battery leakage while machine off

[rackmaster]

T300 will drain battery and will not fire up start engine panel in cab.
So, New battery, cranked for a few days then same deal, it discharges battery over couple days.
checked alternator, its good, ( pulled and took to shop to make sure )
took new battery to napa, it checks good.
what is weird, is even with a fully charged battery now , it will not light start panel up , but if I hook just a little battery charger up , 6a amp for 10 seconds, it will light panel up and start engine.
Im getting 12.8 volts at starter, almost 14 with charger hooked up.
I ve swapped out relays and checked all fuses in panel in cab.
alternator is showing charging good while running

so, something is robbing voltage from battery to panel used to start engine in cab, and also draining battery while not in use.
after it runs a while , it charges the battery enough it will shut off and restart without the charger.

appreciate any help,

 

[mrbb]

I would suggest looking at battery cables and checking voltage at alt, and fuse box
over time corrosion can build inside the insulation on them and cause lack of voltage flow to things

I would also be checking your fuses with a meter to see if you have something drawing power while off, and or a short some place
mice like to chew on wires and can cause electrical issue!
all the more so in winter time when you park a warm machine and they enter for heat an chew to pass time!(rotten sucker that they are)

all machines, all the more modern one's have some power draining when parked, its why many OEM's and or owners add power shut offs at the battery, to help save this from being an issue!

BUT even that is not perfect
over my yrs I have had many power disconnects fail and cause voltage flow, as they can go bad too!
first time one went on me had me going nuts trying to figure out what was wrong, HAHA<
so, if you have one, maybe check on that too!

 

[rackmaster]

I would suggest looking at battery cables and checking voltage at alt, and fuse box
over time corrosion can build inside the insulation on them and cause lack of voltage flow to things

I would also be checking your fuses with a meter to see if you have something drawing power while off, and or a short some place
mice like to chew on wires and can cause electrical issue!
all the more so in winter time when you park a warm machine and they enter for heat an chew to pass time!(rotten sucker that they are)

all machines, all the more modern one's have some power draining when parked, its why many OEM's and or owners add power shut offs at the battery, to help save this from being an issue!

BUT even that is not perfect
over my yrs I have had many power disconnects fail and cause voltage flow, as they can go bad too!
first time one went on me had me going nuts trying to figure out what was wrong, HAHA<
so, if you have one, maybe check on that too!

the cables are putting good power to starter (12.8 v) and alternator is good.
but, im thinking there may be a power leak from main fuse (above battery )to fuse block in cab or bad connection to lose the voltage or maybe a short.
just dont really know where to look , ill work on it some more and hopefully dont have to take to dealer

 

[foton]

a simple VOM , most have a 10 amp load setting . place the meter at the battery ,disconnect the positive cable ,take the red lead of the meter and put it on the positive battery post, put the negative meter lead to the battery cable you removed and see what the meter reads. If it reads anything, start pulling and replacing fuses one at a time till you find the battery drain .this would be best done with two people.

 

[foton]

chances are If you have a radio in the machine you will see a load there for the clock and memory, so that one will be a normal load hopefully.

 

[rackmaster]

a simple VOM , most have a 10 amp load setting . place the meter at the battery ,disconnect the positive cable ,take the red lead of the meter and put it on the positive battery post, put the negative meter lead to the battery cable you removed and see what the meter reads. If it reads anything, start pulling and replacing fuses one at a time till you find the battery drain .this would be best done with two people.

Ill see if ive got someone that has one and can help. I'm not much on elec circuits as i always detested fooling with it. I did read where a person could take a test light and do same thing, and I have a test light .

it does not have many fuses, but has several relays, will they act the same when pulled if the draw is off them?

 

[rackmaster]

chances are If you have a radio in the machine you will see a load there for the clock and memory, so that one will be a normal load hopefully.

it does have radio, but they will not work unless the panel is fired up. ( i dont think, maybe they are supposed to , i know they dont work now but work when panel lights up)
its def a loose or corroded connection somewhere in frame from battery to cab,
or control box

 

[Jim A]

Do amp test between positive battery cable disconnected and positive battery post.
Should be 20 Milla volt or less draw .
ECM and electronics in modern equipment draw a small amount.

An old type 12v test light between positive cable and positive post should not light up if it does that's 1 amp +- way to high of a draw.

 

[foton]

relays can work two ways normally open and normally closed so lets not go down that road. But they will be protected by some sort of fuse first in the circuit where you can measure current flow.

 

[173rdABNVN]

bad diode in the alternator will drain a battery

 

[rackmaster]

Do amp test between positive battery cable disconnected and positive battery post.
Should be 20 Milla volt or less draw .
ECM and electronics in modern equipment draw a small amount.

An old type 12v test light between positive cable and positive post should not light up if it does that's 1 amp +- way to high of a draw.

thanks, its def got a draw somewhere sucking life out of fully charged battery within couple of days.

 

[rackmaster]

bad diode in the alternator will drain a battery

yes, Id read that and was hoping that was issue, but it was not, i took time t o remove and carry to a rebuild shop to have it checked.

