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Premium Member
2013 KLR 650/692, 2017 HD Electraglide Ultra
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More electrical crap to power.

But battery technology has also advanced. The amp-hours tell you how long you can hold down the starter button before the battery discharges, whereas the CCA tells you how much peak current it can deliver to get the bike started when cold. I always thought 14AH was overkill. Save a little cost and trim a little weight by going to an 8AH battery. (Yes, Damocles, I know you know this, but not everyone else does)
 

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Premium Member
2013 KLR 650/692, 2017 HD Electraglide Ultra
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1,540 Posts
Paul, then you should be more concerned with CCA than AH.
 

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Premium Member
2013 KLR 650/692, 2017 HD Electraglide Ultra
Joined
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1,540 Posts
From my above posting, I think it shows that I am.

The starter motor is only Capable of consuming 'X' amount of amps. But I don't know what 'X' is and I have no way to measure it. But the longer one cranks on a starter motor the Less amps there are available from any battery, correct?

Would one be in total error to suggest that we might consume 10% of possible maximum CCA with each 5 second cranking cycle of a starter motor at 0 F? Maybe 5-8% consumed at 32 F?
Not the same thing. Think about those deck-of-cards size lithium battery packs that can start a big V8 engine—lots of CCA (cold cranking amps), but not a lot of AH (amp-hours). Lead acid batteries keep about the same voltage level as they discharge, until they get about 80% discharged, then they “fall off the cliff.” And they deliver about the same CCA (cold cranking amps) until that “cliff” point too. Other factors being equal (and they rarely are), a higher AH battery will deliver the same amps for longer, or more starts, before it reaches the cliff. A higher AH battery usually is bigger and has bigger internal components, more plates, etc., so that it usually also can deliver higher CCA, but not necessarily. It depends more on how the battery was designed and for what usage. RV/boat “deep cycle” batteries do not need to deliver high CCA, but they do need to maximize AH and be able to take the abuse of deep discharge cycles.

Starter current: there is no maximum “consumption” of amps on a starter motor, (until you reach its mechanical torque limit or you start melting insulation!). It will draw whatever it has to draw to turn over the engine. When it’s really cold, your starter probably draws twice the amps as when it starts a warm engine.
 

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Premium Member
2013 KLR 650/692, 2017 HD Electraglide Ultra
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1,540 Posts
PDW: yeah that’s it—save people from themselves!
I don’t know how much current the starter will draw before it turns into a smoke grenade, but that will be the result!

Damocles: Full discharge usually ruins a lithium battery, so most lithium batteries have built in circuitry to prevent them from going to full discharge. It appears that the battery just stops. Lead acid batteries, with some design variations, keep their voltage pretty constant until they reach the “knee in the curve,” after which they drop off quickly. IIRC, a fully charged LA battery reads 12.6 volts, but an 80% discharged one reads about 11.8. This is from ancient memory, so I could be off by a couple tenths.
 
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