It is very close in size and should fit but I cant be sure of the quality.
https://www.ebay.com.au/itm/BRAND-NEW-12V-26A-PREMIUM-CRYSTAL-GEL-RAZORBACK-BATTERY/302541001674?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2055119.m1438.l2649

What's not to like? It's got crystals; everybody knows how powerful they are. It's got gel, which is certainly more stable than pudding. It's premium; that's better than second quality. It has a dramatic depiction of a toothy feline drawn on the case to appeal to cat fanciers. It's named after a Australian horror film character that devoured people—a quality to be sought, certainly—and any University of Arkansas alumnus would be happy to own one too, if only it could be shipped to the USA.

To cap it all, it's suitable for toys.

Rick I just fitted a Dynavolt Nano Gel MG 53030 BMW53030. Fits fine except had to twist the leads 90 deg to get it to fit. $183.00 Au bought from Team Moto Virginia. I was going to fit a Motobatt but struck a couple of reports that the quality had fallen off.
Regards Martin.

Just use a hawker Odyssey PC680 that is half the size of the K100 and the same size as a K1100. Fits the battery tray and they are honest enough to tell you the cranking amps (CCA). The amp/hr rate has little meaning in a starter battery.
You could also ask Crystal Gel what the CCA of that battery is, but I would expect them to print that info on the battery if it was any good.

Though relatively expensive, BMW's own 61 21 2 346 800 is an actual silica-type GEL cell battery. It's the universal battery number 53030 size (the smaller of the two steps in the K100/K75 battery tray).

Though not a GEL, but an AGM, I love my Hawker Energy Odyssey PC680 for durability, longlife and cranking power. I've seen 'em last for up to ten years. I have an extra I use as a workshop power source for air pumps, etc. I was given it in 2012 after it was taken out of a police R1150RT, the jacket had swollen up so it was warranteed. I took it home after 18 months on the dealer's to-be-thrown-away shelf and it holds an honest 12.6 volts right now. I give it a charge up once or thrice a year after shop use.

BobT wrote:Just use a hawker Odyssey PC680 that is half the size of the K100 and the same size as a K1100. Fits the battery tray and they are honest enough to tell you the cranking amps (CCA). The amp/hr rate has little meaning in a starter battery.
You could also ask Crystal Gel what the CCA of that battery is, but I would expect them to print that info on the battery if it was any good.

I agree that Cold Cranking Amps is a critical value in a starter battery.

Does anyone have authoritative information on what the CCA requirements are for our K bikes? I've not seen it in any manuals, though that may be just my blindness.

Another question relates to Rick's original post - the battery is labelled further into the ad as a deep cycle battery. Will that compromise it's effectiveness, particularly long term, as a starting battery?

Bill

Deep cycle batteries have a different plate design from starting batteries that reduces slightly(I think 20-25%) the cold cranking amps.  Since these batteries are intended for providing moderate current flows over long time periods they are not usually rated for CCA.

As far as starter current requirements, I vaguely recall seeing 255 CCA a the rquired battery capacity and 20AH(amp hours).

indian036 wrote:[Does anyone have authoritative information on what the CCA requirements are for our K bikes? I've not seen it in any manuals, though that may be just my blindness.

If you look up the specs on the OEM battery - Yuasa 53030 -- you'll note the CCA is 325 Amps and the nominal capacity is 20AH.  You should select a replacement within these electrical specifications but not exceed a mechanical height of 171mm.  There are a large selection of technologies within this range.

When did Yuasa start as a supplier to BMW?

Dynavolt specifications.
Factory Activated Sealed AGM Lead Acid Series with Nano-Gel electrolyte technology.
No messing around with battery acid - just fit and go!
12 Volt 28Ah Capacity [Cranking Amps 490]
Dimensions (mm) - L 178 x W 123 x H 166
Terminal configuration - Negative [Black] LH front polarity
Terminal type - T 3 LEAD construction.
Regards Martin.

robmack wrote:

indian036 wrote:[Does anyone have authoritative information on what the CCA requirements are for our K bikes? I've not seen it in any manuals, though that may be just my blindness.

If you look up the specs on the OEM battery - Yuasa 53030 -- you'll note the CCA is 325 Amps and the nominal capacity is 20AH.  You should select a replacement within these electrical specifications but not exceed a mechanical height of 171mm.  There are a large selection of technologies within this range.

Deepest apologies for bringing a touch of logic into this but a K100 starter relay is rated at 75A and the starter draws around 50A when cranking a hot engine, so I would say that any battery that has a CCA of 325A would be quite adequate for the job. The initial current draw could be up to 150A but certainly not anywhere near 325A.
A smaller battery like a 10AH with 200CCA would start the bike in ideal conditions but if a bit extra was needed at some time, like a very cold morning, then it wouldn't take much cranking before it died.

