Stator charging systems and LiFePO4 batteries, is it possible?

[KandKKustomz]

Power pole CHARGE..

[lpugh]

Power pole CHARGE..

I would not use on a stator system unless they agreed in writing to pay for any stator system problems that occur. Using one of these would have the same effect as discharged battery or wrong type. Resistance could be built in to system but then you defeat the purpose

[ntslam]

Power pole CHARGE..

The Charge has worked good so far (3 trips) with my AGMs with a stator charger. The unit does allow you to select battery type and either AH or RC to set charging parameters. So I guess time will tell how well it works with the stator system

[CatFan]

Power pole CHARGE..

Mercury says not to use the stator charging systems with multiple batteries.

[Haughton]

Use the Simon kit to replace stator system to alternator

http://www.simonmotorsports.com/2.5alt/2.5alt.html

[lpugh]

Mercury says not to use the stator charging systems with multiple batteries.

That what I would do, thanks for the tip, never new anyone was offering a conversion

[eh2000]

Thank you to everyone for all the help and suggestions. I’ll be home in a few days and provide a more detailed response. The short version is that I’m now more confused than when I started, but I look forward to generating a productive discussion with all of you soon.

[eh2000]

lpugh, do you have any response for the questions I've asked you?

CatFan, thank you for your response. Perhaps you missed my post above about the Theory of Operations for Stator based systems. Would you agree that we have a similar understanding of these systems?

Ann-Marie, great points about Voltage! I've got lots of questions for you.
What are your thoughts on the use of constant voltage vs constant current charging and what do you mean by "current"?
I disagree entirely that stator output is battery voltage, how did you come to this position?
My post is not talking about a 100 amp alternator, it is talking about a 16 amp stator with a regulator that limits voltage to 12.5-14.3 Volts. When functioning properly how can that result in overcharging? I agree that RPM and heat affect the output of the stator. If the current of a stator is dependent upon coil design, magnet arrangement, and RPM, how can a batteries resistance change the amount of current can be produced? I believe the voltage and amp output are independent of the state or type of battery. Internal resistance can certainly affect the time it takes to charge as well as the heat produced, but I don't think it changes the stator output.
I don't understand what you are talking about with regard to "and an alternator cannot put out maximum current into a voltage this high, rated current on an alternator refers to a 10 volt load.

moetorola, welcome to the discussion and thank you for spending a few minutes here. My question for you is how does a battery pull current from a charging source? From my very limited experience, the best way to protect regulators and stators is to keep connections tight and corrosion free.

kandkkustomzhiydrographics, thank you for the recommendation of the Power Pole Charge, I'm not ready to spend that kind of money and this doesn't really answer the question of compatibility between a stator based system and LiFePO4 batteries.

Haughton, I didn't even know that kit was a possibility. Have you ever used one of those?

[yupitsme]

Just food for thought.... On the aftermarket alternator system. The literature states that this is to be used in conjunction with the existing stator charging system. It implies it is not a total replacement for the stator charging system. I could not get to the specifications for the alternator add-on. But... Low rpm output "could" be an issue. The alternator on a ProXS has a 3:1 pulley arrangement to allow for sufficient output at idle/low rpms. As stated earlier did not have access to the specifications but for sure output of the alternator would need to be considered across the full engine rpm range before adapting as a full on replacement of the stator system.

[Ann-Marie]

lpugh, do you have any response for the questions I've asked you?

<SNIP>

Ann-Marie, great points about Voltage! I've got lots of questions for you.
What are your thoughts on the use of constant voltage vs constant current charging and what do you mean by "current"?
I disagree entirely that stator output is battery voltage, how did you come to this position?
My post is not talking about a 100 amp alternator, it is talking about a 16 amp stator with a regulator that limits voltage to 12.5-14.3 Volts. When functioning properly how can that result in overcharging? I agree that RPM and heat affect the output of the stator. If the current of a stator is dependent upon coil design, magnet arrangement, and RPM, how can a batteries resistance change the amount of current can be produced? I believe the voltage and amp output are independent of the state or type of battery. Internal resistance can certainly affect the time it takes to charge as well as the heat produced, but I don't think it changes the stator output.
I don't understand what you are talking about with regard to "and an alternator cannot put out maximum current into a voltage this high, rated current on an alternator refers to a 10 volt load.

