Battery OPTIMA or OEM BMW

I use Red top Optima batteries in all my cars, I truly hate flooded lead acid batteries as they will leak at sometime in their life.

I run a Optima yellow top as well, but mine fits in just like stock.

I have an optima yellow top in mine.

I had an Optima I took out of my Crew Cab Dually, probably two years old (used for my car stereo). It sat in my garage for a year. Then I needed a battery for my 1/2 ton truck. I charged the Optima and installed it. I ran it for three years without problems. Sold the truck with the battery still in it.

Absolutely YES you should buy the optima RED top 6 volt batteries instead of the dealer yellow top batteries. There is virtually NO difference between the RED top optima battery and the dealer yellow top optima battery that the dealer sells. Both are made by optima.

Red top optimas work better than dealer yellow tops in the EOS I have done a TON of homework/ related to this EOS optima battery issue. I can confidently give you the best advice since I spent several years researching this issue. Absolutely YES you should buy the optima RED top 6 volt batteries instead of the dealer yellow top batteries. There is virtually NO difference between the RED top optima battery and the dealer yellow top optima battery that the dealer sells. Both are made by optima. The only difference is that the yellow top version that the dealer sells has a minuscule higher voltage at full storage capacity ( 13.9 volts for yellow tops vs 13.7 volts for the red tops) because it has one more AGM layer wound inside the case, BUT this is the reason the YELLOW top optima battery that the dealer sells fails so often. Unlike the red top, the yellow tops that the dealer sells are prone to short out some internal \"plates\" from any minor impact to the case. Once a optima battery has an internal short, the battery is garbage. So, the dealer yellow tops batteries are actually more problematic and have a much higher failure rate. I have even found that the RED top optima version is BETTER quality and lasts longer because it has a few less layers wound in the case which actually give the \"plates\" more room and prevents them from shorting from any impact to the battery case which is the problem with the dealer yellow top batteries. And there is NO need to have \" deep cycling\" yellow top optima's batteries because the 4 cylinder turbo EOS version use a standard NON deep cycling battery and actually do NOT have any of these battery issues that the 6 cylinder versions have. The reason VW chose the deep cycling yellow tops as original equipment on the 6 cylinders is because VW assumed the yellows have more reserve power to power the energy drain of an owner operating the hardtop with the engine OFF. So with out getting technical, the answer is YES the red top batteries are identical and swap out for your yellow top batteries perfectly. I threw out my dealer yellow top optima batteries and I myself replaced them with the optima red tops and have been PROBLEM FREE SINCE I DID !! I do not know if you are in the USA, but you need to buy TWO 6 volt red top optima batteries. They are an EXACT fit replacement and cost around $150 each shipped. If you are in the USA, Summit Racing sells the shipped for about $140 each. You need two. Any mechanic can swap them out in less than one hour. I did it myself . So if you buy two red tops and pay a mechanic one hour labor you should be under $400 total. And the red top optimas are actually better than the yellow tops. ( this was confirmed by an past employee of optima), I have his post as proof. Also, make sure that your batteries are actually \"bad\". The dealer may tell you your batteries are bad but they may actually be OK. My dealer erroneously tested them installed in the car which 100% will give you a reading on a tester that they have very low CCA (cold cranking amps) and are \"bad\" because the cable connecting them has resistance that throws off the tester. To test the 6 volt batteries they must be tested individually as 6 volts and not in series as 12 volts because if they are tested as 12 volts in series the testing device will 100% erroneously tell you they are bad even if they are good BECAUSE the cable connecting them has resistance that tester assumes is internal battery resistance. I personally spoke to the engineer at optima regarding this. So many VW dealers not knowing this test the batteries together as 12 volts which causes the CCA reading to be less than 180 yet if tested individually would be normal at around 850. I have personally verified this myself. So be cautious if the dealer tells you your batteries tested bad. They MUST BE TESTED individually as 6 volts and not connected together and tested as a 12 volt. Last piece of advice...IMPORTANT.. If you are swapping out batteries you need to keep all the computer settings. In the 2.3 NON turbo cars this is easily done when swapping out batteries since the engine compartment has the jumper cable connections in the engine compartment in front and the batteries are in the rear trunk. You must first attach jumper or booster cables to the front engine compartment jumper connections from another car ( or good 12 volt battery) before you remove the batteries in the trunk so that your EOS does not loose its computer memory settings. Keep the jumper cables connected in the front engine compartment the entire time until the rear battery swap is completed. This is what I did to keep all my computer settings. Mark. PS I am posting this on the forums to help others

I ended up getting a OPTIMA 8040-218 D35 YELLOWTOP from Autozone with a 3yr warranty.

I just threw in a red top in the G60 and it did not fit well at all. The optima website mentioned some sort of adapters that were supposed to fit on the long edges of the battery to make it fit better under the battery holder, but I did not get any with my battery. I ended up shimming it to get it snug.

Every optima battery I have seen in customer vehicles (I'm an auto tech) goes to crap in about 6 months to a year. I think these types of batteries are more sensitive to low voltages. They also don't hold up at all during the freezing winter months.

I had an optima in my garage queen, wasn't even hooked up most of the time(unhooked it till I wanted to drive/work on it). it died 2 years and one month later, with MAYBE 1000 miles on it, no replacement/etc. now it's a doorstop in my garage.