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2017 Focus RS Nitrous Blue
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Discussion Starter · #21 ·
Early ´16 build still on original battery!

Tempted to replace it preventively sooner than later, but also tempted to see how long it will last for and if it will crank when it eventually turns -30C in the next few weeks!! The headunit message about saving the battery is coming up faster than before which may be a sign it’s coming due!

All my previous Fords had the battery fail within 4 years of production (escape, focus st, ex’s focus se…).

🤞
This is essentially why I replaced mine. I'd rather swap it on a nice 70° day when I have the time than in freezing rain when I have to be somewhere. My state of charge was still topping off at 70% full with the original battery, and I know the BMS will just keep shrinking it till things on the car start going wonky with no warning.

I still have the old one on a tender in case I need it, or more likely one of my neighbors need it, but the "0 days old" and 95% charge state I have now means I can forget about it for a few years.
 
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9/22 is pretty old stock. Maybe that's why they are on sale.

I got a battery from my local dealer on Oct 21, 2022 and it was dated 10/22.

It matters less that it's a few months old, compared to what it was doing for that time. Usually they aren't charged on the shelf until they are sold. So if it went flat and they just charged it up before they sent it, not good.

Wish you the best but personally it isn't worth the small savings compared to a dealer where you can check stock dates and you know it's been handled only by battery specialists.
 

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Early ´16 build still on original battery!

Tempted to replace it preventively sooner than later, but also tempted to see how long it will last for and if it will crank when it eventually turns -30C in the next few weeks!! The headunit message about saving the battery is coming up faster than before which may be a sign it’s coming due!

All my previous Fords had the battery fail within 4 years of production (escape, focus st, ex’s focus se…).

🤞

I have not drove my RS for more than 2 months till today.

It was not on a tender as I was not expecting to be gone that long.

But to my surprise, it cranked and no issues so far.


🙏
 

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Discussion Starter · #25 ·
Either AGM holds charge well, or they charged it up before shipping it to me. I threw it on my charger once it arrived and it was already at 95%.
 

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Discussion Starter · #28 ·
Very similar charge curve, but slightly slower rate according to this. I also have the AGM switch on my charger.

 

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Early ´16 build still on original battery!

Tempted to replace it preventively sooner than later, but also tempted to see how long it will last for and if it will crank when it eventually turns -30C in the next few weeks!! The headunit message about saving the battery is coming up faster than before which may be a sign it’s coming due!

All my previous Fords had the battery fail within 4 years of production (escape, focus st, ex’s focus se…).

🤞
I'm curious if your start/stop still functions with that old of a battery. I have a 2017 with the original battery and the start/stop stopped working in my second summer and I was told the battery was the cause. But it's been starting the car in as low as -40C every winter since with no garage, so I haven't replaced it.
 

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I'm curious if your start/stop still functions with that old of a battery. I have a 2017 with the original battery and the start/stop stopped working in my second summer and I was told the battery was the cause. But it's been starting the car in as low as -40C every winter since with no garage, so I haven't replaced it.
I havent used it in years literally!

I used to always turn it off manually until I got the Nutron dongle which does it automatically at startup. It most likely doesn’t work at the moment anyways!
 

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you can always just disconnect the negative line from the terminal. that's if your car is in your garage.

It was in the garage, I was just not expecting to be gone for that long. I was just happy it started and all settings was still there.
 
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Discussion Starter · #36 ·
Having pulled my battery for several weeks at a time, I can confirm (at least on my RS) the only settings that revert are the dashboard dimming setting (defaults to full brightness) and the radio flips to AM band. All the radio presets remain along with the oil life / battery age / etc.
 

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Does it matter how you connect a trickle charger to the battery in regards to the BMS circuit recognizing the extra charge being placed on the battery? I just placed one clamp on the positive terminal of the battery and the other on the negative grounding point to the right of the battery....

My battery is showing signs of low voltage as the battery saving mode pops up on the infotainment screen when I shut it off and am just listening to music waiting somewhere. I make frequent short trips so I imagine the battery is not getting topped up as much as it should be, especially in the winter months here in the Great White North.
 

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Does it matter how you connect a trickle charger to the battery in regards to the BMS circuit recognizing the extra charge being placed on the battery? I just placed one clamp on the positive terminal of the battery and the other on the negative grounding point to the right of the battery....
Yes it matters. What you've done is correct and how I've had mine connected (using a CTEK plug cable with eyelet rings permanently connected) for years. If you connect direct to the negative (and positive) terminal of the battery you bypass the BMS monitor on the neg terminal and that is potentially not good. The workshop manual covers this.
 
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