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Old 03-08-2012, 03:35 PM   #143
JoelWisman
Beastly Adventurer
 
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Joined: Apr 2009
Location: STL, MO, USA
Oddometer: 1,389
My two cents:

Some of the discussion about lead/acid batteries here has been about lead acid batteries "loosing capacity" as it gets colder and becoming "less efficient".

This is true depending on how you define the words, but I think it is probably giving people not heavily educated in batteries the wrong impression.

No battery chemistry I can think of looses amp hour capacity with lower temperatures. What does happen is the battery looses the capacity to support a given electrical demand continuously without falling below a specific terminal voltage.

In other words, if you leave your headlight on without the engine running and it is super cold, fairly rapidly the sluggish chemical reactions in a lead/acid battery will lag and your bike won't start up long before the actual amp hours of the battery are depleted.

Now, turn the key back off, wait 20 minutes for the cold sluggish chemical reactions to ketch back up, flip the key back on, and that capacity less whatever was withdrawn is still there and you can fire the bike right up.

Of course if you leave the key on again or have to crank for a long time and you will have to rest the lead/acid battery again before it can start the bike.


Same thing with the use of the word "efficiency" It is being used in a way that implies that the battery looses ultimate capacity with temperature. It does not, it simply looses efficiency at keeping up with continuous demand. The lead/acid battery converts chemical energy to electrical energy just as efficiently when cold as hot. Thats to say, the losses when converting are nearly the same at different temperatures, it is simply not as efficiently at doing it quickly.


CCA as it has always been defined is only somewhat applicable to modern adventure motorcycles. CCA IS the minimum number of amps the battery will flow at a temperature of 0 F for 30 consecutive seconds without falling below a terminal voltage of 7.2. This is kinda sorta applicable to an R80GS, though I don't know anyone that would crank an R80GS for 30 consecutive seconds, but 7.2 terminal volts is not relevant to more modern fuel injected bikes because the computer checks out from low voltage long before that threshold is reached.

I think pulse amps for 5 seconds is far more relevant at differing temperatures with rest times between attempts to start. With anything other then a diesel this tends to be how people attempt to start an engine and rightfully so.

The 5 second pulse capacity of lead acid batteries is very good, even at oh my god cold.

What isn't so good and screws many people that ride in extremes is just how much more current is required to crank over a super cold engine. I for instance have ridden in minus 40 F, and don't even bat an eyelash when it is merely minus 5 F.

My capo takes 1mS peaks of 340 amps and a 3 second average of 259 amps to start at minus 5 F. The computer remains conscious down to 8.9 battery terminal volts but it, the starter and ignition system would sure like more.

Shorais application chart for batteries is a bad joke, as is their Q&A. They now list the LFX21 as recommended to start the BMW F800GS, up from the LFX14 they used to list. I suspect this reflects that they have noticed that F800GS riders are adventuring into temperature extremes and possibly they are noticing battery failures due to imbalance that is not self equalizing at the F800GSs anemic 13.8 volt charging regulation, but whatever.

They also currently list the LFX 14 for the Aprilia Caponord. This is comedy. The F800GS on it's worse day at the north pole is easier to crank and starts quicker then The Capo in a southern californian summer.

In Shorais FAQ section they state this:

"In any case, CCA ratings aren't about actually drawing that much current from a battery. The typical vehicle which uses a 200A CCA-rated battery, for example, will only draw 45A~80A from the battery. What the CCA rating really intends to convey is how much voltage will be delivered."

What planet are the guys writing Shorais web site from??? I may be willing to buy one of Shorais batteries, but if I do it will be despite the bull they are shoveling on their web site.

45A-80A from a bike with a 200 CCA battery? Get real. The BMW R1200GS, F800GS, ST, S, R, K1300S, Aprilia Shiver Caponord, and Falco all take a 200CCA battery. The shiver is pretty good only needing about a 110 amp 3 second average to start, on a warm summer day but the rest of them are in the 130 amp range or more on a warm day, more when cold.

I am much more pleased with Antigravity, assuming these made up "pbeq" numbers hold any stock between manufactures, as they list a 12 cell for standard duty on the BMW F8 and R12GS as well as Caponord and 16 cell for high power.

Ballistic is recommending an 8 cell for the Caponord, R1200GS, F800GS and a 12 cell for the R80GS. What??? You can kick start the R80GS! I have started R80GS with a 6 volt battery in the field :) It was very warm but thats a bike that doesn't need much terminal voltage to fire.

P.S. Shorai, Ballistic, Your application charts are flawed, Yours too AntiGravity, though just in model years shown, your recommendations seem better. I have screen captures from my scope while measuring cranking amps with a shunt rather then a clamp that gets mislead by strong magnetic fields from the starter and solenoid. I have them for almost everything BMW currently makes as well as Aprilia and most go Guzzi.

I have paperless recorder charts of many of these bikes stock voltage regulator behaviors and a little knowledge too, such as, the R1200GS has an actual pinion that gets shoved into a flywheel as well as a computer that disconnects the starter below 9.8 volts for 100 ms. Cranking it into low voltage makes BMW dealers happy because over time it wastes the flywheel teeth and allows us to bill for pulling the tranny, but it will loose you customers when we explain your fancy but too small battery is responsible.

The Caponord comes complete with an electrical system only the French, Italians, or Brits could design. Voltage drop through the pathetically small solenoid and super long small gauge starter cable is horrible.

The F800GS R/R is a mistake. Voltage is set as if charging a gel battery. Heck, even the BMW's that actually come with a gel battery have a higher charging voltage then The F8. This and slight leakage differences between cells may be killing your batteries. I have a Shorai from F8 duty with 45% imbalance and many stories on the web of sudden death of Shorai batteries in this bike.

Knowledge and screen captures are free to whatever manufacture wants it out of goodwill to the motorcycle community. But all of your application charts are terribly flawed, and recommended battery sizes of at the least Shorai and Ballistic are crazy. Once again, AntiGravity, you seem better with the recommendations.

Alright, long random post. I will finish with this. We need some standardized test data to find differences between brands as well as some specific info for the particulars of the adventure community.

This thread has some good info, but what a lithium battery will do in an R80GS with a modified charging system is good to know but does not tell us much about the remainder of the field. An R80GS is super cool and I envy you _cy_, but that has to be one of the retest adventure bikes still in use on this planet and bares little resemblance to the charging and starting characteristics of more modern bikes.
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Owned to date. Honda Aero 50, Honda Elite 80, Honda Elite 250x2, Suzuki Katana, Suzuki RF600, Yamaha YZF1000R, Kymco Xciting 500, Suzuki GS500, Suzuki Burgman 650, BMW F800GSx2, BMW S1000RR, Aprilia Scarabeo 200, Aprilia Caponord, Aprilia Sportcity 250
I love and miss you Jeneca and I'm sorry.
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