SL/R230: Charging with OE Trickle Charger
Thread Starter
Junior Member
Joined: Aug 2016
Posts: 47
Likes: 4
2008 Mercedes-Benz SL 550
Charging with OE Trickle Charger
Hello all;
I have a 2007 SL550. For the winter, I store it as I really do not drive it in these dreaded northern winters. The spot that I store it at has no electric; so, I have taken out both batteries. This charger is meant to plug into the trunk cigarette lighter receptacle and it would trickle charge both batteries as needed (from my understanding).
As a result; I removed both batteries and brought them home in my garage. I can easily charge one at a time; but I am wondering if daisy chaining positive to negative on batteries and charge empty positive and negative on the different batteries would work and be effective? To be clear. Connect positive on battery A (starter battery) to negative on battery B (main battery from trunk) and connect the charger to the positive on battery B and negative on battery A. Would that be effective or should I just charge each one for a couple of weeks alternating?
Thanks,
Tamer
I have a 2007 SL550. For the winter, I store it as I really do not drive it in these dreaded northern winters. The spot that I store it at has no electric; so, I have taken out both batteries. This charger is meant to plug into the trunk cigarette lighter receptacle and it would trickle charge both batteries as needed (from my understanding).
As a result; I removed both batteries and brought them home in my garage. I can easily charge one at a time; but I am wondering if daisy chaining positive to negative on batteries and charge empty positive and negative on the different batteries would work and be effective? To be clear. Connect positive on battery A (starter battery) to negative on battery B (main battery from trunk) and connect the charger to the positive on battery B and negative on battery A. Would that be effective or should I just charge each one for a couple of weeks alternating?
Thanks,
Tamer
Senior Member
Joined: Nov 2016
Posts: 271
Likes: 23
From: Kirkland, WA
2003 SL500
It will not work. Connecting positive of one battery to negative of another would put them in series with the total voltage of about 24V, while charger is designed to charge at about 12V. Connecting them in parallel is not a very good idea either, because they have slightly different voltages, so one will be overcharged, while another one will be undercharged. So I would recommend just swapping batteries on the charger one at a time. Self discharge should not be a problem, unless they are at the end of their lives.