<SNIP>

"Current" is what flows into a battery to charge it. "Voltage" is what pushes the current into the battery. Resistance is what resists the current flowing when the voltage pushes it.

You cannot charge a battery with constant voltage, the battery voltage changes with charge level and rate of charge so it is NOT constant.
Constant voltage sources have minimum internal resistance in order to keep the voltage constant.
If a constant charger voltage was less than the battery voltage nothing would happen. (Voltage has to be higher for current to flow.)
If the constant charger voltage is higher than the battery voltage the only thing limiting current is the total resistance of charger + wiring + resistance of battery and since all 3 are minimized to improve efficiency you will risk damaging something with excess current.

A "dumb" charger starts with a constant voltage and introduces resistance intentionally to limit current to a safe level. The internal source voltage is selected to be above the maximum battery voltage but low enough that when the battery reaches this value and current drops to zero the battery is not gassing or being damaged.

A "smart" charger recognizes that the later stages of charging get slower and slower as the difference between internal constant voltage and output battery voltage gets less and less. To speed up charging a smart charger will raise the source voltage higher than a "safe" value to force current in quickly but monitors the battery voltage and modifies the source to drop it down to a safe level before any damage is done.

The above refers to a "source" voltage. That is an internal voltage within the charger that you cannot measure. ANY Voltage you measure on the charger output will be very nearly the same voltage you would measure on the battery - - IT HAS TO BE THE SAME, THEY ARE CONNECTED TOGETHER BY COPPER WIRE. Between the internal source voltage and the charger output voltage is resistance (or some equivalent limit to current). It is the source voltage minus the battery voltage divided by the total resistance that equates to the current that will flow into the battery.

So the voltage put out by a stator IS the same as the battery voltage, they are connected together by copper wire (which may have a slight voltage drop less than 0.1 volts).

A typical stator charger is a "dumb" charger, it starts with a safe voltage and allows the charging current to taper off to zero.
Alternators typically have a "smart" regulator that can use a higher "unsafe" voltage but will turn it off before the battery voltage gets too high.
Smart regulators can achieve control of the source voltage by changing the current in the alternator rotor but a stator charger has a magnet for a rotor that cannot be moderated.

Voltage and current are NOT "INDEPENDENT" they are strictly related by ohm's law (even if Trump says they're not). All charging systems have a source voltage which is what would be put out if the current is zero. As you draw current there is an internal voltage drop (source voltage - battery voltage) across a resistance (or its equivalent) and the current amps put out is Voltage/Resistance. Resistance includes wire resistance and battery resistance, both of which are insignificant compared to the intentional current limiting in the charging source.

You are correct that the above has very little to do with battery chemistry. The main influence of battery chemistry is factoring in how much current you can safely force into the battery and how much voltage it can accept safely. Since a stator starts with a source voltage safe for all batteries, it doesn't care what the chemistry is.

Alternator, charger and stator manufacturers will publish a current rating eg. - 100 amp alternator, 16 amp stator. They want the number to look as good as possible. To measure this rating they use ideal conditions. The lower the battery voltage the more current will flow so do the measurement charging a very low battery eg. 10 volts. The higher the RPM the higher the output so test at the RPM that gives maximum. The hotter the alternator the lower the current so measure it when very cold before it heats up. In real life you will not have these conditions and you will not be able to get "rated" output.

[lpugh]

Anne this was very well written but I think he is confused about actual ac stator voltage and rectified DC voltage

[eh2000]

yupitsme, great point. I didn't catch that at first look. If I go that route, which is unlikely I will be sure to get more information. Good looking out.

Ann-Marie, thank you for writing out such a long and detailed explanation. I don't mean any disrespect by my questions, but I do have a desire to learn and become smarter about how this all works. I agree with your analogy of current, voltage, and resistance to hydraulic forces. That is how I think of electricity as well.