I very much doubt if there are any CCA requirements laid down for any K bikes. There is no point in having a battery so high and heavy that it supplies twice as many CCA as is requires to start the engine, as that is all the battery does, start the engine.
Not that the old huge wet battery that was fitted to the K100 was superseded by BMW with a half the physical size and weight, gel or AGM battery as they have just as much CCA power as the old one. 
If my big high compression twin cylinder Ducati can make do with quite a small battery then then my lower compression four cylinder K100 would have no problem with the same battery. 
Batteries have come on a long way since they made the K100, like tyres and oil, use the latest and best rather than to old rubbish and you won't go wrong.
As an aside, I tried a lithium battery in the Ducati, weight of the original Yuasa was 3.6 kgs, lithium was 0.6 kgs. The lithium has more cranking amps and starts the bike with no problem.

I use a Motobatt 32AH but for running my CPAP machine and it will run all night and I know that it will start next day where the smaller 20AH it can get a bit marginal if I am using it for lighting as well.
Under more normal circumstances the 20AH is quite up to the job.

My suspicion is that the electrical engineers at BMW would have been fully aware of the CCA requirements of the engine/starter motor in all conditions, including German winters!

It was an era, however, when automotive batteries of all kinds we're overwhelmingly lead-acid, and amp hours were fairly directly related to the battery CCA. Consequently, the KISS (keep it simple, stupid) principle was applied. Conversely, my 10 year old Evinrude outboard's owners manual warns in big letters that you will have problems if your battery has less than X CCA.

I suspected that the original battery CCA was well above the minimum, as confirmed by Rick. When I replace the dead battery on my original old faithful, I'll err on the side of caution. But I'm still curious about the actual requirements. 😀

Bill

Hello!

I’m using a AGM Battery 12V, 18 AH, [url=Kung Long WP 18-12]Kung Long WP 18-12[/url] used for solar panels. Works in winter as in summer. Cheep and good.
With and without ABS.

https://cdn-reichelt.de/bilder/web/xxl_ws/D600/WP18_12I.png

You’ll find it on eBay.

Cheers

I have a 32aH Motobatt on mine - been there for about six years and has never needed recharging 'off the bike'.

To add to Rick's comments about CCA: I can quote the older Guzzi T-series requirements. Guzzi stated 400 CCA (for initial surge) but just 90A when cranking actually gets underway. They fitted a 28aH lead-acid battery to the original Le Mans 1 series 1 but that was marginal if the engine didn't want to play. From the Le Mans 1 series 2 (and all other T-series) it was upgraded to a 32aH Lead acid. Now, IIRC, the battery specified by BMW for the K100 was the same as the one specified by Moto Guzzi for the Le Mans 1 series 1. That's an IIRC - I'm sure Inge will know!

In Australia the 18AH lead acid battery was the standard size for an of the shelf purchase of any of the K100s and K75s the Police bikes had a 28AH lead acid. The larger 28AH was an extra at time of purchase and I think but will stand corrected that the later K100LTs had the larger battery as standard.

Thanks Rick - my post corrected re: the Le Mans series. I've seen the 28aH in an LT and both LFB and Brick 2 also had one. In the case of LFB ('83 K100) I was told that the 28aH battery had been in there from new. It was certainly scruffy enough and completely fecked. I can't speak for Brick 2 (the one I got from ComberJohn).

Dai wrote: They fitted a 28aH lead-acid battery to the original Le Mans 1 series 1 but that was marginal if the engine didn't want to play.
Now, IIRC, the battery specified by BMW for the K100 was the same as the one specified by Moto Guzzi for the Le Mans 1 series 1. That's an IIRC - I'm sure Inge will know!

About what was factory fitted from new, in the good old days.......

When did get my RS it was a 30 Ah battery mounted (which did last 9 years and 2 months).
That was extra/police spec, the standard version was 25 Ah.

But this could vary with which market a bike was produced for.

A thread can take any number of divergent paths from the original poster's intention, which was simply a GEL cell battery at a price. However, we can all use practical info on a particular subject, especially if it strays only slightly from the original subject.

I was chucking cardboard and paperwork into the recycle bin in a sort of year-end clean out of my garage, and found a Yuasa field guide. It contained some pertinent info and so I thought I'd pop a coupla piccies up here that follow the vein of CCA being discussed. Gents, for your persual, I present two pages from Yuasa's 2016 product manual:


The above battery is the "smaller" version of the two which fit the K75/K100/K1100 trays and measures 186mm x 82mm x 171mm (7.4375" x 3.25" x 6.875"). This YT19BL-BS is rated at 170CCA @ -18c and 440CCA at ambient temps.

And if you go for the YTX range instead of the old YT range they are even better.
For example a YTX14-BS is a 20 Ah battery with smaller dimensions that the above but with 200 CCA at -18°. If that is good enough to start a 1200cc Ducati twin with a compression ratio of 12.5 to 1, then it will start a K with no problem. 
It is the battery that I have been running my K on.

On special now at Supercheap.
Katana Powersports Battery - YTX14-BS
322321




1 Rating Write a review
[size=18]Was
Now [size=24] $114.39 each Ends 12/01/18
Regards Martin.[/size][/size]