As posted before on this question, you can use a battery tender ("trickle charger") anytime your vehicle sits for an extended period of time. Mine sits on a charger 100% of the time. The constant 100% charged battery will last approx 50% longer than if you let it be drained by the alarm systems, constant demand that our vehicles draw when at rest, and short run cycles. Almost everyone agrees that having your vehicle on a battery tender will keep everything at 100%.
In my own experience, a BMW that sits 90% of the month, when put on a battery tender will have a battery that lasts 8+ years. Without one, the high drains and recharging cycles will kill it off in less than 3 years. AGM batteries will die off much sooner as their construction will not withstand multiple high discharge/recharge cycles. A slow drain over a few weeks followed by a high recharge will kill off a battery quickly. That is why most car batteries die off in three years. Parasitic draws only accelerate the problems, which is why you see lots of postings on this problem... Vehicles that are hard to start due to low battery voltage, often end up with other conflicting symptoms like multiple codes, error/warning lights on, all due to electrical issues and a dying battery. A VERY BAD COMBO and hard to diagnose.
Bigger is better (last longer) when it comes to batteries especially when they weigh in at 58# and you have to dig under everything and drag it out of the rear cargo area. You only want to do it once every 8 years....
Now the question I have for the electronic wizards is "what is better for an X5? A battery connected and trickled charged constantly or a vehicle with the battery disconnected from the electrical system but on a tender?" I am beginning to think that having everything activated creates a potential issue long term on stored vehicles. Most car collections use a quick connect at the battery while on a charger standard practice. Thoughts? Or should I move this question to the SAE forum as it is totally theoretical?
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2005 X5 4.8IS
The
Blue ones are always FASTER....
Current Garage:
2005 X5 4.8is
2002 M5 TiSilver
2003 525iT
1998 528i
Former Garage Stable Highlights
2004 325XiT Sport
1973 De Tomaso Pantera, L Model
1970 Dodge Challenger T/A 4 sp Alpine White
1970 Dodge Challenger T/A 4 sp GoManGo Green
1971 Dart Sport, “Dart Light” package
1969 Road Runner 383
1968 Ply Barracuda 340S FB Sea-foam Green