An additional long-winded "word" on batteries. I conducted extensive research when setting up the electrical system on my boat (dead batteries out on Lake Huron = very bad). Ignore any marine references that are NA to autos.
Short Summary: Learn the basic/critical facts about batteries and battery care, and buy the best you can afford.
I generally buy the best for the money, comparing the various ratings, amp hours, etc. I don't scrimp on them, but don't seek out the cheapest either. On my boat I have O'Reilly/SuperStart Marine Deep Cycle batteries because East Penn is a well-respected U.S. battery manufacturer and O'Reilly always handles warranty issues very well, wherever I go in the U.S. And for the quality, O'Reilly prices are very good. In my 2008 Yukon 6.0 I have an AutoZone Duralast Gold battery (Clarios/Johnson Controls), same rationale re: price and warranty.
The information below is an unedited compilation of research I did when I was figuring out the best battery set up for my boat (long-range trawler; 2 x gas V8 engines; 4 x house marine batteries; 1 x start battery; 1 x battery for the windlass and bow thruster; 1 x emergency spare; alternator, shorepower/charger, and solar charging of all Batts). The basic information is obviously valid for car batteries. And the details will certainly be more important in cold climates.
Research
- Heavier = better (more lead/plates/stronger case).
- Avoid batteries made of recycled lead. I guess this is where all the cores wind up. From a pure chemistry standpoint, I don't know why recycled Pb would be any different then "virgin" Pb, but that's the conventional wisdom among battery "experts.'
- Minerals in tap water can affect charge-discharge-charge transformation re: PbSO4/Pb/H2O/SO4/H2SO4 chemistry. Have a jug of distilled water handy.
- Do not charge a Batt that is low on electrolyte – the electrolyte must cover the tops of the plates.
- Do not overfill the electrolyte – just up to the bottom of the fill port is good.
- Paint the Pos/+ terminal area with RED paint to avoid mix-up.
- When connecting/disconnecting Batts, always disconnect the Neg/- terminal first and reconnect it last.
- Ah (Amp Hours) relates to how many amps can be drawn from the Batt at a constant rate for 20 hrs. @ 80° F before voltage drops below 1.75 V/Cell (10.5V). More is better.
- Reserve Capacity (RC) = the number of minutes for which a constant 25 amps may be withdrawn at 80° F before voltage drops below 1.75 V/Cell (10.5V). More is better.
- Cold Cranking Amps (CCA) = the discharge in amps that can be maintained for 30 seconds at 0° F before voltage drops below 1.2
V/Cell (NA in boating climates). General CCA requirements for a 4-cylinder engine is 450 CCA; for a small 8-cylinder, the CCA
requirement is 650 CCA. More is better.
- Marine Cranking Amps (MCA) = the load, in amps, that a new, fully-charged battery at 32° F can continuously deliver for 30 seconds and
maintain a terminal voltage equal to or higher than 1.20 V/Cell. More is better.
- AGM (Absorbed Glass Mat) batteries = sealed/no service; electrolyte is suspended in glass matting, as versus free-liquid = less than upright will not spill; can be discharged below 50%; a low-end AGM = approx. 2 x the cost of a good quality flooded batt = may not be worth the money.
- AGM conventional wisdom: whereas a flooded Batt should not be discharged below 50%, AGMs can be discharged down to 20% before
recharge is necessary. Part of the Flooded v. AGM decision is predicated on the likelihood of discharging a Flooded Cell batt below 50% - not likely under normal circumstances (e.g., 1-2 days on the hook).
- Start Batts v. Deep Cycle Batts:
+ Start: For short bursts of cranking power.
+ Start: Quickly recharged after start.
+ Start: Not designed/intended to be discharged deeply over and over again.
+ Start: Quickly non-functional if used as a house/accessory battery.
+ Deep Cycle (DC): Heavy with thick lead plates.
+ DC: Designed to be discharged to 50% and recharged over and over again. Can be discharged to 30%, but will compromise battery life.
+ DC: Take longer to recharge to full charge than Start Batts.
+ DC: Intended to be used as house/accessory battery, esp. for time on the hook.
+ Dual use Batts are not a good compromise – they cannot perform the house/accessory battery role effectively.
