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The first time I yanked off the plastic "motor" cover (it "shields" nothing) with a bit of difficulty in 2015 & realized it's useless, I just left it in the garage.
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Then as soon as I felt how warm the adjacent onboard charger was* I added a piece of stryrofoam to insulate the heat & started trying to charge at cooler times & places with the hood open if practical.
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* The flat rectangular aluminum box beside the 12V starter battery is the OBC (or OBCM). The "main battery" is under the car's floor.
 

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Battery testers usually test the internal resistance of the battery. The batteries CCA rating is directly associated with the batteries internal resistance. So a 500 CCA rated battery that tests at 200 CCA has a high internal resistance. This will lead to a large voltage drop when trying to draw current. That would be a bad battery. My guess is your battery has a really high internal resistance since the cranking voltage is so low and its complete death is immanent.
 

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Ya, used regularly, a 500e charges its starter battery a LOT, & the car can start even with that battery 80-90% dead (only 10-20% left), so if it shows even the smallest sign of being nearly too low to start, you can bet it's just completely worn out & might leave you stranded at any time, too low to even jumpstart.

Yes, it might jumpstart with old-fashioned cables AND disconnecting the dead battery, but it might not keep running if you reconnect the dead battery, & it might damage the electronics to have no battery connected.
 

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Discussion Starter · #24 ·
You can just monitor resting voltage, preferably after several hours sitting without charging, such as right before opening the left door in the morning, or after an 8-hour work shift. 11.6V (about 20%) is the minimum for reliable starting in the worst conditions of the left door open & the brake pump activating itself.

Good question whether the app has to be open non-stop for the alarm to work! Let us know. Hopefully not, but you wouldn't need to check it very often. It looks like the BM2 alarm only has 10% increments, so I'd set that for 30% & then when it went off I'd start checking periodically until it started getting close to 11.7V at which time I'd start battery shopping again.

Cheap, old-fashioned "flooded" style batteries are supposedly better than Absorbent Glass Mat (AGM) in heat, as long as you keep them topped off with distilled water, so for that type you'd want removable caps. "Gel" style is supposedly even better, but pretty pricey, & Lithium-ion last the longest, but are super-expensive, although maybe similar cost per year.
Wait, I just re-read this. so don't look at the cranking voltage of 3.7V? the battery looks like it's staying above 12V and above. So do i need a new battery?
 

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:unsure: It actually looks okay.

Is it possible that right before purchase it was sitting for a while?

If so, that could have let it drop to what seemed to be around 11.5V. So at first it would fail to start if the brake pump activated, but then it would be recharged after a bit of normal use which charges it while driving and while charging.
 

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Discussion Starter · #30 ·
You have left the humidity sensor unplugged, right?

One of the errors it can cause is "Service PRND". I haven't seen any reports of it making the key stick in the ignition, but there's a first time for everything.
Yes, I finally did that. I don't think we've had the service prnd since then. crossing fingers.
 

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Thank you for confirming!

Maybe I should add "key stuck" to the list of issues that evil piece of crap can cause:

ABS, cruise control, ESC, HSA, PRND, RBS, SRS (airbag), etc.

Now you know why leaving it disconnected is number one on the list of how to fix a "dead" 500e!

Still seems pretty bad that it dropped to 3.78V though.
 

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Sorry I missed this one.

The only thing I know that makes the key stick in the ignition is a dead 12V starter battery, which gets full charging power from the HV battery the entire time the car is on PLUS the entire time the car is being charged. With all that charging, if it ever goes dead in normal use it is simply completely worn out.

The 500e can wear out 12V starter batteries very fast, due to the heat of the adjacent OnBoard Charger & the PIM right below that. It's best to try to charge the car at cooler times/places, & whenever practical leave the hood open while charging. Delete the useless heat-trapping motor cover, & leave in a chunk of styrofoam insulation:
View attachment 114337
my issue is the same--
Thank you for confirming!

Maybe I should add "key stuck" to the list of issues that evil piece of crap can cause:

ABS, cruise control, ESC, HSA, PRND, RBS, SRS (airbag), etc.

Now you know why leaving it disconnected is number one on the list of how to fix a "dead" 500e!

