First time boat owner question here.  I have an 80# Minn Kota Terrova on 40th Anniversary Basstracker that I got in 2018.  Until recently, I feel like I have spent the majority of the time with the motor set to about 4.5-5.5 for 4 years.  However, it feels like I am spending more time 5-6.5 since I started fishing this year in early March.  It really is not a big deal since motor goes all the way up to 10.  However, should I be worried about a steep fall off or will performance just dwindle slowly?  Should I preemptively change the batteries now to avoid a rude awakening on the water where I have to trailer the boat and go home?  

 

 

What type of battery - flooded, gel, AGM?

 

How deep did you drain it each time before a recharge? The deeper you discharge a lead-acid battery, the more 'wear and tear' the plates suffer (yes, they're all lead-acids, just different ways of holding the acid-electrolyte in place)

 

Did you recharge it immediately upon returning home, or let it sit with a partial charge until the next planned outing prep? Letting it sit with a partial charge also can affect the lifespan.

It's the kind that you have to check and fill with water occasionally that came with the boat. 

 

I never go out for more than 5 hours or so, but I go out most weekends through out the season, and I charge it until the "go fish" light comes on.  For some reason Wednesday tends to be recharge night.  If I don't go out the next weekend, I generally do not charge it again.  I just skip a week. 

 

 

 

You should always charge it again, as soon as possible.  When the battery sits with a partial or no charge, the plates get damaged.  

 

4 years for a flooded lead acid battery (the type you have) is probably about average.  If you take proper care of them, they can sometimes go as long as 10.  If you abuse them, you might get one or two years out of them.  

 

Do this.  Charge it up fully.  Then let it sit for a day to wear off the surface charge.  Now take a DMM and test the voltage of the battery with nothing hooked up to it.  That'll tell you what percentage it's able to hold now compared to what it originally provided.  There are charts online that will tell you the approximate percentage of charge remaining and how it compares to voltage.  For example, a new battery will be around 12.6 volts. A battery that only charges to 80% will be around 12.4 volts.  A battery at 50% power is around 12 volts, and basically on its last leg.  

 

As for when to replace it, that's up to you.  It's your money.  Sometimes a cell can die and the battery can become worthless in a second.  That can happen with a brand new battery too.  Other times they gradually die a slow death and you have plenty of time to prepare for a replacement.  They can circle the drain for years, being frustrating to use, but still functional.  There's no predicting the future.  

 

  

5 minutes ago, Bankc said:

As for when to replace it, that's up to you.  It's your money.  Sometimes a cell can die and the battery can become worthless in a second.  That can happen with a brand new battery too.  Other times they gradually die a slow death and you have plenty of time to prepare for a replacement.  They can circle the drain for years, being frustrating to use, but still functional.  There's no predicting the future.  

 

  

 

Do they tend to spiral more often than drop dead on the spot? 

 

Also, do these kind of batteries go on sale?  I have not noticed them on The Latest Sale Thread.  

1 hour ago, Happybeerbuzz said:

 

Do they tend to spiral more often than drop dead on the spot? 

 

Also, do these kind of batteries go on sale?  I have not noticed them on The Latest Sale Thread.  

For deep-cycle use (what you're doing), they spiral down...giving you less-and-less over time. No matter what type you have - always recharge immediately upon returning home...don't let it sit with a partial charge...even if it still has 85%-90%...top it off every time.

 

I would spend the extra money at least get AGMs - they're a little more forgiving....but still charge to full after every trip.

 

You can get a 100ah AGM for under $200 from Mighty Max - either on their site or through Amazon. They've been in business for 16 years and have a pretty good rep.

5 hours ago, Bankc said:

4 years for a flooded lead acid battery (the type you have) is probably about average.  If you take proper care of them, they can sometimes go as long as 10.

I got 4.5 seasons out of my deep cycle batteries (interstates) that came with the boat when I bought it in 2015.  It was pretty easy to tell that the batteries were going.  I'd increase the power dial on the bow mount and I really wouldn't get much more power in response.  I still have the main cranking battery that I bought with the boat but I will be replacing that before May here.  I got 6 full seasons out of that battery which is pretty freaking good for a standard wet cell lead acid battery.  I always charge my batteries up after using them.

 

If you are able to @Happybeerbuzz, buy your batteries in person.  That way if there is a problem you can just bring it back for a replacement instead of monkeying around with shipping those things.

4 seasons is good in my book. My boat batteries go on the charger the minute the boat is back in the shop. Trolling motor battery is 2019 and still going strong. 

 

With vehicle engines, an old, seasoned mechanic once told me to replace every 3 years no matter what. With cold winters and hot summers of the Midwest, it's $100 of cheap insurance vs. getting stranded.  

 

All my ATV's, garden tractor, generator, spare batteries are on trickle chargers year round, whenever not in use. My shop is uninsulated, not heated or cooled...so it can get 100+ in the summer...and below zero in the winters. All batteries perform great. Some are 5+ years old.

I consistently get 5 years out of deep cycle marine batteries when fully charged after each use and never completely deplete them.......Go lithium if you can.