Many here say that an alternator should not be connected to LiFePO4 and that one should use DC-DC Charger

[Padzb]

You can buy an externally regulated alternator for about $100 or have yours converted, and the balmar ars-5 regulator is ~ $270. A few more dollars for the temp sensor for the alternator. That isn't ideal, but would be better IMHO than other options discussed here.

Searched long and hard for an alternator which control constant current output, wakespeed was the only option found though lots control voltage. AR5 doesn´t seem to do current control. If there´s a $100 option to have control over the alternator output I´d order today - any links? Couldn´t find any unfortunately. Voltage control much easier but doesn´t really help limiting the output to a sustainable level.

Bearing in mind these are all just yet more options which aren´t needed but might be useful. If a good few hours under engine are likely then it woukd be simple to run the Bat to bat for a few hours before and bleed off some power from the trojans to the lifepo4 so the trojans get recharged when motoring. Or try the alternator with LiFePo4 with a fan or 2 and mid revs in the anchorage, not keen on that but if you don´t try, you don´t know. Don´t think the fan belt would be too pleased either but dumping a load of power quick anchored up when no sun for a week might be a handy option to have.

 

[wholybee]

There is a setting in the balmar to limit current. Its called the belt manager.
The balmar regulator limits current as a percentage of field voltage. If you run the field at 50% then the alternator is limited to 50% of its output, more or less. This is independent of any charge voltages you set. You would still hit your full charge voltage it would only take longer.
But you don't even need that, it has a temperature probe. The alternator runs full tilt until it heats up Then current is limited to maintain that temperature. This is the preferred way, as you both get the maximum safe current from your alternator, and keep the alternator at safe temperature.
Wakespeed is the Ferrari regulator. But Balmar is highly recommended, most often used, and proven safe for LFP batteries.

The Ars-5 is the baby brother of thier MC-614/618. The Ars-5 doesn't work with large alternators, only up to about 120A. The Ars-5 doesn't have a built in LFP profile, but allows manually setting it up. The MC-614 has an LFP profile so its easier to set up, but they function the same. It doesn't have the features of the Wakespeed but is still superior to running the inverter to a shore charger.

The Ars-5 is more the $100, but i think is the cheapest regulator safe to use with LFP.

Unless.... The Wakespeed grew out of an open source project based on an Arduino. Everything you need to build one is available and could be had for under $100.

 

[Padzb]

There is a setting in the balmar to limit current. Its called the belt manager.
The balmar regulator limits current as a percentage of field voltage. If you run the field at 50% then the alternator is limited to 50% of its output, more or less. This is independent of any charge voltages you set. You would still hit your full charge voltage it would only take longer.
But you don't even need that, it has a temperature probe. The alternator runs full tilt until it heats up Then current is limited to maintain that temperature. This is the preferred way, as you both get the maximum safe current from your alternator, and keep the alternator at safe temperature.
Wakespeed is the Ferrari regulator. But Balmar is highly recommended, most often used, and proven safe for LFP batteries.

The Ars-5 is the baby brother of thier MC-614/618. The Ars-5 doesn't work with large alternators, only up to about 120A. The Ars-5 doesn't have a built in LFP profile, but allows manually setting it up. The MC-614 has an LFP profile so its easier to set up, but they function the same. It doesn't have the features of the Wakespeed but is still superior to running the inverter to a shore charger.

The Ars-5 is more the $100, but i think is the cheapest regulator safe to use with LFP.

Unless.... The Wakespeed grew out of an open source project based on an Arduino. Everything you need to build one is available and could be had for under $100.

Thanks. Missed thast, does some load limiting then. Cheapest I can find in Europe seems to be €360 without the harness. Still 70% of the batteries price & out of budget for something which is just a "would be nice to have but unlikely to be used much". One day maybe.
Spent some time on the wakespeed opensource github, more than a few hours needed there... ?

 

[hwse]

Searched long and hard for an alternator which control constant current output, wakespeed was the only option found though lots control voltage. AR5 doesn´t seem to do current control. If there´s a $100 option to have control over the alternator output I´d order today - any links? Couldn´t find any unfortunately. Voltage control much easier but doesn´t really help limiting the output to a sustainable level.

Bearing in mind these are all just yet more options which aren´t needed but might be useful. If a good few hours under engine are likely then it woukd be simple to run the Bat to bat for a few hours before and bleed off some power from the trojans to the lifepo4 so the trojans get recharged when motoring. Or try the alternator with LiFePo4 with a fan or 2 and mid revs in the anchorage, not keen on that but if you don´t try, you don´t know. Don´t think the fan belt would be too pleased either but dumping a load of power quick anchored up when no sun for a week might be a handy option to have.

