didn't drive much. 14 mo. old batt. dropped to 79% charged. drove every day (neighborhood lap) batt. went up to 83% in a week. what's everybody's average charge ? what's a good average no. ? never used auto. on/off since new batt. saw your batt. drama inspiring this post. cjv2 did your old batt. trigger your amber "check batt" in your dashboard ? I'll operate 'til that little amber light comes on. Romondes batt. tester - I don't want to get that involved BUT.....

 

I'd be curious how you got that % number.

 

Stu-mon is hooked on BimmerLink!!
It tells you the state of your battery.

 

BimmerLink will show State of Charge (SoC) but does not show State of Health (SoH) and it doesn't show you internal battery resistance. Was dancing with this in my own battery drama (see thread at link if interested).

Here's what I can tell you, with 2 batteries in hand:

• one that hit the point where auto start/stop would no longer engage
• one brand spanking new (well, it had a March 2020 date code on it when it arrived on the Nov 19 2022, but you get the idea).
  • new battery restored the auto start/stop (I have other issues apparently unrelated to the battery, but that issue got resolved).

Old battery that was pretty much toast: SoC 98%, SoH 29%, resistance 10.44 megohms
Replacement battery: SoC 95%, SoH 100%, resistance 2.67 megohms

Note the SoC measurements on both. BimmerLink reported similar values for SoC on both batteries. The bottom line is that SoC isn't everything. Heck, I still have that not-dead-but-not-usable-in-the-MINI battery, sitting in my garage disconnected. The SoC still tests great. The SoH and the resistance still stink.

The auto start/stop is a bit of a mine canary. If it stops working it's because the car has decided, based on monitoring whatever the heck it is monitoring (voltage obviously, possibly other things) with IBS, that the battery can't sustain that kind of use. It's not the last thing to go, other stuff can get weird, but when it starts to go your battery is likely on its last legs.

The measurements above were taken with a .

Also note that actual deliverable CCA (at least according to that tester) is CCA times SoH. So with a BMW-factory 800 CCA battery and a SoH of 29%, the CCA you're actually going to get is 238A, not 800A. Which in my case was enough to start the car, but with a pretty thin margin of "you had better turn that car off completely when the engine isn't running."

 

Great info here - I have Bimmerlink and checked my battery health (2019 Cooper 2-door, driven almost every day) and it shows 87% - at which percentage does the battery require replacement? Everything still works fine on mine, engine auto-start was disabled the first day, can't stand it.

 

87% is what mine was reporting well after the auto start/stop stopped kicking in, but before I took to it with the trickle charger and started asking questions about its health.

At 85% I had slow-start/cranking problems. My most frequent passenger noted (by the sound -- man they have good ears) slower starts before I did, but at 85% the car came perilously close to not starting at all. A couple of "sad caranks" and then finally engine turnover.

Same things started happening to a friend with a 2019 F56 at that 87% line. I should note that mine hovered around 87% for a good while, so I don't think you're toast, but I suspect you're on the way to a new battery. Especially if the auto start/stop has gotten flaky on you (enable it and see if it actually works as expected; then just disable it since you don't like using it, nothing wrong with that). The good news is that when it starts to go for real it's slow and weird, not fast and obvious.

Having spent about $60 on that tester I would pretty much recommend that anyone planning to have and keep a MINI eventually get that kind of tech. AGM batteries are complex and neither a voltage test nor BimmerLink (at this time) tell you enough to know battery health.

 

Here's a short but decent writeup on battery testing that gets into the difference between old-school testing of a wet cell battery (or any battery really where the car doesn't have auto start-stop) and dealing with AGM and/or a start-stop context. Pretty digestible as an intro for someone who (at minimum) knows how to connect test leads to a battery.

Link: https://batteryworld.varta-automotiv...ttery-test-car

 

Great, thanks for all the info, appreciate it.

 

hey cjv2 did your old batt.(the one that started your on/off sitch.) trigger your amber "check batt." light = CEL in your dashboard ? I would imagine the new one didn't & mine triggered on my old batt. but my new one so far NOT ! I read about your battery drama last week prompting this question. I just operate until the amber light tells me problem Romondes batt. tester ? I don't really want to go that far BUT..... my starter turns over just fine & motor start after about a 1/2 turn. I don't use auto. on/off just never liked it THANKS

 

Hey @Stu-mon , nope, I never once got the "check batt" light. The first no-brainer obvious sign of trouble was slow crank/near no-start. Tossing a trickle charger on the battery raised the SoC and helped to manage any cranking issues. But as that didn't change the SoH or internal battery resistance, it didn't help things like the loss of the auto start/stop, and it basically left me with the battery being central suspect in "anything else weird going on."

 

All this has me nervous. 2017 Cooper S with 20k miles and starts just fine each time. Never used stop/start so I don't know if it works. Luckily the 2017 was one of the years BMW let you turn it off and it stays off.

Wondering if I should go to the dealer and get it replaced before I'm stranded? I asked about it at last service and they said its $600 so best to wait until I have problems. But low miles don't matter right, it's age-related with batteries?

