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Discussion Starter · #1 ·
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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Font Automotive design Auto part Personal protective equipment Sleeve
Font Automotive design Auto part Personal protective equipment Sleeve
Get a portable rechargable jump starter. They cost from $45 (pictured) to well over $100. You recharge it by your USB Phone charger. I look at mine about once every 2 months to see how much charge it is holding. It's never been lower than 92%.

I have used it three times, and not on the 500e. My wife called at midnight her SUV wouldn't start. I Drove down and it cranked her V-8 no problem.

I was at COSTCO where i saw a guy in the parking lot standing beside his car with the hood up. "Dead Battery?" he said he was going up to the Tire Center to get some one to help him. I told him to wait, I have a jump and you can drive up. When i came back with my little jumpStart he said; "With That?" I told him to go and turn the key. Fired right up. It's a lot easier than cables and you don't even get your hands dirty.
 

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You can get your battery tested to see how healthy it is. If it is really 8 years old, it is probably beyond it's last legs. . .
I'd suggest replacing it if needed with the same exact brand and model that is in there now. 8 years of service warrants repeat business IMO.
I don't know about the quality of batteries today and from 8 years ago. I put a BOSCH in our SUV that cost close to $200. I would think BOSCH was a reputable brand. It failed in a year. Replaced free, and that one failed in a little less than 2 years. I replaced it but I had to pay something. (The warranty on a replacement goes back to the original's purchase date. So my second replacement was almost three years into the warranty when installed new. (Last Bosch I'll buy) I have the purchase date written on the battery. I don't have to go digging through the glove compartment looking for the battery purchase date. I know when the warranty is up too.
 

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Discussion Starter · #5 ·
12V batteries with EVs is complicated business. Since many of the accessories for EVs are 12V like their ICE counterparts, lead acid starter batteries are used as the power system. However, since there is no engine and no starter, the deep discharge functionality of the starter battery is never used. To further complicate the issue, unlike ICE where the alternator only charges the 12V battery when the engine is running, EVs also charge the 12V battery via the DC-DC converter when the EV is plugged in. So, the life of an EV 12V battery ends up being lightly used and almost continuously charged.

As such, the failure modes are weird. With an ICE, the car won't start. But a failing 12V can drive an EV for a significant amount of time, right up to the point where it can't.

Testing is problematic too. 12V starter battery testing is based around deep discharge CCA. Problem is that an EV battery that isn't used in that mode may fail when stressed like that.

I also understand about the jump starter. But it's at best a temporary solution to the problem. I'm really trying to get around the potential supply chain issues of having to secure another battery that fits this usage pattern without having to give an arm and/or leg to do so. And more importantly to have it available for immediate replacement instead of trying to source a battery after the failure has occured.

So does anyone keep a battery on hand? If so, which type? How do you tend it? If you swapped, how did it go?

ga2500ev
 

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Starter batteries are generally not considered deep cycle batteries. They are designed to deliver high current for the starter for a brief period. Marine/RV batteries are designed for deep cycle (bringing to a low charge state without damage). EV's don't really need either capability - unless you need your lights or radio on for extended periods with the car off.

As far as testing goes, my understanding is the test primarily is measuring the batteries internal resistance (the CCA rating is essentially just another term for the batteries internal resistance). The lower the resistance, the higher the current capability. As the battery ages, the resistance goes up lowering the CCA. Typically testing is done when the battery is fully charged (but obviously will check voltage and indicated SOC). Since the CCA requirement for an EV is so low, the 12V battery can appear to be functioning normally right up until it doesn't.

In your case, if the battery is 8 years old, I would have no issue with just replacing it - even without testing. As far as type of battery, I stand by my recommendation to get the same make and model that has served you for 8(!) years.

Generally, I don't think many keep a spare battery on hand for when their car battery dies.
I have 4 deep cycle marine batteries that I store - but not for automotive applications. I tend to them with one of these
 

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If it is really 8 years old, it is probably beyond it's last legs.
Ya, 8 years is almost unbelievable in a 500e which can kill a perfectly good new one in as little as 23 months (shortest report I've seen). I would suspect it might have been replaced under warranty by the original owner, maybe shortly before @ga2500ev bought the car. I suspect the same thing even for mine, which was still working a full 5 years after the car's build date.

& ya, a jumpstarter can only help after it dies, & sometimes not even then: I have now seen at least 3 reports of a 500e failing to be jumpstarted. I just now realized that it might be because the car will start even when the battery is 90% drained, which is way below what would be considered "dead" in a gas car. So when it's so low that it won't even start a 500e, it's really, REALLY dead, at which point jumpstarting sometimes won't work.

