Battery, Alternator or its cutout?

[danhr]

I have a 13BT in BJ74 24volt system. Two Hankook 70 Amp battery (maintainance free).

The problem is that after running (daily) it for two-three weeks it discharges the battery. It discharges by the next morning. I can hear the ignition sound reduction the day before it is to die.

I recharge them but same result i.e. dies after few weeks or left idle for few days. Sometimes it works fine for a month even (even with low usage).

Some said that its alternator cutout fault so I replaced it. Still same result. Then someone said that battery is bad (I was using EXIDE at that time) so I switched to Hankook. Same thing.

I checked the alternator connection and wiring and everything seems in order. I even did the following:

Start the engine, remove the terminal and turn on lights and AC. Still lights were ok i.e. seems alternator is fine.

Besides that even when the battery is charged I have noticed that the battery indicator (Hankook has one) is black which means to recharge.
Whats wrong?

 

[jus cruzin]

you may have something in the system that is using power overnight.

I am not a fan of the hydrometer on sealed batterys because they only measure one cell.

make sure that the top of the batterys is clean, batterys can discharge across terninals if the top is dirty. test:- get a muiltymeter and put the + of the meter on the + terminal post with the - on the meter start at the - post and move it closer to the + post, testing at intervels. your reading should be 0.

what is the voltage of the batt's before you try start in the morning?

 

[danhr]

I am not understanding the test you explained. Questions are:

a)What should I set the multimeter to?
b) The +ve of mutimeter is to be connected to +ve of battery 1 and -ve to -ve of battery2?
c) What do you mean by 'move closer' to +ve end?

I showed it to Hankook dealer. He removed the -ve terminal and connected one end of amp meter to the -ve end of battery and one end to the terminal coming from alternator (the terminal that was connected to the battery actually).

i.e. both ends of amp meter connected to -ve. I didnt understand the connection myself but he argued that since no amps was showing on meter, its the alternator fault. He did the same with +ve end.

 

[Otterav]

Hello,
It may be the alt. Check the voltage of the batteries with the engine off. Should be between 24-26volts. Now start the engine, run it up past 1500-2000 rpms, the voltage should be about 28-30volts. The brushes may be worn and only charging the barrery intermittently, causing the battery to be undercharged. The brushes are easy to replace and quite cheap too.
eric
P.S. What he was checking was the system off amperage draw, engine and ignition switch in the off position should equal 0 amperage. I would bet on the brushes, second would be the voltage regulator, internal or external.

 

[danhr]

Otterav:

I have fully recharged the batteries again. Each battery produces around 13Volts. If I start the engine and rev it up to 2000rpm, the battery show around 27-28 volts. So, is it the alternator?

 

[Tapage]

Just a thought. Maybe the batt are shot ! I have this experience with one optioma yellow top, replaced in warranty.

 

[Otterav]

Otterav:

I have fully recharged the batteries again. Each battery produces around 13Volts. If I start the engine and rev it up to 2000rpm, the battery show around 27-28 volts. So, is it the alternator?

Did you check the everything off amperage draw? The running voltage seems proper in its range, but charging the batteries defeats the diagnostic process.
1) check the amperage draw with everything off.
2) check the systemvoltage with every electrical device in the truck on, creating the highest draw, lights, heater fan, overhead lights, everything possible. you are trying to load the alternator close to its limit. This will help determine the health of the alt at 2000rpm.

Lessee, you recharged the batteries to 13v ea. 26 volts and the alternator puts out 27-28v when running at 2000rpm. 28v is very close to the system design voltage. Charging the batteries was counterproductive for troubleshooting purposes. Start over with the above #1 & 2. Report back
eric

 

[danhr]

Otterav:

Here is what I did:

Took off one of the -ve terminal from the battery. Connected +ve of multimeter to the removed therminal and -ve to the battery -ve terminal. With everything off I got 0.282 amps.

Now here is the strange thing; With the same setup I checked the voltage. It showed around 24Volts, even with everything off. How can it be showing voltage in series?

I have not checked with full load as my multimeter has limit of 10Amps.

