boat.

I used one but it has a switch that I can control the voltage it drops at, use it on my stereo. Nice units.

Lot of good info for ya here Brad. If you’re running 12.5 at idle with a load on your prob ok. Speaking from my PQ experience the dash wiring isn’t great. They run small insufficient gauge wire to the helm and daisy chain everything together. Two things I did that helped a lot; first - run a large power and ground up near helm, set up 2 buss bars and supply dash from there.
Second, power your hatch ram through relays at the rear and control the relays with your dash switch. Your hatch will run faster and won’t make strange things happen with dash while raising hatch.
You probably run at least 3000-3500 when cruising so if alt output is ok at 2000 your good to go.

Liberator221,

Surprisingly, I've got what appears to be a #4 hot and ground wire running to the helm in my boat. It's an '02, so maybe they got with that at some point prior. It is a bit unnerving to have a hot 12v buss bar completely exposed as it is, even if it is under the dash, relatively protected. I feel better having covered it with a couple layers of duct tape. They do daisy chain the 12v and grounds for all the switches and gauges and such, and it does look like the hatch lift is, indeed, powered from the dash. I'm not so concerned about that as I am the voltage drop from the bilge blowers. To be honest, I don't think I've ever looked at the voltage gage while running the hatch up or down. Will have to do that, as well. It just seems odd that such a small draw (blowers) drops the gage that much, given everything else that is drawing on the system as well. It's really the fact that I don't recall it being that much of a drop on the voltage gauge, if any, prior to the rebuild. That's what really got my attention. I think separating the power for them from the dash via relay will ease my concern here, but it won't alleviate an actual problem if there is one.

Part of my concern also stems from the fact that we are now charging both batteries at the same time (assuming the ACR is functioning as prescribed), whereas, prior, we were only charging one at a time, and that this may be why I'm not seeing the voltage I think I should. Is this not of relevant? Nobody has addressed this specific point.

Thanks. Brad.

The pump in question is a used older version, correct? May be time for a rebuild. One of mine failed. Before it failed it was considerably different sounding than the other one. Weldon dude told me that even though it is a "marine" pump, the body (top cap and screws) are not watertight or even have a seal. WTH? Said he recommends it be sealed when I get it back. Apparently, they can get moisture inside and have no way to drain out the water and rust up. Mine is mounted up high enough where there is no way in hell it would get that wet unless the boat sank or you sprayed it with a garden hose all the time. When Weldon inspected mine yep it was full of rust which was the cause of failure in my case. Looked perfect from the outside too. So ya, there is that which may explain your excessive noise. Don't think it should be as loud as you say over the exhaust.

I`ve never heard of, even on the holley tech forums, an ECU "dumping" the tune if the battery is low.
Neither was it ever mentioned at the Holley class I took.

I had a switch at the dash that would actuate a relay and combine both batteries. Came that way from cig. Helps with starting and full voltage. or switch to "all" when starting.

Hook this up to the battery directly and youll get a read out and charging ports, I use these a lot.

There`s always a diferent reading at the dash , mine will be 11v even thou the batteries are at 13.5v .

I had the A-1000`s pumps and they are loud.
Holley pumps were pretty quiet .

Whomever told you that is speading misinformation , must be a democrat..


There is no direct evidence from the provided references or general knowledge that a Holley HP ECU will automatically delete its tune due to a low battery. However, a low battery can cause issues with the ECU's operation, which might be mistaken for a tune being deleted. Here’s a breakdown based on available information and reasoning:

1. ECU Behavior with Low Battery Voltage:
   • A low battery voltage can cause the Holley HP ECU to malfunction, as it requires a stable power supply (recommended to be connected directly to the battery terminals) to function properly.corvetteforum.com
   • Issues such as the ECU not syncing, failing to recognize sensors, or shutting down during operation have been reported when power supply issues occur, as seen in a case where an ECU became unresponsive and would not sync with a computer. These issues could be misinterpreted as a tune being "deleted," but they are more likely related to power supply disruptions rather than the tune itself being erased.offshoreonly.com
   • The Holley HP ECU has non-volatile memory, meaning the tune is stored in a way that does not require constant power to retain the data. A low battery would not typically erase the tune unless there was a catastrophic failure or corruption of the ECU’s firmware, which is not explicitly documented in the provided references.
2. Related Issues from User Reports:
   • In one instance, a user reported their Holley HP EFI setup shutting down and failing to restart, with symptoms like no fuel pump power and a crank-no-start condition. They noted that the ECU was still communicating with a laptop (indicating the tune was likely still intact), but the system wasn’t functioning due to potential power or ground issues. This suggests that low voltage or poor connections could disrupt operation without necessarily deleting the tune.forums.holley.com
   • Another user reported the ECU becoming "totally blank" and unresponsive, but this was attributed to a potential hardware failure (e.g., a bad chip or connection) rather than a low battery explicitly causing a tune deletion.offshoreonly.com
3. Holley’s Recommendations and Safeguards:
   • Holley emphasizes the importance of connecting the ECU directly to the battery to ensure a clean and stable power source, as the battery acts as a voltage filter. A low battery could introduce electrical noise or insufficient voltage, potentially causing erratic behavior, but not necessarily tune deletion.corvetteforum.com
   • The Holley HP ECU includes features like internal data logging with 2GB of memory, which is non-volatile and retains data without power. This further supports the idea that a tune would not be deleted due to low battery voltage alone.summitracing.com
4. Possible Misinterpretations:
   • If a low battery causes the ECU to reset or fail to boot properly, it might appear to a user that the tune has been "deleted" because the system isn’t functioning as expected. In reality, the tune is likely still stored but inaccessible due to power-related issues.
   • Firmware corruption or a failed update could potentially lead to a loss of tune data, but this would require specific conditions (e.g., interrupted firmware update) and is not directly linked to a low battery.offshoreonly.com

