Balmar Alternator Temperate Protection Settings

[SwamiB]

Years later, but still relevant, I hope.

Have read all internet threads on this topic and can confidently add the following info not often known. All temps in degrees C.

Every alternator's heat failure items are the temp specs of the 6 rectifier diodes, the 3 sense diodes, plus the industry rating of the wiring varnish.

In your common garden auto alternator the diodes are good up to 180°C. The rectifier section is the hottest INTERNAL part, more so than the rear, side, or top casing. That's where the most energy converting from AC to DC is dissipated as heat.

Wire classings are:
A 108°C, B 130, F 155, H 180.
Obviously, different manufacturers would save on the cheaper wire and de-rate accordingly. Thus "what is max safe alternator temperature" is a relative thing. Balmar QC would state their max safe temp based on a safety factor of maybe 50%, ie 105 operating temp is probably class F of 155°C. That would be their ***continuous rating*** with sufficient FACTORY COOLING at high revs from the unit's own fan. So be not worried if you run at 105 all day. I saw one alternator industry standard chart that plotted 20,000 running hours at 105 degrees continuous.

All motor windings varnish will discolour dark brown with heat. So if your windings are dark brown, you've approached its limits at sometime. A tiny cheap digital thermometer from even the alternator casing is a good investment on your dashboard as a prior warning BEFORE regulator de-rating. Study this in regards to engine load, engine speed, current drawn, alternator temp, and engine room temp.

Beware: The cooling of the alternator is dependent upon the current being drawn and the speed of its internal fan. Therefore 100A charging at an idle is more heat-dangerous than at full cruising revs. An auxiliary blower for high amps at low revs is a good idea.

Of course, engine room heat raises the "normal" threshold for the alternator's own heat dissipation. Do you know that an alternator is only about 50% efficient. 4hp (3000w) of engine power-in gives only ~1500w (15v @100A) output. That's a wasted 1500w of room heat for your petrol/diesel fuel being consumed! Therefore, charging at full steam ahead is way more efficient than at an anchor idle charging.

I saw one full load bench test of an alternator which did not fail until 155 degrees. So I do not believe that 100 or 108 is anything for angst about.

Hope this helps.

[Networker]

Super helpful, I’ve been messing with heat in the engine room all summer, going to bump it to 105 and see if it can push out more amps longer.

[SwamiB]

To find your happy-place temperature, two things:

You need to monitor actual alt temp on its metal case. Max suggested 105 degrees.
And you need to monitor engine room temp.

From both these, you need to interpret their relationship ACCORDING TO
Charging current (max desired)
Weather (summer and winter very different)
Engine room blow-through via bilge fans
Engine revs AND LOAD.

Get 2 cheap little LCD temp readers like this. Very useful.
https://www.ebay.com.au/itm/273951619561?mkcid=16&mkevt=1&mkrid=705-154756-20017-0&ssspo=_-3-tDJLRwC&sssrc=2349624&ssuid=5eZs7zpVTjy&var=&widge t_ver=artemis&media=COPY

[sailorboy1]

Hope you don't think I told you to do that. Sounds a good way to burn up altenator

[SwamiB]

Agreed that 105 degC is Balmar's stated "max spec" and 100 is their stated "max comfortable". I too would advise <Networker> not to PUSH UP HIS alt temp for more current but to BRING DOWN his ambient temp for more current at 100 deg. The difference in output current of 5 degree rise will be quite minuscule. Might be time for a bigger alternator or a direct flow fan over its fins or better room venting. Or, maybe its running too slow to cool efficiently. Check pulley ratio to alt speed.

[Networker]

I saw another thread in a different site that charged LiFePO at 13.8 and claimed the alternator never bursted up, overheated, and derated at 100c. Going to try this in the AM, but does anyone know if charging at lower volts keeps it cooler?