My alternator was controled by a Heart Interface InCharge regulator. It did a decent job on my LFP batteries but did not have the smarts to limit the output or protect from overheating. I knew that if I allowed the alternator to run flat-out it would cook itself.

• As a first step to improving its performance, I put a 1.0ohn 100w resistor into the blue field wire. That dropped the output from 108A to a bit over 60A which is the max load I can get from the 3/8" v-belt without excessive belt dust. At that output, the alternator case temperature was still at 95º so a bit higher than I wanted it.
• I moved the intake hose from the bilge blower to the outlet of the alternator fan. I also wired it so that it would run anytime the engine was running and I could manually turn it on to cool down the engine space after shut down. That cooled the alternator case down to about 85º.
• I then added a digital thermostat relay into the ignition control wire on the regulator with the max temp set at 95º. The thermistor was connected directly to the alternator output stud on top of the 2/0 ring terminal using a metal "P-clip" to sense the case temperature. This allowed the thermostat to turn off charging if the case temperatuer exceeded 95º which can happen at low rpms or a failure of the bilge blower. The Alternator is hot rated at 100ºC minimum.

These changes allow me to get 60A output with a cool alternator and over temp protection. I also plan the following future modifications.

• to rewire the negative brush to be isolated instead of case grounded and install a PWM controller to replace the 1.0-ohm resistor so that I can dial in the output to best suit my cooling capacities.
• I stall a serpentine belt kit so that I can get the full power the alternator can produce.
• Install a fan powered cool air duct routed to the air intake of the alternator to feed it cool air rather than hot engine room air.

These improvements should allow me to get much closer to the 108A rated output without the risk of damaging the alternator.

 

[Padzb]

My alternator was controled by a Heart Interface InCharge regulator. It did a decent job on my LFP batteries but did not have the smarts to limit the output or protect from overheating. I knew that if I allowed the alternator to run flat-out it would cook itself.

• As a first step to improving its performance, I put a 1.0ohn 100w resistor into the blue field wire. That dropped the output from 108A to a bit over 60A which is the max load I can get from the 3/8" v-belt without excessive belt dust. At that output, the alternator case temperature was still at 95º so a bit higher than I wanted it.
• I moved the intake hose from the bilge blower to the outlet of the alternator fan. I also wired it so that it would run anytime the engine was running and I could manually turn it on to cool down the engine space after shut down. That cooled the alternator case down to about 85º.
• I then added a digital thermostat relay into the ignition control wire on the regulator with the max temp set at 95º. The thermistor was connected directly to the alternator output stud on top of the 2/0 ring terminal using a metal "P-clip" to sense the case temperature. This allowed the thermostat to turn off charging if the case temperatuer exceeded 95º which can happen at low rpms or a failure of the bilge blower. The Alternator is hot rated at 100ºC minimum.

These changes allow me to get 60A output with a cool alternator and over temp protection. I also plan the following future modifications.

• to rewire the negative brush to be isolated instead of case grounded and install a PWM controller to replace the 1.0-ohm resistor so that I can dial in the output to best suit my cooling capacities.
• I stall a serpentine belt kit so that I can get the full power the alternator can produce.
• Install a fan powered cool air duct routed to the air intake of the alternator to feed it cool air rather than hot engine room air.

These improvements should allow me to get much closer to the 108A rated output without the risk of damaging the alternator.

Thanks for taking the time to post that, interesting. The alternator onboard already has a thermometer so temperature gets logged every second on a Raspberry Pi, the trojan lead acid never accept much for long so it pretty much tracks the engine temperature. Maybe one day it can turn on/off the field voltage. irst things first though, see what happens with various options in the real world ?

 

[l00semarble]

Where's OP??? Alternator or DCtoDC?

I'm here but this thread went way outside of content of OP (original post) and I don't have anything constructive to add on the separate gas engine DC generator.

There are such things as marine diesel DC generators which are complete built in solutions like a generator.

 

[hwse]

Thanks for taking the time to post that, interesting. The alternator onboard already has a thermometer so temperature gets logged every second on a Raspberry Pi, the trojan lead acid never accept much for long so it pretty much tracks the engine temperature. Maybe one day it can turn on/off the field voltage. irst things first though, see what happens with various options in the real world ?

When I connected my LFP to my boat, the alternator quickly went to 110ºC and I turned it off. That was why I made the modifications outlined above.

 

[hwse]

I'm here but this thread went way outside of content of OP (original post) and I don't have anything constructive to add on the separate gas engine DC generator.

There are such things as marine diesel DC generators which are complete built in solutions like a generator.

