Larger CCA battery

[Mickey_Fx]

This is an old thread. Reading all the post what I see is a lack of understanding of how lead acid batteries are charged and the charging system found on our Yanmars.

LA batteries are charged via constant potential (voltage). In electrical terms, voltage is pressure. If the charge source is fixed, the charge rate varies with the voltage difference between the source and the battery. As the battery voltage rises due to charging, the lower the voltage difference so the lower the charge rate. When source and battery voltage equal the will be no charging taking place. Think of charging like siphoning water between 2 buckets, one full the other empty. The rate of transfer between the full and empty buckets is greatest to begin with and declines as the water levels near each other and flow stops when they are the same.

Now for our Yanmar charging systems. From the schematics I've seen, all have only 2 wires that connect between the alt and the "voltage regulator". Notice, there is no direct connection betwen the alt and battery. With this system no real regulation of the voltage can be made by the alt. The function of the VR is to rectify the AC voltage to DC. It regulates the voltage down stream by shunting some of the power to ground until the set regulated voltage is reached. From a practical standpoint this is the reason why these alt are so small power wise. They function the same way you find in small engines we find in lawn/garden tractors.

LA batteries when in normal condition have very small self discharge rates, ~.1%/day of remaining capacity. On my garden tractors they sit for about 5 months over winter and they never see a charger. At most, they see a few mins from a charger while I check fuel & oil levels before starting the first time in the spring. They always have adequate power to start the equipment and the batteries last at least 5 yrs. The Yanmar sees some use over the winter months but never sees a charger and never a problem. If you can't keep your battery charged over the winter without it being discharged when time comes to put the equipment back in use, you likely have some problem(s) that need addressing.

 

[J_J]

Mickey FX,

If you were referring to me, I believe that I have a good understanding of how alternators work in tractors, cars, and small engines. What part do you think that I don't understand? I have quite a few years working on generators, alternators, batteries and regulators. There is not a whole lot to understand. They are simple in design. For the most part, if they don't work, you simply replace them. Trouble shooting is the key to solving problems with todays electronics or electrical products.

On most any regulator, you have A/C going to the regulator, and there are 4 connections, one ground, two A/C wires, and one wire for DC battery voltage. The A/C voltage is rectified and sent out to the battery The field current and speed of the alternator determine the current and voltage. You generally always need more voltage than the source you are trying to charge. You can have 14.2v up to 15v and still be safe. There will be voltage drops throughout the machine as you trouble shoot different components.

 

[Pete Milley]

It is my understanding that an alternator was designed to deliver constant voltage regardless of rpm/speed, unlike a generator. Hence the lights don't dim at an idle.

 

[SPYDERLK]

Now for our Yanmar charging systems. From the schematics I've seen, all have only 2 wires that connect between the alt and the "voltage regulator". Notice, there is no direct connection betwen the alt and battery. With this system no real regulation of the voltage can be made by the alt. The function of the VR is to rectify the AC voltage to DC. It regulates the voltage down stream by shunting some of the power to ground until the set regulated voltage is reached. From a practical standpoint this is the reason why these alt are so small power wise. They function the same way you find in small engines we find in lawn/garden tractors.

Sounds like a zener diode limiting voltage by wasting current. I guess Yanmars must also be unusual in the respect of rectification happening in the "voltage regulator". For many years the rectification has been done conventionaly by six diodes in the alternator. The regulator just samples batt V and energizes the alt field rotor appropriately so that a correct amount of power is induced in the stator and fed thru the 3phase rectifier to bring the battery to nominal V, and then tapers field current to maintain it there.
larry

 

[J_J]

It is my understanding that an alternator was designed to deliver constant voltage regardless of rpm/speed, unlike a generator. Hence the lights don't dim at an idle.

No, if that were true, the voltage would be constant at all times.


The regulator will attempt to maintain a pre-determined charging system voltage level.

When charging system voltage falls below this point, the regulator will increase the field current, thus strengthening the magnetic field, which results in an increase of alternator output.

When charging system voltage raises above this point, the regulator will decrease field current , thus weakening the magnetic field, and results in a decrease of alternator output.

 

[Mickey_Fx]

My previous comment wasn't directed to any specific person, just an observation noted from reading all the posts.

JJ, not sure what you mean by "most any regulator". Are you talking about Yanmar and sim systems or that generally associated with automotive charge systems? If the later, I have to agree with SPYDERLR's comments. One comment you made if you are talking about the Yanmar system is, there is no field winding. I also disagree with your comment about being OK to have voltages up to 15V. That's way above the point where a nom 12v LA battery would be happy. A typ automotive charge system doesn't go much beyond 14.25V. Any charge voltage above ~13.9 can be an issue. Voltage and duration will determine what happens. Can be as little as overcharging, i.e. boiling of the electrolyte, to shortened life.

You gave some of your background so I've give mine. A retired Eng from HP. In the mid-80's I did some research on LA batteries for use in portable medical equipment. Based on that work our equip moved from Ni-Cads to LA and the whole industry followed within a few yrs. Not claiming to be an expert but I', more than familiar with care and feeding of LA batteries and typ charge systems.