Still seems pretty bad that it dropped to 3.78V though.
I have the same intermittent problem last couple weeks.. PRND errors and others. I also get the key stuck when I try to start and I get an error message( of various types) and all 4 park, reverse, drive, red button lights are all on! then one cannot pull the key out. The only option is to disconnect the 12V battery, or wait a while. Battery is only a few months old and tested at 12.6 volts at the O'Reilly parts place when I took it out to check it there. Humidity sensor disconnected. Any ideas?
 

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my issue is the same--


I have the same intermittent problem last couple weeks.. PRND errors and others. I also get the key stuck when I try to start and I get an error message( of various types) and all 4 park, reverse, drive, red button lights are all on! then one cannot pull the key out. The only option is to disconnect the 12V battery, or wait a while. Battery is only a few months old and tested at 12.6 volts at the O'Reilly parts place when I took it out to check it there. Humidity sensor disconnected. Any ideas?
also checked VIN at mopar and the U69 thing was fixed apparently.
 

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Battery is only a few months old and tested at 12.6 volts
That's adequate, but it seems strange: My own "microscopic" battery (1/10 original size) is over 2 years old & it doesn't drop to 12.6V until it's parked unplugged for a few days. I VERY strongly recommend EVERY 500e owner add a bluetooth battery monitor/alarm such as this BM6:
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Any ideas?
Ya. You're partway through step 3. I recommend finishing #3 & if that doesn't work, proceed to #4 & 5. It seems like you can ignore #6 though:

 

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That's adequate, but it seems strange: My own "microscopic" battery (1/10 original size) is over 2 years old & it doesn't drop to 12.6V until it's parked unplugged for a few days. I VERY strongly recommend EVERY 500e owner add a bluetooth battery monitor/alarm such as this BM6:
View attachment 114449



Ya. You're partway through step 3. I recommend finishing #3 & if that doesn't work, proceed to #4 & 5. It seems like you can ignore #6 though:

OK, will do- on to #4, thanks.. the reason I was bringing it up was that #3 did work, but temporarily- and I suspected the procedure was mainly for a non-working car, in my case, between the issues it worked completely normally, which would send it off to a different diagnostic..
 

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OK, will do- on to #4, thanks.. the reason I was bringing it up was that #3 did work, but temporarily- and I suspected the procedure was mainly for a non-working car, in my case, between the issues it worked completely normally, which would send it off to a different diagnostic..
PS also, the test of 12.6V was after a few days uncharged..
 

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OK, will do- on to #4
Sorry. I was assuming you only disconnected the 12V for a few minutes like the first part of step 3, & hadn't tried a few hours yet like the last part of step 3.

The procedures are to clear computer glitches.

There are glitches that affect operation, glitches that show warnings but don't affect operation, & glitches that only show on OBD. It seems logical that some glitches could be intermittent, or that a partial reboot would clear them temporarily.
 

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No matter what, everyone should get a bluetooth monitor so they know what's happening. The car's own warning is basically useless, with a very high probability of leaving you stranded, unable to even jumpstart*:


* Why wouldn't it jumpstart? Because unlike a gas car, a 500e will often start perfectly fine with NO sign of imminent failure even when its starter battery is literally 90% dead. By the time it won't even start it could be even lower. That's so low that it sometimes can't be jumped. A couple of owners have already reported that happening.

You could jump it with old-fashioned cables & the dead battery removed, but then it might not continue to run with the dead battery reconnected, & it might damage the electronics to run it with no battery at all.
 

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No matter what, everyone should get a bluetooth monitor so they know what's happening. The car's own warning is basically useless, with a very high probability of leaving you stranded, unable to even jumpstart*:


* Why wouldn't it jumpstart? Because unlike a gas car, a 500e will often start perfectly fine with NO sign of imminent failure even when its starter battery is literally 90% dead. By the time it won't even start it could be even lower. That's so low that it sometimes can't be jumped. A couple of owners have already reported that happening.

You could jump it with old-fashioned cables & the dead battery removed, but then it might not continue to run with the dead battery reconnected, & it might damage the electronics to run it with no battery at all.
update-- after having the battery out for several days to get it tested, when I put it back in the problem has gone-- for about a week now, fingers crossed- so it seems there could be something to the very long wait with battery disconnected. I had only tried short times before.
 
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