[SwamiB]

Mate,
1. Every alternator, engine room, DC charger, battery bank is different. One cannot GUESS or proscribe from another's system.
2. First, you need to understand your own equipment better. Read up on LiFeP4 charging algorithms. Read up on Balmar's preferred charging profiles. It's all in their manuals. Ask your battery maker for theirs. It's all quite variable. Some manufacturers say charge to 14.6v no probs, then soak, then float. Why think LOWER than 13.8? Crazy. Lower voltages undercharge your lithiums. Are you new to lithiums?
3. Instead of jumping to premature conclusions and TELLING us what you're gunna "try", why not list your gear, its specs, tell us what youre trying to achieve, and ASK for advice on how to achieve that.
4. You first asked about temperature. If that's your problem, then address THAT instead of tweaking charge parameters.

What are your battery AH?
What is your alt amps?
What are your cruising revs and alt revs at idle.
Do you sit for days discharging then try to re-charge, at anchor, in an hour???
Do you have sufficient engine heat venting?

[sailorboy1]

Originally Posted by Networker

I saw another thread in a different site that charged LiFePO at 13.8 and claimed the alternator never bursted up, overheated, and derated at 100c. Going to try this in the AM, but does anyone know if charging at lower volts keeps it cooler?

Current is what is going to heat the alternator. You can either charge fast and generate a lot of heat, or slower and generate less heat. I have changed my temperate setting to 95C. I am more interested in protecting the alternator than charging faster.

[Networker]

Dropping down to 13.8 made a HUGE difference in the heat generated. It held higher output much longer, which is what I want when at anchor. Still eventually got to 100c after 2 hours, but it was night and day difference. Motoring, I don’t care if it drops down output as I’m motoring for a while, but at anchor, I want as much as fast as I can get it.

I still have solar so it will still charge at the higher voltage from those, but keeping the regulator at 13.8 seems to help. Will keep playing around.

[Networker]

Originally Posted by Networker

Dropping down to 13.8 made a HUGE difference in the heat generated. It held higher output much longer, which is what I want when at anchor. Still eventually got to 100c after 2 hours, but it was night and day difference. Motoring, I don’t care if it drops down output as I’m motoring for a while, but at anchor, I want as much as fast as I can get it.

I still have solar so it will still charge at the higher voltage from those, but keeping the regulator at 13.8 seems to help. Will keep playing around.

Ok I mucked around all day, the 13.8 did not make the alternator cooler, the target temperature you tell the Wakespeed to hit did it. If I picked a 100c target temp to manage to, whether it was 13.8 or 14.4, it would dial up and down the field % to keep it right at the temp. Same behavior happened at the lower temps. The trade off was reduced output as it dialed down the field %.

In the end, managing for temp at 1800 engine RPM’s, I’d get 40 amps if I shot for 85c, 65 amps at 90c, and 105 amps at 100c. So I’m currently 14.4v targeting 95c as well and getting about 98amps. The engine room at that setting gets to 98F.

Good learning experience for me, though probably obvious for a lot of you. I’m now looking at radiator-type fans to explore putting on the pulley to cool the alternator more, as the engine room already has 2x 220c exhaust fans.

[SwamiB]

Originally Posted by sailorboy1

Current is what is going to heat the alternator. You can either charge fast and generate a lot of heat, or slower and generate less heat. I have changed my temperate setting to 95C. I am more interested in protecting the alternator than charging faster.

To SailorBoy and Networker.

Yes and no.
Ambient temperature room venting
PLUS alternator fan speed
PLUS engine temperature transfer heat via the metal to metal mounting of the alternator
PLUS current
ALL OVER TIME
equals the total temperature the alternator will rise to.

Every factor above is a variable and crucial.

The room temp is crucial, hence summer/winter can be a factor.

Underway vs anchored changes fresh air flow-through if you only have passive vents, or else vent fans are needed.

An alternator has an internal fan. It's specs show current vs revs vs temperature (above ambient) rise. If you try to charge at idle IT WILL NOT COOL anywhere near as half much. A 100 amp vs a 200 amp alternator will obviously heat up vastly different at 80 amps because of its wiring and fannage design. That's why I asked what your alternator is rated at vs YOUR EXPECTATIONS of current desire.

