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This idea for this post was suggested by my friend Bill Bullers of BBRacingLLC.com. He asked me for a 'cheat sheet' type of thing to explain the terms we use to explain our batteries capabilities. That seems like a very good idea so here I am, on a Friday afternoon, doing a quick post. I hope people find this helpful.
I'll use one of our popular drag race batteries as an example. The P.10S is used in Hayabusa. It is more than capable of starting the biggest engines, and easily supports 'total loss' systems on nitrous bikes.
Well, how do I know that for sure? Do the specs of the battery give an indication?
Yes, they do.
P.10S has the following specs:
720ca (cranking amps)
12ah (amp hour) 'capacity'
13.2v (volt)
For drag race motorcycles, let's agree that the charging system doesnt get much of a chance to actually charge, since the bikes are running for such a short time. Further, a motorcycle charging system doesn't actually work below 2500-2800rpm (Hayabusa). So, if you look at how you are using your bike at the track, it should be clear that you are going to need to understand 'capacity'.
We measure capacity in AH (amp hours). This is the amount of power (current) that the battery can supply for 1 hour. So, the P.10S can supply 12 amps for 1 hour. Or, 24 amps for 30 minutes, and so on. Now, if you have a Busa, it is likely that you are using between 15-30 amps while idling, and more during the run. Oh, and you also used a bunch of power to start the bike. And, dont forget about all that time you had the key on while you were downloading data and making changes to your ECU.
Boy, that capacity figure is pretty important.
How about the charging system? Shouldn't that recharge the battery?
No, not really. The Busa charging system produces a max of 35 amps- but remember it only does that around 5000rpm and above. How much time do you spend at or above 5000rpm at the track? My observation is that this is maybe 45 seconds total.
So, you spent all that time playing with the ECU, starting the bike multiple times, putting heat into the engine before you roll to the lanes...so it wont be long before your battery is almost empty.
This is why we also strongly suggest using one of the Optimate chargers at all times when you are at the track. Notice how the top teams treat their battery and charger setups- they keep them plugged in at all times. Why? Because they know that a fully charged battery means hotter spark, which means more HP, which means they just put you on the trailer.
How about ca (cranking amps)? This one is simple- this is the amount of power that our batteries will produce for 5 seconds. In my opinion, if your bike hasnt started within 5 seconds, you have a big issue to resolve.
Voltage is the last spec to consider. All bikes run what is called a '12 volt nominal' system. Our 13.2v battery is considered a '12 volt nominal' battery.
Now, we also make 16v batteries for motorcycles and cars, but these really cant be used in bikes running a standard ECU or standard coils. 16v systems do offer significant advantages over the 12v systems, but they also require additional parts and tuning.
Now- I was asked to say a few words about charging lithium motorcycle batteries, because apparently there is still confusion about this- despite the blog post that I wrote nearly a decade ago. That is also the most visited page on our website, so it might be cool to read.
Given that page is now quite old, I am going to create another post this weekend which will explain what chargers we recommend, why using the correct charger is important, and finally, why you should not use the charger from your RC car collection on your new motorcycle battery.