Cooked Balmar AT-200

[Jd1]

Don't put the regulator into the engine box. This should go a long way towards reducing thermal cycling

[a64pilot]

Originally Posted by transmitterdan

A 28% reduction in current reduces the diode temperature rise (all other things being equal) by 28%. It reduces the winding rise about 50%. So the 150-200C diodes drop about 20-30C. Not enough to solve your problem I think. To make a significant dent in overheating you need 10X more airflow or a 50% reduction in current.

I'm not real sure about the math, but this is I believe a pretty true statement.
You can try putting a blower fan to force air through the alternator and it will help some, but maybe not as much as you would like.

I think the real truth is that these high power small frame alternators are capable of very high power output, for short periods of time, like maybe 5 min or so. Go beyond that and you'll likely burn them up.
It's kind of like hopping up a motor, I can build one to make 300 HP out of a 1 Liter motor. Just don't expect nearly that kind of power continuously.

I think to make these things last a good long time, they need to be derated by about 50%, it seems. Or at least that is my observation from very limited experience.
What I do not know is there an output that most small frame alternators can make before heat gets out of control, and is this number pretty much the same for all "sizes" of small frame alternators, or is this number more of a percentage of rated output?

Best thing you can do for your regulator is get it out of the engine compt, or maybe at least mount it way down low where it's cooler, electronics don't like heat

[George DuBose]

Originally Posted by NahanniV

Or, look at something other than Balmar !!!

Absolutely brilliant comment!!! How about a suggestion?

[kenbo]

Originally Posted by hellosailor

jd-
There are all sorts of issues and solutions to diode cooling that only an engineer in the business or a hard enthusiast would be aware of. For instance, forced air cooling. If there is a heat sink on the diode frame, it is intended to have forced air cooling ALL THE TIME and your test without that, should have thrown a red flag. Typical small frame alternators have one "pusher" fan in the front of the alternator, blowing air into it. The heavy duty alternators often have two fans, one pushing, and a second on the rear "pulling" as well. That's done by necessity.
Then there is diode rating. Diodes rated more conservatively will be larger and more expensive, but they help ensure proper operation. And like all electronic components, a diode's life is cut in half with every 10C rise in temperature. Start with 100 years to 20C and raise the temperature six or eight steps...see how that gets chopped.
AC Delco (I'm pretty sure) at one point marketed a line of alternators with internal spike protection, since normal startup and shutdown throws spikes that can kill the electronics in a regulator and harm the diodes. They found out that the spike protection components failed more often than the rest of the alternator and killed it even sooner. ooops.
And then there are the made Germans over at VW-Porsche-Audi. They've been using water-cooled alternators (shades of video gamers!) in their top-end cars for some years now. Apparently cools great, although the US companies say that's got to create leak problems and shouldn't be necessary.
Remote diodes? More connections, more voltage drop, more complications. Can make cooling easier, certainly makes it easier to use robust diodes in a big heat sinked frame.

There's all kinds of things you can do, probably all have been done before and they are generally not done because of the possible complications. Forced air? With an air source outside the engine bay? That's a fairly easy one, compared to everything else.

There are several point made here are that are in error or misleading to the discussion.

The airflow across an alternator is back to front, at least on the thousands that I have worked on.

Having a remote bridge rectifier is a great modification. Depending on the alternator it can remove 50% of the heat and should result in LESS not more voltage drop. I say this because the wiring going from the alternator to the bridge rectifier is AC not DC, no voltage drop. And if you locate the rectifier closer to the battery bank the DC voltage drop should be less, not more. Plus if done correctly, the only wires on the back of the alternator is the 3 conductor cable carrying the AC from the stator to the remote rectifier. You can eliminate the B+ and ground cables.

Small case alternators have a power ceiling, if they didn't there wouldn't be any need for large case alternators. Large case power starts at about 160A and will run continuously. Small case alts with one external fan have a heat ceiling of about 95-100A, dual internal fan models can go to about 120A. After that you have to make design mods or derate.