So one solution is to check the resting voltage periodically, after the 12V is 2 years old (click to enlarge):
Watch Light Vehicle Hood Automotive tire

Check after several hours parked unplugged, like after work or sleep. When it gets close to the 11.6V minimum to reliably start the car, start shopping for a new battery.

I'm too lazy to get out the $10 portable one on the left, so I got the $22 permanent-mount one on the right, from BatteryTender.com
 

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If a battery is so dead it can't be jumpstarted with one of those small jump starter batteries, it might be worth trying to disconnect the dead battery and hook up the jump battery directly. That way the jump battery isn't trying to charge the dead battery and start the car. Not sure what to do after that, but at least you can get the car started.
 

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disconnect the dead battery and hook up the jump battery directly
I thought of that too, so I tried it but it didn't work. Apparently jumpstarters won't work when there's no voltage at all.

So unless anyone else has some new ideas, we're back to having OBD on hand, although when jumpstarting doesn't work that also requires having AAA or walking to a parts store to buy a new battery & the tools to install it (unless you also carry those in the car).

So it seems to me like failure prevention by periodically checking the resting voltage is the best.
 

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I thought of that too, so I tried it but it didn't work. Apparently jumpstarters won't work when there's no voltage at all.

So unless anyone else has some new ideas, we're back to having OBD on hand, although when jumpstarting doesn't work that also requires having AAA or walking to a parts store to buy a new battery & the tools to install it (unless you also carry those in the car).

So it seems to me like failure prevention by periodically checking the resting voltage is the best.
Interesting, must be a safety feature. But jumping from another car battery that trick should work. . .
 

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Starter batteries are generally not considered deep cycle batteries. They are designed to deliver high current for the starter for a brief period. Marine/RV batteries are designed for deep cycle (bringing to a low charge state without damage). EV's don't really need either capability - unless you need your lights or radio on for extended periods with the car off.

As far as testing goes, my understanding is the test primarily is measuring the batteries internal resistance (the CCA rating is essentially just another term for the batteries internal resistance). The lower the resistance, the higher the current capability. As the battery ages, the resistance goes up lowering the CCA. Typically testing is done when the battery is fully charged (but obviously will check voltage and indicated SOC). Since the CCA requirement for an EV is so low, the 12V battery can appear to be functioning normally right up until it doesn't.

In your case, if the battery is 8 years old, I would have no issue with just replacing it - even without testing. As far as type of battery, I stand by my recommendation to get the same make and model that has served you for 8(!) years.

Generally, I don't think many keep a spare battery on hand for when their car battery dies.
I have 4 deep cycle marine batteries that I store - but not for automotive applications. I tend to them with one of these
My theory is batteries last about 6 months past their warranty. The manufacturer doesn't want to replace batteries at full cost. You can get a cheap battery at WalMart for about $50. And replace it every 3 years. Keep a portable Jump Starter, ($50-$75) in the boot, and you can always impress your friends and neighbors that you jumped a V-8 pick up truck with your little jumper. (Plus there are no cables and your hands stay clean)
 

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My theory is batteries last about 6 months past their warranty. The manufacturer doesn't want to replace batteries at full cost. You can get a cheap battery at WalMart for about $50. And replace it every 3 years. Keep a portable Jump Starter, ($50-$75) in the boot, and you can always impress your friends and neighbors that you jumped a V-8 pick up truck with your little jumper. (Plus there are no cables and your hands stay clean)
Totally agree. I don't keep a jump starter though. We have a second car we can go get a replacement battery with if needed.
 

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12V batteries with EVs is complicated business. Since many of the accessories for EVs are 12V like their ICE counterparts, lead acid starter batteries are used as the power system. However, since there is no engine and no starter, the deep discharge functionality of the starter battery is never used. To further complicate the issue, unlike ICE where the alternator only charges the 12V battery when the engine is running, EVs also charge the 12V battery via the DC-DC converter when the EV is plugged in. So, the life of an EV 12V battery ends up being lightly used and almost continuously charged.

As such, the failure modes are weird. With an ICE, the car won't start. But a failing 12V can drive an EV for a significant amount of time, right up to the point where it can't.

Testing is problematic too. 12V starter battery testing is based around deep discharge CCA. Problem is that an EV battery that isn't used in that mode may fail when stressed like that.

I also understand about the jump starter. But it's at best a temporary solution to the problem. I'm really trying to get around the potential supply chain issues of having to secure another battery that fits this usage pattern without having to give an arm and/or leg to do so. And more importantly to have it available for immediate replacement instead of trying to source a battery after the failure has occured.

