BMW 740 Battery

The 7-series BMW is one of the larger sedans on the road, so it should come as no surprise that these luxury sedans use fairly large batteries. Which battery they use can depend on a variety of factors, including the model year. The BCI fitment guide offers all the information you need. Unfortunately, it requires some translation, starting with the footnotes in the second column:

The 45 footnote likely indicates the use of an auxiliary battery that is either a Lithium-based product or not a typical BCI battery, more likely a powersports-sized battery. In this instance, it is recommended to check the size listed on the battery and replace the battery with the same size. Footnote 54 indicates the battery must have a vent port that allows it to vent to the outside atmosphere. That is due to the fact that these batteries are mounted inside the vehicle and in the unlikely event that they vent gas, it is both flammable and toxic, so you'll want that to exit the vehicle. This is not an issue for OPTIMA batteries, as our DH6 and DH7 YELLOWTOP batteries both offer ports for external venting.

Footnote 57 indicates BMW used various sizes during production, so it is again wise to check the size of the battery currently in your vehicle. The good news with this footnote, is that it is likely that you may be able to use a variety of battery sizes with the proper holddown, varying from H5 all the way to the massive H9. Footnote 67 indicates the vehicle's battery management system must be re-set after installation. Nearly all BMWs manufactured after 2002 have this requirement, which is intended to provide battery charging characteristics throughout the battery's life and hopefully, increase battery lifespan.

This can be performed with a scan tool or by a qualified independent or BMW-affiliated service specialist. Footnote 71 indicates you should contact a service specialist before changing the battery, which is specific to the auxiliary lithium battery. Footnote 73 simply calls out once again the fact that you are dealing with a lithium battery and should only replace it with an identically-sized lithium battery.

The third column indicates the battery group size and again, some translation may be required here.

At this time, OPTIMA does not offer a direct-fit replacement battery for the BMW 740. However, we will be offering a DH5 YELLOWTOP in the Spring of 2023 and our friends at Weistec offer holddown adaptors that will allow you to use an OPTIMA DH6 YELLOWTOP in the Group 49/H8 applications. You'll note the fitment guide indicates there are optional fitments, which means there's a good chance an OPTIMA DH6 will probably fit in your BMW 740.

Batteries are an expensive investment and not one you want to make on a regular basis. For that reason, we highly-recommend regular use of a quality battery charger or maintainer, to keep the battery voltage properly-maintained and maximize battery lifespan. Even vehicles that are driven on a daily basis can slowly discharge their batteries over time, so we recommend a minimum charging routine of at least once a month initially.

Fully-charged, OPTIMA YELLOWTOP batteries will measure about 13.0-13.2 volts. If you find your OPTIMA battery is fully-charged when you check it on a monthly basis, you can extend your maintenance charging window. If you find it is constantly below a full state of charge, you may want to charge it more frequently, until you find an appropriate cadence for your application.

We're so confident regular charging will extend the lifespan of your OPTIMA battery, we'll add an additional year of free replacement warranty coverage to your OPTIMA battery, if you purchase it from us at the same time that you buy our OPTIMA Digital 1200 battery charger and maintainer. This unit will also provide pre-charge voltage status, so you'll know where your battery voltage is before your begin charging.