There are marine DC diesel generators, but they are not very common.

8080VP-13

5.5 kW Marine DC generator, hybrid power, hybrid propulsion, house power, emergency backup, luxury, cruising.

polarpower.com

 

[l00semarble]

There are marine DC diesel generators, but they are not very common.

Agree

 

[Padzb]

When I connected my LFP to my boat, the alternator quickly went to 110ºC and I turned it off. That was why I made the modifications outlined above.

Datasheet for mine says up to 110DegC so we´ll see how long that takes, guessing not too long but won´t know without checking. Only another option but not necessary. Solar usually is enough, should be even better with LiFePo4, no more watching the amps drip, drip in as the lead acid crawls back to 100% ?

 

[hwse]

On my boat, I do not have solar. I have typically used about 140Ah per day when cruising in the summer. With a single 4D Lifeline this meant that I needed to run my generator a lot to keep up. In the two 10-day cruises since installing my 560Ah LFP bank, I have used just 100Ah per day in spite of adding a 54-qt freezer. Some of this is due to improvements I made to the icebox conversion system but the LFP voltage of 13.2v certainly boosts efficiency by a minimum of 6% just do to working voltage. Anytime the engine is running I am putting in 60Ah which is much more than I could ever put into the FLA. So far, I have not needed to run the generator at all and have gotten all my power just in moving from place to place. Both of those cruises were windless with only one day each when I could sail. If I get windier conditions, I will probably need to make some power but now have a pair of Victron IP67 30A chargers.

 

[Padzb]

hwse, thanks, always nice to hear how others are doing it day to day. I should be fine with solar most of the time plus various options to get a top up if the sun doesn´t shine for a while. And a so far untested towed generator under way which should help a lot.
Tested running a mains charger through the inverter, 28A 12v DC in made 20A out, so nice to have yet another option though doubt it will be needed much.
Only had the LiFePo4 running for a few days, wow! My life has changed! No more constant slight stress about constantly trying the get lead acid back to 100% at least every few days for max life, tbh didn´t really notice it that much until it wasn´t there but it´s for the past decade full time liveaboard it was a tiny little bit like having a baby ? "Need some water? Heard the fridge shut down, you really need charging don´t you, poor thing - don´t worry I´ll run the honda genny for hours and hours.."

LiFePo4 are full on machines. On or off, constant high voltage.
Lead acid is emotional and needy ?

 

[scubadoo]

Hi. New to this forum.
We have been travelling full-time in our motorhome here in New Zealand for the last 8 years.
I installed a 300Ah Sinopoly 4 cell battery as the only battery in the vehicle on day one. No internal BMS. It can still deliver c4000Wh.
It both starts the Mitsubishi Canter 3.9l turbo diesel engine often multiple times a day and runs all the RV goodies.
It is connected to the stock 100A rated alternator via a series120A Victron ArgoDiode Battery Isolator that lowers the end charge voltage to 14.1V and also lowers the current just a little. The battery is always at 100% SOC once the battery terminal voltage reaches that 14.1V.
The alternator has survived all those 8 years charging at 70-80A without releasing too much smoke yet.
Unlike that Victron video at fast idle the alternator spins >3000 RPM.

 

[fratermus]

this was put out as a "you have to" mandate twice in a recent thread

Yeah, I have a personal rule to block/ignore anyone who uses the phrases "you have to" or "what you need". Worst of all is "What you want".

found this youtube pretty detailed / good info charging of LifePo4. For example, at 3:00... you can see 1500 RPM / 65a on a regular alternator starting to smoke.

Yes, a 300Ah LFP bank at 50% DoD can smoke an idling alternator (Expom ER-438740) from a ≤two-liter eastern european vehicle on a bench.

At 3:20... they start testing a Balmar alternator

... at 2,114 RPM, 41% faster than the Expom. This was an oversight, right? Right?

Also, the Expom comes in 70A and 90A models. The 96A cap shown on the configuration software for the Balmar series six (with optional temp sensor) suggests it was either 100A or 120A.

The marketer that pitched this idea deserves all the raises in the world. The social media person who disabled comments deserves the next raise.

 

[hwse]

The point that I believe that the video was trying to make is that left to its own devices, an alternator will lose its smoke when connected to a 50% SOC LFP of any significant size. A small alt will lose its smoke making a little bit of power and the great big high-capacity alt will lose its smoke making a big pile of power.
The problem is that almost no alternator can run at max power 100% of the time. The advantage of the Balmar is not in the alternator, it is the regulator that lets you reduce the output to a level that the cooling will keep up.
My own personal setup has a 108A Ample Power alternator that back in the day were marketed as "hot rated 100% duty cycle". With FLA they are nearly indestructible but now that I have LFP, I need to add additional cool air ducting and a means to recuse the output current by reducing the field voltage. I also have a case thermostat that turns it off if the case gets too hot.

