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Battery drain problem on '07 Spyder


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Hello,

I had an e-gear snap test done recently and the tech told me the battery voltage was very low at 12.05volts. This test was conducted without the car running, just the key switch on. I had no trouble starting and driving home. Today I bought a new battery, charged it up on the bench, then installed it in the car. With the key turned on and the engine not running, my voltmeter read 12.08v at the battery terminals.
With the engine running, I measured 13.8v at the battery terminals.

As this is a new battery, with key switch on dash display on etc, but engine not running, the voltage level should be around 12.5 to 12.8 volts, is this correct? Also, What is a normal voltage level with the key off and nothing else running?

Is it possible there is some parasitic drain going on in the car to bring the voltage down to 12.05v? If so, where would I check first and with what sort of methodology e.g pull ancillary fuses one at a time until battery voltage goes up etcetc?

I normally keep the battery topped up with a tender, so it's not left for long periods without charge.

Your advice would be greatly appreciate.

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Voltage test on battery is done with key off. Should be around 12.6.  Its normal for voltage to drop when key is on as many items power up with key on and draw on battery. 12.+ volts with key on is none issue in my book. 

At this point it does not sound like you have a issue.

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15 hours ago, jefflambo said:

Voltage test on battery is done with key off. Should be around 12.6.  Its normal for voltage to drop when key is on as many items power up with key on and draw on battery. 12.+ volts with key on is none issue in my book. 

At this point it does not sound like you have a issue.

Ok, thank you. I was told that the battery voltage had to be above 12.5v in order to reprogram or change settings in the ECU using the LARA software otherwise the ECU could get corrupted. Is this unfounded info I've picked up and would 12.+ be ok to program the ECU?

Cheers,

 

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5 hours ago, ToadNZ said:

Ok, thank you. I was told that the battery voltage had to be above 12.5v in order to reprogram or change settings in the ECU using the LARA software otherwise the ECU could get corrupted. Is this unfounded info I've picked up and would 12.+ be ok to program the ECU?

Cheers,

 

If you are doing programing work on a ECU a battery charger that has support mode should be used. Voltage never stays that high with the key on with out support. LARA is not that sensitive to voltage as other platforms are. But as a good rule a charger with support mode should be used.

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