 

Romondes RD510 huh ? just might have to grab one in the future. curiosity killed the cat, but satisfaction brought 'em back. the batt.s seem to be the sticky point with these Minis (I'm '15 F-56) since I don't use my auto. on/off so I rely on Bimmerlink & Amber Light. this has gotten me curious about SOH, knowing I can find SOC whenever I want. THHANKS MAN

 

I have a 2017 S as well. Hi five woot So the good news for you is that 100% of my experience applies to your ride, ha. The issue I have is that I use ECO mode a lot -- which automatically turns the start/stop back on. After I get certain unrelated kinks worked out of the car (see the thread I linked to in an earlier post, seems I have a software gremlin related to power steering assist if nothing else), I'm going to circle back to having better control over the auto start/stop than having to keep hitting the off switch.

Anyway, to your questions.

• With batteries, it's not *just* age-related. That matters, but temperature is a big one -- cold will put the whammy on a battery like nobody's business, and will do it fast -- if you are in cold-winter climes you don't have to drive the car to land that one.
• Also, the MINI is very much "alive" even when parked in your garage. Not driving it means the battery will slowly get drained but never get recharged (it gets recharged by the alternator when driving). Obviously this doesn't apply if you are making a point of charging the battery with some kind of external charger, but you get the idea.

So a 20K-mile odometer on a 2017 with original battery says to me "interesting if that battery is still in good health." Literally 5 years, give or take, of precious little recharge, on a car that is something like HAL 9000 (meaning always "doing something" -- electrically -- even when you're not looking).

Three things jump out to me about your inquiry.

(1) $600 is a lot to shell out (though not unreasonable, labor pricing is what it is) to install what is, on average, a $220-$240 battery. If you can handle the install and registration yourself, do it. It's not exactly like an old school battery install, and you need BimmerLink or similar-function software to get the registration done, but it's 100% doable. The most annoying part for me personally was that the battery is literally 51 pounds (grrr).

(2) I would self-diag your battery before replacement, especially if at the end of it all your replacement path is that $600 install by your shop. The diag tool I have mentioned set me back $60 -- a tenth of what you're looking at. I growled at spending it but I am now REALLY glad I have it, for any and every car I ever get near again, whether mine or that of a friend in need. Battery health mysteries cause lots of people lots of headache. Even though I had to replace my battery, I've now done it with clear confidence and understanding of why the old one needed to go, rather than a guess. That will also be true of every battery replacement I do going forward -- bonus. Yay.

(3) Even though you don't use the auto start/stop, you can use it temporarily to get a sense of how your battery is doing. Light it up. It should kick in pretty much at every stop at every stoplight. If it doesn't kick in at all, ever, your battery likely has something up. If it kicks in once or twice and then never kicks in again, means about same. What I saw was it kicked in less and less until it finally just wouldn't come on any more. And you get an indicator on the instrument panel every time it "declines" to kick in, so you won't be wondering when or whether the car is making that decision. You will know *every* time.

Hope this helps.

 

Glad to help. See my note in post immediately above this one about using the auto start/stop diagnostically. It's not gonna kill the car or make you get stranded and you don't have to leave it on -- just kick it on temporarily to see how it behaves, and when you're done making observations to your satisfaction, go back to your usual non-use of it. Cheap and easy diagnostic tool and comes with the car too

 

Thanks for the write up! I might end up looking into one of the diagnostic tools. Might be fun to use for other stuff too. I feel like I've been lucky with this car. Had it since brand new, and the only issues I've had are that is likes brakes. Mostly from rust on the rotors from lack of use. I have not had battery issues or engine mount issues (yet). Thanks again!

Because I don't drive it that much, occasionally I think of letting her go to a better home. Because she does sit outside all year long. I wash every month and wax once a year. But then I get in and drive and it's just so fun and it knows how to do exactly what I want, when I want. It is the closest thing to a Segway scooter that I can find on four wheels!

 

I looked at the video of the Romondes RD510 & I'm ordering one this a.m. it appears to be the real deal & I like it. how often do you use yours ? every 6 mo.s ? on that note, just ordered one & will have it on my doorstep mon. for $70. I really like the SOH act, seems like the thing to know. my F-56's birthday was Nov. it just turned 8 & odometer just turned 44K. it's a cherry ride & prolly my last ride ! so, keeping it perfect as cheap as I can is the gig. Be Ever Aware Of Your Surroundings.

 

There a 25% coupon, click it below the name, Its $49 plus tax after coupon.

cancel the order, and go back to the page, click the coupon, and reorder.

 

I just ordered one. $49.49 after 25% off.
I have 4 vehicles, makes $ sense to own one!!

 

I haven't even had my RD510 a full month, so haven't established a routine yet. I'll probably check monthly just to get a bead on whether I understand how the car is using power, and then move to a less frequent check. Findings will determine whether my final routine is quarterly, 6 months, or 12 months.

 

I ordered mine through Amazon - coupon ? never occurred to me. oh well

 

In Amazon, under the price they'll often have a coupon.
Especially when you look at something for a few days.
The AI wants you to buy it!!

 

I fell asleep at the wheel, oh well. $20 ain't gonna break my heart. HOWEVER I did finally see your coupon, mebbee next time