battery overcharging

[StarTech]

Bert, An open diode will not pass anything (light switch off). Think of an open circuit as two pieces of wires not tied together electrically. Now if the diode was shorted it be as if the wires were tied together electrically (light switch on).

With diodes there one other possible failed and that is a leaky diodes. Think of it as a water faucet that does turn off completely and just drips out some electrical impulses.

Yes diodes are considered one way devices but do fail three ways. Dead short, completely open, or leaky. And in this case it sounds like it might a leaky diode. Just not sure as I never fully tested a working dual circuit for what should be being observed on a test meter. Briggs just never published what I think they should have. And I do need get a new test lead for my oscilloscope as a mouse chewed the old in two.

Reference info on half wave rectifier circuits.
https://www.electrical4u.com/half-wave-rectifiers/
Note the battery is considered a large capacitor then smooths out the waveform.

 

[jlhert]

Briggs & Stratton
17.5hp Intek IC
model 31C707-0154-E1 from 2004

I probably have a compression release issue. (probably not relevant to this thread)
I think I have a battery overcharging issue. symptoms- when I put my volt meter on my battery when its running I got 15.9 volts. I can smell battery acid, I have an issue with my battery connection and corrosion.

My old battery only lasted 2 cutting seasons and I brought it in over the winter and put it on a tender.

I can't get to my mower today its raining. I am not even sure where the voltage regulator is.
Is testing at the battery sufficient?

I bought a new battery and turned in the old battery in for the core charge with out testing it.

I did a engine swap. I am not sure I hooked up the electrical connections correctly. although it starts and runs. The lights did not work after I did the engine swap, but I am not sure the lights worked before I did the engine swap.

Can someone give me some direction?

When engine is running you are measuring charging circuit voltage not the battery voltage. Charging circuit voltage will be higher.

 

[justin@justintime]

If you have a black and red wire on a single plug, that's the most common on all your happy homeowner tractors and is Briggs dual circuit both AC/DC stator. DC is achieved by the use of a simple diode (in the black shrink tubbing before the engine side plug). This set up is most common and also cooks batteries as it is unregulated AC/DC voltage. Simply buy Briggs #790292, regulator and it is plug-and-play. I sell this repair often and use an aftermarket by DB electronics part # ABS6004. I've never bothered to find out if the regulator needs to be grounded but I just do it anyways. This will give you your unregulated AC voltage to the lights and Regulated DC voltage to the battery. Be sure to match it up with a good battery, not one you already cooked or you can potentially burn up your $100.00 stator

 

[vap0rtranz]

When engine is running you are measuring charging circuit voltage not the battery voltage. Charging circuit voltage will be higher.

Yup. I thought the same and wondered what is the cutoff voltage for overcharging that would kill a battery because the OP is thinking >15V is killing their battery.

Those of us who have equalizer battery tenders can get to >15V when in cold temps. A battery that occasionally gets above 15V shouldn't kill. Otherwise nobody could do equalization / desulfators.

This B&S alternator / generator shouldn't be equalizing but seeing that voltage once on a multimeter isn't necessarily going to kill a battery. The excess acid that the OP saw might just be an overfilled wet cell. I've overfilled a cell when topping off and had that happen.

 

[StarTech]

Yes the DB ABS6004 needs to be ground as that is the return path for the regulator.

 

[StarTech]

Yup. I thought the same and wondered what is the cutoff voltage for overcharging that would kill a battery because the OP is thinking >15V is killing their battery.

Those of us who have equalizer battery tenders can get to >15V when in cold temps. A battery that occasionally gets above 15V shouldn't kill. Otherwise nobody could do equalization / desulfators.

This B&S alternator / generator shouldn't be equalizing but seeing that voltage once on a multimeter isn't necessarily going to kill a battery. The excess acid that the OP saw might just be an overfilled wet cell. I've overfilled a cell when topping off and had that happen.

Most 12v lead acid can tolerate up to 16 vdc but it the AC component that worries me here as it seems to extremely high. Should be under 16 vac if the diode is good. But as I said before I never fully tested the dual circuit voltages on a good one to know definitely the general range. But I will later but that don't help right now.

 

[VegetiveSteam]

Thanks for this info.
I am not sure how to test the diode and stator, but I did put a multimeter on the battery when it was running and I got 15.9 dc volts and when I switched the Multimeter to ACV I got 33.

I don't understand the duel charging stuff, but it seems like 33ACV going to the battery is bad?

I don't know if you're still struggling with this or not but it sounds like you've determined you have an unregulated dual circuit system. If that is the case then it is working as designed and you're trying to fix something that isn't broken.

