Question; regarding drain on battery

Drnick

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Is there more of a drain on batttery while it’s locked or unlocked, i.e.
Does the alarm system use more
Current while on, or is there still a drain
Of battery while it off? Reason being,
I have car on trickle charge (under hood connection) and charger is still registering yellow ( charging) and hasn’t gone into green ( storage) mode?! It’s been on trickle for over
24 hrs?!
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J29DB03

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I’m honestly no help in answering your question but would you by chance have an OBD adapter? If so and don’t mind spending $30+ you could get BimmerLink which gives you the ability to see what % the battery is currently at. Maybe a way to monitor it.
 

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Check owners manual of the trickle charger. They've stages. If it's on slow charge, few amps, it may take a while...
Can't speak intelligently on drainage. I do wonder that myself.
Alarm, remote sys, parasitic loss...
 

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I've seen trickle chargers/maintainers go for a day or two before they go into storage mode. Maybe get your battery tested?
 

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First thing I do when I buy a new car is place it on my battery tender when I get home.. it takes about 1-2 days to get to float depending on how depleted the battery was.

I think my Supra took 2 days.

I have my car on the battery tender during the week and during winter.. I don't remember if I armed her or not. Either way never had an issue.
 

zulhijj

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You can do some quick calculation to approximate “worst cast to charge it”. My dealer swapped my battery before purchase but I think the original bmw ones are rated at 90Ah, right? If so, what’s the maximum charging current of the trickle charger you bought? Mine was 4.3A so basically 90 / 4.3 = 20 hours or so. The loses for the car just sitting there at likely minimal (in the hundreds of mA so you can ignore those for the basic calculation). It’s not perfect but a starting approximation. So if mine was plugged in for 2 days then I’d assume something is wrong. Easiest way to check is if you have a current probe you can just clamp it on one of the wires in the trunk.

Sorry - forgot to mention this is for the bulk charge stage. If you’re waiting to get to float that’ll likely take another 10h on top of this depending on the algorithm of the charger. The charger manual usually gives the “worst case time” per stage too.
 

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Or just get a trickle charger with a screen showing current charge/stage/etc. Many out there even with phone apps...
 
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Thx, I put a volt meter on it, the trickle charger I use I’ve been using on all my motorcycles, they charge rather quickly
But there 1/8 the size, I’ll just keep an eye on it, or get a specific trickle charger for this car.
 

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Or just get a trickle charger with a screen showing current charge/stage/etc. Many out there even with phone apps...
Mine has a fancy red/green multi-color LED.. which was cool until it was not.
 

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FWIW: To help conserve the battery, I use the idrive controller button called "option" on the lower right side to turn the car off when I park it (and not lock it, such as in the garage). My routine is:

1. Open driver's door
2. Press "Option" on idrive
3. Select "turn car off" (or whatever it says)
4. Get out of car
5. Shut driver's door

I notice most of the dashboard lights shut off using this method. No need to do this when locking the car as things seem to shut off in locked mode.
 

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I noticed that I can have the AC running in the car while engine off for several minutes and the battery tender remains in float.. This includes the 7min or whatever it takes for the car to shutdown.

So, whatever's draining the battery while parked appears to be something different on my car. Not that my car has any parasitic drain issues, etc., the usual operational stuff that delay shuts-off in the car does not appear to pull much current.
 

gcmak

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I have a small tender b/c I don't have any urgent time needs on any of the cars in my family. On the Supra if I come back from a long highway drive, the charger turns 'green' within 24 hours. If I've been taking short trips or left the car sitting a few weeks, it has taken 48 hours to turn green. The battery is large. From the manual, it says its better to lock the car to ensure electronics are turned off but certain bits of the car are never fully off...as an example, you car can be locked and 'off' for days but you can still wake it via the Supra app - albeit it takes a good few minutes.

So I do think thats why the manual advises something like keeping the car on a tender if you plan to leave it sitting for a month. I put a tender on it once it has sat for 2 weeks and I don't plan to drive it soon thereafter. Don't want to damage or need to replace this monster battery...
 

Andrew4Supra

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Once the car is turned off… I always press the radio volume button in to shut the system or car fully.
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