We need to get a new battery for our 2010 RX350 (similar issues as the other posts about these batteries on here) and I'll be doing the swap myself. I remember seeing a post awhile back when we first bought the car about the steps to follow after installing the new battery and of course I can't find it anywhere and forgot to bookmark it. It may have just been some basic resetting of the pre-sets for the windows/seats/radio etc.. but I thought there was more to it. Appreciate if anyone can link to this thread as neither the Club Lexus or Google searches are turning it up. Thanks!

Edit: poked around some more and found this thread related to GS' - same set of things to check for our RXs? Thanks!

 

I have recently swapped out the battery for our 2011 RX350, I didn't have to reset window/seats as it still remembers the previous settings.

You will lose your radio presets, but the radio will remember the previously paired phones.

 

if you have an old cigarette lighter adapter, you can wire a 9v battery to it to keep all your settings.
Works on most cars. Some cars need a stronger voltage source so you might need to wire an extra 9v in series.

Or just buy one off amazon/ebay

 

FYI, 9V in series will fry your electronics. Good thing the cig lighter is disconnected when the vehicle is off.

 

battery voltage is more than 9v (spikes up to 15v) when the alternator is running..how will it fry your electronics?. A single 9v battery holds 15mAh. Two 9v batteries in series holds the same amperage. Same amount to run a larger flashlight. Its not guaranteed to fry your electronics.
Either way as i mentioned.some cars need that extra voltage.. not necessarily lexus so start with the 9v.

If the cig lighter is on a switched 12v circuit, the key must be in the acc position for using the 9v battery trick. Many dealers and service centers use this method to keep their customer's settings.

 

After removing the cosmetic covers, and removing the hold down, it took less than a minute to actually swap the battery. There was nothing to reset in that short period of time.

 

All 3rd gen RX are push-button start. There is no ACC key, so it is not an option.

2x 9V batteries in series will be 18V. If both of them have enough current to keep up at 18V, it may be just enough to cause muti-ECU failures. It is not the battery capacity, which is how long it will sustain a discharge that you're worried about, but rather how much current it can provide for a short amount of time. I bet it will be around an amp, or 18WT in case of 2x batteries.

One can use a jumpstart cables to keep the vehicle powered while the battery is pulled. But, there's always a possibility of a short, so proceed at your own risk.

 

What about keeping a battery tender attached to the cables when changing the battery? Much lower charge rate than a regular charger. I ask because I have a battery tender and plan to replace my battery with one from Costco this fall as it is the original in my 2010, although it is garage kept, has low mileage and still works just fine.

 

Should be alright. Doubt it will spike when you disconnect the battery.

 

I would not feel comfortable using a battery tender attached to the cables with battery disconnected..Battery tender requires a battery with at least 3 volts to act as a load. Battery tender also does not output a constant voltage.

I have measured battery voltage with battery tender connected and It will vary as designed. It uses a 4 step charging process, (Initialization, Bulk Charge, Absorption Mode, Float Mode). Current output varies significantly to eliminate Sulfation.

 

This is exactly what happened. Everything else (including the seat/mirror preferences for the buttons on the driver's door) were saved, just lost radio presets. On the plus side our XM radio started picking up channels again (we didn't pay for it but never got our free 3mos) haha.

 

I use a portable jump starter to keep power to the system while replacing the battery.