 

[UnexpectedBill]

yes, Id read that and was hoping that was issue, but it was not, i took time t o remove and carry to a rebuild shop to have it checked.

Back in the 80's I worked at a shop rebuilding alternators and starters to support myself. Do not automatically believe that just because the alt makes charging current that it can't have a bad diode. I saw plenty of times an alt will charge the battery when engine is running, but leak current in the reverse direction when engine is off. Most places just check output, not for leaky diodes, so it will test good, but still drain the battery.
A diode can be bad w/out being completely shorted to ground. If you don't have a VOM, a simple test is to just disconnect the red output wire from the alternator. t's hot from the battery so be careful and tape it w/electric tape to prevent it touching anything. If the battery quits going dead, that's it.

 

[rackmaster]

Back in the 80's I worked at a shop rebuilding alternators and starters to support myself. Do not automatically believe that just because the alt makes charging current that it can't have a bad diode. I saw plenty of times an alt will charge the battery when engine is running, but leak current in the reverse direction when engine is off. Most places just check output, not for leaky diodes, so it will test good, but still drain the battery.
A diode can be bad w/out being completely shorted to ground. If you don't have a VOM, a simple test is to just disconnect the red output wire from the alternator. t's hot from the battery so be careful and tape it w/electric tape to prevent it touching anything. If the battery quits going dead, that's it.

Yes, I understood that. they do a great job and I specifically got them to check the diode, if you ever need a first class shop to do one, precision rebuilders in Lexington tn. Ive used them for years, rather have one they rebuild as a new one.

 

[rackmaster]

Do amp test between positive battery cable disconnected and positive battery post.
Should be 20 Milla volt or less draw .
ECM and electronics in modern equipment draw a small amount.

An old type 12v test light between positive cable and positive post should not light up if it does that's 1 amp +- way to high of a draw.

I did this today, put the meter on 10amp and it shows zero. tried test light, it will not llight up. took the main fuse out to make sure the terminals were good, looked under cab for any rub spots, none. put battery back on and it started. started it again, same thing. then on third attempt, it would not fire up the start panel in upper portion of cab. I'm leaning toward a loose connection in control panel or a faulty one . no reason it should not light up to allow machine to run.

 

[foton]

I agree if you used a meter ,it will not lie to you, what you have is a resistance problem. check the key switch if it is a keyed machine.

 

[Jerry01314]

A good alternator should produce about 13.5 to 14.5 volts with the engine idling. If the voltage reading is low (12.5 volts or less), it indicates a charging problem but does not tell you what's causing it. That's why bench testing is so important.

I found this on the internet because 12.8 seemed on the cusp to me.
If you have a heater that can be a big draw?
Did you test it for open short by just touching terminal to battery to see if their is a spark, key off?
https://www.counterman.com/how-can-you-tell-if-an-alternator-is-good-or-bad/
Have tested the starter?

 

[rackmaster]

A good alternator should produce about 13.5 to 14.5 volts with the engine idling. If the voltage reading is low (12.5 volts or less), it indicates a charging problem but does not tell you what's causing it. That's why bench testing is so important.

I found this on the internet because 12.8 seemed on the cusp to me.
If you have a heater that can be a big draw?
Did you test it for open short by just touching terminal to battery to see if their is a spark, key off?
https://www.counterman.com/how-can-you-tell-if-an-alternator-is-good-or-bad/
Have tested the starter?

battery reads about 12.85 yesterday at starter , and will read 14 or so when running, i had the alt bench tested.
ill update the thread for more info.

 

[rackmaster]

T300 will drain battery and will not fire up start engine panel in cab.
So, New battery, cranked for a few days then same deal, it discharges battery over couple days.
checked alternator, its good, ( pulled and took to shop to make sure )
took new battery to napa, it checks good.
what is weird, is even with a fully charged battery now , it will not light start panel up , but if I hook just a little battery charger up , 6a amp for 10 seconds, it will light panel up and start engine.
Im getting 12.8 volts at starter, almost 14 with charger hooked up.
I ve swapped out relays and checked all fuses in panel in cab.
alternator is showing charging good while running

so, something is robbing voltage from battery to panel used to start engine in cab, and also draining battery while not in use.
after it runs a while , it charges the battery enough it will shut off and restart without the charger.

appreciate any help,

UPDATE;

I've decided that battery drain may not be an issue with the new battery, I assumed it was because I would have to hook a charger to battery to light up the run panel so it would start. previous battery would leak down, but it did show a weak cell.

1- I've checked all fuses with control panel active, they show 12.8 volts.
2- control panel shows 12.8 v on pin that feeds it, and I'm using the black wire as ground, so I assume that everything is grounded until it reaches the control panel.

what the CRAZY thing is, I can put a 6 amp charger on battery for 5 seconds and the control panel will allow the run button to light the panel up,
why does this extra current , maybe 2 volts, allow this to energize, so that machine can be started.

maybe its the contol panel

i never could figure out how to edit the original post with this update:

 

[brdgbldr]

If you haven't already, find and clean any and all grounding points.
Not just at the battery but at the engine. Trace the negative cable and clean and tighten all connection points. These bolts get corroded or loose and cause all sorts of strange problems.