Balmar Overheating and Wiring Questions

[jonfreeman]

Interesting problem. The last few times I have gone out, when I shut down, I have a very hot electrical smell permeating the cabin. No obvious melting wires, or smoke, and I have scoured the boat. Anyway, I have narrowed it down to the alternator (took it off, and smelled it up close - THERE is the smell). I am taking the alternator to the shop today to have it checked, but here are my two questions:
- The belt is appropriately adjusted, the voltage was 14+ on the dash meter, and the bearings are smooth and quiet, so why the overheating?
- Why would there be a wire with a slow blow fuse from the output (+) pole to the ground pole on the alternator? This makes NO sense to me, but has been there since I bought the boat.

BTW - As I was removing the alternator, this fuse wire came apart mechanically (may have BEEN apart before I started). This wire REALLY puzzles me.

The previous owner installed this alternator (BALMAR 912-75D - Dual pole with a jumper bar- one output) and a 3 stage regulator (In Charge). Vintage is around 2001, I believe. Specified output is 90 amps. (2) 4D batteries were new last year. Wiring is stock config from Catalina (I know, I know), except the charge wire is #2AWG to the starter.

Any advice or guidance you can provide is much appreciated.

Jon Freeman
Catalina 310 "Summer Sojourn"
Tacoma, WA

 

[Rich Stidger]

Jon,

Some comments-

First, your 912-75D is a 75A output, not a 90A. See the attached file for specs.

Possible reasons for hot running-

1. Your batteries were significantly discharged and the alternator was maxed out.

2. The external voltage regulator has failed and is full-fielding the alternator. This would produce a 14+ volt output.

3. Since your batteries are only a year old it is unlikely that one of them has a shorted cell, but that would cause the alternator to max out and run hot.

4. One or more of the six power diodes in the case is shorted. A electrical shop can determine if that is the case. I would put my money on this cause given your odor and temperature issue.

I can't explain the fuse connected to the positive output. Are you sure it is a fuse? Are you sure it is connected from positive to case ground?

 

[Bill Roosa]

The wire is probably a "zap stopper" It blows when it sees a high voltage. Kinda like a sacrificial diode with 30+ volt forward rating. If you turn off the 3 way disconnecting the batts with the alternator still energized it can cause a voltage spike which will take out the diode pack. The zap stopper is designed to blow first and save the pack.
You can test it by running a diode check, passes current from + to - at some voltage (don't know what that is but something above max alternator regulated output) and does not pass current the other direction at all.

 

[Stu Jackson]

It All Depends on How It's Wired

Where does your alternator output go? To a 1-2-B switch or to the house bank with a combiner, echo charger or something else to the reserve bank?

Rich's suggestions are very, very good.

I also agree with Bill, that sounds suspiciously like a zap stop, used when the AO went to the 1-2-B switch C post to avoid shorting out alternator diodes if your AO went to the C post. If you move your AO to the house bank, you can forget about the need for the zap stop, so maybe you don't even need to test it.

Jon, I know you're active on the C310 forum, so you most likely have read everything Maine Sail and I have been discussing about where the AO needs to go.

Help us to help you by finishing the description of your system.

Added: You also should be familiar with the Small Engine Mode if you have a Balmar (or Xantrex) external regulator. Except for the ARS4 (which also had the feature but not shown in the manual), just RTFM. ")

 

[Maine Sail]

The item with the fuse is most likely a Balmar TSP, transient spike protector, and as others have noted it protects your alternator from an inadvertent pass through the OFF position with the motor running ONCE....

Heat almost always equals deeply discharged batteries and an alt working hard to bring them up. If the bank is big the alt works a long time at or near full output and this can cause almost any alt to develop heat related issues then eventual failure.

With two 4D's you could have as much as 360 Ah's of battery. If they are typical flooded batts then your looking at an acceptance rate of about 90 amps in bulk charge. This "acceptance rate" exceeds your alts capability and if deeply discharged you could see your alt working very hard for a few hours or more. Even Balmar's don't like to run at full output for long periods.

Alts also need air. How tightly sealed is your engine room and what are the operating temps in there?

Fixes: Alternator temp sensor and do not discharge your bank below 50% of capacity. If you smell it getting hot you can also cut the RPM to idle and your alt will produce less but still charge and it will cool off some. Also if you don't have a battery monitor this may be a good time to invest in one...

If your regulator was full fielding your alt you'd see a voltage of 15-17+ volts and 14+ (14.0 - 14.8) is certainly in the correct operating range. It sounds to me like the batts were still in bulk and had not reached target voltage which would likely be somewhere between 14.4 and 14.6..

There is always a possibility of a bad battery, a specific gravity test will show this if flooded, but try to ascertain how deeply you are discharging them when this heat occurs first and what the amperage the alt is putting out is.

 

[Marc14857]

Last year my 100 Amp Balmar failed while I was on Cape Cod. Had an external AR4 regulator. I ended up having Balmar ship me a replacement 70 series which I installed with a new AR5 regulator so I could get home. I did just have the failed alternator rebuilt for a spare. It was only two seasons old. The shop said that the alternator definately overheated as the windings were fried as well as a couple of diodes. Cost me about $175 for the repairs. The shop also said that the most probable cause of overheating was a failed regulator or bad battery. I did have to replace my (2) 4D batteries shortly after the alternator failed but I thought that the battery failure was rellated to the alternator failure. I know suspect that the failed batteries caused the alternator failure.

 

[Maine Sail]

Last year my 100 Amp Balmar failed while I was on Cape Cod. Had an external AR4 regulator. I ended up having Balmar ship me a replacement 70 series which I installed with a new AR5 regulator so I could get home. I did just have the failed alternator rebuilt for a spare. It was only two seasons old. The shop said that the alternator definately overheated as the windings were fried as well as a couple of diodes. Cost me about $175 for the repairs. The shop also said that the most probable cause of overheating was a failed regulator or bad battery. I did have to replace my (2) 4D batteries shortly after the alternator failed but I thought that the battery failure was rellated to the alternator failure. I know suspect that the failed batteries caused the alternator failure.

I see it with AGM's and large wet banks even with perfectly good batteries...

COOKED

 

[jonfreeman]

Wow folks! Great response. I dropped off the alternator at the shop, and hope to hear the verdict today. Meanwhile, I am headed to the boat later today to test the batteries (voltage and hydrometer). I will also look at setting up the "small engine mode" with a switch. I am hoping the old InCharge has that capability. Manual is on the boat, I think.

Incidentally, I WAS on the hook this last weekend, so bank 1 WAS way down, and boat was switched to BOTH to start up and get home.

I also know I need to rewire the AO charge circuit off the switch (Stu), but that will have to wait till winter.

I will follow up, as I proceed on this.

 

[Stu Jackson]

I also know I need to rewire the AO charge circuit off the switch (Stu), but that will have to wait till winter.

Jon, no it doesn't. Just move the AO off the C post of the switch to the house bank post of the switch. Finish it up in the winter.