Charging problem

[htiek126]

The 78xx and 79xx fixed voltage regulators are available in variable voltage formats. I believe that RadioShack has the 317 regulator, and there are other inexpensive regulators available at places like www.dgigkey.com. Or you could use the 7815 with a power diode in series to drop the voltage about .6 volts to 14.4 volts. I am not real familiar with wet cell battery chemistry, but I know they are easily damaged when they are not kept fully charged.

Keith

 

[Keoke]

Quote:
I have to agree with soundguy that the system is designed only to maintain the battery. We all know that a diesel requires no energy to run. This is why we are working with very small volts/amps.

Bruce, maintain the battery at what state of charge, 100%, 50% or maybe a lessor value?? I am all for keeping a battery at it's normal 100% charge. What state of charge do you think a battery should be maintained at?
By the way, the shut off fuel solenoid requires around 2 amps to keep open while engine is running.
Bottom line, there is no free electrical ride, and don't forget the starter draw needs to be replaced, even on a diesel.

cheers,

 

[bruce1966us]

I have a question that is somewhat off subject. What type of regulator did the old Murray, Craftsman, etc. riding mowers use?

Thanks,
Bruce

 

[bruce1966us]

George,

There is no fuel solenoid on the YM1401 or YM1100 that we are talking about so that is not an issue. I beleive that these smaller, older tractors may be designed to constantly charge at a very small rate. For example: A YM1100 running at 800-1000rpm with the headlights on will have a dead battery after a few hours. These low volt/amp dynos only charge at 13-13.5 when running at 2000rpm.

IMHO

Thanks,
Bruce

 

[Keoke]

Bruce, 13 to 13.5 volts looks like a very good range for a low output unit. Anything above 12.8 vlots delivered to battery, with enough time, will keep a battery topped off. The amount of amps absorbed by the battery is determined by the difference in potential between the alt voltage and the batteries voltage.
Keeping a battery topped off is especially critical during the winter months since a battery power drops off dramatically when temp drops. A fully charged battery is about 40% sulphric acid and 60% water. A dead battery is almost 100% water and hence subject to freezing.
I have no idea of who makes the VR units used in riding lawn mowers. However, if these units use PM type alternators/dynamo, then it would seem, that these VR's could be made to work on Gregs tractor. Of course their alt amperage outputs must be the same or more then the tractor output. This is because this type of VR converts the excess charging enegry to heat in the regulator. So, you can guess what a high output PM alt would do to one of these small capacity VR's that could not absorb the excess wattage.
Bruce, Americans tend to call charging units alternators and everbody else calls them dynamos. Technically, alternators are supposed to be AC producers and dynamos are usually DC producers. Nevertheless, we use both names interchangebly all the time and it causes no harm.

cheers,

 

[bruce1966us]

I agree

Bruce

 

[Soundguy]

""Soundguy, I get Normde's point so this will be my last post on this subject.""

I think it may be mine as well.

""My reply is as follows:
A single wet cell fully charged (1.260/ 1.280 specific gravity) has static 2.13 volts per cell. This 2.13v times 6 cells = 12.78 volts for a fully charged battery. A 12 volt battery at 12.0 volts is less then 50% charged. Batteries continually kept at this low charge rate will die very quickly from sulphation of their plates.""

Never said it was the optimum fix.. just a stopgap measure. Besides.. if a 15v reg is available.. it will be the better choice to start from.

""In addition, there will be a voltage drop from where the VR ties into the alt to battery circuit so that when alt current finally get's to the battery it will no longer be at the VR's 12 volts but at a lesser value.""

If the proper gauge wire is used, with good connections, there should be no more than a negligible voltage drop across a couple feet of copper. Maybee in the 100'ths.. probably in the 1000's range.


""Bottom line, why would one want to design a voltage regulator that would keep a battery at less then 50% charged?""

If I wanted my tractor to start, and I didn't have access to the optimum componets to make a regulator, the 12 reg. would do it.


""Also, if one was to put a fully charged battery in this tractor then, with tractor running, all loads would run off the battery (higher EMF) instead of the alternator until the battery is down to less then 50% of it's potential.""

I stated as much.. that the battery would be in a state of discharge, untill the potential of the battery was less than the charging potential.

"It doesn't cost much more, if any, to go a VR in the std 13.8 to 14.8v range so a VR in this range seems like a better bet to me for this application."

Money wasn't an large factor in my statements.. parts availability was. Radioshack is only a marginal parts house.. if the person performing this repair has access to a better house.. say like newark, etc... then ther probably won't be a problem. On the other hand... rs does sell a 317 variable vr.. but then we are getting back into building a more complicated circuit. An irf-511 powered PWM is going to be even more complicated for an individual without good electronics background. However, if they feel froggy, and want to do electronics via 'cookbook', they have more than enough options right now to go build a circuit blindly from schematics, whether it be a variable vr circuit, any one of the constant current circuits, a series pass regulator, or a pwm.... they can take their pick.

Soundguy

 

[LLove]

Real late model GM alternators are of the PM type, and are also self regulating without the field control from the ECM.
Building a retro-fit control circuit is always a Fun challenge, but if he is only reading a 15 volt output at full throttle, he might try turning on the headlights to see if the output falls into an aceptable range of 13.25- 14.75 volts.
It would be a shame if the problem is only a poor ground connection a the VR case mounting...
Seen quit a few alternators, and external regulators get replaced for problems located in wiring, connections, and so forth.
But it has been a fun thread to read. Lloyd

 

[jimstractors]

Greg,
Sorry, I got lost in the long thread....YES! the Kohler regulator works fine. I haven't had to charge the battery once since replacing it. Here is what I ordered:
Kohler reg. from jackssmallengines.com for $36.82 + $5.00 shipping, no tax.
Their part # ST435081.
Thanks,
Jim

 

[gbirky]

Jim,
Thanks for the info. Now just remind me - you put this on a YM1401.

1) Does the 1401 alternator have the bridge rectifier in the alternator or in the regulator?

2) Does the Kohler regulator have a built in rectifier?

3) Is the part # ST435081 the Kohler number?