 

[fratermus]

left to its own devices, an alternator will lose its smoke when connected to a 50% SOC LFP of any significant size.

I hadn't realized this thread was in the Marine subforum -- I thought it was in Vehicle Mounted Systems. Mea culpa. I defer to local expertise.

 

[Marinepower]

The point that I believe that the video was trying to make is that left to its own devices, an alternator will lose its smoke when connected to a 50% SOC LFP of any significant size. A small alt will lose its smoke making a little bit of power and the great big high-capacity alt will lose its smoke making a big pile of power.
The problem is that almost no alternator can run at max power 100% of the time. The advantage of the Balmar is not in the alternator, it is the regulator that lets you reduce the output to a level that the cooling will keep up.
My own personal setup has a 108A Ample Power alternator that back in the day were marketed as "hot rated 100% duty cycle". With FLA they are nearly indestructible but now that I have LFP, I need to add additional cool air ducting and a means to recuse the output current by reducing the field voltage. I also have a case thermostat that turns it off if the case gets too hot.

Just to emphasize this above point on heat generated by LFP charging via an alternator, in my small, marine engine compartment, my 110amp Balmar will overheat (108c) in about 20 min if not de-rated to about 65amps continuous ( accomplished by the Balmar regulator "belt manager"). This is not even at idle, but at over 2000 rpm.

However, I way prefer alternator charging LFP over a DC/DC charger solution - as it's far more efficient. My power use is not limited by the size of my LFP bank, it's limited by how much charging I can get into it each day.

Others who have lots of solar and sun may not need to rely on their alt for the bulk of their charging and a DC - DC might be perfect for them.

MP

 

[hwse]

Just to emphasize this above point on heat generated by LFP charging via an alternator, in my small, marine engine compartment, my 110amp Balmar will overheat (108c) in about 20 min if not de-rated to about 65amps continuous ( accomplished by the Balmar regulator "belt manager"). This is not even at idle, but at over 2000 rpm.

However, I way prefer alternator charging LFP over a DC/DC charger solution - as it's far more efficient. My power use is not limited by the size of my LFP bank, it's limited by how much charging I can get into it each day.

Others who have lots of solar and sun may not need to rely on their alt for the bulk of their charging and a DC - DC might be perfect for them.

MP

Have you done anything to improve the cooling? I have had some very good success with moving the intake for my bildge blower to the outlet ports on the alternator. I am also going to install a powered cool air-intake duct to blow cool outside air directly into the alternator case.
I will have both of these fans wired so that anytime the engine key is on, they will be running. I can also manually override the blowers so that they can run after I shut off the engine to cool the space down.

 

[Marinepower]

Have you done anything to improve the cooling? I have had some very good success with moving the intake for my bildge blower to the outlet ports on the alternator. I am also going to install a powered cool air-intake duct to blow cool outside air directly into the alternator case.
I will have both of these fans wired so that anytime the engine key is on, they will be running. I can also manually override the blowers so that they can run after I shut off the engine to cool the space down.

I have an extraction fan pointed at the back of the alt. It makes some difference, but not a lot.

I have a high / low switch hooked up to the alt. (Balmar's "small engine" mode). So I typically charge at a lower rate, depending on my power needs that day. I run the extraction fan only when I have the alt. at full power (small engine mode "off").

I think an externally rectified alt. might be the way to go to get rid of waste heat. Pricey though.

Or perhaps the newer Balmar model alts. that appear to be more efficient ( ie less heat per amp).

MP

 

[hwse]

My engine space is very hot without a blower because I fully sound insulated it which reduced the airflow and provides thermal insulation as a side effect. That means that it is normally about 160ºF/71ºC just from the diesel engine. My alternator's cooling fan is on the front pully which pulls that hot air in the back and expels hotter air from the front. My bilge blower intake is at the front of the alternator, so it is removing the heated air off the alternator and that has allowed me to run my 108A Ample Power at a constant 60A with a case temperature of about 190ºF/88ºC.
I think that adding a cool powered duct to bring cool outside air directly to the back of the alternator will have a significant effect on reducing the alts temperature. Right now, I cannot go any higher than the 60A I am getting because of the stupid 3/8" v-belt, but after I add a serpentine belt kit I hope to increase that to at least 80A and maybe a bit more. I have an Inkbird digital thermostat that cuts power to the regulator to shut down the charging if the alternator case temp goes over 212ºf/100ºC as a safety backup.