Too late? Maybe handy FYI?
The Odyssey battery shown is a type that is commonly(?) called AGM (Absorbant Glass Mat), recombination, etc etc. These are NOT lead-acid, NiCad, Gel etc. They are zero maintenance in terms of adding water etc (they are "dry").
In theory they are a perfect battery for cars etc EXCEPT that they do not tolerate overvoltage nor undervoltage. Many years ago, Exide released the "TorqueStarter" batteries which were the of same type. They recalled them after about 12 months due to failures (exchanging them for lead-acid types). The reason was that many vehicles would charge > 14.5V, or the battery would be discharged below acceptable limits (about 10.5V - or 1.75V per cell (6 cells) from memory).
I was heavily involved in batteries for Telco systems some 15 years ago. We'd typically use these AGM types for UPS (Uninterruptible Power Supply) systems. (Back then lead-acids were common; these days AGMs are almost always used).
I remember the general principles though some details are sketchy (eg, charge rates).
Ideally AGMs are recharged using "constant current" (25% of C10 capacity I think) but not above 14.5V. Above this, the battery could be harmed. In severe cases, a runaway thermal overload would occur (I've seen a 400V bank of 12V AGM blocks with totally distorted cases!).
AGMs have no "loose acid". Instead they have an "acid-soaked" gauze or mat that surround the lead (or whatever) elements. Break an AGM's case and they may still hold charge for a day or two.
There brilliance is lower internal resistance than other (lead acid) batteries. Hence the Odyssey 680 - a mere 16AH (@ C10 rate) battery much smaller than a Piazza/Impulse etc car battery - has a CCA (cranking capacity) of about 250A (compared to say 440A for a normal Piazza battery).
They are great for high-discharge applications (engine starting). They also have excellent storage capability (unused lead-acids should be charged at (say) no more than 3 month intervals; AGMs can survive more than 6 to 12 months without top-up).
They're probably the best battery for audio-buffs with big power demands and crap all over any lead-acid battery with OFC (Oxygen Free Copper) leads, gold-plated terminals and any other associated accessories as flogged to most hi-spending audio suckers (noting some exceptions to my generalisation!).
If an AGM battery is dischared, it must be recharged quickly to avoid damage (lead-acids are nowhere near as critical).
Exact details vary with manufacturer and the exact type of construction. For example, for Odyssey, see
http://www.aeroparts.com.au/odyssey_air ... rom_ae.htm - note the claimed >1,800A short-circuit current for the 16AH Odyssey 680!
Note - DO NOT short-circuit AGM-type batteries (as a PC hard-disk found out when dropped on my UPS's 12V AGM battery) - normal car batteries are bad enough!
See also
http://www.odysseybatteries.com/charging.htm. Google etc will have other good battery refs for those interested, but even I have been ... er ... confused by all the info.
Whilst AGMs are not "publicly released" for auto applications because of the above, many find them terrific for bikes, cars etc despite the harsh charging and discharge conditions.
Even I was impressed when a mate went to his old 1967 Isuzu Bellett - untouched and standing idle for 2 years with its still connected, 10 year old (since it was obtained second-hand!) AGM battery - and started the Bellett within seconds! (It was a Gates 40AH type; new cost about AUD$240 in 1990.) And I'm lucky to pull 4 years from good lead-acid batteries! (PS - "WITHOUT PREJUDICE" - stay away from Apollo batteries unless they have improved in the past cople of years.)
I have some scavenged-for-free Yuasa 38AH and SBS 40AH AGMs that I may use in my Piazza and Isuzus. If AGMs survived my mate's 1960's mechanical-voltage-regulator'd Bellett, it's worth a try!
Generally, AGMs can be used in any orientation (including up-side-down). If not for their initial expense and the complications above, I'm sure all vehicles would use them. Maybe when we convert to switched (stator) alternators or 48V car systems?
Note too that the smaller AH capacity is not a problem provided it can crank (CCA) say 100A for starting; that accessories/loads are not supplied for a long time without adequate alternator charging (the AH capacity at a certain discharge rate (C1, C10, C20 etc) determines this), and that the alternator adequately handles any load (once recharged after starting, the alternator supplies all required power - the battery merely acts as a "reserve" (like a capacitor) when loads are switched on/off until the regulator etc respond (eg, a car without a battery usually stalls if indicators or stop lights are used; PS - do not run an alternator without a battery unless some 12-14V "reference" is provided to stop the alternator output rising and frying any loads!).
More bluddy ramblings from me! And to think I've responded to a Septic inquiry! (Just stirring - I have to keep up my Ozzie pretence!)
I'd be interested in how the Odyssey 680 fares in a Piazza. 16AH seems a bit small, but.....
Cheers,
Peter (IZU069)
IZU069 - ISUZU means a lot to me.
