jonathan58

Sometimes my 2004 LS430 with 125K miles will start up just fine and I can drive a short distance, park and wait for my wife to run an errand in a store. I keep the engine off but sometimes fiddle with the radio, or use the flashers or do nothing at all. When I go to start the car again 10 or 20 minutes later, she sometimes won't turn over and I have to get a jump. Then the car starts right up just fine. I replaced the battery about a year ago because of this problem, but it's still happening. I do not drive the car often with days between drives and almost always local driving. But the question is: Why would the car start up just fine and not start up later? Should I look at something other than the battery?

Thanks,
Neverready.

LeX2K

First step is check the battery voltage, both with the car off and with the engine running. If you don't have a test meter get something like this.

jonathan58

Thanks. I assume I check to see if there is a big difference in the values using the meter. If there is, then what? And is there a normal range for the output while it's on?

PrimeDave

If the car is not driven frequently enough this exact scenario will happen. The easiest way to avoid this is to get a battery tinder aka trickle charger etc. I don't drive my car daily, and when I do all of my trips are very very short, literally a couple miles and then I'm home again. I'm out of town half the month every single month as well. I have mine hooked up to a trickle charger when I'm out of town. Car fires up and starts every time with no issues, even with my short trips when I'm actually in town. The age of the battery doesn't matter in this situation, its not going to hold a charge if its not being driven enough (alternator charges the battery when driven etc) and if there is no battery tinder to help it when the car is sitting overnight etc. Also, If you must sit in the car when your wife is in the store for 20 mins, and you're using the electronics in the car (radio etc) leave the engine on...

chuyrobles

I agree, it appears you are not driving the car long enough to charge the battery. Car battery experts say it takes about ten minutes of driving to make up for battery power lost during start-up. A trickle charger is designed to keep the battery fully charge between start-ups. I have two 1-amp Noco chargers, one is on my mom’s 98 Sienna; the other on my motorcycle. They run about $25 plus anther $12 or so for the quick disconnect wiring. I tuck the connector behind the grill on the Sienna so I don't have to open the hood to connect it.

There is a small possibility the alternator may not be charging the battery properly. A volt meter can help check it. At idle, the ideal voltage output is 14 volts. Anything under 12.6 volts means the battery is not being charged at all because that is it’s sitting voltage. To further evaluate the health of the alternator, take a second voltage reading at about 2K rpm with a load on it (fan on high, lights on, wipers on) - the voltage difference between that and at idle should not exceed about a volt. And the voltage should never drop below 12.6. I am not happy if any of the readings are below 13 volts. If you have any doubts, them Aurozone type stores can check the car’s charging system at no charge.

AVSRacing

Check your battery terminals, are they tight? I was chasing a weird electrical no start problem on my old BMW and turns out the battery cables were loose after an accident.

jhubb01

Hi guys replacing a bad alternator and putting in a new interstate battery. Comments?

5spd97

You still need to use a trickle charger if the car sits for weeks at a time. There are always small parasitic current draws even with the car off; such as clocks, alarms, key fob recognition, etc. A new battery should show 12.6 volts or more at rest and a lead acid battery at 12.06 is considered 50% discharged. Each time you let your voltage get down in the 50% range it permanently damages the battery and I can say from experience that you can ruin a new battery in less than a year by not keeping it charged. I have a bunch of cars, trucks, motorcycles, boats, lawn mowers etc that get occasional use and I seem to spend my life screwing with batteries, chargers etc.

Even removing the battery from the vehicle is a short term solution if its not maintained in a charged state. Get a trickle charger.

jonathan58

Really appreciate the information, some of which I have never seen anywhere before. I hope I didn't damage the battery already.