Lead acid batteries (of any variety) do not cope well with long periods of disuse. In normal use, the acid forms a soluble sulphate but when it's parked an insoluble sulphate forms which clogs the battery cells. You need to use a conditioning charger such as an Optimate.

The high cost option is a Lithium starter battery. These can stand for 12 months and lose just 10% charge with absolutely no harm done. Products by JMT are now affordable. They use almost all of their charge capacity so can be 1/3 of the amp hour capacity of a lead acid. Lead acid will only deliver 30% at full current; after that you will only get a couple of amps.

Snags -
Cost. Lead acid is still cheaper.
Lithium don't like really cold weather so need a heavy current to pre-warm the cells before starting the car. Engine cranking will do this but on modern cars this will mess with the electronics so not a great option.
Never discharge too far or it will become an expensive brick. Leads acids will be damaged but but might be recoverable. Lithiums won't.

Benefits -
Much less weight
Much smaller
Once the cold car is turned over they will keep going. Lead acid gives one chance and that's it.
No sulphation
Very low self discharge with no dis-use damage
Much longer service life.
Can be fast charged with no damage.

Note These ARE NOT the same as pocket cell booster packs or phone or computer lithium batteries which will catch fire if not connected to the correct charger.
http://batteryuniversity.com/index.php/learn/article/types_of_lithium_ion

Thank you!!!! It took me 16 times but it started after 6 weeks.

Agrestis said:

This looks like an old thread, but I had this problem after our 500 sat in the sun for 3 months. Here's what worked:
1. Charge the battery.
2. Turn the ignition to the first position. You can hear the fuel pump running in the back of the car. The pump will stop automatically in 3 or 4 seconds.
3. Turn the key off, then perform 2. again.
4. Repeat. Try 10, 20 times.
5. Turn the ignition key to the second position to crank the starter, and you should start OK.

Click to expand...

Yes

You need to get the Oil pressure back to enable injection of fuel

If it needs oil pressure to start maybe the oil filter drains
back to the sum and it takes a long a lot of cranking
to refill and get enough pressure up.

2hnds said:

i use a power cut-off switch to keep a charged battery, but after more than 30 days away, the car will not start unless i push-start it..it turns over but sounds like it has no compression...after 4 or 5 attempts at cranking, it still just makes the same sound...i revert to push starting and have been able to start it that way....Detroit customer service has no answers for me and my dealership told me i should buy a different car..they said this car wasn't designed for my driving needs.(sitting at the airport for than a month at at time) imagine that!!! this has been going on since i purchased the car new in 2012..500 POP standard trans. any help?

Click to expand...

I own a 2014 Fiat 500L, a 2015 Fiat 500 Sport and a 2015 Fiat 500L Urbana. These move my family around. If you know the Houston TX area then you already know you need multiple cars.

All three vehicles have the same problem, and have owned them for a few years. If you park them for three weeks or more, they will not start right away. You have to hold the key in the cranking position for about 10 minutes, and keep pumping your throttle till it starts.

LISTEN TO ME:

You have to hold the key in the cranking position for about 10 minutes, and keep pumping your throttle till it starts. If your leg doesn't hurt pumping the throttle (accelerator), it will not start. But once it starts, it will start normally again until you leave it parked again for over three weeks.

Case in point; the Urbana is the latest acquisition. I bought it from an auction and it had a left fender needing replacement. The body shop finished the body work and told me the vehicle won't start. They were frustrated because their mechanic was at a loss. I went there the following morning and performed my miracle. It took about 15 minutes to start up and has started normally ever since.

My amateur diagnosis is this 1.4L powertrain has a defective fuel pumping system. When the vehicle sits for a period of time the fuel drains back from the lines into the gas tank. Maybe the pump needs a backflow preventer to solve this problem.

The ship is still in disbelief when I started the Urbana. So be rest assured; when next it won't start, be ready to pump and end up with a tired leg .

Why this Fiat? They were the only 2-3 year old vehicles I could purchase for less than $10k. Now I love them