I question your statement about not being able to charge a battery with constant voltage. This and this are my sources. If these sources are wrong or poorly worded please advise.

I disagree with your description of how a "dumb" charger functions as well as your description of a "smart" charger. In addition to the sources above, I offer this source as well.

Again, I'm not trying to disrespect you, but I am noticing differences in multiple sources vs what you are saying here. Perhaps I'm just not reading or comprehending what you are writing correctly. What is your view on the statements made by the sources I provided?

I think I understand what you are saying about "source" voltage, but it seems like a very clunky way of describing a sense voltage circuit on a charger. I agree that if the charger is on and the cables are attached, that if measured the battery voltage and the charger output voltage will be the same. I'm not sure that is a useful statement however, because I assume that as soon as you disconnect the charger a different voltage will be realized on the battery. Maybe I need to reflect on this a bit more.

I agree that the charger has a maximum voltage output that is preset based on the type of battery to be charged. I agree that some chargers can sense the battery voltage and thus are capable of multi-stage charging (constant current, constant voltage, and float). Source voltage - battery voltage / resistance = current. I can see how this agree's with Ohm's law.

On to the stator discussion, woohoo! I agree that a battery will have to endure the voltage output of the stator (after the regulator has converted the AC to DC and then only a certain threshold voltage to the battery) due to being connected by copper cables. I agree that a stator is a "dumb" charger, but I don't think it can taper off a current. At best the regulator can ground voltage in hopes of only providing a specific voltage to the battery. I don't fully understand how it grounds voltage to prevent too much voltage, but I'd like to learn. I think the stator puts out whatever it puts out based solely on RPM and thus there is great danger of overheating batteries or burning up regulators and eventually the stator itself after prolonged use if maintenance is not performed regularly on both the charging system and the battery. I don't see anyway for the voltage or current to be reduced while the engine in running, aside from grounding. If anything I think the regulator can only ground excess in hopes of preventing overheating the battery. This is speculation on my part and I'm interested in your response. I disagree that an alternator can use an "unsafe" voltage level, it can only do what it has been programmed to do. I understand (perhaps incorrectly) that alternator output can be manipulated by RPM and/or by the magnetic field of the rotor being changed by the regulator through the applied voltage. Perhaps this is what you mean by an "unsafe" voltage? Don't most alternators max out at 14.4 or 14.5 volts? Furthermore, why are we talking about alternators. This is a topic about stators (specifically the 16 amp stator on my engine).

I agree that a stator has a magnet for a rotor that cannot be moderated.

I agree that voltage and current are related and that Ohm's law helps to understand that relationship. I'm not sure what Trump has to do with any of this. I'm trying to understand your statement on charge sources. I think I agree with your statements for what it's worth, but I'm not sure how it applies to the question of using a Stator based charging system with LiFePO4 batteries.

I absolutely agree that battery chemistry is a factor in how much current can safely be forced into the battery (or from it). I understand this to be referred to as C rate. I do think it is worth investigating the internal resistance of different battery types due to the previously mentioned Ohm's law. I assume that all cranking batteries will have lower internal resistance that deep cycle batteries. Additionally, I assume that LiFePO4 batteries will have less variation of internal resistance than Lead Acid batteries over similar conditions. I think that could be very important, but I'm not sure. There has been much discussion so far about batteries "pulling" current and I don't think they can do that.

I agree with marketing statements about alternator and stator output. I agree that lower battery voltages will result in more current, but not because the battery is "pulling" current. I think it is absorbing the current that is pushed to it. I could be wrong about this. I agree that rated output will only be realized for very short durations. Hence my skepticism that a particular battery type will damage a stator type charging system because the only thing that changes output are RPM and yes heat. The battery chemistry just can't affect output. This is the crux of the question at hand and I thank you for bringing this discussion back on subject.

lpugh, I would love to hear where I'm confused. Again, I'm just here to learn and make good decisions for my boat so that I don't waste money or create a dangerous condition. Thank you for staying with this thread and I look forward to your answers to my questions, or your critique of my theory of operations.

