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At the start of my last AC charge (12:35) the Kona decided to charge the aux battery for a full hour, twice as long as the normal 30 minutes I've seen all other times I've checked it. Something must have kicked that off..., perhaps cold temps as we approach winter or a poor result from a test it carried out behind my back. I think the reason for the lower voltage immediately afterwards is that while AC charging continues (through 16:30) the system voltage is forced to around 13.1 V by the LDC. The earlier 20 minute battery saver event when finished just shuts down the system so the battery voltage is measured essentially unloaded.

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Oh yes, almost forgot to mention it. 12V battery went flat again the other morning after being fine the day before. So much for the denials and blame on dashcams. Let's hope the updated ECU software sorts this mess out :rolleyes:
 

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Oh yes, almost forgot to mention it. 12V battery went flat again the other morning after being fine the day before. So much for the denials and blame on dashcams. Let's hope the updated ECU software sorts this mess out :rolleyes:
when I took mine in for the BMS update, they tested the12v battery first saying they could not apply the software update as the 12v battery was in poor condition. After initially saying it was going to cost £140 for anew battery (£100for battery and £40 to fit) it was confirmed the battery is covered for 2 years unlimited mileage. So I would just get them to put a new battery on under warranty rather than risking the bms update will cure it
 

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It does seem the 12V battery can be damaged by a severe discharge and that the chances of further problems are increased by not subsequently fully charging it off-line. The Kona's systems as they stand can barely keep a healthy battery alive, much less revive one that has been severely discharged.
 

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I noticed the other day that the battery saver was going again. I had the high voltage battery software update done and the BS+ option is gone out of the menu. However, it still charges the battery since I've seen the light ...

I don't know and don't really have the tools to closely monitor the battery, if they changed the behavior.
 

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Snag yourself a BM2, you'll love it. Check the install photos over at insideevs, no need to loosen the clamps. Just use (2) M6 low-profile nyloc nuts and a lump of Bluetack. Squeeze the spade lugs into a circle to make them stay on.
 

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when I took mine in for the BMS update, they tested the12v battery first saying they could not apply the software update as the 12v battery was in poor condition. After initially saying it was going to cost £140 for anew battery (£100for battery and £40 to fit) it was confirmed the battery is covered for 2 years unlimited mileage. So I would just get them to put a new battery on under warranty rather than risking the bms update will cure it
Thanks, useful to know. When they looked at the 12V battery a few months back, they did a load test on it and said all the cells were fine and it charged up fine again overnight, so I suspect it's ok. I will talk to them about it though, thanks (y)
 
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It does seem the 12V battery can be damaged by a severe discharge and that the chances of further problems are increased by not subsequently fully charging it off-line. The Kona's systems as they stand can barely keep a healthy battery alive, much less revive one that has been severely discharged.
Lead acid battery chemistry doesn't like being discharged full stop. No-one can fix this. Keep 'em topped up or expect to replace them.
 

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Lead acid battery chemistry doesn't like being discharged full stop. No-one can fix this. Keep 'em topped up or expect to replace them.
Of course, but I'm just being kind to the many here who have experienced battery problems but are soldiering on without a replacement.
 

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Of course, but I'm just being kind to the many here who have experienced battery problems but are soldiering on without a replacement.
Some interesting information in this service bulletin about how to charge the 12V battery (on page 5) in order for the car to "learn" the battery SoC. So make sure you connect the negative terminal at the correct place. (You can forgett all the bluelink guff :) )

John.
 

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Some interesting information in this service bulletin about how to charge the 12V battery (on page 5) in order for the car to "learn" the battery SoC. So make sure you connect the negative terminal at the correct place. (You can forgett all the bluelink guff :) )

John.
Good find. I'll be keeping this document for future reference should the battery depletion happen to me.
 

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Aside from ensuring that the charger negative connection is at the chassis side of the sensor, the other takeaway from that ICE-focused document is that if the aux battery drops below 30% SoC you should use a commercial-sized battery charger to revive it.
 

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Battery was flat as a pancake this morning. When I jump-started it, it said the boot was ajar but my wife said she'd firmly closed it when she last used it because it had complained about it being slightly open.
It does feel like for whatever reason, something (sometimes) is causing the boot to unlatch, which then keeps triggering the sensor causing the car to repeatedly wake up and go to sleep (or stay awake), particularly in windy conditions, thus running the battery flat.
I think this is one of many potential causes but there is often a theme of people finding the boot ajar.
Booked in to the dealer next Saturday to have all the ECU updates and maps done...
 

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Not good, are you still on the original battery or was it replaced at Christmas when you had problems?
I now have a special technique for closing (slamming) the boot lid.
 

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Original one, which of course Hyundai swore blind was fine and there wasn't a design flaw ("It was your dashcam, sir") 🤦‍♂️
 

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Better luck this time then,hopefully it will fail the test and be replaced . My new battery is treated with TLC with a monthly trickle charge, it no longer overcharges when on a run like it did when new, so I am hopeful.But I was not checking my original battery frequantly, Why would I it was only 15 months old snd batteries on previous cars have lasted up to 10 years.

I trust they will replace this time.
 

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I doubt it very much indeed. They will say "Ah the BMS update will fix that sir. Bring it back in if it fails again." You know what dealers are like, why do something useful if you can postpone it and hope the problem goes away?
 

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@Richard Gledhill , you just need to keep coming with flat battery to your local dealership. My battery never failed the test but after 5th time I dropped the car to Hyundai garage they were told by Hyundai UK to just replace the battery.
They knew something was wrong as it also failed with them when they charged the battery and it went flat by the next morning.
Blaming your cameras is BS. Just keep pesting them.
Similarly as @Electra Glide in Blue - after replacement I treat the battery with smart charger. For now it's a small price to pay for trouble-free car.
 
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