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I don't understand the reluctance to replace, for $150, something that could easily cost you far more if it were to fail. I work in telecommunications and a sealed battery that just sits at float voltage is usually bad within 7-8 years. We test for 80% capacity because it's known that once the battery has lost 20% of its original capacity the failure rate shoots way up. It's not reliable at that point. Replace the stinking battery. If you own metric sockets and a decent extension or two it's super easy to do it yourself. I did mine last year as it was original. This isn't rocket surgery. <--- Intentional, duh.
 

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Discussion Starter · #23 ·
It's not the money, it's the hassle. If one waits until failure, then one is over the barrel to whatever situation is at hand to get the battery replaced. If one has already prepared for failure, then swapping is a simple solution.

For me it's twofold. First is that I likely need to replace the original battery just because it's been at least 5 years. But in addition I'd like to be prepped for an unexpected failure since it's clear from the postings here that is a common 12V battery failure mode for 500e EVs.

ga2500ev
 

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Right. Don't wait. If the battery is 7 years old you've gotten everything you can expect. Buy a new battery and install it.

Failures are over-represented here because people having 500e problems do a web search and find this forum. We see a disproportionate amount of neglect and mistreatment. Many more folks aren't having problems and don't come here.
 

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Agreed: It's not just the money, it's the hassle of replacing it later, even if you're prepared. Btw, you don't need anything metric: A 1/2" socket fits fine on the lower clamp bolt, & a crescent wrench on the little terminal clamp nuts.

Unexpected failure is unlikely if you just use a voltage gauge (see post #7). The problem is simply that the car's own warning is set so low that even when it's not quite low enough to warn you, it won't start if the brake pump happens to cycle on when you open the door (that buzzing sound you sometimes hear, but not always).

The right door doesn't activate the pump, & mine will start from the right at 11.3V (~10%), but if the pump happens to come on with the left door, it won't start even with 11.5V (~18%). That's why you should replace it when it gets close to 11.6V (~20%) after the longest rest you normally give it, whether that's unplugged all day at work, or the morning after it finished charging at 8pm, or on Monday after sitting all weekend. Ideally avoid waking it up, by leaving the hood popped, or leaving the left door on it's 1st latch (it will still lock with the key, but then the alarm is off).
 

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I keep forgetting about the $25 Bluetooth Battery Monitor BM2.

It has an app that will check without even opening the door, or hood!

It also has daily notifications & an alarm. It's only in 10% increments but you'd get plenty of warning if you set it to 30%:
Font Screenshot Technology Electronic device Multimedia


Just put "bm2" in the Amazon search field & scroll down if needed to find this:
Product Automotive lighting Font Gadget Technology

It says it only uses 1.5mA, so adding that to the car's normal sleeping drain & an OEM-sized Interstate* would last about 77 days parked unplugged with the alarm on, but you can set it to warn you well before that.

Even my tiny 6Ah battery would still last 8.5 days with the alarm armed & 10.5 with it off in my garage. Double that for 12Ah, triple it for 18, etc.

ps: I learned about this on the 2nd-gen 500e forum.
* The only one I found Ah specs for.
 

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Many of the lithium-based jump starters now have an "emergency" mode that bypasses all of the internal electronics and just connects the internal battery directly to the battery clamps. There are of course all sorts of warnings associated with this, because the protections for reverse connection and direct shorts are disabled, and with a lithium battery of that size there's a very real chance of lighting it on fire if either of those events happens for more than a second or two. However, this mode allows you to start a completely dead battery, or I suppose even just connect directly to the car battery leads with no battery at all, although in my mind there would be a lot of unknowns and I don't think I'd try it.

Since the 500e requires so little current to "start", compared to a regular IC engine, even the smallest of these lithium boost-start units will be sufficient. I keep a relatively small one (intended for 4- and 6-cylinder engines) on board. Since I was out of room in the spare tire compartment (actually, of course, the "flat fix" compartment), I just tossed it under the driver's seat, and it's stayed there quite solidly despite the occasional (OK, almost constant) "spirited" driving I do with the car.

So far, my battery is working fine. I believe it's the original one on my 2017, and last year it was analyzed by the dealer and pronounced completely healthy. (I also have my own battery health checker, but haven't gotten around to checking the Fiat's battery yet.)
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Mark Moulding
 

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Seeing all these recent posts of failed 12V batteries causing major headaches with 500e has me a bit skittish. My 2014 which seems to have its original battery is way past its expiration date. As my 500e is still my daily driver for now, I'm thinking that being preemptive in terms of replacement may be a good idea.

I'm thinking now to go ahead and buy the replacement and either swap it out, or to keep it on a tender such that when the current battery fails, it can immediately be swapped out. I've had this option open in a tab for several months:


Any thoughts on the best way to navigate the situation? I know from past experience that if you wait for failure that the solution will be much more stressful and expensive due to time pressure to get it fixed. So, I'm wondering what's best practices to get ahead of the situation.

ga2500ev
Change it now will avoid any 12v problems. I have a 2017 Fiat 500e and already put a new battery in. Best to change it proactively.

God bless you!
Brian
 

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Seeing all these recent posts of failed 12V batteries causing major headaches with 500e has me a bit skittish. My 2014 which seems to have its original battery is way past its expiration date. As my 500e is still my daily driver for now, I'm thinking that being preemptive in terms of replacement may be a good idea.

I'm thinking now to go ahead and buy the replacement and either swap it out, or to keep it on a tender such that when the current battery fails, it can immediately be swapped out. I've had this option open in a tab for several months:


Any thoughts on the best way to navigate the situation? I know from past experience that if you wait for failure that the solution will be much more stressful and expensive due to time pressure to get it fixed. So, I'm wondering what's best practices to get ahead of the situation.

ga2500ev
 

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My 2018 has a battery that has a March 2018 date of manufacture so it is going on 4.5 yrs of service however it still shows 12.5 v after sitting for several days. I plan a preemptive replacement when it drops below 12.0 v. I monitor the voltage every couple of weeks usually just before I charge the car. it is used primarily to run short duration errands every few days.
 

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I monitor the voltage every couple of weeks usually just before I charge the car... every few days
That's a good plan IF you charge right before driving*, after the car has been sitting a few days. It's the sitting that matters, parked without charging.

This would be super-easy with a $25 Bluetooth "BM2". Just set the alarm for 30%.

*Many drivers charge right after driving. Checking then would give a deceptively high voltage reading.
 

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That's a good plan IF you charge right before driving*, after the car has been sitting a few days. It's the sitting that matters, parked without charging.

This would be super-easy with a $25 Bluetooth "BM2". Just set the alarm for 30%.

*Many drivers charge right after driving. Checking then would give a deceptively high voltage reading.
(y)
 

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Discussion Starter · #34 ·
Turns out my request was quite prescient. My daughter attempted to take the 500e and got the dreaded 12V error and a no start.

Fortunately I inhabit this forum. Using ETS's famous trick of entering from the passenger side and turning the key, it started right up. I drove it to my local battery shop. I ended up getting a brand new Group 26 for $95. Major disaster averted.

Here's to another 6 years of reliable battery operation.

ga2500ev
 
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