 

[J_J]

My previous comment wasn't directed to any specific person, just an observation noted from reading all the posts.

JJ, not sure what you mean by "most any regulator". Are you talking about Yanmar and sim systems or that generally associated with automotive charge systems? If the later, I have to agree with SPYDERLR's comments. One comment you made if you are talking about the Yanmar system is, there is no field winding. I also disagree with your comment about being OK to have voltages up to 15V. That's way above the point where a nom 12v LA battery would be happy. A typ automotive charge system doesn't go much beyond 14.25V. Any charge voltage above ~13.9 can be an issue. Voltage and duration will determine what happens. Can be as little as overcharging, i.e. boiling of the electrolyte, to shortened life.

You gave some of your background so I've give mine. A retired Eng from HP. In the mid-80's I did some research on LA batteries for use in portable medical equipment. Based on that work our equip moved from Ni-Cads to LA and the whole industry followed within a few yrs. Not claiming to be an expert but I', more than familiar with care and feeding of LA batteries and typ charge systems.

If the Yanmar alternator does not have a field winding, what does it have to induce a field.

Even if the regulator is separate from the alternator, the grounding of the alternator and regulator is one of the paths for voltage and current.

This statement has to do with battery chargers.

Many modern chargers are charging wet cell batteries at much higher voltages than previously. 14.8 to 15 volts is becoming common. This increases the charge rate and performs a mild equalization charge. It is not recommended that such a charge voltage be used from an alternator as the alternator does not have the ability to drop to a lower float charge the same way that a dedicated charger does.

Another observation that I have made with Ni-Cad batteries is that on an 18v DeWalt charger, I have measure the charge voltage at 24 v. A 12V charger will charge at 15-16 v.

I really see no problem with charging at a higher voltage, because if the system is well regulated at say 14.2v, it may start out at 15v, and as the charge builds up to the regulated voltage, the amount of charge tapers off.

How many of you have used the 125 amp mode on some of those large chargers to get a fast charge on a battery.

Yes, I agree that if left on for a while, the water will boil out, or the sides will bulge and maybe explode.

Do you have a schematic of a Yanmar charger system?

If the alternator goes out on my Kubota, I think I would replace it with a small one wire Ford alternator. Way cheaper and will allow more acessories.

 

[SPYDERLK]

If the Yanmar alternator does not have a field winding, what does it have to induce a field.

Even if the regulator is separate from the alternator, the grounding of the alternator and regulator is one of the paths for voltage and current.

This statement has to do with battery chargers.

Many modern chargers are charging wet cell batteries at much higher voltages than previously. 14.8 to 15 volts is becoming common. This increases the charge rate and performs a mild equalization charge. It is not recommended that such a charge voltage be used from an alternator as the alternator does not have the ability to drop to a lower float charge the same way that a dedicated charger does.

Another observation that I have made with Ni-Cad batteries is that on an 18v DeWalt charger, I have measure the charge voltage at 24 v. A 12V charger will charge at 15-16 v.

I really see no problem with charging at a higher voltage, because if the system is well regulated at say 14.2v, it may start out at 15v, and as the charge builds up to the regulated voltage, the amount of charge tapers off.

How many of you have used the 125 amp mode on some of those large chargers to get a fast charge on a battery.

Yes, I agree that if left on for a while, the water will boil out, or the sides will bulge and maybe explode.

Do you have a schematic of a Yanmar charger system?

If the alternator goes out on my Kubota, I think I would replace it with a small one wire Ford alternator. Way cheaper and will allow more acessories.

Probably permanent magnets.

I find that wet cell lead-acid will charge to around 14.7+ at a fast charge rate, but if you then reduce the charge rate to about 1/4A they will continue on up to 15.2+ over a 2day period because they develop a surface charge over and above the deep charge. Most of the newer automotive systems charge the battery pretty fast up into the mid 14s then slack off slowly to high 13s for a float - like on a long trip. The regulator controls the alt to achieve this.

Youre probably seeing the full wave rectified peak on those chargers. There may be a capacitor holding the peak and giving you the measurement even with a true RMS meter. A battery will do this to an [lesser] extent also.

Regulator is built into the 1 wire alts.
larry

 

[California]

Keep in mind Yanmar used several types of charging systems. One of the best known, on YM2000, was a conventional Hitachi alternator and regulator same as what Hitachi provided to Datsun for automotive use.

 

[BobRip]

Bob,

I know this is an old post, but.

Since the beginning of the car, battery, and charging system relationship, , we have been charging dead battery's. The only problem trying to start a car with a dead or weak battery, is that there is not enough energy left in the battery to turn the starter. If you jump the battery, and it starts, then the regulator system takes over and charges the battery at the max rate until charged.

I think we are saying about the same thing with just some different wording. I agree with all of your comments in this thread. Charging systems and batteries can be complex. Particularly batteries. Any time you talk about batteries it is difficult to be totally correct since there are so many variables. Most car charger systems start with a higher voltage and then drop to a lower voltage once the system is warmed up.