New Balmar Alternator Charging Question

[OceanPlanet]

Otherwise, with the small case alt being used with the MC614, use the belt load manager setting to scale back the max field % to no more than 80% (B4). That will help delay the overheating. If it still heats up, then scale it back more....

[john61ct]

Originally Posted by Pizzazz

bulk charging. In this mode the battery takes as much current as is available up to about 1/3 of it total capacity (e.g. for 100 AHr battery the max charging current is around 35A.

Not all lead is the same: some banks **much** lower, others a bit higher.

Originally Posted by Pizzazz

It is a very painful (meaning slow) process to charge wet cell batteries above 80% (the 80% figure can vary a bit based on temp, battery condition, etc. but it is definitely not 95%).

Yes slow, but slow does not imply painful, unless you're trying to do it with dino juice, which I agree is stupid.

Originally Posted by Pizzazz

1) Accept that your batteries will only reach a max charge of 80%.
...
Your batteries will not last as long as they could but will last a long, long time. If you feel bad about using only the 50% to 80% state of charge range, feel free to discharge to 20%. It will not be as bad as some people will lead you to believe.

Everything is relative, but two points. If a situation required such abuse, the bank would last maybe 20% of their potential cycles if they were treated properly. With a very expensive Rolls/Surrette bank sure, that would still be years, especially if you pushed keeping them past the recommended scrapping point of 20-25% AH capacity loss. Only day-sailors or those staying close to civilization should take those chances, true cruising liveaboards not so much. And with a large bank, that would be a huge waste of money.

Less so with cheap GC2s, but those would be ready to scrap well within a year of daily cycling, maybe under $500 with a small bank, bu very inconvenient, IMO to be avoided if at all possible.

Originally Posted by Pizzazz

Spend the extra effort to always charge to 95-100%. This means either long generator run times, extensive motoring or massive amount of solar.
...
You will constantly worry about your state of charge and will rearrange your life around your batteries.

Does not need "massive" solar at all, depends on usage patterns and the bank's CAR. You just burn fuel in the morning, until SoC is X%. X needs to be just long enough so the panels can finish the "long tail", and will vary by the weather; at first it will take calculating with your battery monitor and some trial & error guesstimates, but soon enough it becomes second nature, no big deal at all.

Remember, by the time you stop your morning dino juice run, the Amps accepted by the bank is much lower, and will continue to drop. In fact most solar installs have Free excess output in the afternoon, which can be put a load dump into heating water or making ice.

Originally Posted by Pizzazz

Even then, assuming you start fully charged at sunset, you will quickly drop to 80% since most people consume large amounts of energy in the evening (lights, pumps, laptops, TV, like a regular house).

But that is not a problem from the bank's POV, as long as true 100% Full is touched every cycle for even a minute, and they always stay above 50% they're happy.

Originally Posted by Pizzazz

You will gain double the expected lifetime of your batteries.

If you keep the AH loss "scrap point" constant, more like 5-10 times, especially when **both** drawing down to 20% SoC *and* consistently failing to get more than 90% full.

Originally Posted by Pizzazz

95% of the boaters I know follow approach 1.

Yes, but 95% of boaters are not cruisers, get back to shore power very quickly, only use their boat a short total time per year.

Most of the rest aren't making a conscious informed choice, they just don't care about the issue and/or are ignorant of the details.

[john61ct]

And besides LiFePO4, choice #4 is Firefly Oasis, lead-based AGM with a unique chemistry whose reduced capacity from PSoC is easily restored via a simple discharge / recharging protocol.

And much cheaper than LFP, around $500 per $100AH.

Also doesn't mind going below 50% as much, so that reduces the extra cost factor quite a bit.

But if PSOC really is unavoidable, LFP properly cared for, comes out cheapest of all over a 20-year ROI window, even at 7+ times the initial investment.

But most people with that kind of scratch don't keep their boat that long.

[Maine Sail]

Originally Posted by deluxe68

But it is only putting out that much for 5 minutes. By 30-40 minutes it is putting out about 40 amps and the batteries are still only around 85-90% charged. The lowest I let them get this week was 70% charged.

At 70% SOC you're starting from basically the absorption point in the SOC curve so your bulk duration will be very short.

Once you are in absorption (constant voltage) the battery determines how long it takes to get full. Count on at least 3.75 4 hours once you hit target absorption voltage before your batteries are anywhere close to full. With lead acid batteries (AGM are still lead acid) the last 10-15% of charge is critical to longevity but also excruciatingly SLOW to get back into the batteries.

Once you hit absorption the size of your alternator really means nothing as the battery can only accept XX amps @ XX.XX volts @ XX SOC. The rate of current acceptance continually declines once voltage is held steady (absorption) and SOC increases.

Here are a couple of examples at two charge rates....

.2C Charge Rate From 50% SOC
From 50% SOC to 100% SOC with a Lifeline AGM, at a .2C charge rate (20% of Ah capacity), you're looking at about 5:45:00 as a bare minimum duration to get to 100% SOC, and this is without your charge source dropping to float prematurely. At a .2C charge rate over 80% of the total charge duration will be during "absorption" and about 20% of the duration will be in bulk..

.4C Charge Rate From 50% SOC
From 50% SOC to 100% SOC with a Lifeline AGM, at a .4C charge rate (40% of Ah capacity), you're looking at about 5:30:00 as a bare minimum duration to get to 100% SOC, and this is without your charge source dropping to float prematurely. At a .4C charge rate over 94% of the total charge duration will be during "absorption" and about 6% of the charge duration will be in bulk.