So does anyone keep a battery on hand? If so, which type? How do you tend it? If you swapped, how did it go?

ga2500ev
I also understand about the jump starter. But it's at best a temporary solution to the problem.

The portable jump start will come in handy some dark and rainy night in a sketchey neighborhood. It will make your car run so you can get to WalMart or AutoZone and buy a new battery.
 

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Discussion Starter · #14 ·
I also understand about the jump starter. But it's at best a temporary solution to the problem.

The portable jump start will come in handy some dark and rainy night in a sketchey neighborhood. It will make your car run so you can get to WalMart or AutoZone and buy a new battery.
It's the second item I'm trying to avoid. What's the best battery to buy as a backup? For example Walmart only has a single H5 sized battery for the 500e and it runs $150.

The best I've seen so far is ETS's thread on lightweight motorcycle batteries:


I guess I'm wondering is there a way to keep one (or even two) of these in reserve such that the time and cost to swap are minimized? It's unfortunate that lead acid batteries really just cannot be sat on a shelf until they need to be used like alkalines.

Batteries like those are small enough they could be kept in the 500e if there were an effective way to tend to them.

ga2500ev
 

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I also understand about the jump starter. But it's at best a temporary solution to the problem.

The portable jump start will come in handy some dark and rainy night in a sketchey neighborhood. It will make your car run so you can get to WalMart or AutoZone and buy a new battery.
It's also handy for helping other people out. I don't remember what the 500e's manual said about this, but my hybrid cars haven't been able to jump-start other vehicles in the same way that an ICE car can, and so I've been carrying portable chargers for a while now. The ones they make these days are nice and small.
 

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The manuals have detailed instructions about getting a jump, but they don't say you can't give one (or that you can). I don't see any reason why you couldn't, especially since the battery is gas car size, unlike some hybrids.

lead acid batteries really just cannot be sat on a shelf ...

... kept in the 500e
Lead acid batteries will last several years sitting on a shelf or in the back of a 500e IF the charge is topped off periodically.

So you might have a great idea there: I'm trying to think of a reason why it wouldn't work to keep a little motorcycle battery* under the seat, & plug it into the car's 12V outlet for a few days every month, or maybe even just leave it plugged in. Just make sure to cover the + side with electrical tape or something, so nothing can short it out.
 

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* with terminal adapters. Make sure to mount them in advance, since I needed different screws than what they came with:
Office equipment Camera accessory Home appliance Gas Audio equipment

That would seem to eliminate the need for a jumpstarter or cables or a voltage gauge, but requires carrying a ratchet, 9" extension, & 1/2" socket, and swapping it out when the old one dies.
 

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You'd also want to figure out how to mount it when you do swap it out, even though I drove with my 3Ah unmounted because it's so light that the cables are stiff enough to keep it from moving too much. I even forgot about it & slid around my favorite left-turn off-ramp with no ill effects:
Motor vehicle Product Gas Machine Automotive tire
 

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You could use a really tiny one like the 3Ah shown above, but you might want to choose a size so you can just leave it installed when you recycle the OEM one:

In MILD weather, for each Ah of capacity you can park unplugged for about 1.5 days with the alarm on (about 2 days with it off, such as in a private garage). For example, 3Ah x 2 is 6 days in the garage, and x 1.5 is 4.5 days with the alarm armed. Below freezing you need to at least double the size.

However, they're SO small & light & cheap that you can even quadruple the size & still come out ahead. I ended up with the 6Ah below, because 6Ah x 2 is 12 days in my garage, & I got tired of switching the 3Ah off* every time I didn't know if I'd be parked unplugged for more than its 6 day limit in my garage.
Automotive tire Automotive lighting Finger Battery Gas

* On the 3Ah I added a cheap little disconnect switch (blue knob):
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But if you're going to buy the $47 parts* & prepare to mount them, it would be easier to just leave the little new battery installed now.

That way you don't need to keep it charged, or carry a ratchet/socket/extension, or swap it out when the old one dies when you're in a hurry on a rainy night.

*Add a $22 volt meter & you'll likely never be stranded by a dead battery, as long as you check it once in a while. Add a $7 switch IF you're often parking long-term unplugged:
Light Motor vehicle Automotive fuel system Automotive exhaust Automotive exterior


However, there seems to be no need for either a gauge or switch with one of these:
Audio equipment Peripheral Font Gadget Electronic instrument

I costs about the same as an OEM replacement, & it would last about 7.5 days in my garage, before it self-disconnects, holding 12.4V in reserve to start the car 3 months later just by pushing the button on top.
 
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