Possible Electric Problem

[wisconsinjim]

Hey folks can you help me out on this one, my battery drains to zilch overnight and I cannot think of anything I did to deserve this. I am using an auto ranging DMM set at the DC VOLTS scale, with battery positive cable disconnected I put one (neg) probe on the positive post and the positive probe on the positive cable I get a reading of 11.94 Volts yet at night in the dark I do not see any spark that would indicate a short. How can I see if there is a short?

[Jpony56hd]

The first thing to do would be to take the battery out and get it checked at a local auto parts store that does that. If the battery is good unplug the alternator/regulator and see if it still discharges. Generally a short that bad should blow a fuse long before it could drain the battery overnight.

[dpinvidic]

Are you able to fully charge your battery.
It is fully charged if you let it sit disconnected for several hours and then measure 12.7v
across the terminals.

Your DMM should be able to measure amps, but us usually limited to 10a max.
I suggest you get a 7.5a or 10a fuse and use it to connect the positive battery cable.
if it does not blow, then you are under 10a and it is safe to measure with the meter.

make sure you know how to measure amps with your meter.

regards,
dan

[wisconsinjim]

Yes that is what I am doing wrong, I am reading voltage and I should be reading amps, I am going out now to charge the battery up and then look at the amperage to see if there is something using power.
Thank you for jogging my feeble brain.
Jim

[dpinvidic]

Originally Posted by wisconsinjim

Yes that is what I am doing wrong, I am reading voltage and I should be reading amps, I am going out now to charge the battery up and then look at the amperage to see if there is something using power.
Thank you for jogging my feeble brain.
Jim

You know you have ti switch the red probe to another jack on the meter to meassure amps.
AND DON'T TRY TO MEASURE VOLTS WITH THAT CONFIGURATION.....

DAN

[billdor]

Hi Jim
The easiest way by far to troubleshoot this would be to charge the battery then leave the pos. post off overnight. if the battery is dead in the morning you will need a new battery, if it is not, you can start pulling fuses with your meter hooked on amps as Dan suggested above to find the troublesome circuit. Each time you pull a different fuse, check the meter to see if you still have the draw. When the draw goes away you have found the circuit that is the culprit.

[wisconsinjim]

Originally Posted by dpinvidic

You know you have ti switch the red probe to another jack on the meter to meassure amps.
AND DON'T TRY TO MEASURE VOLTS WITH THAT CONFIGURATION.....

DAN

Yes I swapped it to the 20A fused circuit and all I got was zeros I then started to charge the battery and poof I blew the transformer fuse to the power company will try again in the morning.

[wa8yxm]

Your post indicates a charged converter and a totally discharged (I mean flat dead) battery

With the negative (black) lead on the battery and the red on the post you should see a NEGATIVE voltage on the meter and yes that sounds normal.

There are parasitic loads.. That's what you are seeing,, The Explosive gas detector,, Control computer for water heater, Fridge, possibly your air conditioners and of course the filter cap on the converter. They all present loads under that condition.

CURRENT would be more important. (reverse leads to measure)

[dpinvidic]

Originally Posted by wisconsinjim

Yes I swapped it to the 20A fused circuit and all I got was zeros I then started to charge the battery and poof I blew the transformer fuse to the power company will try again in the morning.

This sounds very wrong.

I charge my batteries from a 20amp outlet all the time.
What kind of inverter charger do you have?

For a magnum, you can change the max charge current to a lower number.
Remember, the amps that you read from the inverter for battery charging ARE NOT the amount of amps you are drawing from your outlet.

If you read around 80amps fo charging current, that would be about 9amps from the AC source.

On a side note, there is usually a large inrush current when you first reconnect the RED battery cable, and this will usually blow the fuse in your meter.

What you should do is short out the meter leads, so the inrush bypasses the meter. Then remove the short....while the meter is still connected....now you can see the drain current. It is usually 1 or 2 amps when everything is off and no shore power connected.
The inverter is usually connected DIRECTLY to the batteries...so even with the disconnect swith open, there will still be some drain.

Regards,

Dan

[wisconsinjim]

Hold on folks we are getting way to techy here this is for my starting battery and it is not connected to anything other then the vehicle electrical which is minimal. I have charged the battery and now show 12.75 V I will check it again in the morning to see what the voltage is.

[dpinvidic]

Sorry, that was not clear from your post. So the only way the chassis battery will charge is if there is a separate BatteryMINDer. When you leave it overnight, it should be disconnected to prove the battery is good.
Regards,
Dan

[wisconsinjim]

I just checked the battery and I am down to 12 volts so seems I have an internal short in the battery morning will tell me more.
Thank you all for your knowledge it is appreciated.
Jim