Going to be gone for a month. Disconnect battery?
02-11-15, 04:24 PM
#31
After the last several posts in this thread, I was motivated to do a Google search and a little reading. The main thing that I learned was that there is a lot I don't know about batteries and about chemistry. 
What I also learned, however, makes me feel comfortable about using the Battery Tenders inside the garage. It would appear that danger from gas build up (and possible explosion) would be insignificant as long as the battery is not being overcharged. The circuitry inside the Battery Tender is designed to monitor the charge level of the battery and to supply a charge level sufficient to keep the battery fully charged, and, as the battery achieves full charge, the charge level is reduced to a level that maintains the full charge but that does not overcharge the battery.
Another thing that I learned is that, while the Battery Tender products are designed to monitor the battery charge level and to vary the level of charge being supplied to the battery to keep it fully charged without overcharging it, some of the less expensive trickle chargers do not do the same thing. Instead, they supply a constant low level charge, and, while that low level charge is not likely to overcharge the battery, that is not an absolute certainty. Knowing that make me feel better about spending the extra money for the Battery Tender products and about not having bought one of the less expensive trickle chargers.
If someone with better knowledge of batteries and their chemistry knows something different, I would hope to see what he/she has to say.
What I also learned, however, makes me feel comfortable about using the Battery Tenders inside the garage. It would appear that danger from gas build up (and possible explosion) would be insignificant as long as the battery is not being overcharged. The circuitry inside the Battery Tender is designed to monitor the charge level of the battery and to supply a charge level sufficient to keep the battery fully charged, and, as the battery achieves full charge, the charge level is reduced to a level that maintains the full charge but that does not overcharge the battery. Another thing that I learned is that, while the Battery Tender products are designed to monitor the battery charge level and to vary the level of charge being supplied to the battery to keep it fully charged without overcharging it, some of the less expensive trickle chargers do not do the same thing. Instead, they supply a constant low level charge, and, while that low level charge is not likely to overcharge the battery, that is not an absolute certainty. Knowing that make me feel better about spending the extra money for the Battery Tender products and about not having bought one of the less expensive trickle chargers.
If someone with better knowledge of batteries and their chemistry knows something different, I would hope to see what he/she has to say.
Last edited by sderman; 02-11-15 at 04:27 PM. Reason: typos
02-11-15, 04:54 PM
#32
Lead Lap
Unfortunately the OP who started this thread has nowhere to plug a battery tender in and won't be using one.
02-12-15, 06:11 AM
#34
Your car will be just fine without disconecting the battery cable. I've been sitting in my GS messing with the settings on the nav screen when the car will turn off, enable battery saver, right when I'm running through settings options. It also does this if I leave the trunk open--it will turn off the trunk light to save the battery. In short, 1 month just leave it alone, it will start back up with no problem.:thumb up:
02-12-15, 06:36 AM
#36
Lead Lap
Thus, in a climate where the temperatures are likely to be at 50 degrees or at 70 degrees, it may be the case that leaving the vehicle for a couple of weeks won't be an issue, but, at 20 degrees, the same idle times may well cause a problem. And, if the battery's charge level is completely depleted, not only are you going to lose vehicle settings, but it is likely that the battery will sustain permanent damage and never be able to hold a charge again.
I know that, with my GX, last winter, I was snowed in for 4 days, and the temperatures during those 4 days were in the range of -10 to -20. After just those 4 days and with a brand new battery, I was barely able to get the vehicle started, and, during the extended cranking period that it took to start the vehicle, I lost vehicle settings and set off several of the vehicle's trouble codes.
02-12-15, 06:57 AM
#37
There may be one variable I'm not accounting for. My trips, prior to that 3 week sit, were all short. It's highly likely that the battery was already diminished, since the alternator wasn't able to fully charge it. If the OP's trips prior to letting it sit are long enough, he may be ok. I would still have a back-up plan in place, though.
02-12-15, 09:19 AM
#38
Your right, I've read several threads too. The battery saver is easily testable, just sit in your car with ignition in ACC, engine off, with the radio on. It should shut off at around the 30 min mark, and say something like battery saver in effect on the dash screen.
02-12-15, 09:25 AM
#39
02-12-15, 09:43 AM
#40
I'm still thinking that this is a Panasonic battery issue. Do the ES and 4GS use the same model Panasonic battery??? The two cars are not assembled at the same plants in Japan. Do the IS350 have this same issue? I don't look at that forum very often.
02-12-15, 10:48 AM
#41
Lexus Champion
Battery-saving function
The battery-saving function will be activated in order to prevent the electronic key battery
and the vehicle battery from being discharged while the vehicle is not in operation
for a long time.
● In the following situations, the smart access system with push-button start may take
some time to unlock the doors.
• The electronic key has been left within approximately 6 ft. (2 m) of the outside of the
vehicle for 10 minutes or longer.
• The smart access system with push-button start has not been used for 5 days or
longer.
● If the smart access system with push-button start has not been used for 14 days or
longer, the doors cannot be unlocked at any door except the driver’s door. In this case,
hold the driver’s door handle, or use the wireless remote control or mechanical key, to
unlock the doors.
The battery-saving function will be activated in order to prevent the electronic key battery
and the vehicle battery from being discharged while the vehicle is not in operation
for a long time.
● In the following situations, the smart access system with push-button start may take
some time to unlock the doors.
• The electronic key has been left within approximately 6 ft. (2 m) of the outside of the
vehicle for 10 minutes or longer.
• The smart access system with push-button start has not been used for 5 days or
longer.
● If the smart access system with push-button start has not been used for 14 days or
longer, the doors cannot be unlocked at any door except the driver’s door. In this case,
hold the driver’s door handle, or use the wireless remote control or mechanical key, to
unlock the doors.
FWIW, I've left my IS for a few weeks at a time without issue. Note that this was in a garage, however, so not in the extreme cold.
02-16-15, 06:46 AM
#43
Driver School Candidate
Join Date: Apr 2014
Location: CO
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For you Battery Tender owners. I plan to leave my car in an enclosed garage for 4 months connected to the Battery Tender. The battery will be fully charged to start. Any concerns? Thanks.
02-16-15, 08:29 AM
#45
Lead Lap
I believe that the instructions that come with the Battery Tender do advise you to periodically check to make sure that the battery is not getting hot, but I've never seen the battery getting hot, and I've been using Battery Tenders for lots of years.