2nd Battery

[Destroyer]

Originally Posted by The Bottom Line

Just a quick question. I've heard a lot about how great the Optima marine batteries are. Would they eliminate the need for a second battery? Is it more battery for the electronics and all of that? Does anyone use them and any feedback would be great.
Thank you

Not trying to scare you or anything, but...how valuable is your life? You cannot control everything all of the time, especially when you're out on the water, so you try to control those things that you can, as best as you can. A second battery is peace of mind. It's another control.

So, what kind of a battery should you get? Well, only you can decide that, but, thanks to the internet, we can at least get a few guidelines.

Wet Cell (flooded), Gel Cell, and Absorbed Glass Mat (AGM) are various versions of the lead acid battery. The Wet cell comes in two styles; Serviceable and Maintenance free. Both are filled with electrolyte and are basicly the same. (I prefer one that I can add water to and check the specific gravity of the electrolyte with a hydrometer). The Gel Cell and the AGM batteries are specialty batteries that typically cost twice as much as a premium wet cell. However they store very well and do not tend to sulfate or degrade as easily as wet cell. There is little chance of a hydrogen gas explosion or corrosion when using these batteries; these are the safest lead acid batteries you can use. Gel Cell and some AGM batteries may require a special charging rate. If you want the best,most versatile type, consideration should be given to the AGM battery for applications such as Marine, RV, Solar, Audio, Power Sports and Stand-By Power just to name a few. The Optima battery you asked about is an AGM battery

Now lets look at how batteries are rated.

CCA, CA, AH and RC. What are these all about? These are the standards that most battery companies use to rate the output and capacity of a battery.

Cold cranking amps (CCA) is a measurement of the number of amps a battery can deliver at 0 ° F for 30 seconds and not drop below 7.2 volts. So a high CCA battery rating is especially important in starting battery applications, and in cold weather.This measurement is not particularly important in Deep cycle batteries, though it is the most commonly 'known' battery measurement.

CA is cranking amps measured at 32 degrees F. This rating is also called marine cranking amps (MCA). Hot cranking amps (HCA) is seldom used any longer but is measured at 80 ° F.

Reserve Capacity (RC) is a very important rating. This is the number of minutes a fully charged battery at 80 ° F will discharge 25 amps until the battery drops below 10.5 volts.
An amp hour (AH) is a rating usually found on deep cycle batteries. The standard rating is an Amp rating taken for 20 Hours. What this means, say for a 100 AH rated battery is this: Draw from the battery for 20 hours and it will provide a total of 100 amps. That translates to about 5 amps an hour. 5 x 20 = 100. However, it's very important to know that the total time of discharge and load applied is not a linear relationship. As your load increases, your realized capacity decreases. This means if you discharged that same 100 AH battery by a 100 amp load, it will not give you one hour of runtime. On the contrary, the perceived capacity of the battery will be that of 64 Amp Hours.


So, we now know that AGM batteries are the best, and that if you want a good battery for your boat you should get one with a high RC and AH.

And lastly, a few do's and don'ts



Battery Do's

• Think Safety First.
• Do regular inspection and maintenance especially in hot weather.
• Do recharge batteries immediately after discharge.
• Do buy the highest RC reserve capacity or AH amp hour battery that will fit your configuration.

11. Battery Don'ts

• Don't forget safety first.
• Don't add new electrolyte (acid). (Use only distilled water)
• Don't use unregulated high output battery chargers to charge batteries.
• Don't place your equipment and toys into storage without some type of device to keep the battery charged. (Float charger)
• Don't disconnect battery cables while the engine is running (your battery acts as a filter).
• Don't put off recharging batteries.
• Don't add tap water as it may contain minerals that will contaminate the electrolyte.
• Don't discharge a battery any deeper than you possibly have to.
• Don't let a battery get hot to the touch and boil violently when charging.
• Don't mix size and types of batteries.

Hope this helps