Have a 2008 BMW 650 twin which I guess is a bit of a lump of an engine to get started! It’s always started promptly altho the first 1-2 ‘cranks’ seemed hard work.

Over the last couple of weeks, it’s feeling sluggish starting each morning and turns over 6-8 times before firing up. I park in an underground car park and it starts much better on my return journey home. I charged the battery with an Optimate charger which gave a ‘good’ reading.

I tested the battery yesterday:
– c.12 V with ignition off
– c.11V with ignition and lights on
– dips to 8-9V when starting

I’m guessing the battery’s wearing out – but it’s the first time I’ve had a twin, and wondered if this was just typical of that type of engine in the cold?

Any thoughts? And if the battery needs replacing, any recommendations of make/brands/type?

Many thanks

Odyssey for really big engines can’t be beaten as they have huge cranking amp reserves.
Other option is to look at the new LiPo/LiFe versions as well.

12v is low I think, shold be miore like 12.5 IIRC. New battery time IMO.

Those ‘Motobatt’ AGM batteries are supposed to be the business, pricey though. PP is right, 12.6 – 12.7 is normal.

Anyone had experience of the Motobatt’s?

Thanks

New battery time.

I used Yuasa’s high output batteries- very reliable and they kicked the bike over much faster. When you’ve got a big twin covered in a slab of ice, that’s good!

I’ve had a Motobatt AGM in my Multi for the last couple of years with no complaints.The bike lives outside, but I’m able to use an optimate by cunningly running the wires through an air vent. The bike can be a bit of a struggle to start if it’s been left for a while, especially in the winter, but the battery has plenty of oomph and hasn’t let me down yet.

How’s the rectifier

FWIW, fitted a Motobatt and all looking good again

+1 Yuasa

Japanese manufacturers OEM choice. My m’bike lives outside and after 1 year it’s still spinning engine faster than I can spin pedals on ma bicycle. And I don’t use m’bike that much these days so it stays for weeks untouched. Very well impressed.

Not cheap though.