Conclusion: There is no conclusive evidence that a low battery will cause a Holley HP ECU to delete its tune. However, a low battery can lead to operational issues, such as the ECU failing to function properly, which might mimic symptoms of a lost tune. To avoid problems, ensure the ECU is connected directly to a healthy battery, as recommended by Holley, and check all power and ground connections if issues arise. If you suspect a tune has been lost, it’s more likely a symptom of a power issue or ECU malfunction rather than an automatic deletion caused by low voltage. For further diagnosis, connecting the ECU to a laptop to verify the tune’s presence or consulting a Holley EFI dealer for support is recommen

Good to know they address the power concerns on the newer models.
Just a suggestion; make two temporary jumper wires. Disconnect volt gauge and connect jumpers from buss bats to gauge. Run boat at idle and 2000 with blowers on to see if readings change. You’ll know if you have a problem or just bad reading.

Dan,

Don't think he's a Democrat. He's into way too many things that Democrats hate.

I'm just passing along what I've been told by someone that deals with Holley ECMs on a daily basis. Literally. He does a full tune at least once a week. If he tells me he's seen it happen, I'm inclined to believe him. I didn't ask him what that voltage was. Hell... It might be something pretty crazy low. He also indicated it had only happened because someone had tried starting the engine while the batteries were already really low. If I had to guess, I'd say it didn't "dump" the tune, but rather the file had gotten corrupted. I know I had thumb drive lose files this way when power went out and I had it plugged into a computer. Flash memory is vulnerable to power flutter. Besides, He wasn't trying to scare me. I had my concerns about it, and his intention was to reassure me it wasn't something I'd need to worry about. It is just something that has been in the back of my mind since noticing the low voltage readings. My antennae are getting sore from trying to stay aware of everything that could go wrong with this engine after the rebuild.

It's all good. I think DiamondDave can rest easy on this topic.

Good to know on the A1000's. That's what the builder was recommending when we were in the process of the rebuild. Tuner tells me the difference between loud and quiet is "gear pump" and "turbine pump". My Weldon is a gear pump. I thought the Aeromotive was a turbine? Yes/no? Genuinely don't know.

I don't see a volt readout on the USB port widgets you posted. ???

Thanks. Brad.

Liberator221,

"Buss batts"...? You mean from the battery to the gauge?

Thanks. Brad.

Buss bars sorry. Your #4 power and ground feeds you said we’re at the helm from the rear.
other than these little gremlins are you happy with the report/rebuild?

I’m thinking your ok just bad readings on gauge but I know the thought of dead battery in middle of Cumberland isn’t good

Liberator221,

Wouldn't that give pretty much the same reading, unless you're just trying to jumper past the wire already going from the buss to the gauge?

Overall? Yes, in the fact that I've got my boat back and the piston failure didn't cost any real boating time (the weather has sucked up until the last month or so). I'm down on power, when I really thought we'd be up by a good bit. Increased valve lift by .030", roller rockers, modified intake, removing plenum for better airflow and a smaller blower wheel. All signs indicated we'd be up in power and I'd be looking for a 30P prop to crack that 80MPH mark. But we're barely cracking the 70 mark, as I'm about 2500RPM off pace. Tuner says it's because the original build, with the ProCharger, didn't pull the timing like it should have (ProCharger doesn't address the ECM at all). We were running NA timing at ~3lbs of boost (most likely the leading factor in the failure), and now we're at a conservative boost timing at WOT. I think there's some room for improvement, and the tuner is willing to play with it, but he's a little apprehensive, given the stock iron heads. A couple of individuals in the know have told me we could go 3-4° more advance and recover most of what's missing pretty safely. We are going to try and get back together after this weekend, a handful of new plugs in hand, and work on it.

Thanks. Brad.

my bad

:ernaehrung004:

Here is what I replaced one of my Aeromotives with:

Weldon Pump LLC 1100-A Weldon 1100-A Electric Fuel Pumps | Summit Racing

That is the pump Eddie Yong put in my Velocity. That was 2013. Gone through another rebuild and still good.

Padraig

Dave,

I wonder if This one would suit my needs @<600HP.

Thanks. Brad.

I wouldn't charge both batteries on the alternator. That is putting quite a load on the alternator.

I would wait till you get back and plug the house battery into a charger.

The small blowers aren't your issue.

UnderPSI,

That die was cast when the decision to convert to Holley was made.

I don’t have it rigged for “start/house”. It is batt1/batt2”. Except for the ECM connected directly to batt1 and Mercathode to batt2, everything runs from the output lug of the selector switch.

Are you suggesting I find a higher output alternator?

Thanks. Brad.

Running jumpers straight from power points to voltmeter would bypass all of th dash wiring to tell you if problem was in there.

No just have 1 battery connected at a time when engine is running

Weldon 1100A is what I have always used. I believe it is a much better pump than the Aeromotive for the same $$$