Replace 7-year old battery in BMW even though there are no problems?
- Thread starter barlowc
- Start date
The Diehard platinum is no longer a relabelled Odyssey AGM. It Has not been for many years now.
Which outfit makes what battery for whom with whatever sticker placed on it, is ever changing, and could be different in different regions of the country. Even looking at case designs and comparing to pics online is no guarantee.
Buy the heaviest AGM in your group size.
See if it actually weighs what they claim it does.
Remain suspicious. bring a digital voltmeter, buy the highest voltage one on the shelf, it could be in the back,
Hopefully it is freshest one too.
Which outfit makes what battery for whom with whatever sticker placed on it, is ever changing, and could be different in different regions of the country. Even looking at case designs and comparing to pics online is no guarantee.
Buy the heaviest AGM in your group size.
See if it actually weighs what they claim it does.
Remain suspicious. bring a digital voltmeter, buy the highest voltage one on the shelf, it could be in the back,
Hopefully it is freshest one too.
To continue the very good thoughts in the post above this one....
Weight comparison...
A Thin Plate Pure Lead battery made by Northstar in the group 24f size weighs a staggering 57 pounds....
A highest end flooded acid 24f battery weighs 44.5 pounds...
That is the difference between a legitimate heavy duty potential deep cyle/starter battery and a routine flooded starter battery.
The only way to truly maximize that $340 TPPL AGM Northstar battery's potential is to properly recharge to truly 100 percent after use and maintain that battery at all times. That type of battery could give over 1,000 deep cycle uses if properly taken care of. A regular AGM battery that is around $200 that will be fortunate to get 300-400 deep cycles of taken care of properly.
Weight comparison...
A Thin Plate Pure Lead battery made by Northstar in the group 24f size weighs a staggering 57 pounds....
A highest end flooded acid 24f battery weighs 44.5 pounds...
That is the difference between a legitimate heavy duty potential deep cyle/starter battery and a routine flooded starter battery.
The only way to truly maximize that $340 TPPL AGM Northstar battery's potential is to properly recharge to truly 100 percent after use and maintain that battery at all times. That type of battery could give over 1,000 deep cycle uses if properly taken care of. A regular AGM battery that is around $200 that will be fortunate to get 300-400 deep cycles of taken care of properly.
Get the battery load tested. Know, don't guess. Most auto parts stores do it for free.
My AGM battery in the trunk of my 2008 E350 is original so almost 13 years old at this point, just a few more month. How did you determine state of charge? That's supposed to be battery voltage at 70 degrees with no load after siting for a few hours. Connected to the car is not the no load state. I charged up mine once after I left the fog lights on. Checked the voltage a couple hours after disconnecting the charger and then put it in the car. Battery voltage was .3 volts lower once it was hooked up.
From your list, my favorite is the Champion from Pepboys, they usually run a discount on it and they've been having a $40 rebate on it for a long while on the AGM. It's also a JCI battery. The one in my Mercedes was a Varta battery and JCI was the maker of it. Advance Auto and Autozone also have discount codes, you can find them on retailmenot.com. Usually around 20-25% but with the pandemic, sometimes only 15%.
My AGM battery in the trunk of my 2008 E350 is original so almost 13 years old at this point, just a few more month. How did you determine state of charge? That's supposed to be battery voltage at 70 degrees with no load after siting for a few hours. Connected to the car is not the no load state. I charged up mine once after I left the fog lights on. Checked the voltage a couple hours after disconnecting the charger and then put it in the car. Battery voltage was .3 volts lower once it was hooked up.
From your list, my favorite is the Champion from Pepboys, they usually run a discount on it and they've been having a $40 rebate on it for a long while on the AGM. It's also a JCI battery. The one in my Mercedes was a Varta battery and JCI was the maker of it. Advance Auto and Autozone also have discount codes, you can find them on retailmenot.com. Usually around 20-25% but with the pandemic, sometimes only 15%.
Check at Sams-mine has East Penn.
Around here NAPA AGM are made by East Penn.
An app called BimmerLink which connects to the Bluetooth OBD-II that I have.
The only thing about the Champion is that it has a 48-month free replacement warranty whereas most of the others are 3-years. As for pricing, the numbers I listed reflect all of the current discounts. (i.e. 25% off Pep Boys, 20% off AAP and O'Reilly, only $10 off at AutoZone)
I'm not sure I'd really trust that. Battery may just be discharged. Normally you'd put it on a charger to know exactly what your maximum state of charge is. You should also get it load tested. I gues Pepboys finally stopped their $40 rebate on the battery. They had that since last year and still had it a couple months ago. Probably sales are back up again so not so much discounting now or they just need every dollar they can get.
If BMW battery location is like Mercedes i.e. under rear seat or trunk, they last forever. On my 4th Benz and all of the batteries last a longtime even in brutal TX heat. I don't believe in replacement until I have a weak start.
Three years ago I was in the same boat as you. My 2005 Civics battery was seven years old and my thought was to replace it. Well, I decided to keep it and I now check the acid level three or four times a year. After checking the level i clean it up with baking soda and charge it. I keep saying that I should replace before it leaves me high and dry but now it is a game to see how any years I can get out of it. I have jumper cables in the trunk just in case!
I replaced a 12 year old BMW brand battery in my 1998 BMW last time around. I think newer BMWs are harder on batteries. Once I notice cranking slow down I replace immediately. 10+ years is not uncommon for in car mounted batteries I have found.
The Duracell AGM (East Penn) from Batteries+ also has a 48 month warranty.
I have three vehicles, all with Walmart Everstart Maxx batteries. An 8, 6 and a 4 year old. All are still doing great. I usually replace them before they fail me but I have jumper cables and emergency road service so I will wait for symptoms before replacing.
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- Aug 21, 2020
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They have self-contained units that you do not need another vehicle for a jump.
Since you're in Michigan, replace it before winter. You could try to stretch it beyond that, but the cost per year probably won't go down much compared to the hassle of a single time you have to jump it in bad conditions.
JHZR2
Staff member
Agree. Testing is the only thing that provides a definite basis. You can calculate battery impedance from it. THe small capacitance testers sometimes give an impedance value too, but a real load test is definite...
Since the BMW batteries are in the trunk, and this is a daily driver, this battery has a good chance of lasting a long time. IME, BMWs can have fairly high parasitic loads if they sit a long time, but a DD wont be as affected...
JHZR2
Staff member
That SOC is based upon the battery voltage.
State of Health is what you want to know, and is incrediby hard to truly determine, short of a true capacity and load test.