[Paul L]

Originally Posted by OceanPlanet

Virtually no normal small case alternators can cool themselves enough to run high output for very long. ........

Which kinda begs why they are marketed as high output, specifically marine designed, upgrades. They just can't deliver on what they are sold to do.

[a64pilot]

Originally Posted by Paul L

Which kinda begs why they are marketed as high output, specifically marine designed, upgrades. They just can't deliver on what they are sold to do.

They are high output, just have short duty cycles, and in truth duty cycle will vary based on engine room temp.
I would however like to see them quote a duty cycle to be completely honest.
I'd be surprised to see in excess of 100 amp continuously out of a small frame alternator due to heat build up.

The other thing in my opinion that kills them is we don't turn them at nearly the RPM they should be to get max power out of them, they should be geared very much higher than they are.
I think they should turn about 8000 RPM, but do not quote me on that as it's a belief is all.

[john61ct]

Many high output amps are wound these days specifically to output big amps at high idle. Changing pulley size may well be more trouble or costly.

Yes many big large frames like Leece Neville truck alts can output rated amps all day long, but there often just isn't room for these, especially on land, so people often buy custom-wound "drop in" replacements for stock.

Cooling is yes of course critical, sometimes the diode set is moved off the alt body, active vent fans, etc.

As is a good external VR like MC-614 that will dynamically de-rate based on high temps.

Those that can't / don't want to carry a separate genny will go to all this trouble and expense, to be able to pump in big amps in < an hour of high-idling their propulsion engine.

Which stategy works best with either solar to finish the long tail, or converting to Firefly or LFP as already discussed.

[deluxe68]

I think when we get back on the boat I will change the settings on the regulator to derate the alternator 20%. Because the boat is on a mooring we were running the engine every morning to take hot water showers. Hopefully that will keep the alternator temperature down.

[a64pilot]

Derate it yes, but also bump the RPM higher than idle, a slow turning alt builds heat for two reasons, first at lower RPM it has to work harder to make the same power as at higher RPM and of course the fans are turning slower.
Also consider putting engine in reverse to add some load, this will also heat the water faster as well as be better on the engine.

[john61ct]

As the bank SoC rises, charge all your screens, turn on a water heater or ice maker, turn up the tunes and make blender drinks, do something useful keeping the load up on that engine.

I've heard of Arduino-based VRs that automate that "excess load dumping" like wind and hydro controllers have to, would be very useful for big solar too.

[deluxe68]

We were back on the boat for a week and de-rated at the regulator by 28%. At a high idle (2000RPM) the alternator would put out 133 amps for just a few minutes before heating up to 100C and automatically derating by 1/2 to 65 amps. After 5 minutes it would jump up to 130 amps until it got too hot. All on bulk mode charging. When it got to absorption it settled at 60 amps, cannot remember the temperature.

Called Balmar and they said it was probably due to being installed in a closed area. I said that I did not know of any sailboats that had their engines out in the open. Their reply was that lots of powerboats have open engine compartments. I also asked what the cutoff for engine room temperature was and got no answer. They offered to look at the unit if I shipped it back. Since I am 3,000 miles away I would have to pay the yard to remove and box it. Another $300 down the drain. I asked if they test the alternators on a boat they said no, on a bench at room temp.

Next step is derate the piece of junk by 35-40% and look at adding forced air cooling just for the alternator. I will get some baseline engine room temps before I start any adjustments or other modifications.

[john61ct]

I've heard of people moving the diodes off and away from the alt body, but that may only apply for externally regulated?

You can get server farm fans run on 12V that move massive CFM, can point right at the hotspot, may make a difference even before you get venting to/from outside?

[Jd1]

I have determined that my sustainable output of an AT-200 is approximately 100A at an engine bay temperature of around 55C .... these are all approximate figures but give you an idea.
I have also set up cooling air directly onto the back of the alternator but so far I have not run tests with forced air.
Note that the diode pack runs around 30C hotter than the frame based on my testing. I have my temperature limit set up to 90C and feel much better about that than 100C which is the default MC-614 setting.

[deluxe68]

Originally Posted by john61ct

I've heard of people moving the diodes off and away from the alt body, but that may only apply for externally regulated?

You can get server farm fans run on 12V that move massive CFM, can point right at the hotspot, may make a difference even before you get venting to/from outside?

There is a kit for that but it runs nearly $1,000. It seems to be well made and has ample cooling fins and a fan. I thought about running an intake duct from the vent near my companionway to the front of the alternator. But that opens the increased possibility bringing in water and blowing it into the alternator. I will look at setting the duct to pull air from the back of the alternator and send it out of the compartment vent.

edit. There is a pic on the Balmar site where they have a cowling attached to the rear of a large frame alternator for cooling.

[john61ct]

If the engine room ambient really gets that hot, better to bring outside cool air right to the alt.

Obviously need to watch out for where the increased outflow goes, avoid unintended consequences.

Or worst case vent both in and out.

If you need to pay labor, it may just be cheaper assuming all diesel, to refit with a robust large-frame truck alt like Leece Neville, adding high-flow fan to those not too pricey.

Unless your engine room is just way too hot?

Just spitballin obviously