Edward993

Hey all,

Anyone replace their aux battery with an inexpensive sealed battery? I found an AGM style for 1/3 the price of the MB, and 1/2 the price of the replacements available at the local Autozone or O'Reilly. Thoughts?

Edward

VegasE

Replaced mine with one made by Duracell several years ago at Batteries+. About the same price as part shop no names. No issues

ygmn

GO cheap...only a battery

KEY08

Buy two or three so then you’ll have a couple spares.

Edward993

Thanks guys! I figured as much ...it's only an aux battery so I normally wouldn't care since I hate the Eco function anyway. But I just want it working because my wife likes the brake's "hold" function. Gonna go order it now ...thanks, gents!

Edward

leardriver

I used a $35 ebay Chinese battery. It works flawlessly.

KEY08

The ESS system works off the main battery. Just an FYI

KEY08

we are talking the small trunk battery I believe. Not the dash bat from early builds

S-Prihadi

Edward,
The appointed AGM battery by MB for both main engine one and the baby aux one at the trunk is matched to the alternator for AGM..where a tiny bit higher charging voltage than non AGM battery.
Since you dont like to use Eco mode ( same as me ), I think its okey to use what you have choosen.
If you like Eco mode, then an AGM one would be ideal for long term reliability due to matching with alternator charging profile.
Now my OEM baby aux battery is 6 years old and so far so good....coz I dont use Eco mode.

Once in a while, do check the sealed ( VRLA ) battery you bought, for sign of over charging and gassing off because usually VRLA likes 14.1 volt as bulk charging and 13.6 volt for float.

E63Mitch

Can you OP or anyone else link the battery they purchased?

E63Mitch

Can you OP or anyone else link the battery they purchased?

Either of these work and is one better than the other?

kajtek1

I bought OE aux battery at FCP Euro due to their lifetime warranty.
I plan to keep the car and since those batteries seem to last less than 3, years, I bet I will get 2nd and maybe 3rd one for free

jonUF02

I just replaced the AUX battery in the dash with $13 one from Amazon. Warning went away, no problem.

Edward993

The black one is a sealed lead-acid battery (so won't spill and needs no vent), whereas the blue one is an AGM style. No functional difference that I know of, but then again the CCA for the black one is not stated, so one can make the argument that the blue AGM style is the better battery. BUT, as referenced earlier, if one never uses the ECO function, who the heck cares (yes, that's me and the wife ...we turn it off as a habit every time).

Here's the link for Walmart ...same price as amazon: https://www.walmart.com/ip/YTX14-BS-...0001/382940373

Edward

Edward993

Good stuff, sir...thank you for that!

And just as a data point for anyone interested, our E350 is a 2014 model, and we bought it in Aug 2016 with approx 21k miles on it, and the aux batt displayed "malfunction" within days of purchase. So the new factory aux batt (dealer had replaced it under CPO warranty) lasted 4 years exactly, and we never used the ECO function. Batteries are weird like this, IME. Over the many cars and motorcycles I've had in decades (including those of family members since I was the designated family wrench), I have owned and seen some that lasted 6+ years, others a scant two, and I've never seen any correlation with brand name and lifespan whatsoever (will never buy an Optima again, for example!). So at $43 shipped to my door, I think it's a good gamble

Edward