Open Source Arduino Alternator Regulator

[markxengineerin]

you don't actually talk about your intended charging algorithm

I was planning on letting the community handle that one. For my prototype, I just send 40 amps out of my alternator until my lithium bank reaches 13.5V, or until I overheat the alternator (which does not happen at 40 amps anyway). The batteries will not reach full charge this way, but that's what solar is for, and I would guess many boats are in a similar situation.

BTW, I can point you to the VSR designs if you want.

Sure, I'd like to take a look at anything non-proprietary.

Are you planning for your regulator to follow this sort of charging profile?

Yes, that would be easy to accomplish

I'm undecided on how many current sensors to include as default, one or two. I agree that only sensing the battery is ok if the alternator thermal protection is working well, but I personally prefer to control to a known-safe current AND monitor temperature, for redundancy. Most boats probably already have a battery shunt to tap into to see what's happening with the batteries, and it will be easy to read those.

I love the display idea, & would like to know more about that.

Nothing special, just a cheap tiny OLED. Here it is in non-packaged form:


I will do two thermistors (or whatever temp sensor we end up with) because they are so cheap.

[nfbr]

Originally Posted by Jon Hacking

I'm now pretty convinced that a "tail-current" charge is the best way to fully charge just about any boat battery, lead/acid or LiFePO4.

[*]LiFePO4 batteries prefer to be charged to only ~85%, but it's hard to know when this is reached[/LIST]

Hi Jon. Do you have data to back the above?
All Li chemistries are very ok with voltage based charging. Sense the knees basically. Curves are ideal.

I have Al’s WS, and it’s algorithms and noise sensitivity suck for Lithium. It works, but its fussy and unreliable. Victron MPPT is much better.

The 85% applies to LiIon but has been pretty well disproven for LiFePO4
I’m in an airport hotel on pone so would need a desk to provide data / references.
The quickest three would be Rod Collins, Tesla and Andy’s OGG.
LiFePO4 doesnt like high voltage, but high SOC seems to be ok, particularly if daily cycling.

Its a bit soon in the project for algoithms, easy to tune later.

And skip Pb algorithms. Lead is dead.

[nfbr]

Re thermistors. When the wiring run is 5-10m from batts to engine room, and the rotor field and high current wires are in the same loom, the WS500 gets sad from the noise, induced current and the resistance of the length. Shielded wire and calibration offsets needed. Thermistors suck on longer runs. Same for millivolt current shunts.

If you put the controller beside the engine, then the battery sense wires have the same problems. Current / Temperature. Voltage sense is less twitchy.

These have been my regulator pains.

[stormalong]

Originally Posted by nfbr

And skip Pb algorithms. Lead is dead.

Lead is alive and well.

I have been following this thread since the beginning, have six Trojan T105 golf cart batteries. They last about ten years if properly cared for and are relatively cheap.

Right now I am still using an Ample power SAR that I installed in 1992. David Smead did a lot of research on the proper way to charge lead acid. David and his company have passed. Some day this regulator will fail and I would like to have a reasonably priced replacement rather than the overpriced products on the market today.

BTW, nfbr, is this the same Razzle Dazzle that was in the 1998 Darwin-Ambon race? Beautiful boat.

[nfbr]

Originally Posted by stormalong

BTW, nfbr, is this the same Razzle Dazzle that was in the 1998 Darwin-Ambon race? Beautiful boat.

Unsure. Joop was original owner and thats about the right time and place.
Yep, she’s wonderful.

I’d be surprised if you could get lead cheaper than lithium now if you count cycle / capacity. >$400 for 300ah@12v that should do >3000 cycles at 80% dod.
Thats cheap.

[fireant]

I find it interesting as I just started to play with Arduino and learn about it.

[Jon Hacking]

Mark, I don't think it's proprietary. Al abandoned this project to help start WakeSpeed, but left it in the public domain AFAIK.

First, there's a Google Groups discussion at smart-alt@googlegroups.com
It hasn't been very active for a while now. Not sure if you want to start this up again, or start your own, or ???

https://ArduinoAlternatorRegulator.blogspot.com/ contains a good overview of the VSR system.

