Too high battery charging voltage

[XGamer223]

Hello folks,
my used MTD (13dh452e676) had his cables fiddled around with (very badly that is). Also the charging wires have been disconnected.

So I went trying to fix it. Found out that the engine has a two output wire from the alternator, one with a diode and one with pure AC for lights.

There is no regulator, none at all (there are some holes left of the oil fill/oil rod that looks like where a regulator would go, but that's most likely a placeholder (?)).

So I checked the voltage at the diode output, and at "DC" it reads about 27/8 volts at full throttle, but goes as low as 11-12 volts with throttle at lowest point. Checking with "AC" one the multimeter, it reads about half of 27 (13-14 that is). The diode is fine, checked it and the results are good as a diode would be.

Checking the briggs manuals, they say that no regulator is needed with a single diode output. But the high voltage at DC checking worries me a lot, I don't want no battery acid spraying under my seat...
As I connected the diode output to the battery, and checking it then, the voltage raised (quite quickly actually) at the battery terminals (for like 2-4 seconds before I disconnected it).

Is this normal? Do I need one of those super-overpriced regulators? The engine parts diagrams show nothing useful, but the mower parts diagram don't show any need for a regulator.

Briggs model is 217807, type is 0426-B1.
Thanks in advance!

 

[slomo]

Your parts list shows a regulator. Briggs part 794360. It's part 501A in the parts list.



Click on the link below to pull up your parts.

https://www.thepowerportal.com/ipls/ipl.htm?md=2178070426B1~_IPLURL_LO.pdf

 

[Scrubcadet10]

have a look through these

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[StarTech]

Are you checking without being connected to battery as the battery will load capacitively and regulate the voltage somewhat.

But if you worried about the voltage level then of course you can add the 790292 voltage regulator which will also boost the 3 amp max to 5 amp max.

 

[bertsmobile1]

The single diode is a crude , rude , unsofisticated charging system that works "sort of ".
It uses the battery to regulate the charging, has nothing to prevent overcharging and because you are pumping in pulsed DC that varies from 0 Volts up to whatever the maximum is ≈ 14 V then drops down to 0 again the battery life will be shortened and will tend to gas if you fitted a flooded cell battery ( which you should not use on a mower ) .
Good news is all B & S stators will interchange so you should be able to find a blown engine with the rod / counterweight hanging out the side for less than the price of a new alternator .
You can use the chart Scrubby linked to work out what alternator is fitted and if the regulator / rectifier is there on the dip stick tube .
Note that it needs a ground strap .

 

[XGamer223]

Are you checking without being connected to battery as the battery will load capacitively and regulate the voltage somewhat.

But if you worried about the voltage level then of course you can add the 790292 voltage regulator which will also boost the 3 amp max to 5 amp max.

Hi and sorry for very-late answer, was really busy lately.
I checked both with and without battery connected, without the battery it's 25+V, with the battery it's 13-14 and slowly rising (as it charges), but I don't think it's very safe to do so.
These regulators do work on single diode setups?

 

[XGamer223]

The single diode is a crude , rude , unsofisticated charging system that works "sort of ".
It uses the battery to regulate the charging, has nothing to prevent overcharging and because you are pumping in pulsed DC that varies from 0 Volts up to whatever the maximum is ≈ 14 V then drops down to 0 again the battery life will be shortened and will tend to gas if you fitted a flooded cell battery ( which you should not use on a mower ) .
Good news is all B & S stators will interchange so you should be able to find a blown engine with the rod / counterweight hanging out the side for less than the price of a new alternator .
You can use the chart Scrubby linked to work out what alternator is fitted and if the regulator / rectifier is there on the dip stick tube .
Note that it needs a ground strap .

Hi, and sorry for the late answer.
Why shouldn't I use a flooded lead acid cell on the mower? These sealed cells are damn expensive, I know they're safer and longer lasting, but damn 20Ah costs more than a 75Ah car battery.
But I'll try to get the voltage regulator, even though some schematics show that I do need one, some show that I don't. Seems like I do, no idea why it isn't on my mower already...
Thanks for the advice!

 

[XGamer223]

have a look through these

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Thanks, seems like I do need a regulator. No idea why it isn't already fitted on my owner. Thanks again, very helpful!

 

[XGamer223]

Your parts list shows a regulator. Briggs part 794360. It's part 501A in the parts list.

View attachment 57688

Click on the link below to pull up your parts.

https://www.thepowerportal.com/ipls/ipl.htm?md=2178070426B1~_IPLURL_LO.pdf

Thanks, the document really come in handy.
Seems like I do need a regulator after all. Thought that I diode would be enough, as no regulator wasn't strappd on my mower when I got it. I knew that the hole on the dipstick wasn't just a placeholders.
Thanks for the advice!
P.S sorry for late answer!

 

[bertsmobile1]

Hi, and sorry for the late answer.
Why shouldn't I use a flooded lead acid cell on the mower? These sealed cells are damn expensive, I know they're safer and longer lasting, but damn 20Ah costs more than a 75Ah car battery.
But I'll try to get the voltage regulator, even though some schematics show that I do need one, some show that I don't. Seems like I do, no idea why it isn't on my mower already...
Thanks for the advice!

BEcause the unregulated charging system causes excessive gassing which corrodes everything and of course requires constant water additions
The plates are poorly supported so fracture sooner with the rough bumpy ride due to the lack of suspension.
Sealed batteries are only marginally more expensive that open flooded cells and will generally last twice as long.
Batteries are a funny thing.
No factory deliberately makes cheap batteries.
All of the production lines are set for top quality batteries
However every single battery undergoes a dozen test as they come offthe production line.
Those that fail get the cheap brand stickers put on them'
The ones that pass all test well get the expensive brand sticker put on them and then get packed into cartons .