jodeb720 wrote:
I'm going out on a limb, but I'll bet he'll end up with a set of GC's and will need a way to recharge them when he gets home to full top them off.
Few, if any currently offered 'garage' chargers is actually going to be able to 'top off' a deeply cycled battery even if new, and especially not an older one. Like almost all automatic charging sources, they guess, or have a preset algorithm as to how long to hold higher voltages, and drop, almost always prematurely, to a float voltage where little to no charging occurs, and certainly cannot top off a regularly deeply cycled battery(s). This is the single biggest cause of premture lead acid battery demise on the planet. Living chronically undercharged.
Also it is possible that plugging in a few hours here or there might occur, and 12 amps is a pitifully low amount of charging current for 220Ah of depleted battery. A pair of healthy depleted GC-2s can accept what? 65 amps for a good period of time before battery terminal voltage rises to mid 14's. So a 65 smp charger can do in an hour on a healthy capacity of depleted battery, what would take a 10 amp charger 6.5 hours.
Ignore the battery amperage Nannies who say low and slow is always best. low and slow is only best when time to recharge is NOT a factor and the charging source can and will seek then hold higher voltages for as long as is required to maximize specific gravity, before reversion to a 'float' or maintenance voltage.
Good luck finding a bells and whistles automatic smart charger of more than 25 amps, but that is really the minumum I would recommend for a pair of GC-2's.
I'd buy the 36 amp Megawatt or A 350 to 500 watt Meanwell adjustable voltge power supply for under 100$, remove the cover( 5 screws) and upgrade the 60Mm fan to something larger and dual ball bearing, set it to 14.4 to 14.8v unloaded, and run it through a 8 hour intermatic spring wound timer then attach clamps to battery posts.
The Megawatt will have 36 amps available to seek a chosen absorption voltage and then hold it as long as the spring wound timer has not expired.
What absolutely is annoying as all Eff, is an Automatic charging source wich consistently stops well short of full charge, no matter how many times the surface charge is removed by loading the battery, and the unit restarted. Been there, done that, and the charging source was lucky to not be swung by its ac power cord into the nearest telephone pole followed by a string of violent curses that turns the skies black and the neighbors running for the hills.
My neighbors have all sorts of different battery chargers they have/had a ridiculous faith in, until I come down with the hydrometer and find specific gravities still deep in the red, below 1.220, and then put my Meanwell rsp-500-15 on it set for 14.8v, and 6 more hours are required and about 20 to 30more AH required to actually fully charge the starter battery that their chargers said were fully charged.
It becomes a lesson in futility to actually fully charge the battery with most automatic 'smart' underchargers. Full charge is NOT determined not by a green light and well worded marketing of the latest and greatest charger offered to the battery ignorant public, but by a temperature compensated turkey baster style of hydrometer on flooded battreies. Amperage the battery is accepting at absorption voltage is another good indicator, and absolutely necessary for verifying full charge on AGM's.
Getting regularly deeply cycled batteries back to full charge is the best way to get ones money's worth from deep cycled lead acid batteries, and few if any current offerings in the garage charger market will be able to maximize specific gravity of such a battery, and this statement is provable, time and again, with a hydrometer and the gumption to actually use it, or the Ammeter withteh batery still at absorption voltage, or both.
A proper charging source which can actually achieve a true full charge, will pay for itself in extended battery life. Hoping and praying the green light on most automatic charging sources marketed to the general public, is not mocking you, is foolhearty at best.
Generally they are a waste of both money and time, as they cannot do what they say they can, which is truly fully charge a battery. They will certainly charge a starter battery enough to start the vehicle, but this is hardly a benchmark one should be proud of. Many vehicles in need of a jumpstart could likely have a 100 watt solar panel hooked directly to the battery aimed at the sun for an hour and allow the engine to start. It does not really take much battery capacity to actually crank a modern fuel injected gas engine.
Putting a handle on, and sacrificing a pair of 8awg or thicker copper jumper cables on almost any converter, Progressive Dynamics, Iota, or Powermax, will be so incredibly superior a charger than any of the sleek plastic covered sexy garage chargers one can buy in walmart, it is ridiculous. The battery will last so much longer when they are truly fully charged that the ROI on the converter turned portable charger, might easily be realized on the first set of GC-2's.
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As far as alternator charging goes, I got an E-mail from Renogy today advertising a new 20 and 40 amp DC to DC charger for a fraction of the price of similar devices, which will raise or lower vehicle voltage to the house battery for more complete battery charging, and eliminate the need for any other isolation device, whether triggered solenoid, or Diode based isolator or the thousand other products marketed for this purpose.
https://www.renogy.com/renogy-12v-dc-to-dc-on-board-battery-charger/
I've no experience with this product nor do I have any affiliation for Renogy and cannot and will not vouch for its quality or function, but similar devices by other companies are much more expensive.
What one can get away with, is a matter of 'for how long'.
Charging deeply cycled lead acid batteries fully is vital to their longevity, so saving a few bucks initially, Will quickly cost more money when those batteries fail prematurely from chronic undercharging, which is practically guaranteed with most currently available 'smart' chargers.
Spend more on a product which can do what it says it can, rather than throwing away money on something ultimately futile and disposable.