Up at the top of that document are some buttons. Probably the best for your use is the HW Overview, which contains circuits for each section. It's fairly old (2010, I think) so there may be better HW out today.

While I personally went over to LiFePO4 several years ago, there are obviously several cruisers who are still on lead/acid. I guess it's your decision if you want to support them, or make a LiFePO4-only controller. But I will say that folks still using lead/acid probably aren't into a lot of DIY, so any controller would need to be fairly complete.

[Jon Hacking]

Originally Posted by nfbr

Hi Jon. Do you have data to back the above?
All Li chemistries are very ok with voltage based charging. Sense the knees basically. Curves are ideal.

I have Al’s WS, and it’s algorithms and noise sensitivity suck for Lithium. It works, but its fussy and unreliable. Victron MPPT is much better.

The 85% applies to LiIon but has been pretty well disproven for LiFePO4
I’m in an airport hotel on pone so would need a desk to provide data / references.
The quickest three would be Rod Collins, Tesla and Andy’s OGG.
LiFePO4 doesnt like high voltage, but high SOC seems to be ok, particularly if daily cycling.

Its a bit soon in the project for algoithms, easy to tune later.

To be honest, no, not really. There's a fair amount of discussion about this on the Lithium Batteries on a Boat FB forum, but no real sources that I'd trust. My phone certainly stops at 85%, to preserve battery life, but it's LiIon, not LiFePO4. If you have some more detailed links, I'd appreciate them.

I agree that charging to lower voltages is better, especially since my cells (from RJ) don't seem to be well matched. I charge to 13.9v & then do a tail-current charge from there, mainly to keep my cells better balanced. I find that as they pass the knee, the lowest cell can easily become the highest, thereby nullifying any earlier attempts to balance that low cell up.

Sorry you're having issues with the WS. I'm using Al's VSRs, which are really just an earlier version (& much cheaper). I haven't noticed the issues you raise, but I'm not looking for noise, which really needs a scope.

On our cat, the house batteries are under the helm, amidships, 7m from the engines. I mounted my VSRs near the batteries, so the voltage & current sensing wires (twisted pairs) can sense more accurately. Only my field & alternator temperature wires go all the way to the alternators. There may be noise on them, but it doesn't seem to affect operation.

[markxengineerin]

@JonHacking, thanks for the link

From the prior open source alternator:

I had three primary goals I wanted from the Field Drive:

1) Support for HIGH drive and LOW drive (P and N-type) alternators
2) Support for Field Currents up to 20A, allows driving of two or even three alternators in parallel
3) Support for Field Voltage from 12v to 48v, independent of the rest of the battery / system voltage.


Point #3 is perhaps one of the key differentiators of this regulator vs. anything else available. It allows you to use say a 12v alternator to charge a 24v battery. The Field stays 12v, but the battery voltage sensing and such are 24v. Many people are doing this with great success, ala the LN555 type alternator. It also allows one to have say a 12v engine driving a proper 48v alternator.

How many people are really doing #3? My "cheaper" idea does not allow this, but the more expensive one does. Maybe a $10 or $15 difference in components.

[CaptainRivet]

Originally Posted by markxengineerin

@JonHacking, thanks for the link

From the prior open source alternator:


How many people are really doing #3? My "cheaper" idea does not allow this, but the more expensive one does. Maybe a $10 or $15 difference in components.

If its 15$ nobrainer so you can do 3. I don't do 3 now but if a economical regulator allows me to do i will go that route as its one of the biggest reasons i didn't go to 24V yet.
If that regulator is below 300$, its an absolute bargain and saving here and there another 30-50$ is saving on the wrong end.

Another idea from 20years experience working with lifepo4:
The alternator shutdown can be always ramped down from any load to 0A in 3 till 5sec as every lifepo4 is robust enough that under all circumstances this is possible. That would avoid any surge or spikes.
To make sure the alternator can always do that its connected directly to the battery with its own disconnect, this would also insure the field wire always gets the power it needs to ramp down.
The only scenario where this is not possible when you have an internal bank short and the battery fuse cuts the whole bank off but then the alternator spike and surge is your smallest problem plus acceptable and the avalanche diodes in a proper regulator should survive that.
Actually surprised nobody till now thought of that as it solves the 2 major problems with Alternator lithium charging simple and effectiv.

