Long Story Made Short
BMW motorcycle enthusiasts that desire the best for their bike understandably purchased the MotoBatt MB51814 sealed AGM Quadflex battery. Over the past couple seasons, however, they were often left frustrated and discouraged. You see MotoBatt made an error in sizing the MB51814 which replaces the Yuasa 51913 and 51814 conventional batteries. BMW owners that had ABS and required the 51913 battery discovered that the MB51814 was a hair to wide and a smidgen to long. Those that originally required the 51814 conventional batteries (generally the bikes without ABS) seemed to have no issues. Under closer inspection it was determined the OEM 51913 had a slight taper to it making the bottom narrower. MotoBatt did not catch this distinction when they first went into production.
The Long Way Round
It took Ewan McGregor, who played Obi-Wan Kenobi in the prequel trilogy of Star Wars and Charley Boorman who appeared in The Serpent’s Kiss and Hope & Glory, 4 months to travel 19,000 miles on their 2004 BMW R1150GS during the filming of Long Way Round. They showed patience and perseverance as the challenges and hardships stacked up in front of them. In the same way, it took MotoBatt a while to compile the data and redesign the internals of the battery, but they finally did so in late in 2012 and its new case is perfect. To date we have had zero calls regarding fitment issues with these new slimmer batteries. Patience and perseverance was essential. BTW: the BMW R1150GS uses the MB51814 replacement battery.
The New & Improved MB51814 BMW Replacement Battery
Look at the side-by-side comparison below to see the OEM specs and the new measurements for the MB51814. MotoBatt accounted for the taper and made the battery slimmer. Also note the 15% increase in amp hour (Ah) which is very important for BMW riders with all the electronic equipment on board. The cold cranking amps (CCA) also increased by 15% to 120% depending on which numbers were used for calculation. Typically if you increase Ah you need to decrease CCA and to increase CCA you need to decrease Ah. As you can see, the advanced AGM MotoBatt MB51814 has managed to increase both numbers. The QuadFlex terminal design is brilliant as it allows for a second set of terminals to attach all your accessories without overloading the primary set. This greatly reduces accidental discharging of batteries from loose connections.
Yuasa 51913
- 7.32 x 3.23 x 6.73 (186 x 82 x 171)
- 19 Ah
- 100 or 190 CCA (we have found mixed info from the OEM)
MotoBatt MB51814
- 7.20 x 3.15 x 6.69 (183 x 80 x 170)
- 22 Ah
- 220 CCA (use to be 260 CCA)