Onan BFA 4.0 boiling battery

[Surfinhurf]

Pulled a BFA 4.0 out of a RV last year,,put it on a cart and have been using it a couple of times a month with no problems. After running my 220 welder for about an hour last night,,I brought it in the garage and saw some fluid leaking from the top of the battery and it sounded like it was boiling inside. Dead short in battery?? Something in the charging system?? Where do I start?

The genny started up no problems this morning so the battery is still cranking.

Thanks

HURF

[Billy J Shafer]

The charging system on a BFA is about two amps. So I would have the battery checked.

[Dave Edmonds]

Measure the voltage across the battery with the genny stopped, and with it running. As Billy stated, the charger isn't big, so the voltage with it running should not be a lot higher than with it not running. I don't know if it's possible, but a leaky or shorted diode in the circuit could subject the battery to an AC component along with the DC, creating some form of "trauma" in the battery. Was the battery warm/hot when you checked it? The "boiling" could possibly be creation of some form of gas inside the battery, which is (usually) hydrogen and oxygen - very dangerous if exposed to a spark. Like Billy, I would suspect the battery itself, but it wouldn't hurt to do some checking. I had a trolling motor battery on a "trickle charger" that decided to explode in my storeroom, scattering battery acid onto things that I didn't want battery acid on (motorcycle, air compressor, steel door, etc.)!
Dave Edmonds

[Billy J Shafer]

I was in a hurry this morning so short answer. I agree with Dave. Check things out before you spend money. Your battery voltage with it running should not go above 14.5. It has a small charging system so unless something is wrong it should not charge at more than two amps

[BTPost]

Check the Charging Resistor (R1) and see if it is shorted.... This would allow a much higher charging voltage than normal, IF the resistor shorted....

[Surfinhurf]

Battery was at 12v when I started the genny,,no issues. After a half hour of welding, battery was at 16v and boiling, battery was not hot.

HURF

[VaughnSimon]

After a half hour of welding, battery was at 16v and boiling, battery was not hot.

Just a wild guess... Perhaps some past owner "fixed" an open charging resistor by installing a jumper wire across it?

Vaughn

[Surfinhurf]

Where would this charging resistor be located?

Thanks

HURF

[Elden DuRand]

If the battery was at 16 volts, no wonder it was boiling!

As said, look to see if the series charging resistor is either set to too low a resistance (if variable) or has been jumpered-out.

Take care - Elden
http://www.oldengine.org/members/durand

[Billy J Shafer]

It is under the band on the gen end. Remove the cover and you will see it.

[Dave Edmonds]

Your problem could still be the battery itself. If the internal resistance of the battery is high, the charging voltage would be high, since there's no "real" regulator in the circuit. If the battery is good and is being charged with 16 volts, it should probably get hot as well as boil. Check the resistor anyway.
As mentioned before, if the battery is boiling, it's probably putting out some hydrogen and oxygen, which is easily ignited, with ugly results. Be careful - defective batteries (and even non-defective ones) can be dangerous.
Dave Edmonds

[Surfinhurf]

if it was charging at 16v wouldnt I get that reading anytime the unit was running. I checked the battery before start and it was 12v,,after start 14v,,1/2hr later 16v.

I will check the resistor tonight and take the battery to Auto Zone to have it checked out

Thanks

HURF

[Elden DuRand]

Hurf:

If all the cells in the battery are "boiling", and the way you describe it, you have a simple case of overcharging.

Take care - Elden
http://www.oldengine.org/members/durand

[LPOCHE]

I had my CCK do that one time.. .
The starter solenoid had stuck... once the engine started.. the start windings started generating MASSIVE current into the battery..
I was busy messing with the carb before I noticed..
VERY DANGEROUS situation

[George Clark]

ok send me an email and I will send you the manuals you need also what size welder are you running, welders can create serious heating problems with generators if they are not sized correctly, welders create power factor issues that generator fields do not appreaciate,georgenfw@hotmail.com
geo

[Surfinhurf]

Originally Posted by LPOCHE

I had my CCK do that one time.. .
The starter solenoid had stuck... once the engine started.. the start windings started generating MASSIVE current into the battery..
I was busy messing with the carb before I noticed..
VERY DANGEROUS situation

What did you do?

Had the battery checked it is OK

Waiting on a Manual to try to start debugging charging system.

Thanks

HURF

[Darxen]

Here is a great BATTERY site, to learn about batteries !

http://www.progressivedyn.com/battery_basics.html

This site has pretty much all the information you will need to understand about batteries.

A 12 volt battery really consists of 6 cells of about 2.2 volts each,,or a total of about 13.2 volts at FLOAT point,,at rest about 12.8 Volts !! Normally in a high charge,,you will never want to exceed 14.4 volts ! A good charge rate, voltage wise is about 13.6 volts. How QUICK your battery attains this voltage, depends on the charge rate in AMPERES ! The higher the charge rate,,the quicker it will charge. You almost NEVER want to charge any battery at a rate, greater than 10% of the capacity of the battery, or say for an 80 amp battery, a maximum rate of 8 amps. Normally, a trickle charger will provide about 1 amp or less, to keep a battery charged. I believe the ONANs charge at about a 1 amp hour rate. A high rate of charge, will boil off the water, will heat the battery up,,and can warp the plates,,shorting it out.

IF you hook up a digital volt meter to your battery, most likely it will show about 12.8 volts fully charge,,,then when you crank your motor,,it will drop down to maybe 10 or 11 volts !! How far it drops is based on "internal resistance". To much,,and it will not crank !! The only good way to test a battery is "under load" when it is drawing say 10 or 20 amps..! You can have a battery that measures 12.8 volts..BUT will not light a 12 watt light bulb..becaue of high internal resistance. VOLTAGE on a battery is NOT an indication of how good it is! Only when it is under load, and you measure the voltage, does it have any meaning towards being good or bad !

This web site: http://www.progressivedyn.com/battery_basics.html

is your best education on batteries !

Good luck,,any questions email me at darxen@aol.com

Good luck,,ZAP !