Battery Charger - Back Current

[David.]

Exide have phoned me back and confirmed the following, both the BMW OEM (Exide) and the Exide aftermarket batteries are identical.

The difference is at what temperature the CCA is quoted. BMW is 200 CCA at -10 degC whereas the Exide is 170 CCA at -18 degC which is the EU standard.

By specifying the CCA at a higher temperature, BMW make their battery look better when it isn't.

See this Yuasa guide, Guide to understanding battery specifications (yuasa.co.uk)

[Casbar]

Excellent David, great bit of research  8)  Think I'll see if there is an issue with the battery or something else is happening, then buy the battery from somewhere else. If its cheap enough, I'm not bothered if it has a 1 or 2 year guarantee, don't want to effectively pay extra for an extra years guarantee

[David.]

If you've got or have access to a voltmeter, that should be all you need to diagnose the battery. Alternatively, remove the battery from the bike, fully charge it and take it to an auto electricians and ask them to load test it. Or, if the bike won't start, call BMW Emergency Assistance and let them do the diagnosis.

Then, if it's duff, buy this Exide one for £45, AGM12-16 EXIDE MOTORCYCLE BATTERY 12V 16AH 170A 4920 | AGM Batteries | Batteries & Power Electronics | Battery Group

[Casbar]

I can measure the voltage etc, but can't measure the drop or simulate the load when cranking. You can measure the drop with a multi meter that has a recording ability, but its not as good as a load drop test. Guess I'm more worried about if there is something else going on. Not bother about buying another battery, I might just get one and see how it goes.

[David.]

Measure the battery voltage after it's fully charged.

If you keep an eye on the multi meter whilst starting the bike, it'll give some indication of what is going on, a min. of 9.6v is recommended.

Once the bike is running, check the voltage from the alternator/voltage regulator, should be 14.2v - 14.8v.

If the charging system on the bike is u/s, you'll just knacker another battery.

[David.]

I see that R1250RT's have an on-board system voltage warning, if this is not displayed, hopefully the alternator is functioning correctly.

Has this replaced the voltage display on the dash.

[Casbar]

Ive ordered an exile 12-16 delivered for £48, hope your are correct and its the same CCA as the BMW one  8)

[David.]

I can only report what Exide told me but you have saved £50.

[David.]

Has this replaced the voltage display on the dash.

Found this video, "How to monitor battery voltage during start 2013 BMW R1200GS", https://youtu.be/a-D81Tyo5Ss

In this example, the voltage starts off at 12.4v, drops to 11.9v when cranking and recovers to 14.1v with the engine running at idle speed.

Must be because the GS is the better bike.