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  1. #16
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    Why all the hub-bub for AGM? Do folks understand the plus and minuses of AGM vs. flooded cell?
    2005 Magnum RT---Viper Venom Red----440ci Aluminum block----Short Runner Valve Intake--410mm BAER 6S Monoblock Extreme--Eibach Multi-Pro 2

    Custom--Grille Work--Hood--Headlights--Side View Mirrors--Rear Spoiler--Rear Diffuser--SRV Control System--Turbine Wheels




  2. #17
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    Quote Originally Posted by Hemissary View Post
    Why all the hub-bub for AGM? Do folks understand the plus and minuses of AGM vs. flooded cell?
    Definitely interested in hearing from you on this subject. I've got an AGM from Odyssey in my truck though it doesn't make much sense as I drive it almost daily, for a 45 min to 1 hr trip each way. It has lots of opportunity to stay charged and no sitting around to discharge.. So any benefit I might have realized is negated.

    On the other hand, the 300 might not move for 2 weeks at a time, just hiding out in the garage. It's got a regular battery though it doesn't seem to sit long enough to notice any weakness from running down.

    Richard
    06 Silverado ISS / 06 Silverado SS / 06 300C SRT8

  3. #18
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    Quote Originally Posted by Hemissary View Post
    Why all the hub-bub for AGM? Do folks understand the plus and minuses of AGM vs. flooded cell?
    Lithium ftw


    Sent from my iPhone using Scat Pack Forums

  4. #19
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    Main reason more models are going to agm batteries is due to gassing, we are moving more batteries into passenger compartments and agm batteries put off little to no gassing under normal circumstances. Batteries generally fair better in a more favorable temperature range such as the climate controlled passenger area.

  5. #20
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    Quote Originally Posted by someotherguy View Post
    Definitely interested in hearing from you on this subject. I've got an AGM from Odyssey in my truck though it doesn't make much sense as I drive it almost daily, for a 45 min to 1 hr trip each way. It has lots of opportunity to stay charged and no sitting around to discharge.. So any benefit I might have realized is negated.

    On the other hand, the 300 might not move for 2 weeks at a time, just hiding out in the garage. It's got a regular battery though it doesn't seem to sit long enough to notice any weakness from running down.

    Richard
    I posted this a few years back: Lead Acid (Flooded) Battery Basics

    There is way too much going on with either battery technology to spell out, so I'll touch on the basics.

    Advantages of AGM (Absorbent Glass Mat)
    - Will not spill acid when tipped over (its trapped in the AGM)
    - Lower internal resistance; when compared to flooded cell (FC) lead acid batteries, AGM batteries will self-discharge at a slower rate, offer more current to a load, can be charged faster at a higher (current) rate and therefore provide more current at lower ambient temperatures
    - No venting, unless abused (vents are sealed, but once the seals are broken service life is significantly compromised)
    - Can be deep cycled; this means AGM batteries can be discharged to ~80% of their rated capacity (FCs - only 50% before permanent service life losses occurs)

    Disadvantages
    - Very sensitive to overcharge; maintenance charge (otherwise known as float charge) must be held to 2.25 - 2.30V / cell (multiply by six for 12V batteries). This means our typical automotive charging systems with a nominal 14.40V can overcharge AGM batteries. During warm weather, this will significantly reduce service life
    - Maintenance (trickle) chargers used for FC batteries are overcharging AGM batteries
    - Do not like heat at all
    - Steady decline in amp / Hr capacity
    - Relatively low specific energy (i.e. energy density) compared to FC (similar rated FCs can supply more on-demand current).

    To summarize; IMO AGM does not offer enough advantages over FC to make the extra cost worthwhile. If you tend to play music for example without the vehicle running, the deep discharge aspect could be valuable. Otherwise, the overcharging, sensitivity to heat and steady capacity loss (FC offers more of a performance curve as opposed to steady decline from first-use on).

    I'll leave the other thread to extol the advantages / disadvantages of lead acid flooded cell batteries. Its worth noting though, the term cold cranking amps (CCA) is marketing flotsam. For starters, everything to "acquire" that advertised marketing value, for example test temperature @ 0C, for only 30sec and maintain only 1.2V / cell. In the real world, paying more for a higher CCA (bigger dick syndrome) has no bearing on starting 99% of the vehicles at any particular time of the year.