 

[denis]

I can smell a 12V item hackwired direct to one battery

 

[Martin White]

A quick test you can do is to bridge the gap between each fuse with an ammeter. This will quickly locate a circuit with an excessive parasitic load on your batteries. Over time even a small load can kill good batteries. I quickly located a problem on my truck a while back using this method. You should ideally not have a draw much over about 50-60 milliamps. Some vehicles are lower than that. But if you see anything much over 100 milliamps there is probably a problem with that circuit. I read somewhere that modern cars are designed to start after being left for several weeks, with a good battery, so the parasitic loads are kept by manufacturers somewhere within these parameters.

 

[mobi-arc]

DON'T remove a battery terminal while the vehicle is running...it's the fastest and easiest way to wipe out rectifiers. The removal of a battery cable was valid with your Daddy's generator, not with alternators.

 

[Otterav]

Otterav:

Here is what I did:

Took off one of the -ve terminal from the battery. Connected +ve of multimeter to the removed therminal and -ve to the battery -ve terminal. With everything off I got 0.282 amps.

Now here is the strange thing; With the same setup I checked the voltage. It showed around 24Volts, even with everything off. How can it be showing voltage in series?

I have not checked with full load as my multimeter has limit of 10Amps.

Well,
You have a large resting load. With a draw of .282 amps that will discharge your system quickly a few days will draw it down low enough to cause problems. You need to locate the cause of the current draw. Even if you remove the negative cable from the battery that will preserve the charge state of the battery. Find the draw and you will find the solution to your problem. Remember look for the easiest solution to a problem that will most likley be the answer. Go here: http://en.wikipedia.org/wiki/Occam's_Razor
Good luck
eric
P.S. Report your findings
P.S.S. Remove your fuses one at a time and check for a current across the terminals, this will help isolate a circuit.

 

[danhr]

There is a wire connected to battery; if I remove it, amps goes almost to zero. Removing this wire results in ignition to not function.

 

[Otterav]

There is a wire connected to battery; if I remove it, amps goes almost to zero. Removing this wire results in ignition to not function.

That is probably your fuseable link, without a pic or better description its kinda hard to diagnose. That probably narrows it down to the entire truck with the exception of the starter and the alternator charge cable. Hook the wire back up and remove one fuse at a time checking the amps like you were doing. The fuse that you remove that drops the amps is probably the circuit that is causing the problem.
eric

 

[danhr]

Today, the battery again drained out. One battery shows around 9 Volts while the other around 11.

I regularly take it out for a spin yet still.

Otterav:
I had been occupied, I will do as you suggested right now.

 

[danhr]

The wire that I said 'reduced' the amps when disconnected, my mistake. It did not reduce at all. So ignore that.

I removed fuses one by one but amp still remained 0.28xx. I checked the wiring of converters and disconnected them (by removing their fuse), still amp remains in 0.2 range. What else do I need to do?

 

[Ron R]

Disconnect the alternator and look what the draw does.

 

[danhr]

There is a plug (grip) located just on top of alternator. I unplugged that but the draw reamins intact.

OR do I need to remove additional wires to disconnect alternators (which ones?)

 

[Dougal]

The wire that I said 'reduced' the amps when disconnected, my mistake. It did not reduce at all. So ignore that.

I removed fuses one by one but amp still remained 0.28xx. I checked the wiring of converters and disconnected them (by removing their fuse), still amp remains in 0.2 range. What else do I need to do?

I had a similar issue which plagued me for years, I finally beat it about 12 months ago.

For me the draw was the same (about 0.2 amp), which would make the vehicle sluggish to start over 3 days and almost impossible to start after a week.

I found it was the ignition lead for the alternator that was drawing approx .15 amps, I had to wire it in through a relay so it was only activated when the ignition was on.
That dropped my draw to about 0.03 Amps and solved the problem.

My problem was the result of paying a professional auto electrician to install the alternator. This was after his second attempt to wire it in, the first attempt resulted in 16v charging and a tacho not working.

 

[Ron R]

There is a plug (grip) located just on top of alternator. I unplugged that but the draw reamins intact.

OR do I need to remove additional wires to disconnect alternators (which ones?)

Don't know your type of alternator, but if there are more wires leading to it, disconnect them as well (and make sure they're insulated!!).

See also Dougal's posting.
If you experience the same I would go for a check on the alternator/regulator (if separated) and not choose for his option (relay). I agree this does what it has to do but it just complicates matters and makes it more prone to malfunctions.
I love the KISS-viewpoint.