Balmar cleverly calls their derating circuit a "belt manager". How many high power small case alts do you think they'd sell if they called it " mandatory heat limiting circuit". BTW, a simple 0-20ohm pot or rheostat in series in the field wire will accomplish the same thing as "belt manager" but allows you to adjust to the temp conditions in the alternator in real time. I always found Balmar's reed switch programming methodology awkward to use.

[Jd1]

Originally Posted by a64pilot

You can try putting a blower fan to force air through the alternator and it will help some, but maybe not as much as you would like.

Actually , cooling air grabbed from outside can make a tremendous difference but you should not depend on that cooling air to produce outputs higher than what the alternator can do without that cooling air. Use the the cooling air only to bring the temperatures down for longer life.

I think the real truth is that these high power small frame alternators are capable of very high power output, for short periods of time, like maybe 5 min or so. Go beyond that and you'll likely burn them up.

This is a dangerous trap! The alternator may still be only moderately warm at the 5 min mark but the diode pack can heat up MUCH quicker than the alternator and you might be cooking the diodes.

I think to make these things last a good long time, they need to be derated by about 50%, it seems. Or at least that is my observation from very limited experience.

Correct! Closer to 60% in my case but that really depends on the installation.

What I do not know is there an output that most small frame alternators can make before heat gets out of control, and is this number pretty much the same for all "sizes" of small frame alternators, or is this number more of a percentage of rated output?

My vote goes for a percentage ... but with a sample size of exactly 1, it's difficult to be sure.

[Jd1]

Originally Posted by kenbo

Having a remote bridge rectifier is a great modification. Depending on the alternator it can remove 50% of the heat and should result in LESS not more voltage drop. I say this because the wiring going from the alternator to the bridge rectifier is AC not DC, no voltage drop.

Huh ?????

BTW, a simple 0-20ohm pot or rheostat in series in the field wire will accomplish the same thing as "belt manager" but allows you to adjust to the temp conditions in the alternator in real time.

Not true. A rheostat reduces the drive across the board whereas the belt manager is a maximum limit. If your regulator wants to provide 49% drive and you have the output limited to 50%, you will in fact get 49% drive. A Rehostat would give you 25% drive. You only want to cap the maximum and not reduce everything so a rheostat is not the way to go.

I always found Balmar's reed switch programming methodology awkward to use.

Whoever came up with that abortion of a user interface should be shot!

[Jd1]

Originally Posted by George DuBose

Absolutely brilliant comment!!! How about a suggestion?

Arduino based Alternator Regulator: 2017 but only if you are technically capable. This is not a 'consumer' device YET.

[hellosailor]

Greg-
What the Balmar tech said about "price point" is really the key. There have been all sorts of objective engineering studies relating to how long components and assemblies can or should operate. And pretty much every really large manufacturer also conducts warranty cost analysis studies, on everything from luxury cars to tv sets, to determine how many will fail in a given time period, so they can set aside enough money to cover the warranty repairs. (Or change the length of the warranty.)

Thousands of solder joints? Yeah, there have been studies on soldering versus crimping versus wire wrap and other methods of assembly, all part of the same. Bottom line is that a "properly designed and engineered" electronic assembly, using discrete parts, has an expected operational lifetime of 100 years. Per the USAF from a 1960's or 70's study. And when the discrete electronics are replaced by IC's, that goes up to 1000 years. So it is certainly possible to build an alternator and regulator that will last along time, with the bearings and other moving parts being routinely replaced as they wear.

What it would REALLY cost them to build more robustly...Dunno, but in today's market a company often builds "just enough" to capture a price point in a market. I suspect the really good stuff comes from some of the boutique brands where "a guy" is offering something better. And you just have to figure out which "guy" really does or doesn't have something better.

What you can do with any electronics is pay attention to heat. Obsessively. Because with every 10C rise in temperature, the working life of the components is cut in HALF. So, if you start by saying something can last for 100 years at "room temperature", 20C? And you step that up to "engine bay" temperature? Maybe 70-80C?

