Deep Cycle Battery life span question

I want to make sure I understand this right, see yellow highlight below. So wearing your battery down on each us is good? So if I go fishing, and go to charge m battery, and it says 80%, maybe I should not charge it back up wait till mhave the nect fish trip?


https://www.solar-electric.com/learning-...les%20vs%20Life

NO NO NO!

DOD = DEPTH OF DISCHARGE! The article is saying the deeper you DISCHARGE a battery, the lower the number charge/discharge cycles you can expect to get in the service life of the battery. Deep Discharging is BAD!

An 80% Depth of Discharge means you have used 80% of the battery's capacity, with only 20% remaining. You NEVER want to do this to any battery in your boat if it can be avoided. That I recall, it's pretty standard for detail info on batteries like we use in our fishing boats to call for discharging no greater than 50% (and less is preferable). Also, you should recharge to full charge ASAP after use. NEVER store the boat with partially discharged batteries with plans to charge them the day before you fish again. Many manufacturers will state that any discharge of 50% or greater will significantly/adversely affect the overall service life of the battery.

All the no-no things I mention above will kill your batteries much faster. Use the biggest battery you can, and discharge it no lower than necessary. Then, recharge ASAP. If the batteries are maintenance batteries (where you can check electrolyte and add DISTILLED WATER ONLY), be sure to keep the electrolyte at the proper level - which is NOT to the top of the battery, btw.

So after use, when I charge it, and it say "80%", that means 80% charged and 20% DOD. Right?

That's what I always done, but that DOD % got me confused.

Correct! If you come home and the charger indicates 80%, that's 80% charged. That means you only used 20% of the battery capacity (approximately). This is very good. Low stress use such as that along with prompt recharge will give you the best service life you can hope to get from the battery.

There are 2 types of batteries. Cranking and deep cycle. Cranking batteries are used to start a motor. They should discharge very little to just get the motor running. They are not designed to go below that for very many times. A deep cycle (trolling motor battery) is designed to be deeply discharged and recharged many times.

Agreed!

And....... 80% DOD is actually OK for true deep cycle batteries in some applications.
So called "marine" batteries are actually not true deep cycle batteries, so taking them down too far damages them more.

The proof is in how many cycles, how deep.

Marc

Agree with all of this. I've heard arguments that the "Dual Purpose" or "Marine" batteries such as those sold at Walmart are suited for deep cycle applications. Not so. A Marine battery is nothing more that a starting battery. A dual purpose battery has a little heavier plate construction but they aren't suitable for much more than occasional running of lights or a stereo.They are basically HD starting batteries.
True deep cycle batteries are marked as such on the case. If it don't say it it ain't it. Deep cycle batteries are rated on number of discharges. These ratings are based on a 50% discharge between chargings. While an occasional extreme deep discharge won't kill a battery, it does contribute to the deterioration and reduced life of the battery

Yes, Sir. Deeper cycles always shorten battery life.

Good deep cycle batteries will go 1000 to 1200 charge/discharge cycles at 50%
But they will still give you 500 to 750 charge/discharge cycles when you drain them down to only 20% remaining.

For some folks, 1,000 days of fishing occurs quickly, others may take many, many years.

Most deep cycle batteries die young from incorrect charging.

Marc