- Charging Phases:
+ Bulk: High-charge phase; up to about 70-75% of total charge; voltage at about 14.4V; when 70-75% charged, CHGR will
automatically switch to acceptance/absorption phase.
+ Acceptance/Absorption Phase: Voltage maintained at 14.4V, gradually reducing until a rate of 4% of the battery’s capacity is reached; at 4% of the battery’s capacity, the CHGR will automatically switch to the float stage.
+ Float Phase: CHGR voltage reduces to 13.3V; maintains Batt at spec voltage level.
+ Equalization Phase: Designed to minimize buildup of lead sulphate; charges at 4% of capacity until voltage reaches 15.5-16.2 volts, which rattles the sulfate particles out of the battery plates, forcing them back into the electrolyte. Can be done too often if battery is on constant charge – need to use/draw down the charge level periodically.
+ Minimum charging amperage = 10% of bank(s); e.g., 480Ah House bank = 48A CHGR; 15% is better, e.g., 72A CHGR; House
(480Ah); Start (110Ah) = 590Ah = 60A-90A CHGR recommended. Replace 55A CHGR with 75A CHGR?
+ A fully-charged Batt should have no less than 12.7V a minimum of one hour after engine shutoff. To be sure, check to ensure the electrolyte is at the proper level and check it after 24 hours of shutoff. If much below 12.7V, e.g., 12.4V, the Batt could be going south. Think about a Batt check at O'Reilly/AutoZone and a pre-emptive new Batt. Testing batts is valid only when the electrolyte is at the proper level and the Batt is fully charged and stabilized, a minimum one hour after charging.
- Flooded Batts rarely last as long as asserted, e.g., a 48 mo. Batt may last only 36 mos. Pre-emptive replacement at 75% of stated
lifecycle?
- Do not over-stress the Batt terminals – use a Batt lift mechanism that does not pull on the terminals and use a terminal puller to remove the terminal clamp.
- A separate Battery bank (two or more Batts connected in parallel or series) should consist of the same size, type, and age Batts. Not a problem if one Batt bank is occasionally connected to another, non-matching, Batt bank via a crossover.
- Be mindful when using the a crossover – when not managing a charging source (e.g., ALT, CHGR, Solar, etc.), the weakest Batts will
draw down the strongest Batts.
* Cost per unit comparison:
Type Cost # Cycles Cost/Cycle Cost/Ah* Effic. Factor
Flooded $100 2,650 Avg $0.04 $0.00017 0.82
Gel $213 1,400 Avg. $0.15 $0.00027 0.52
AGM $200 3,000 Avg. $0.07 $0.00014 1.00
*Actual will probably much higher – for order of magnitude only.
The major battery manufacturers are: Clarios/Johnsonson Controls; East Penn; and Exide. Details below:
BRAND: MANUFACTURER
ACDelco: Clarios/Johnson Controls
Advance Auto: Clarios/Johnson Controls
AutoCraft (Advance): Clarios/Johnson Controls
Autolite: Clarios/Johnson Controls
AutoZone: Clarios/Johnson Controls
Batteries-Plus: East Penn
Bosch: Clarios/Johnson Controls
CarQuest: East Penn
Champion: Clarios/Johnson Controls
Costco: Clarios/Johnson Controls
Deka: East Penn
Delco: Exide
Delco-Remy: Exide
DieHard: Clarios/Johnson Controls
Duracell: East Penn
Duralast (AutoZone): Clarios/Johnson Controls
Equalizer: Clarios/Johnson Controls
EverStart (Wal-Mart): Clarios/Johnson Controls or Exide
Exide: Exide
Firestone: Clarios/Johnson Controls
Interstate: Clarios/Johnson Controls
Marathon: Exide
Motorcraft: Clarios/Johnson Controls
NAPA: Exide or East Penn
Optima: Clarios/Johnson Controls
Orbital: Exide
Pep Boys: Clarios/Johnson Controls
Sears: Clarios/Johnson Controls or Exide
SuperStart (O’Reilly): East Penn
Note: Regarding Exide Batts, the company is now owned/operated by another, but availability of Exide Batts at Home Depot indicates they are still being produced/sold. But if an Exide fails, the warranty must be serviced through the mfr., not HD. Probably better to buy through a seller who will honor the warranty on-site, e.g., O’Reilly (SuperStart mfr’d by East Penn).