The only thing that will cause over charging in a charging system would be a faulty regulator which it sounds like your system doesn't have. There is nothing that can fail with the stator or diode or wiring in an unregulated dual circuit system that will cause over charging. Those types of failures would only cause under charging or no charging. The Briggs manual doesn't tell you what the voltage should be on the battery charge wire, they only refer to amps and they say it should be between 2 and 4 amps.

I know you're working on a Briggs but I'm going to talk Kohler for a minute as basic electrical theory doesn't care what brand it's on. It still works the same.

Kohler tests their 3 amp unregulated charging system by voltage. Briggs tests by amps. They both state a minimum number but Kohler goes by volts and Briggs goes by amps. Kohler says the minimum dc voltage output on their battery charging lead should be 20 vdc. By that test you're actually not putting out enough voltage. Since Briggs doesn't give a voltage measurement I can't say if your 15.9 is low so the best test would be an amperage test. They don't give a maximum voltage because higher voltage doesn't matter. When it's working properly Kohler's unregulated 3 amp system is normally around 30 vdc. If it's putting out less that 20 vdc you would typically have a bad stator winding or maybe lost a flywheel magnet. If it's putting out zero, that would mean an open diode, bad flywheel magnets or again, a bad stator winding.

Think about this. What creates the charge in a charging system? A stator, flywheel magnets and engine rpm. The stator only has so many windings, the flywheel only has so many magnets and the engine only has so many rpms. To increase the charge rate you'd have to add more stator windings or flywheel magnets or increase engine rpms.

Again, all of what I am saying is based on an unregulated system. If you find out yours does have a regulator, you have a bad regulator.

 

[2ball]

Yes the DB ABS6004 needs to be ground as that is the return path for the regulator.

Can I ground to the black metal frame? or do I need bare metal? I see a ground on the bare metal heat shield on the other side of the engine, but the black metal frame would be closer and easier.

 

[2ball]

If you have a black and red wire on a single plug, that's the most common on all your happy homeowner tractors and is Briggs dual circuit both AC/DC stator. DC is achieved by the use of a simple diode (in the black shrink tubbing before the engine side plug). This set up is most common and also cooks batteries as it is unregulated AC/DC voltage. Simply buy Briggs #790292, regulator and it is plug-and-play. I sell this repair often and use an aftermarket by DB electronics part # ABS6004. I've never bothered to find out if the regulator needs to be grounded but I just do it anyways. This will give you your unregulated AC voltage to the lights and Regulated DC voltage to the battery. Be sure to match it up with a good battery, not one you already cooked or you can potentially burn up your $100.00 stator

I am reading AC volts on the battery when its running. 33v using my HF multimeter. is that ok, or should something be cutting those out before the battery?

 

[Cajun power]

without knowing specifics, look at voltages in voltage regulator.

on many mowers, there is also a charging system diode installed in the charging system circuit. While these rarely fail, they can fail.

another reasons for an overcharging condition is not related to charging system circuit, but a bad battery...or a bad ground. Check the ground and make sure it's solid electrically. Then do a load test of the battery. That will tell you if the battery state of charge has degraded down to the point where overcharging is a result.. Eventually such a downgraded battery will fail...and conversely, a failed overcharging system will cause a normally good battery to fail. One reason for premature failure of batteries is bad connections. Make sure they are clean and a good solid connection...all of them. Another reason for premature failure of batteries is using cheap battery maintainers that do not work correctly and end up overcharging instead of trickle. Another reason is that there may be some kind of parasitic drain on the battery, so when you put the battery maintainer into that, it sending more than just maintaining levels of charging into the battery. This will cause the battery to fail quickly. Another reason is that batteries tend to have very short lives in very cold weather. So storing batteries and even maintaining them in very cold weather ...well they fail quicker than they would in warmer climates.

do the simple things first: check all battery connections and cables...load test battery and ohm check cables. check those grounds too!

then check the voltages at your voltage regulator. I think there are several good youtube videos out there showing how to check them and what to expect.

check the charging system diode...it may have failed. rare, but it does happen.

also check all wires and cables in the charging system...look for any corrosion or insulation damage or where wires and cables might be touching metal through chaffed insulation.

last: get a CORRECT diagram for your electrical circuit schematic. That should be your guide for proper connections and devices. Don't guess. It's a common mistake to just hook things up on memory or guessing. I always take pictures before I disconnect ANYTHING. It makes things easier. It's a good habit to develop. Even though these are very simple electrical systems on mowers, you can still make mistakes or overlook something. Get a CORRECT diagram and start checking everything before you do anything. Sort that out first. Then you have the confidence that your troubleshooting will be dependable.