Importance of battery amp/hours - BMW Luxury Touring Community
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post #1 of 4 Old Jan 2nd, 2008, 10:15 am Thread Starter
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Importance of battery amp/hours

A number of members recommend the Odyssey PC 680 as a replacement for the factory gel cell. The PC-680 has 17 amp/hours while the original battery had 20 amp/hours. How important is it to match the original 20 amp/hours? Are there other factors that are involved that make the amp/hours unimportant? Thanks
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post #2 of 4 Old Jan 2nd, 2008, 2:13 pm
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Location: Casper, WY, USA
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A 20A/hr battery will run for 3 hours longer at one amp draw (in theory at least) than a 17A/h battery.

What's important for a start battery is the CCA value. Can the battery in question deliver the amperage at design voltage needed to start the engine reliably and repeatedly? And have some reserve for hard start situations? There are a whole boat load of other factors come into play. Charge level, ambient temps, oil, etc, etc. But the CCA number is a better value to consider for comparing starting batteries than A/hrs

The attraction of the Odysee is it's ability to survive deep discharge as well as operate near the norms of a conventional lead/acid setup. Most LA setups, if deeply discharged (left those lights on? Turned the key to far when parking again, eh? or like me - left all the radio gear running.) will degrade their ability to provide sufficient amperage at design voltage for starting. Do that enough times and you've a toxic paper weight. I've collected several.

I've been using a 17A/hr rated battery for better part of 3 years now - no issues at all. I've run it totally dead many severals of times too (those pesky radios!) and it still keeps on going. The 'traditional' LA battery I used to have "died" totally on me after the 3rd accidental deep discharge. That's when I started looking for an alternative.

Marine style batteries - like those used for trolling motors - are designed for deep discharge, but they don't supply the short durration, high amperage power needed for starting - well. They'll do it a few times, but it degrades the battery for deep discharge. Kind of the reverse of a traditional starter battery.

The Odysee is designed to do both - deep discharge AND high Amp starts - reasonably well. It doesn't do either as well as a single purpose battery might - but it does do both better than a either type of single purpose could.

So, if you're after maximum CCA or you're after maximum A/hr - each of those qualities are aimed at different duties. Choice is good!!

Me? I want my bike to start in spite of my in-attention to a couple extra switches and my laziness at not installing a 'cut-off' relay - yet. So far - it's done very well for me.


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post #3 of 4 Old Jan 2nd, 2008, 2:21 pm
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I had the pc680 and felt that it did not "fast" crank the engine as the original battery. A few years later I switched to the Westco 12V20P battery and it made a big difference in turning the engine over. The westco is rated at 20 AMP hour and has a CCA of 275, in which the pc680 is rated at 17 AMP hour and 220 CCA.

Mike Trevelino
Williamsburg, VA
2008 RT
2000 LT - Totaled at 99,960 miles

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post #4 of 4 Old Jan 2nd, 2008, 2:53 pm
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I have never used the Odyssey battery so I can't comment directly on its' merits. I have been using the Panasonic LCX1220P for the past year and a half and have been very pleased.

See this post for a recent battery update.

Res ipsa loquitur, sed quid in infernos dicet?

Alan Stuber
2003 K1200 LTC Titan Silver
Austin, Texas

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