[jrspop]

I have gone through 3 Lithium starting batteries with my 250 Pro XB. Can't tell you why, love them for trolling though. Going on 4 years with my trolling batteries.

[Rumour2u]

I know guys going on 10 years with lithium starting batteries.

[KJINTF]

My Yamaha F90, Stator charging system includes an external Rectifier/Regulator assembly. The system consists of multi-phase AC windings with several fixed permanent magnets in close proximity. The coils supply current to a full wave rectifier assembly then onto a regulator (Both Rectifier and Regulator functionality are in one sealed package). This setup should not be used without an attached battery. The RR will overheat with all its magic smoke being freed.

The cranking battery loads the charging system by dropping the system voltage below the set point enabling current to flow into the battery, once the battery charges up it's terminal voltage goes up to the set point. A Zener diode within the regulator sets the max output voltage (Yamaha many times uses >15 Volts as this set point). When above this max voltage the regulator simply shunts the excess power from the multi-phase windings to ground, creating HEAT, thus a large heat sink and cool location in the front of the engine for the R/R assembly. IMO a very poor fixed voltage design. Many of Yamaha's larger engines RR's are water cooled and continue to let out magic smoke from time to time.

My stator system can supply at most 20amps which is easily enough to boil a FLA when well above gassing voltage for long periods of time and depending on the BMS system within the Li battery could destroy it.

I use a manually activated 400amp contactor assembly with extensive metering & monitoring allowing me to connect the cranking FLA battery to others when I want to reduce its charge and or charge one of the two 100amp Li batteries used for the trolling motor.

This system has been in place and operational for 15 months now with zero problems. Yes it can be done but you will need to take care

[CatFan]

I know guys going on 10 years with lithium starting batteries.

Which stator charging systems are they using with them?

[Ann-Marie]

All charging sources have a source of voltage, usually an AC voltage from a line transformer or the stator winding of an alternator or "stator".
That voltage is rectified to produce a DC source voltage that has to be higher than the maximum battery voltage in order to charge the battery. All you see with a meter is the output voltage which will be equal to the battery voltage.

The DC source voltage then goes through some means of regulating the current going to the battery so that the source is not overloaded. In its simplest form it can be a resistor. If the source voltage is 14.5 volts and the battery is at 12 volts, for a 10 amp charge the resistance would be 14.5-12 = 2.5/10 = 0.25 ohms.

When the battery voltage gets to 13 the current would be 14.5 - 13 = 1.5/0.25 = 6 amps. When the battery gets to 14.5 the current is zero and the battery is fully charged. This is what your references refer to as a "constant voltage" charger, the source is constant but the battery voltage is not constant, it is limited by a "constant voltage". All you see with a meter is the output voltage which will be equal to the battery voltage and is NOT constant.

In a smart charger when the battery voltage is up to 13 volts the current would still be 10 amps so with the 0.25 ohm resistor you can calculate the source voltage as 13 + 10 * 0.24 = 15.4. And when the battery voltage is up to 14.6 volts and the current is still 10 amps the source voltage would be 14.6 + 10 * 0.24 = 17 volts. This is what your references refer to as "constant current" because the Voltage is not constant. This type of charger will have to stop putting out current when the battery is fully charged. It can do this by changing the internal voltage (to say 14.5) and that will turn it into what they refer to as a constant voltage charger but that is NOT necessarily what the battery voltage is.

A "constant voltage" charger cannot have a constant voltage on the output or on the battery because the battery voltage has to rise as it charges, it is the internal source that is constant.

This is a very simplified description, in actual fact there are much more sophisticated ways of controlling the charging current and voltage.

[eh2000]

jrspop, excellent feedback. What brand and model of LiFePO4 batteries failed on you. If you don't want to mention the brand in an open forum perhaps you could PM me. I would like to look at the specs as well as the BMS program for those batteries to help understand the situation.

Rumour2u, that is great to hear, just want I wanted. I'll echo CatFan, do you know what outboard is being used with them? Also, do you know the brand/model of LiFePO4 batteries? Feel free to PM me if you don't want to mention the brand here in an open forum.

