Battery charging question

[Weirdnerd]

I have a marine battery, and as much as they cost, I want to pamper it, I have a Schauer A6612 4 amp battery charger I got many years ago, but I wonder how to know when it has fully charged the battery, is it a function of voltage, or amperage drop on the amp meter?

Let me elaborate, when I start the charge, it shows 4 amps load, then starts dropping until it reaches 1 amp...then it stays there, usually I stop the charge when I see the "one amp" mark as I believe it will just cook the battery off, is that the right way to do it?...I am used to the fancy schmancy computer controlled chargers at work, and I have very little experience with the solid state " transformer/diode" types...

A good "teaching" will be good for me.

[Miriam C.]

My old battery charger boiled over a battery one time. I now have one that turns it's self off...

I also have a cheapy battery maintainer....Works great and has a green idiot light for me to know I am charged... love that kiss...

[Weirdnerd]

He he.... I am a fast learner, I have a solar panel that is supposed to keep the battery charged, of course from harbor freight

http://www.harborfreight.com/15-watt-solar-battery-charger-44768.html

But from time to time I recharge the battery ( once every five trips, eh..I have had five trips and this is the second time I charge it ( the first time was when I bought the battery), my main question was to know when the amperage on the ammeter reached one, or should it reach zero? to show full charge.

So far it has gone down from 4Amps to 3.5Amps in four hours, at this rate it should be charged by tomorrow at around 7 AM.

Is there any formula, say, if the battery is rated to 80 amp/hour, divided by 4 amp hour charge rate, equals 20 hours time to charge, or something like that?

[teardrop_focus]

You don't specify which type of marine battery you have... does it allow the addition of distilled water to the electrolyte? or is it a sealed, VRLA/AGM battery?

If it's a sealed AGM (absorbed glass mat), you most DEFINATELY want to use a modern, microprocessor-controlled charger... definately. Good ones are +/- $80 and worth every penny, especially considering that good batteries can cost over 200 dollars.

...but even more important is the fact that if a modern, sealed, vrla (valve-regulated lead acid) AGM is "overcharged" it will vent, ruining it's ability to remain "recombinant". AGM batteries make their own water. Using the wrong charger (old school timer-types) can kill them.

Battery technology has improved dramatically; use a charger designed to not only charge these batteries to their full potential, but also protect them while charging.

Welcome to T&TTT.

[Weirdnerd]

The battery is an Duralast, 140 amps, open cell, from Wally Martinez (640 amps cold cranking) open cell, ( you can refill the distilled water)

[bobhenry]

Get yourself an inexpensive mulitmeter and set it to DC volts

12.4 - 12.6+ is about as good as it gets.

These are great little tools to have testing light bulbs (using ohms setting to check continuity)

Looking for grounded hot wires same way

Plug in at the campground and nothing happens ~ set to AC Volts and check for shore power at the panel.

You know you want one now you have an excuse.

[Weirdnerd]

hehe, I have two, one in my tool box, and other in the laundry room, I am a micro electronics aficionado, it's quite useful to figure out many things.

[dh]

HA HA, I still have my Radio Shack clam shell meter from back in high school. And yes, I still use it ocasionally.

This is the one I use nearly every day at work



The clamp amp meter is a life saver

[Shadow Catcher]

What will work sort of, and what is best for your battery are two different things. Quite frankly there are an awful lot of contradictory bits of advice when it comes to charging batteries and getting the most out of them.

Types of Chargers

You can find cheap single-stage bulk chargers rated from 5 Amps to 40 Amps or so in the automotive department in Wal-Mart. There are not what you want for battery charging in an RV. What you need is a "smart" charger with control circuitry that will fully charge your batteries as quickly and as safely as possible.

Batteries don't charge in a linear fashion. When they are deeply discharged they accept a charge more quickly. Then, as they approach full charge (say 85% or more) they gradually slow. Then after becoming fully charged they require a small charge to maintain at 100%. For this reason you need a 3 stage (or 4 stage) charger:

* Stage 1 is called Bulk Charge. When a battery is 50% to 90% charged it will take a charge very quickly. A smart charger senses the battery voltage and supplies maximum current at an increasing voltage level to attain a nearly full charge.
* Stage 2 is called Absorption (or Acceptance). At this stage voltage is held at a preset maximum level (typically 14.5 volts) while current slowly tapers off until the battery is 100% charged. High-end chargers may also include a temperature sensor that measures battery temperature. Optimum charge voltage varies based on temperature from as low as 13.8 volts to around 15.5 volts.
* Stage 3 is called Float. After a battery is fully charged it requires a lower voltage to maintain its charge while waiting to be used. This is typically 13.5 volts for regular lead/acid flooded cell batteries, and 13.2 volts for AGM batteries. As with stage 2, the optimum voltage varies with temperature.
* Another 4th stage that some chargers are capable of is known as Equalizing. This involves taking the batteries up to a higher voltage level, about 15.5 volts (or 1 volt higher than Stage 2 if you're using temperature control), for about 2 hours. This ensures all battery cells are equally charged. A more complete discussion of equalizing is included in some of the links at the bottom of the page.
source http://www.macandchris.com/BatteryChargers.htm

From the Lifeline battery folks
http://www.bdbatteries.com/mcharging_procedures.php