    Its also worth repeating that thee best FC batteries on the market are NOT aftermarket name brand - no matter what the marketing BS happens to be. The best are what a / any Dealership sells. Why? Cause no Vehicle Manufacturer can afford to put cheap azz batteries in new cars that offer crappy service life, they've got the be those offering the highest service life available. Did you know that there are only a few FC Manufacturers across the continent; only one has a reputation above reproach - East Penn. Any and all FC lead acid batteries manufactured by East Penn that are marketed by resellers are considered top of the heap. So ask who(!) actually makes a name brand before buying.


    Quote Originally Posted by DBL.DWN View Post
    Lithium ftw


    Sent from my iPhone using Scat Pack Forums
    Lithium (Li-Poly / Li-Ion)
    Lithium, especially Lithium Polymer is f'n dangerous...this can not be understated. Be mindful of Lithium technology, even the hard-cased cells in your laptop and especially the Li-Poly (formable) in cellphones. Many who build / fly model aircraft have burned down their cars or houses by not following precisely the charging regime that is an absolute requirement for this technology. The amazing properties of Li-Poly energy density is difficult to adequately describe; A high performance 4-cell Li-Poly pack of say, 4000ma (4 amp hour) can supply upwards of 280A continuously with a short term burst (in the milliseconds) that is well in excess of 1000 amps. All this from a four cell pack that are connected in series with a form factor of ~5" x 2" x 2".

    Lithium must never be overcharged...nor must they be allowed(!) to fall below their rated discharge voltage (~3.0V resting)! Lithium absolutely requires specialized smart chargers.

    Note that both technologies are called out as 3.6-3.7V nominal per cell. Fully charged is ~4.2-4.35V depending on cathode material and electrolyte configuration. If overstressed , deep discharged or overcharged, once a cell reaches thermal runaway, it can not be extinguished and creates a cascading failure by igniting adjoining cells until the active agent has been consumed (Lithium - while oxidizing produces its own oxygen).

    Storing at full charge is a no-no. Li-Poly in particular loses capacity and runs the risk of swelling (out-gassing) if left at full charge. We monitor voltage / capacity and after every flying session use the special / dedicated smart chargers we use to discharge each and every cell to 50% of their rated capacity. This is where typical Lithium technology's (again - depends on cathode / electrolyte) point of equilibrium resides (the safest for storage).

    As far as using Lithium for a vehicle battery; There's zero reason, unless its an all-out racing environment requirement where every last gram of weight saving is paramount. No matter what, they will require battery management smarts (either built in or as an ancillary).

    Many years ago, during the design phase of a standalone backpack-based GPS / DGPS positioning system that could also be mounted on an ATV or Vibrator (seismic), I designed a 21.6V battery pack that used series / paralleled 18650 cells. In order to utilize Lithium technology (relatively new at the time), we needed to show that in a field environment that these battery packs could consistently (100%) supply start-up / boot-up PWR at -40C, operate continuously for 9hrs on one charge, be hot-swappable with a replacement pack for uninterrupted data transmission....and were actually safe(?) to use. This required building packs and testing in a protected / secure environment in any manner possible that would create a hazard. Needless to say - this aspect turned out to be not only a lot of fun but spectacular. Catastrophic failure, fires, explosions, toxic gases were observed until we reached conclusive data that defined operating limits and charted the service routine required for safe operation by warm bodies that were not likely to have the needed respect required(!) in typical field environments :^)



    To give some credence to my intellectual knowledge, batteries and I go a long LONG ways back in both professional electronics-based design / application and my favorite hobby / sport. For starters, they are the blood in your veins when it comes to model aircraft (battery failure = no control). This includes flooded cell / AGM batteries that are used for starting, winch-launching or supplying current to field charge other airborne systems / propulsion batteries (NiCD / NiMH / Li-Poly-Ion). Nowadays, for flight systems we now use exclusively Lithium Polymer (LiPo, bagged cells) and Lithium Ion (Li-ion, hard-cased), specifically 18650 (cylindrical; 18mm diameter / 65.0mm length) cells to configure packs to meet specific voltages. For example, a jet turbine I fly has four separate battery packs; 2 for control systems (redundancy), 1 for jet turbine start-up / control, 1 for electric retracts / brakes.
    Last edited by Hemissary; 01-18-2019 at 01:16 AM.
    2005 Magnum RT---Viper Venom Red----440ci Aluminum block----Short Runner Valve Intake--410mm BAER 6S Monoblock Extreme--Eibach Multi-Pro 2

    Custom--Grille Work--Hood--Headlights--Side View Mirrors--Rear Spoiler--Rear Diffuser--SRV Control System--Turbine Wheels

    Thanks Dextar thanked for this post
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