TransIdiot gets it backwards once again

From : tbone

Q: no numb nuts we are searching for the cause of over current thru the battery what kills me is that he knows that because he suggested it but he keeps going back to how much voltage the vr is putting out via the alternator. i keep telling him its not the voltage but if the voltage is continued beyond when its needed i.e. current pushed in when no demand is present. but hey its tbone. -- max give a man a match and he is warm for a short while. light him on fire and he is warm for the rest of his life. on tue 23 aug 2005 040213 gmt max dodge max340@verizon.net wrote lets forget all the little biy squabling and answer the ops question. the voltage must be checked across the battery posts - pos to neg. if the voltage is within spec under 14.6 with a fully charged battery and the battery still boils the battery is shot. checking from pos to engine or body ground will generally give a higher voltage if the ground is bad. if the wire from the alternator output has high resistance measuring from the alt output t0 ground will give a higher reading than across the battery. no shit and this is what i was saying all along. the voltage however does not have to be measured across the terminals in this case because as your examples have clearly demonstrated the voltage will not be higher at the battery than at these other measurement points and we are looking for an over voltage condition at the battery. no numb nuts we are searching for the cause of over current thru the battery .

Replies:

From : max dodge

good point -- if at first you dont succeed youre not cut out for skydiving this is a bit basic but is the battery securely mounted so that it does not bounce around my jeep had the hold-down bold rust away and the battery would nearly tip 45 degrees toward the engine. unlikely but worth a shot to ask... -jerry good point about that intermittent a bad sense point for example on the regulator say when it heats up could definitely cause the overcharge problem. and for the record i measured the battery voltage at the positive terminal of the battery and at the regulator plug with reference to chassis ground maybe i should have used engine ground technically they are the same. the sense lead runs through 2 fuses both good from the battery. ill have to hunt around for a peak hold volt meter are you suggesting that an over current drawing starter motor could also cause the battery to spit thanks t bone for the helpful comments. you have to take into account that your problem may be intermittent. just because the regulator behaves normally while on the bench or while idling in the driveway doesnt mean that it or its wiring is ok. you will need to keep a voltmeter connected in the car with you for a while to monitor it. if it has a peak hold capability that would be best but otherwise you will need to keep it in a place where you can see it without taking you eyes off of the road any more than you would to look at any other gauge. another thing to think of is that it is not voltage that causes a battery to vent and spit fluid it is current and high current can flow on both sides such as bad turns in the starter. i would probably look at the sense wire for the regulator and make sure that it is in-tact and has a good solid connection to whatever power source it is tapping from. a bad wire or connection here can cause your problems for sure. -- if at first you dont succeed youre not cut out for skydiving ok you guys seem to know it all thats not intended as a slight 91 plymouth laser i know dodge truck ng but it is a chrysler product and i do own a dodge truck and well you guys know it all. constant clear liquid around the battery especially around the top vents very corrosive. no the battery does not have a leak battery was three years old exchanged with another three year old battery same thing clear liquid around battery. constantly adding water to the battery. removed regulator from the car set it up on the test bench regulator turns on alternator at 13.8 volts and turns off the alternator field winding at 14.2 volts at about 70 degrees f. battery voltage measured at the alternator/regulator is the same as the voltage measured at the battery. this vehicle uses a separate wire to measure the battery voltage for the regulator tests ok same voltage at either end of the wire. with the car running the measured output voltage of the alternator is 14.2 volts. manual says voltage should be between 13.9 and 14.9 volts question is why am i boiling the batteries. car runs fine starts ok no other problems. .

From : transurgeon

no numb nuts we are searching for the cause of over current thru the battery what kills me is that he knows that because he suggested it but he keeps going back to how much voltage the vr is putting out via the alternator. i keep telling him its not the voltage but if the voltage is continued beyond when its needed i.e. current pushed in when no demand is present. lol every time i read this from you it just makes me laugh harder. how exactly is the vr going to know if the battery needs charging or that the headlights and or wipers happen to be on in an older vehicle the point maxi is that it cant and fortunately it doesnt have to. all it needs to do is keep the voltage with a given set of parameters and the system will take care of itself including the battery. -- if at first you dont succeed youre not cut out for skydiving .

From : tbone

on tue 23 aug 2005 191540 gmt tbone t-bonenospam@nc.rr.com wrote on tue 23 aug 2005 040213 gmt max dodge max340@verizon.net wrote lets forget all the little biy squabling and answer the ops question. the voltage must be checked across the battery posts - pos to neg. if the voltage is within spec under 14.6 with a fully charged battery and the battery still boils the battery is shot. checking from pos to engine or body ground will generally give a higher voltage if the ground is bad. if the wire from the alternator output has high resistance measuring from the alt output t0 ground will give a higher reading than across the battery. no shit and this is what i was saying all along. the voltage however does not have to be measured across the terminals in this case because as your examples have clearly demonstrated the voltage will not be higher at the battery than at these other measurement points and we are looking for an over voltage condition at the battery. as for the battery being shot that possibility has been substantially reduced as the op indicated that this condition is occurring with more than one battery so unless both of them are shot although still a possibility the problem seems to lie elsewhere. he said he used another 3 year old battery. what is the average lifespan of todays batteries just under 3 years - so the chances are pretty good he has two bad batteries. .