ToyotaLexus

I was looking at my nephiew's new Mercedes yesterday. I was suprised by how tiny the battery was... until I found out it's only for starting the vehicle. In the trunk, there's another larger battery for accessories... Apparently new Mercedes now have two batteries as standard. The one responsible for the starting the car is never allowed to drain below a certain voltage, so, it's nearly impossible to be stuck with a dead battery.

Is there a way I can do this on my Lexus by hooking up an additional battery in the trunk? I assume I'll need some type of device to regulate the additional battery? Any advice appreciated!

Big Mack

iTrader: (1)

You can do it with an extra battery and a battery isolator, but it won't stop a dead alternator from killing the batteries - nor will the Mercedes. If there is no power going in, the battery will eventually die because the alternator won't be able to recharge the starting battery or the auxiliary and you won't know until it's dead. Of course, there are warning signs, but if you continue to run on the battery it's going to die.

For the cost and weight, I don't think it's a worthwhile "upgrade" if you want to even call it that. Unless you plan on playing a big stereo with the car off, adding batteries isn't needed - and it will kill an alternator faster if it's trying to charge multiple batteries since there is more of a load.

Big Mack