If you just changed from AGM to Lithium, an alternator upgrade is highly beneficial for MORE THAN DOUBLING your charge rate. My previous system was hot with 25A into a 100ah AGM. My new 200ah Lithium can take 100Amps charge, so my new alterbator is a 160a one. No heat probs at 80A. This is why I asked your batterry specs.

Obviously your alternator casing heats up in parallel to the engine block to which it is bolted. My old engine sea fed runs at 50°. Does yours run with a thermostat up to 82°C. In which case, your alternator *AND A STUFFY ENGINE ROOM* will soon get to 82° even if not charging at all!

Obviously time charging affects heat. But, if you take my advice and put a couple of cheap temp sensors on your alternator, you will learn where the sweet spot of happy charge temp is. 30 mins at 100A is a very different heat curve to 50A for 2 hours. Time vs revs vs current vs heat vs fuel are the variables.

[SwamiB]

Originally Posted by Networker

Dropping down to 13.8 made a HUGE difference in the heat generated. It held higher output much longer, which is what I want when at anchor. Still eventually got to 100c after 2 hours, but it was night and day difference. Motoring, I don’t care if it drops down output as I’m motoring for a while, but at anchor, I want as much as fast as I can get it.

I still have solar so it will still charge at the higher voltage from those, but keeping the regulator at 13.8 seems to help. Will keep playing around.

Mate, you are not considering battery health. You are only considering the voltage parameter as affecting temperature. If you study lithium charging, the 13.8v is considered 90-95% full. All well and good, you might think. But those who know (the actual battery makers) say that 14.6v is the best max voltage charge rate. Interesting chemistry occurs in the very top zone to lengthen battery life. By all means, limit your charging CURRENT to keep alternator temperature down. But of course this lengthens charging time needed, but your batteries will love the 14.6 better than the 13.8. Do you get my point?

There is a simple reason that 13.8 "works cooler" than 14.6. Your automotive alternator is made for a non-lithium car system which has a happy voltage ceiling of 13.5 -14.2v. So demanding 14.6 is a step up in heat load. However, 14.6 is what the new lithium technology needs for best life. Lithium was first envisaged for solar and EV use. RV and boats came later, that's why there is an alternator regulator lithium mismatch.

Given the relative costs of those 3 components, my priority would be to design and run a boat house system to preserve the $$$$ lithiums.

It sounds to me that either you are being time and current greedy, or your alternator is under-powered for your litium bank.

You first stated that a hot alternator was your concern. Tweaking voltage is a poor man's solution to a problem you are overlooking in a system which is deficient in overall set up -- ie, current desired (battery bank and usage) vs current generation (ie alternator size and thus heat).

[Networker]

Originally Posted by SwamiB

To SailorBoy and Networker.

Yes and no.
Ambient temperature room venting
PLUS alternator fan speed
PLUS engine temperature transfer heat via the metal to metal mounting of the alternator
PLUS current
ALL OVER TIME
equals the total temperature the alternator will rise to.

Every factor above is a variable and crucial.

The room temp is crucial, hence summer/winter can be a factor.

Underway vs anchored changes fresh air flow-through if you only have passive vents, or else vent fans are needed.

An alternator has an internal fan. It's specs show current vs revs vs temperature (above ambient) rise. If you try to charge at idle IT WILL NOT COOL anywhere near as half much. A 100 amp vs a 200 amp alternator will obviously heat up vastly different at 80 amps because of its wiring and fannage design. That's why I asked what your alternator is rated at vs YOUR EXPECTATIONS of current desire.

If you just changed from AGM to Lithium, an alternator upgrade is highly beneficial for MORE THAN DOUBLING your charge rate. My previous system was hot with 25A into a 100ah AGM. My new 200ah Lithium can take 100Amps charge, so my new alterbator is a 160a one. No heat probs at 80A. This is why I asked your batterry specs.

