Adding second battery
Thread Starter
Super Member
Joined: May 2015
Posts: 600
Likes: 45
From: Minneapolis, MN/Breckenridge, CO
2010 E550 4Matic Sport P2
Adding second battery
My 2010 E550 is a 4matic. As such, the battery is under the hood. I was curious if I could add a second full sized battery in the trunk where the rwd models have one. My thoughts behind this is I live in a cold climate, do make a number of short trips, have a hardwired radar detector, aftermarket sub and amp, and now plan to hardwire a dual dash cam. I can buy one of the cell link b or blackvue batteries, but for roughly the same cost, I could add a full second agm. I know running the wiring will be somewhat time consuming but I am able to do so myself. The camera will run when triggered as I'm sick of door dings and scrapes and the associated costs of fixing them.
I'm curious if there is a downside to going this route. Will charging be compromised/excessive strain put on the alternator? Would I be less likely to recharge when driving?
What are your thoughts on upside vs downsides?
Thank you!
I'm curious if there is a downside to going this route. Will charging be compromised/excessive strain put on the alternator? Would I be less likely to recharge when driving?
What are your thoughts on upside vs downsides?
Thank you!
Super Member
Joined: Feb 2013
Posts: 580
Likes: 62
From: Maryland
2013 E550 4Matic
Subscribed for answers to this question... I wanted to get a sub/amp for mine, but wasn't sure if there's a good way to connect a battery in the trunk to the alternator without an OEM harness.
I wonder if you could use a smaller motorcycle/lawnmower battery to power those accessories, since it won't be responsible for cranking the engine or anything. I have a nice 2lb Lithium battery for my bike that has more CCAs than the OEM one, and weighs 1/3 of it. Something small and light like that would be ideal. Plus, it's not lead-acid and I don't have to worry about it tipping over for whatever reason (like doing donuts in the snow this winter
)
Edit: Here's the battery I was talking about, on the left:
https://cdn.shopify.com/s/files/1/02...g?v=1373665848
I wonder if you could use a smaller motorcycle/lawnmower battery to power those accessories, since it won't be responsible for cranking the engine or anything. I have a nice 2lb Lithium battery for my bike that has more CCAs than the OEM one, and weighs 1/3 of it. Something small and light like that would be ideal. Plus, it's not lead-acid and I don't have to worry about it tipping over for whatever reason (like doing donuts in the snow this winter
)Edit: Here's the battery I was talking about, on the left:
https://cdn.shopify.com/s/files/1/02...g?v=1373665848
Last edited by blegthbloo; Dec 12, 2016 at 08:17 AM.
Thread Starter
Super Member
Joined: May 2015
Posts: 600
Likes: 45
From: Minneapolis, MN/Breckenridge, CO
2010 E550 4Matic Sport P2
I wonder how our cars electronics would react to one of these setups? Placement of a fullsized unit isn't an issue as there is a location from the factory in the trunk (for rwd cars), while my awd is in the front. I would be in a factory location and easy to affix with OEM parts. I wonder if doing the install with a battery isolator so that they both charge properly/automatically would trigger any fault codes or issues.
MBWorld Fanatic!
Joined: Oct 2010
Posts: 5,123
Likes: 1,288
From: Southern US
2010 E550, 273 Engine: 2012 S550, 278 Engine
I wonder how our cars electronics would react to one of these setups? Placement of a fullsized unit isn't an issue as there is a location from the factory in the trunk (for rwd cars), while my awd is in the front. I would be in a factory location and easy to affix with OEM parts. I wonder if doing the install with a battery isolator so that they both charge properly/automatically would trigger any fault codes or issues.
Reading your posts I get the feeling you want the extra battery because of the dash cam you plan to install...?
What is the amp load the camera pulls? If you get a battery with 700 Ah capacity it would run that camera for 700 hours if it pulls 1 amp current, i.e. about a month with a full charge so you could run the camera from the battery in the trunk and throw a charger on it every couple of weeks or so over night. No wiring required to the alternator.
Thread Starter
Super Member
Joined: May 2015
Posts: 600
Likes: 45
From: Minneapolis, MN/Breckenridge, CO
2010 E550 4Matic Sport P2
Reading your posts I get the feeling you want the extra battery because of the dash cam you plan to install...?
What is the amp load the camera pulls? If you get a battery with 700 Ah capacity it would run that camera for 700 hours if it pulls 1 amp current, i.e. about a month with a full charge so you could run the camera from the battery in the trunk and throw a charger on it every couple of weeks or so over night. No wiring required to the alternator.
What is the amp load the camera pulls? If you get a battery with 700 Ah capacity it would run that camera for 700 hours if it pulls 1 amp current, i.e. about a month with a full charge so you could run the camera from the battery in the trunk and throw a charger on it every couple of weeks or so over night. No wiring required to the alternator.
The added power of a second full battery if properly installed seems at least in theory to be beneficial for times that a number of short trips are made and the batteries could fully recharge when on longer drives. Alternatively the plug and play option of the dashcam specific celllink b battery which would offer less recording time is the backup plan due to it being easily removed from the vehicle and charged inside as needed.
Member
Joined: Nov 2015
Posts: 206
Likes: 38
From: Southern
2014 E-350
To each their own...but your car battery is for (1) starting the vehicle and (2) running electrical items while your engine is off. Your radar detector and cameras require very little juice and will primarily be running while the engine is on.
Your alternator serves two purposes (1) to power all electrical items while engine is running and (2) to recharge your battery. Most modern alternators handle normal amps/subs and accessories without a problem, because most vehicles have stock amps & subs now anyway, and far more electronic/electric equipment than in the past.
Unless you're running a super sound system or you're experiencing frequent battery issues, I wouldn't bother with a secondary battery.
