Battery drain even after battery selector switch is off

[pilzdad]

First off, I did a bunch of searching around on here and couldn't find anything related to a battery switch. I found that taking the negative battery cable off, or positive, and putting a multimeter on it will help determine some sort of battery drain. I have a 2 battery setup with selector switch for each one. Battery one has zero drain. However battery two shows up with having a leak to the tune of 11 volts. There is only a bilge hooked up to that battery and if I disconnect the bilge, it still shows up. Any thoughts on what it could be?

2000 cobalt 246.

thanks for your help.

Dave

 

[Jlawsen]

Re: Battery drain even after battery selector switch is off

Do you have a clock? If the bilge pump is automatic it will always draw some current, you may have two separate connections to that. I had a Rule that required wiring to both the pump and the switch so it could be run in manual or automatic mode. Seemed odd to me but hey, what do I know. Also, if you have an automatic charging relay (ACR) it will always draw some current.

 

[Silvertip]

Re: Battery drain even after battery selector switch is off

11 volts is not a "leak". A discharged battery will measure 11 volts and that does not represent a leak. Current flow is what you are looking for. But your eyes can tell you what is drawing current if that's really happening. So lets start with some basics.

1) What lead you to the conclusion that there was a drain on battery 2? Was it dead all the time?
2) With the switch set to off, the only way there can be a drain on BAT 2 is if something is wired directly to it, or to the BAT 2 post on the switch.
3) If BAT 2 is repeatedly discharging and nothing is connected to it, you have a bad battery. Remove it and have it load tested at any auto store. Just make sure you charge it before you do this. You can't load test an already dead battery.

 

[TerryMSU]

Re: Battery drain even after battery selector switch is off

First off, I did a bunch of searching around on here and couldn't find anything related to a battery switch. I found that taking the negative battery cable off, or positive, and putting a multimeter on it will help determine some sort of battery drain. I have a 2 battery setup with selector switch for each one. Battery one has zero drain. However battery two shows up with having a leak to the tune of 11 volts. There is only a bilge hooked up to that battery and if I disconnect the bilge, it still shows up. Any thoughts on what it could be?

2000 cobalt 246.

thanks for your help.

Dave

Dave:

Current is measured in AMPS, not VOLTS. To measure current, you must first break the connection and then insert the ampmeter in series. Most meters will have a separate connection for current vs voltage. For your specific test, break the line as you have done by removing the clamp. Then set the meter to AMPS (or better yet MILLIAMPS). The probes on the meter are typically plugged into the common terminal and the amp (or milliamp terminal). This is usually a fused connection in the meter. If you blow the fuse, it will protect the meter, but it is usually a special fuse and will be hard to find and relatively expensive.

Note: If you put excess current thru an unfused ampmeter, you will permanantly destroy the meter. Do not try to run your starter or radio thru the amp section in your meter.

The following analogy may be helpful in understanding current vs. voltage. Think of it like a hose and water. The rate at which water flows (for example, gallons per hour) thru the hose is like current. The pressure drop along the hose (For example, the difference in pressure between two points along the hose [in pounds per square inch]) is like voltage. To know how much current is flowing thru a hose requires some sort of way to insert a flow meter in the hose.

TerryMSU

 

[Don S]

Re: Battery drain even after battery selector switch is off

Could also be a defective battery. Get it load tested.

 

[pilzdad]

Re: Battery drain even after battery selector switch is off

Could also be a defective battery. Get it load tested.

Had both batteries tested and they are good. The real problem I'm having that is causing me to think its the batteries is this....I just installed a new radio and still using factory 4 speakers that came with. Whole setup is sony. When engine not running, radio is clipping out at certain volume. When engine is running, no limit to how high you can turn it up.

I thought that the batteries discharged would cause this to happen but it does it on battery one and two just the same. So I had both tested at an auto store and they are good. Nothing else hooked up to the batteries less that bilge pump and the selector switch. Everything shuts down as far as i know when the switch is in the off position.

 

[glenn property of pam]

Re: Battery drain even after battery selector switch is off

stereo sound is pulses of electricity sent to the speakers which makes a magnet pull on the cone to produce a air movement that we interpret into sound. the more electricity the stronger the magnet the higher the sound. batterys produce around 12.6volts the alternator produces around 14v when the engine is running the extra 2 volts equals more sound at the highest volume. so do you have a battery problem.......nope.
change the title of the post to "need a stereo to rock the lake" that will get the attention of the guys that can help you

 

[PuddleJumper]

Re: Battery drain even after battery selector switch is off

Since you changed radios, did you check to see if the impedance (speaker ohms) match what the new radio is set up for. Impedance mismatch can cause the problem you describe.

