jbl-1985

Folks, trying to determine if it is safe to leave a charger on my RX300 at a rate of 2amps without disconnecting the battery. The Lexus manual says always to disconnect the battery when doing any charging (at least that is what I have heard before) as it can damage the electronics.

I have one of those 3 tiered chargers, 2, 8, and 12 amps. My thought was to leave it on set at 2amps. Too much charge with the battery connected? She is going to again be in storage for a couple months.

Comments very appreciated.

bob2200

The biggest danger is freezing temperatures and a discharged battery.

I would take the battery indoors (i.e., temperatures above 40 or 50 degrees), and just charge it for a few hours when you return.

A potential problem with long-term charging is the boiling away of water. In the old-days, you just topped up the battery water level with distilled water. This is not as easy with new batteries.

DaveGS4

iTrader: (2)

Just make sure the charger you use is a true trickle charger. I have several chargers and the one with '3 settings' isn't a trickle charger and doesn't have the circuitry to 'float' and not overcharge, etc that the trickle chargers are.

Used to use one on my old GS, my wife's NSX since they didn't get driven much. Currently have one on my wife's track car since it has a tiny little lightweight battery and use a double trickle charger on boat batteries when we pull them out for the winter. All the vehicle ones are used w/o disconnecting with no problems.

kalali

Get a Battery Tender and be done with it...I have two; one on the bike and one on my track car and I leave them on the entire winter.

salimshah

2 amps is not trickle charge.

If you want, you can use the 2 Amp setting with 1/2 hr daily [with programmable lamp modules].

Keep in mind the battery needs to be in well ventilated area and in an environment free of sparks/flame.

Salim

carguy07

Money well spent: http://cgi.ebay.com/ebaymotors/ws/eB...4689&viewitem=

Plug it in and forget about it.

Gazootech

Battery tender is the best idea otherwise disconnect battery leave in car and charge

code58

X3 2 amp is way to much for a trickle charger. Most all battery chargers these days have a taper feature to them, but I don't think they ever taper down as far as "trickle".

jbl-1985

Thanks folks for all your feeback. Sounds like the battery tender unit is the best way to go, and will not harm the electronics if you leave the battery connected to the car.

Really prefer to not have to disconnect the battery and then have to reset all of the radio stations, normalize the windows, etc...Also, one time I had the battery disconnected I reconnected it with a spark on the negative terminal and later I had a CEL come on and long story short, the Throttle Position Sensor was malfunctioning. Can only think that the reconnect surged the system and caused that to happen. Maybe not I guess we'll never know, but nonetheless don't want to go there again if I don't have to.

Again, thanks very much.

kalali

At the risk of stating the obvious, with a Battery Tender you need to leave the battery connected.

jbl-1985

No problem - This is exactly what I want to be able to do - beats disconnecting, charging fully, and then re-connecting.

jbl-1985

Really dumb follow up question: Where is the most common place that you would hook up the negative end of the trickle charger to the frame? You would hook the positive up directly to the battery, and the negative connector would most likely go where? Why can't you just hook it up to the negative terminal of the battery itself?

bob2200

Good question. I think the reason for the common suggestion to hook up the positive cable first, and then the negative cable someplace else, is to prevent the unlikely chance of a spark from the connection igniting hydrogen gas from the battery and causing an explosion. Another related danger is hooking up a battery charger to a frozen battery, which can also potentially be very bad news. Almost any metal in the engine compartment is probably grounded, although hooking up near fuel lines is probably not a good idea.

salimshah

As bob2200 pointed out spark. spark occurs on completion of circuit and the start of current flow [also happens when and where the circuit is broken]. So the idea is to have the spark away from the battery (which has hydrogen and oxygen in a gas form.

Incidentally the disconnect is more critical as Hydrogen and oxygen are produced as the charging happens. That is why it is recommended to charge the battery in a well ventilated area so that he hydrogen gets dispersed.

If there are no leaks fuel lines are safe ... but then why risk it.

Salim

picomode

Battery tender would be fine. I am currently charging using my CTEK charger while I write this. It is a trickle charger with many settings and is fully automatic it is similar to the battery tender. It comes with a couple of quick-disconnect wiring harnesses. One of them allow you to wire it to the terminals permanently so you can plug the car in very quickly without having to use alligator clips. The second harness has the alligator clips. Very sweet tool. If I drain the battery heavily in one day I'll top it off overnight on the trickle setting without disconnecting the battery.

My RX has an Interstate battery with accessible filling ports for each cell. Using the automatic CTEK over the years I have never had to top up the water. I have never disconnected the battery to charge.

Any new charger worth buying will be "fully automatic". They detect the charge state of the battery and cut back the charging current when the battery is fully charged. This prevents the boiling off of the fluid. The very cheapest may just be crappy always on type chargers with no detection circuitry.