I never get door dings or scrapes from other people - I pride myself on staying damage free. But that takes work - parking only in end spots, hugging the outside where no one can park next to me...parking far out in lots...staying away from shopping cart returns, etc. An extra minute or two but worth the ding-free lifestyle. The camera you plan to use may or may not ever pay off (you'd have to get license plates, track down owners, file claims, etc.)...sounds like it could be more hassle than it's worth. But again to each their own, let us know if you accomplish this so we can learn how!
Your alternator serves two purposes (1) to power all electrical items while engine is running and (2) to recharge your battery. Most modern alternators handle normal amps/subs and accessories without a problem, because most vehicles have stock amps & subs now anyway, and far more electronic/electric equipment than in the past.
Unless you're running a super sound system or you're experiencing frequent battery issues, I wouldn't bother with a secondary battery.
I never get door dings or scrapes from other people - I pride myself on staying damage free. But that takes work - parking only in end spots, hugging the outside where no one can park next to me...parking far out in lots...staying away from shopping cart returns, etc. An extra minute or two but worth the ding-free lifestyle. The camera you plan to use may or may not ever pay off (you'd have to get license plates, track down owners, file claims, etc.)...sounds like it could be more hassle than it's worth. But again to each their own, let us know if you accomplish this so we can learn how!
Last edited by fosterelli; Dec 13, 2016 at 07:31 PM.
Super Member
Joined: Feb 2013
Posts: 580
Likes: 62
From: Maryland
2013 E550 4Matic
To each their own...but your car battery is for (1) starting the vehicle and (2) running electrical items while your engine is off. Your radar detector and cameras require very little juice and will primarily be running while the engine is on.
Your alternator serves two purposes (1) to power all electrical items while engine is running and (2) to recharge your battery. Most modern alternators handle normal amps/subs and accessories without a problem, because most vehicles have stock amps & subs now anyway, and far more electronic/electric equipment than in the past.
Unless you're running a super sound system or you're experiencing frequent battery issues, I wouldn't bother with a secondary battery.
I never get door dings or scrapes from other people - I pride myself on staying damage free. But that takes work - parking only in end spots, hugging the outside where no one can park next to me...parking far out in lots...staying away from shopping cart returns, etc. An extra minute or two but worth the ding-free lifestyle. The camera you plan to use may or may not ever pay off (you'd have to get license plates, track down owners, file claims, etc.)...sounds like it could be more hassle than it's worth. But again to each their own, let us know if you accomplish this so we can learn how!
Your alternator serves two purposes (1) to power all electrical items while engine is running and (2) to recharge your battery. Most modern alternators handle normal amps/subs and accessories without a problem, because most vehicles have stock amps & subs now anyway, and far more electronic/electric equipment than in the past.
Unless you're running a super sound system or you're experiencing frequent battery issues, I wouldn't bother with a secondary battery.
I never get door dings or scrapes from other people - I pride myself on staying damage free. But that takes work - parking only in end spots, hugging the outside where no one can park next to me...parking far out in lots...staying away from shopping cart returns, etc. An extra minute or two but worth the ding-free lifestyle. The camera you plan to use may or may not ever pay off (you'd have to get license plates, track down owners, file claims, etc.)...sounds like it could be more hassle than it's worth. But again to each their own, let us know if you accomplish this so we can learn how!
Trending Topics
Member
Joined: Nov 2015
Posts: 206
Likes: 38
From: Southern
2014 E-350
You make good points (and I am also part of the Ding-Free Club lol)... in my case, I would want the separate battery simply so that I don't have to run an amp power cable through the cabin (thus ripping up all the trim pieces, potentially cutting through the firewall, then putting all the things back and hope I didn't forget to snap something in place or, worse, break a tab or two along the way). Also, because of laziness. lol
Not sure how you'd get around that from the rear. Unless you want to go through the hassle of manually charging with an external battery charger. But if I were doing this, I'd mirror the setup of OEM vehicles with dual batteries (like diesel trucks). Then I'd be worry-free.
MB World Stories
The Best of Mercedes & AMG
Flawlessly Restored Mercedes 190E Evo II Heads to Auction
Verdad Gallardo
Electric Mercedes C-Class Unveiled: 11 Things You Need to Know
Verdad Gallardo
Mercedes EQS Gets A Major Update: Everything You Need to Know
Verdad Gallardo
5 Underrated Mercedes-Benz Models That Don't Get the Love They Deserve
Verdad Gallardo
Mercedes 300D Has Pushed Well Past 1 Million Miles and It Ain't Stopping
Verdad Gallardo
10 Most Reliable Mercedes-Benz Models You Can Buy Used
Verdad Gallardo
Mercedes Teases Updated EQS With Steer-By-Wire and a Yoke
Verdad Gallardo
8 Mercedes Models With Poor Reliability Records
Verdad Gallardo
Magnificent New Mercedes-Maybach S-Class Revealed: 12 Things to Know
Verdad Gallardo
Thread Starter
Super Member
Joined: May 2015
Posts: 600
Likes: 45
From: Minneapolis, MN/Breckenridge, CO
2010 E550 4Matic Sport P2
You'd still be running cables. On my Super Duty truck the secondary battery's positive terminal cable runs to the positive terminal on the primary battery, and the alternator connects at that same primary battery's positive connection.
Not sure how you'd get around that from the rear. Unless you want to go through the hassle of manually charging with an external battery charger. But if I were doing this, I'd mirror the setup of OEM vehicles with dual batteries (like diesel trucks). Then I'd be worry-free.
Not sure how you'd get around that from the rear. Unless you want to go through the hassle of manually charging with an external battery charger. But if I were doing this, I'd mirror the setup of OEM vehicles with dual batteries (like diesel trucks). Then I'd be worry-free.