To simplify things i would just focus on Lithium charging regulator and forget all that complicated lead stuff, there are enough external regulators that do that properly. And i am sure the request for them are getting smaller and smaller as lithium is cheaper then AGM now....and will get even cheaper due to EV crises as the manufacturers need to sell their cells.

[markxengineerin]

I want to go with the "1-wire thermometers" instead of thermistors, but how to mount something that looks like this:


To an alternator/battery in a cheap, easy, reliable way? I've used dental cement to attach accelerometers to engine blocks and that worked. I hate to suggest a glue, but it would be universal... And easy enough to detect when one has fallen off and needs to be fixed.

https://www.analog.com/media/en/tech...ts/ds18b20.pdf

On that note, is there something like "1-wire" but meant for remote sensing of small voltages? So far, my search has not turned up much, maybe could combine a chip like this https://eu.mouser.com/datasheet/2/60...00-3122386.pdf
with any i2c voltage chip, in a separate module that mounts near the shunt and transmits back to the Arduino with "1-wire" which I understand is capable of much longer distances than i2c alone. But that seems like it should already be a product- anyone know?

[CaptainRivet]

Originally Posted by markxengineerin

I want to go with the "1-wire thermometers" instead of thermistors, but how to mount something that looks like this:


To an alternator/battery in a cheap, easy, reliable way? I've used dental cement to attach accelerometers to engine blocks and that worked. I hate to suggest a glue, but it would be universal... And easy enough to detect when one has fallen off and needs to be fixed.

https://www.analog.com/media/en/tech...ts/ds18b20.pdf

On that note, is there something like "1-wire" but meant for remote sensing of small voltages? So far, my search has not turned up much, maybe could combine a chip like this https://eu.mouser.com/datasheet/2/60...00-3122386.pdf
with any i2c voltage chip, in a separate module that mounts near the shunt and transmits back to the Arduino with "1-wire" which I understand is capable of much longer distances than i2c alone. But that seems like it should already be a product- anyone know?

I would stay with thermistors that offer a proper mounting solution. The temp probe is the most important part in a external regulator as it protects the alternator from burning up...if that probe falls off the alternator can and will be damaged over time.

[markxengineerin]

I'm confusing myself here, do we need 24V and 48V capability on the field? The first part of this makes it sound like YES, the second part NO.

[CaptainRivet]

Originally Posted by markxengineerin

I was planning on letting the community handle that one. For my prototype, I just send 40 amps out of my alternator until my lithium bank reaches 13.5V, or until I overheat the alternator (which does not happen at 40 amps anyway). The batteries will not reach full charge this way, but that's what solar is for, and I would guess many boats are in a similar situation.


Sure, I'd like to take a look at anything non-proprietary.


Yes, that would be easy to accomplish

I'm undecided on how many current sensors to include as default, one or two. I agree that only sensing the battery is ok if the alternator thermal protection is working well, but I personally prefer to control to a known-safe current AND monitor temperature, for redundancy. Most boats probably already have a battery shunt to tap into to see what's happening with the batteries, and it will be easy to read those.


Nothing special, just a cheap tiny OLED. Here it is in non-packaged form:


I will do two thermistors (or whatever temp sensor we end up with) because they are so cheap.

I like that simple approach.
What i would do is ramp up the field current till alternator reaches 100 degrees case temp and then modulate field current there so case stays at 100 degrees and let the alternator what it can deliver then. The voltage is adjustable, i would go with a default of 13.8V then ramp it down as I described above.
Like this you get the most of every alternator and all what a LFP really need.
Solar is much better to deliver tail current or absorption for the ones that wanna spend a lot money for the last 2%.

[nfbr]

You can PWM the rotor current. No need for DC. But give your switching frequency and inductive damping some thought.

DS18B20 temp sensor is waterproof and <$2

Display / Diag / output useful is what is presently limiting field < target
Eg. Full / Temp Limit / Volt Limit (Bulk / Adsorb / Float) / Load Limit

Gear Input switch is worth having to auto limit output. Small engines cant do prop and large alternator at full power.