1975 R75/6 Battery?

[enzorocket]

________hello.
Totally new to the forum and to owning a classic... its been a long time dream to own a BMW R75 and I finally have one (1975 R75/6). Have found out pretty quickly that ive bought a hobby and one that will definitely keep me on my toes!

Question to the forum if anyone can help.

I have had repeated issues starting the bike - especially now its 3ºc in the UK... It never seems to fire.
I spent all weekend trying to get it started, ending up draining the battery and repeating the cycle the following day.
I have changed the plugs, checked for spark which is all good and ensured fuel is coming into carbs (I have managed to get it started over the last few weeks using easy start spray - but not this time).

After a no-go on Sunday - the AA (The AutoMobile Association (AA in UK) to have a look at it. They turned up Monday, plugged their portable batter pack to mine asked me to turn it over... As soon as I hit the ignition button she turned over and fired! boom - right off the bat - no hesitation at all. Amazing.

It seems the battery i had in there just doesn't have the welly to crank her over, so started researching new batteries.
Odyssey Extremes have come up several times as they apparently have twice to three times the cranking power of a standard battery - and the model im looking at getting is the PC535 - which has terminals the correct way and also will fit in my existing battery box.

Wondering if any of you guys have had any experience with these batts and that ive made the right choice?


thanks in advance - Enzo.

[schrader7032]

Welcome! The Odyssey battery does seem to be a good choice for people. According to the Odyssey site, the PC925L is the battery for your bike. Not sure about terminals, but additional brackets should be available to suit your needs. Also not sure about sizing but it should fit.

I'm more of a fan of the old "wet" batteries as the charging system was designed to work specifically with those types of batteries. The newer types of gel, AGM/VRLA batteries will work but life could be compromise to a small degree. Also, the newer batteries don't give much of a warning they're beginning to die..."wet" batteries tend to show their age little by little.

Good luck!

[enzorocket]

________many thanks for coming back to me. Yeah i did see that when I put the details in - but they are much bigger than the 535 - and im going to have some trouble fitting it. Appreciate the advice and feedback!

Enzo

[Hugh003]

I got a Yuasa 53030 battery for my R75/6. It's big - the tool tray doesn't fit and you need to slacken the two sub-frame bolts to install it. You also need to tilt the battery tray back.

[Randolph]

I recently retired an Odyssey PC925LMJ from my R90/6 after ten years. Duty cycle was probably four to six starts/day going to/from work and errands. It still checks okay at 400CCA. The new one checks okay at 1,000CCA.

[khittner]

In all likelihood, you're going to want more amp-hr. capacity and cold cranking amps than the PC535 provides. The charging systems of airheads are pretty reliable, but not particularly strong, and the OE Bosch starter motor draws a lot of power that it takes the alternator awhile to replace, even when ridden at a reasonable pace. Stop and go traffic, and a lot of idling in slow traffic, can run down a healthy battery fairly quickly. The later monoshock airheads came OE-equipped with a smaller battery (18 amp-hrs.?), and many were replaced by the larger ones, like the PC925L, in pretty short order. Many owners did this even though it required the amputation of the extended/deep tool tray that BMW had put in to occupy the space that larger battery previously filled. Even with a more powerful battery than you're currently considering, it'll be prudent to put a charger pigtail on the new battery's terminals and connect up your choice of smart battery charger/maintainer when the bike is not in use.

[Didess]

I always use one of these gel batteries for my bikes:
https://www.motorcycleparts-hornig.com/ ... ttery.html