The later ES hybrid models have a jump point in the under-hood fuse box. Is there any reason not to use this for a battery maintainer? Sure, you could attach directly to the battery in the trunk, but with the trunk lid closed, charging gases accumulate, and if the lid is left open, the courtesy light stays on.

 

If the car is stored/parked inside an enclosed garage, roll the back windows down and run the extension/power cord thru the open window.

 

...you mean use a charger in the 12v. outlet? You can’t do that; the 12v. sockets are switched off when the power is off. My question is: can you use the underhood jump points for a battery maintainer. Does anyone know???

 

No, connect charger directly to the battery as you would if the cranking battery was under the hood.

 

And how to you get to the trunk? Remember, we are talking about a hybrid here.

 

I'm not familiar with the Hybrid models interior, BUT if they are similar to the gas models, fold the rear seat armrest down, and run the cord(s) thru the opening. If you don't have this feature, well, nevermind then. LOL

 

Charging gases should only be generated when you are actually charging the battery up from a partially or completely discharged state. If you are only using a trickle charger to "maintain" charge, then the vehicle parasitic "drain" should be using the power provided by the trickle charger rather than the battery. If that is the case then there is no actual "charging" required and thus, no gas generation. Yes? No?

 

In the 6th generation ES the drive battery is behind the rear seat, so that route is blocked. As an FYI, the 7th generation moved the battery to under the seat so it has the same trunk and passthrough as the standard gas engine models.

 

The 110v AC cord of a 12v DC trickle charger will not harm or be harmed by closing the
trunk lid on it, if in a secure garage just press it down nearly closed. The correct Lexus
12v battery is a special application type that can be installed in a closed compartment
such as the trunk of the ES or under the cargo floor of the RX. When used to start the
Hybrid it only needs enough juice to close a relay, the 288v DC traction battery actually
spins Motor Generator 1 (MG1) to start the IC engine.