20-30-40-50-60-70-80 That's halving the original life, six times. 50%, 25%,12.5%, 6.25%, 3.12%, 1.6%....So you've taken the original life of 100 years and cut it down to about 19 months before a failure should be expected. Radical, huh?

[kenbo]

Quote:
Originally Posted by kenbo
Having a remote bridge rectifier is a great modification. Depending on the alternator it can remove 50% of the heat and should result in LESS not more voltage drop. I say this because the wiring going from the alternator to the bridge rectifier is AC not DC, no voltage drop.
Huh ?????

What did you not understand. Have you installed a remote bridge rectifier?
It's pretty simple stuff.

[kenbo]

Quote:
BTW, a simple 0-20ohm pot or rheostat in series in the field wire will accomplish the same thing as "belt manager" but allows you to adjust to the temp conditions in the alternator in real time. Not true. A rheostat reduces the drive across the board whereas the belt manager is a maximum limit. If your regulator wants to provide 49% drive and you have the output limited to 50%, you will in fact get 49% drive. A Rehostat would give you 25% drive. You only want to cap the maximum and not reduce everything so a rheostat is not the way to go.

Yes, but....me thinks you're overthinking this. A voltage regulator regulates the voltage the alternator produces, NOT the power, the battery does that. I don't know the circuitry in the belt manager, it may be a simple amperage cap in the field circuit but does that matter, the voltage regulator will send as much amperage as it can through the field circuit (up to about 8 amps) until the Vset is reached, the starts trimming back. I don't care if my regulator is delivering 8 amps and my pot cuts it back to 5, or if the regulator is capped at 5 by belt manager. Does it matter? I don't think so.

[Jd1]

Originally Posted by kenbo

Quote:
Originally Posted by kenbo
Having a remote bridge rectifier is a great modification. Depending on the alternator it can remove 50% of the heat and should result in LESS not more voltage drop. I say this because the wiring going from the alternator to the bridge rectifier is AC not DC, no voltage drop.
Huh ?????

What did you not understand. Have you installed a remote bridge rectifier?
It's pretty simple stuff.

The part that the "huh?" refers to is that AC is supposedly giving you no voltage drop.

[kenbo]

Originally Posted by Jd1

The part that the "huh?" refers to is that AC is supposedly giving you no voltage drop.

Using your 12v/200A/2400 watt alternator as an example. If you disconnect the existing rectifier on the back of your alternator and run 10awg wire from each stator lead (3) to the remote rectifier for a distance of 10 feet, the AC voltage drop in those conductors would be 0.5% when you are at MAX power. 8awg would drop it to 0.3% but why?

The power lost (heat) in rectifying the current makes 0.5% insignificant, that why I said no voltage drop in the AC wire. And conceivably, you could mount the remote rectifier much closer to the battery bank decreasing voltage drop in the DC cabling as well but that's up to the topography of each boat.

A well made 420A remote rectifier can be bought for $150 with 12-70A 300v non-avalanche diodes and powered cooling.

[rom]

Originally Posted by kenbo

A well made 420A remote rectifier can be bought for $150 with 12-70A 300v non-avalanche diodes and powered cooling.

I am looking at this right now, did you install it ? any results you can share ?

[daletournier]

I've been frustrated with the reg limiting my alternator output, realistically my 100amp alternator has been a 30amp alternator up until now.
I moved my blower fan ducting so its literally touching the back of the alternator and this has made a huge difference.
Mounting the reg outside the engine bay is sound advice, ive seen several install close to engine regs fail .
It seems like there is a market for better cooled altetnators, the current ones should be advertised as" 100amp high output alternators(sometimes)"

[ayates]

Originally Posted by NahanniV

Or, look at something other than Balmar !!!

I have been really impressed talking with these folk: Marine Smart Energy

No connection, and not actually purchased an alternator from them yet. But they have been great to work with pre-sales.


Allan.