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Parasitic battery drain on '07 Spyder?

1068 Views 6 Replies 6 Participants Last post by  tor

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 I would expect that the with key switch on but engine not running, the voltage level should be around 12.5 to 12.8 volts, this I assume would even be with some current load from the dashboard lights, ecu etc. Is this correct?

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?

Your advice would be greatly appreciated 馃檪
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Step #1: Clamp a amp probe on it with the key turned off and see what it says.
Step #2: Buy a battery tender
Step #1: Clamp a amp probe on it with the key turned off and see what it says.
Step #2: Buy a battery tender
Thank you. I have a CTEK battery tender that I normally use to keep the battery charged - It hasn't given any indication that the battery couldn't be charged and seems to complete it's charge cycle. As you say, I will get an ammeter on the job. What is the normal voltage at the terminals with key on (dash lights up etc) but engine off?
A parasitic draw is a test with everything off and all lights off and the car sitting for at least 15 min so it goes to sleep and then testing the amperage draw accros the negative battery terminal. This will tell you if something is causing a problem. Next is figuring out what it is. You tube has some vids on how to do a parasitic draw but you will need a few tools. Harbor Freight or your local tool supply place might be able to help. Hope it helps.
Dallas Lamborghini told me Gallardo's drain their battery's. They gave me a CTEK battery tender and I have never had a battery problem keeping the tender on between drives.
I just checked the voltages on mine 2007 Spyder which has a 2 month old battery (Yuasa 5000, 100Ah)
Starter key OFF: 12,65V, Starter key ON: 12,37V (Engine OFF)
Are you sure your new battery have been fully charged? Maybe you should try to let the charger stay on for an extended period of time.
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