Obviously your alternator casing heats up in parallel to the engine block to which it is bolted. My old engine sea fed runs at 50°. Does yours run with a thermostat up to 82°C. In which case, your alternator *AND A STUFFY ENGINE ROOM* will soon get to 82° even if not charging at all!

Obviously time charging affects heat. But, if you take my advice and put a couple of cheap temp sensors on your alternator, you will learn where the sweet spot of happy charge temp is. 30 mins at 100A is a very different heat curve to 50A for 2 hours. Time vs revs vs current vs heat vs fuel are the variables.

Tomorrow I’ll do a rpm test, holding everything else constant. My initial test was tonight at low RPM and it got hot at 14.4v at 1200 RPM, hot 95c fairly quick, tomorrow I’ll blast it at 2400 RPM, you’re thinking it will be the same temp, just higher output? Seems like it.

[Networker]

Originally Posted by SwamiB

Mate, you are not considering battery health. You are only considering the voltage parameter as affecting temperature. If you study lithium charging, the 13.8v is considered 90-95% full. All well and good, you might think. But those who know (the actual battery makers) say that 14.6v is the best max voltage charge rate. Interesting chemistry occurs in the very top zone to lengthen battery life. By all means, limit your charging CURRENT to keep alternator temperature down. But of course this lengthens charging time needed, but your batteries will love the 14.6 better than the 13.8. Do you get my point?

There is a simple reason that 13.8 "works cooler" than 14.6. Your automotive alternator is made for a non-lithium car system which has a happy voltage ceiling of 13.5 -14.2v. So demanding 14.6 is a step up in heat load. However, 14.6 is what the new lithium technology needs for best life. Lithium was first envisaged for solar and EV use. RV and boats came later, that's why there is an alternator regulator lithium mismatch.

Given the relative costs of those 3 components, my priority would be to design and run a boat house system to preserve the $$$$ lithiums.

It sounds to me that either you are being time and current greedy, or your alternator is under-powered for your litium bank.

You first stated that a hot alternator was your concern. Tweaking voltage is a poor man's solution to a problem you are overlooking in a system which is deficient in overall set up -- ie, current desired (battery bank and usage) vs current generation (ie alternator size and thus heat).

My specs are:

1200 AH lithium
Balmar 170 alternator
Wakespeed 500

1600w solar (6 panels/6MPPT’s)

2 220 CFM exhaust vents. Not sure how air comes in (it’s now on my todo list, after your posts).

I have this thing instrumented to the gills via Cerbo, Victron and Nema2k sensors, VRM, etc so I am able to see ambient temp, battery, alternator, and current inside the engine room, which I estimate to be 300 cubic feet (I’m on a center console). I could run all sorts of tests to see all the trade offs.

I believe based off what you’re hinting at, I need to see what my airflow in is, how much, and I’d like to get a nascar style fan pointed at the alternator, either electric (and take the penalty hit) or see how effective a fan on the serpentine belt pulley could be since it’s spinning anyways, why not add a fan to it? I am also time and current greedy, I’d rather burn everything out yearly and replace if I had to.

I’m not money constrained, so I’ve looked at that system from Calder that does 9kw at 48v, (integral?). But it takes time and machine work to fit it on my engine. I can’t get an off the shelf larger alternator than the Balmar 170 for my Volvo penta md22, however with machine work, I could. I just haven’t had time.

I like sailing and being out here, so I always try the fastest solution, not cheapest.

I also don’t care about battery health or the alternator and am happy to burn through a bank and alternator each year if it means I can have power. I obviously don’t want fires though. I just want to enjoy sailing at anchor in remote places and have some (not a ton) of power.

[SwamiB]

There's one cheap quick fix to MAYBE lower alt temp and that is a direct fan onto and through the alternator -- because obviously your revs at 1200 are not cooling enough by its own fan. And who wants to run at 3000rpm at anchor. A 100mm 12v computer fan with cowling, or just a dashboard fan, MIGHT fix it. If alt temp (100c) is way higher than room temp, then guess what, the alternator needs more cool air through it. You could always duct some of the incoming fresh air straight onto the alternator. Problem solved.