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12 Volt Auxilliary Battery

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So I noticed the other day that after about five minutes with the ignition on (but the car not running) my 12 volt battery was too weak to start the vehicle. I had been playing around with the blue gauge mod as discovered by RXREY. Plugged in my electronic charger and it showed around 12 volts, but the % display only showed 45%. Kinda figured the battery was on it's last legs to only have 5 minutes of capacity. However, it still showed good voltage, so I left it in the vehicle.

Anyhow, charged it, went through the ISC learning procedure and went on my merry way. Immediately noticed that the ICE didn't run as much and I could stay on electric for much longer (this is what happens when you do the ISC learning IF your battery has dropped below 7 volts or if you disconnect it). However, I had recently done the ISC learning before killing the battery, so it was weird that doing it again improved the efficiency of the ICE.

This morning, the car started up fine, but I noticed again that the ICE was running too often and too easily (just a dab of the gas and the ICE was running and this was after reaching operating temp). Did the ISC learning procedure and all was fine again.

Took the battery out and to the local auto parts place. They threw it on a diagnostic tester which revealed good voltage (12.4) but the CCA were down to 200 (and the battery is supposed to be 450 or 500). The machine recommended 'replace battery'.

Now I know the CCA doesn't mean a thing on our vehicles since the battery doesn't turn a starter. I'm no electrician, but I guess the low amps were somehow affecting the computers (memory?) and I was losing the Idle Speed Control setting overnight. Or possibly, the voltage was dropping overnight when it was cold out, but still had enough to start the computers?

Anyway, a new battery is in as we speak (no I didn't get the Optima yellow top). I had a store credit at Canadian Tire which brought the cost of their Eliminator top of the line battery down to $45. Also they had a coupon on the battery - for an extra $9 I could triple the replacement warranty. So I now have a full replacement warranty for NINE (yes 9) years.

I'll follow up on if the ISC resets again with the new battery, in which case, the dealer may need to dig deeper with their special Lexus diagnostic computer.

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