 

[Jlawsen]

Re: Battery drain even after battery selector switch is off

stereo sound is pulses of electricity sent to the speakers which makes a magnet pull on the cone to produce a air movement that we interpret into sound. the more electricity the stronger the magnet the higher the sound. batterys produce around 12.6volts the alternator produces around 14v when the engine is running the extra 2 volts equals more sound at the highest volume. so do you have a battery problem.......nope.
change the title of the post to "need a stereo to rock the lake" that will get the attention of the guys that can help you

I agree with the last line. I don't buy the 14v theory since that would limit the use of the system to only applications of higher than normal voltages. You would think that Sony would just step up the voltage in the unit if it needed it. There's plenty of current available in those batteries to accomodate it.

 

[glenn property of pam]

Re: Battery drain even after battery selector switch is off

ok thats a fair surgestion the speakers could be the wrong ohms the speakers could be wired up on 2 channels instead of 4 the wire going to the stereo could be the wrong gauge the speaker cable could be cheap made in china stuff etc etc etc and from the posts ive read on here from stereo guys all of them could be the reason.......but heres the big question why does it get better when the engine is running?.........thats why i surgested getting the guys who do boat stereos to come chip in.......either way i dont think its the batterys which is where the first post started.

 

[Silvertip]

Re: Battery drain even after battery selector switch is off

None of the wire gauge, speaker impedance, stuff has anything to do with a "drain" with the battery switch off. Nothing is running so it can't cause a drain. Now the term "drain" may be open to discussion and that has not been actually confirmed and it cannot be until a current measurement on that battery is taken and it is confirmed that there is or is not a current flow. Sound quality is affected by speaker impedance, wire size, amplifier power and obviously by the quality of all the components in the system. Those are two distinctly different issues. So is it a battery drain or s sound quality issue we are trying to solve.

 

[glenn property of pam]

Re: Battery drain even after battery selector switch is off

post #6 silvertips the op says why hes looking at the batterys as a problem

 

[Silvertip]

Re: Battery drain even after battery selector switch is off

post #6 silvertips the op says why hes looking at the batterys as a problem

OK -- given that the problem occurs with both batteries and I take it the problem is still there when the BOTH position is selected, then the batteries are NOT the problem. Two batteries in parallel should operate the most robust basic audio system regardless of battery size. So start looking at wiring issues. Measure voltage into the radio with both the radio and the ignition off and again with the engine running at 1500 rpm. Then make the same measurement with the radio ON. Just guessing that the voltage will be below 11 volts with the engine off and radio ON. That says there is voltage drop in the power lead if the batteries measure 12.6 AT THE BATTERIES. Make battery voltage measurements at the battery posts -- not the terminals connected to them. As input voltage gets to a radio it is regulated internally within the operating voltage range of the radio so radio volume does not vary based on input voltage. The low and high voltage cut off circuits protect the radio from voltage surges that drop below or rise above whatever the range specification is for that particular radio. As voltage approaches either of those cut off points you may very well notice a decrease in sound quality. So far we've seen nothing but speculation. Until some actual testing is done that's all this thread will be.

 

[generator12]

Re: Battery drain even after battery selector switch is off

I'm with Silvertip. I'll bet if you measure the voltage - engine off - at the radio itself, when it's not performing correctly, you'll see significantly less than the 12.6 volts you'll find at the battery terminals under this same condition. In fact, I'm betting that you'll find that voltage varying slightly with radio volume. This means that the wires to the radio are too light a gauge, and that the radio is drawing enough current to drop voltage across those wires. If you find this condition, replace the wires with a larger gauge. (It's been years since I've seen this happen, but I definitely have seen it happen.)

This is NOT related to any battery drain when the switch is off. If that's happening, you'll need to trace the wires from battery through switch to see what is not being disconnected when that switch is off.

The information given above on current (amps) versus voltage (volts) is correct. An ammeter check can only be made with the meter in series with the load. (You're connected to only one of the two wires.) System voltage is measured from one wire to the other.