I Decided To Fully Charge My Battery...

[Jim Nazium]

I was getting the feeling my factory batter was low. I know I was reading about how bad it was to remove the front battery, but my battery was never fully charged. I disconnected it last night and let it charge overnight with my battery charger (has overload, and over charge protection). As soon as I plugged it in I found the battery was pulling about 7 amps (my charger has a guage to measure draw). Sure as !Removed!, I knew it. Battery was still drawing about 7 amps after about 2 hours of charging. Next morning, Meter was showing less than an amp in trickle mode only. I have always disconnected the ground pole before charging any car battery, seeing as how you do not want to damage any electricals.

This morning I reconnected the ground, closed up the battery cover and waited about an hour (I was installing mud guards). After I started up, I noticed right away I was able to pull out of my garage on battery power alone (even though it is winter). As well, I drove clear around two city blocks before the engine kicked in as I was merging onto the main road.

I will say this, the factory battery sure is puny. OK, it's ligther than a typical vehicle battery that relies on one source only, but for the amount of electronics and heft of this vehicle you would think Lexus would of offered a beefier battery. And, it's not like you can upgrade the battery, there's no space for anything bigger.

Now, I know about this...

http://lexushelp.com/Ownership/Bulletins/EG/EG010-05.htm

But I'm not going to fret over it just yet. I will bring it up to the dealer in a couple of weeks as I will be taking the RX400H in for oil change. I will see what he has to say about this. I will tell him I think the battery was disconnected while my vehicle was in storage, see what he says.

Cheers

MadloR

[wwest]

What you have forgotten, is that your hybrid has a bi-directional DC-to-Dc converter. On the go, your hybrid battery is not only used to maintain a low "charge" on the auxillary 12 volt battery, it supplies most of the 12 volt "juice" for all of the accessories.

So, basically, there is no reason to EVER fully charge, top off, your 12 volt auxillary battery nor is there any good reason for it to be of very high capacity, size. In point of fact if the system were to do that constantly, "over" charge the 12 volt battery, the life of the auxillary 12 volt battery would likely be significantly shortened.

Did you know that the hybrid battery can be recharged via the dc-to-dc converter?

That, apparently, effectively, is what you have done.

By topping off, "over-filling" your 12 volt battery you have "forced it" in effect, to carry the entire accessory load. Since it was over-charged, 13.62345 volts, the hybrid battery did not supply any current flow to the 12 volt accessories via the DC-to-Dc down converter.

So of course it took longer for your hybrid battery to discharge to the point wherein the ICE had to be started.

Again, there is absolutely no reason for the system to maintain the 12 volt auxillary battery at a high state of charge.

[SOMEONE ELSE'S GOT MY NAME]

The 12V. is mearly to boot the ECU's. Thus, if you have 8 flashlight D cells wired up, even THAT would do the trick. Weird.