Short

[farmingdad]

2011mountian air. Chassis battery's go overnight with master switch turned off I can take 60 amp fuse out at the battery box an it is ok , house battery's are ok , what could could keep a ngative pull on the battys

[MrWizard]

quick answer yes

if the contacts are stuck closed, its the same thing as the disconnect switch being in the power on mode
all the switch does is control the relay/solenoid

i think i would check that starter circuit, starter relay/solenoid and the starter motor it self

[farmingdad]

The negative pull has burnt my alternater up , still got a short with alternator off of it , could a selenoid cause it to pull power from battery even if master switch is off

[Passin_Thru]

ECM, TCM, and any other CM will bleed electricity and that sir is not a short. A short is a direct conection from Positive to Negative circuit that allows a current to follow an unplanned or accidental path. That said, never leave batteries untended-unchartged for long periods as it WILL cause an ECM to die.

[ScottG]

Bad diode in alt.

[farmingdad]

I found out when alternater is gets warm when batteries are hooked up

[time2roll]

Get a DC clamp-on ammeter and find where the power is going.

[farmingdad]

Put new batteries in chassis I even ck the fuses taking one at time out still got pull on batteries. I got house turned off and chassis switch off ??

[MrWizard]

Chevy 454?
This engine starter system is notorious for parasitic drain
Sticky pitted contacts in the starter relay

I had two of them that would drain a new battery in 3 days
A weak battery, that shows good voltage but no longer has full capacity
Will drain in one night , IF this is your problem

[Sam_Spade]

dougrainer wrote:
I doubt batteries are OK. What makes you think they are OK?

Careful here.

He was talking about chassis battery and house batteries in the same sentence.
House OK, chassis goes dead.

Either the chassis battery is dying or it is not being charged.

On most units with only ONE disconnect switch, that does only the house batteries.

[dougrainer]

I doubt batteries are OK. What makes you think they are OK? Also, unless you take the time to FULLY charge them, they will not hold a charge. You need to post MORE info. There is NOTHING that will drain 2 good batteries overnight, even the headlamps being left on.
1. HOW and how long have you recharged the batteries?
2. Are the batteries the original batteries?
3. ONE bad battery will drain the other battery in a bank
4. Regardless if you have 1 bad battery you ALWAYS replace all batteries in a bank at the same time.
5. HOW did you check/determine the batteries were good? Doug

[10forty2]

As said above, if the battery is original, it's probably time for a new one. If it's a new battery, then you'll need to do some elimination to find out what's drawing so much current. Get an ammeter and put it inline with the positive lead....in between the battery and the load. Set it to read the amp draw and them start systematically unplugging fuses to see what drops the current flow significantly. It might take you a little time, but it will be well worth the effort to find a faulty component if you have one.

[YC_1]

If the batteries are bad then any tiny bit of drain can cause them to short internally.

Measure the voltage on each battery and write it down. Take pictures at the same time for future reference.

Get a simple hydrometer to check them. They are easy to use. Any automotive shop has them.

Check the charging voltage to see if they are getting enough.

If these are original batteries and you are a new owner it is time for fresh ones, hence the pictures to make sure you do not leave one wire off.

Look in storage compartment for lights left on.

[MountainAir05]

you will have to find out what is still hot and draining. Radio memory, alarm if you have one. Engine ECM (time to power down) Trans ECM same thing. You should be able to see what that one fuse powers. alternator diodes if bad. Did this just start ?