KJINTF, I'm very encouraged by your post! Thank you for bringing the word "shunts" to the discussion, I was trying to remember it yesterday. Sounds like your Yamaha and my Mercury have similar charging systems. If you have the time can you describe the specifics of the metering and monitoring system that allows you to have success? Have you ever used a Sealed Lead Acid or LiFePO4 starting battery? If I understand what you are saying the 400 amp contractor is only used to charge your trolling motor batteries with your outboard? Thank you for joining the conversation.

Ann-Marie, thank you for being so patient with me. I'm finally starting to understand what you are saying. I agree that all charging has to have a source and that normally this is from AC that is rectified and regulated into DC. I'm also willing to concede your points on the dumb vs smart chargers and I thank you for contributing. Does your analysis of the conversation thus far lead you to any conclusions about using a stator based charging system with a LiFePO4 battery?

[KJINTF]

Thought I would clarify a few things
The motor with it's < 20amp stator system internally comsumes several of those precious little amps to simply keep the motor alive, my guess it takes at least 5 or 6 amps for the Coils, Injectors, VST pump, etc...
Leaving very little for the external battery - No I have never used a sealed LA or Li battery for the cranking battery and have no intention to do so because of the 15+ Volts the system supplies.
There is a big difference between Li battery charging and simply topping up the Li battery with my Yamaha system.
To properly charge the LI batteries I use a modified 75amp RV Converter with 4awg wire and SB75 high current connectors directly to each battery
Metering and monitoring consists of Integrated Bluetooth functionality (Ionic Batteries), External high quality 4 digit voltmeter connected directly to the batteries, High current switching system that can parallel batteries off the cranking battery, Sona alert with low/high voltage / temperature triggers, switchable current meter, etc.
I do not consider the Yamaha stator system a battery charger, however it does do an OK job at keeping the Li batteries topped off and operational for several days without external charging being required.

[eh2000]

KJINTF, thank you. I have thought about how many amps the engine consumes just in operation from the 16 amps the stator provides, but I don't know where or how to measure that. I also assume that the engine consumes fewer amps at idle than it does at WOT due the required increase in frequency of ignition pulses as well as the increased output of the fuel injection system. Perhaps a clamp on meter could give an indication? Or even possibly by measuring what is going into the battery?

The 15+ volts is exactly where I think this discussion needs to go. When I get my new voltage regulator installed I'll take measurements to determine if I do in fact have high voltages. If I do, I see two possible pathways to solve this issue.
1) A voltage regulator that limits the voltage to whatever is appropriate for a given LiFePO4 battery. Ideally this would be a user defined value. I think the Balmar 614 allows for this.
2) A BMS that will cut off the voltage into the battery AND a load that will prevent the destruction of the stock voltage regulator and/or stator. I'm thinking either another sacrificial battery or something more like the Sterling Alternator Protection Device.

However, if I do not have high voltages coming from the voltage regulator, I see no reason why a LiFePO4 battery couldn't be used. I recognize that lifespan MIGHT be reduced due to the way a LiFePO4 battery needs to be charged vs what is happening to the battery on a long run while hooked up to the stator output.

I agree that LiFePO4 charging is unlike Lead Acid charging. I have no interest in on boat charging of the batteries, but like you point out I recognize that the stator & voltage regulators will be providing voltage & current to them while connected.

I understand your monitoring system, but it sounds like it is mostly the trolling motor batteries you are monitoring and metering due to the desire to use the stator to keep your batteries "topped off". I could be incorrect about this. I'm not looking to charge any batteries on the water. I accept that some charging will have to happen when connected to the stator system.

I want completely separate house, trolling motor, and cranking battery banks, with the only similarity being they have the same chemistry and are located in pretty much the same part of the boat. If I can solve one of the two paths above I think I will be good. Additionally, the original post was that I've found many other examples of people with stator based system using LiFePO4 batteries with no ill effects.

Do you have a recommendation on the best way to measure voltage regulator output? I'm thinking a multimeter hooked up to the battery terminals while the engine is running would work?