31 Series run time in 24 volt configuration

Not sure if I’m expecting to much from my new Optima BlueTop D31M series batteries. I had 27 series lead acid batteries previously and thought this time I’ll go 31 series because I only got 2 years from the last set.

I’m in an 18′ Lund Alaskan tiller with a 75 Yamaha. We just got back from a week trip. Our 80 lbs 24 volt Terrova seemed to be more powerful but I felt like the run time was quite low!

I got 3 days using the anchor and some moving around on the spots and 1/2 day trolling at 1.5-1.7 mph. I charged them over night and they were fully charged when we went out the next day. This time 4-6 hours trolling at the same speeds, sometimes we were up closer to 2 mph but batteries were 1/2 drained.

Does this sound reasonable, sound reasonable for 31 series agm batteries?

Greg,

I don’t think an Optima BlueTop D31M is a deep cycle battery. According to the specs it has 75 AH capacity. But those ratings are based on a fairly low amp draw.

Two Interstate Deep cycle batteries would of been a better choice. They would of had a lower price tag, but would of required a little annual maintinance.

What you got sounded reasonable for the battries that you chose.

OH! Maybe I miss understood the specs, I knew they were not pure deep cycled but the reserve size I saw lead me to believe they would be suitable

They list Reserve Capacity @25 Amps: 155 Minutes but they also list
C20 Capacity: 75 Ah, so I’m not sure which one I should have used to make my decision.

I only have a 13″ opening so I had to find one that would fit in the boxes. That’s why I went with 27 series originally.

There is definitely an issue with capacity on those batteries. I run a 17ft jon boat on two group 31 agms. I can honestly say that I have not found the end of them while trolling at 2mph.

Optima batteries are not what they used to be. Your experience is the same I had with my last Optima set-which were replaced 2 times under warranty before I demanded my money back. I have two fishing buddies with the same issue in the last couple of years. Last fall on Bay de Noc we were only able to fish 3-4 hours and the Optimas were dead-completely! I now happily run interstate batteries and have had the same set for the last 4 years! Fish hard all day and have never been below 50% charge after fighting strong winds/current all day. My friends have replaced theirs with NorthStar AGMs and love the run time they are getting from them.

Thanks Guys, ya I dropped $1100 on a new starting battery and 2 31 series Blue Tops. I’ll be returning them, they are not as strong as I expected based on their specs

Yeah Optimas are definitely not what you want for trolling motor batteries(or anything else for that matter). I found that out the hard way and mine are past warranty.

Art are you running Interstate AGM or the conventional batteries? Group size?

I have a 36v syatem powered by group 31 northstar batts on a heavy WX2100. Never seen below 50% drawdown and usually only down 25% after a full day. And when I troll I use the Ulterra to steer on settings 3-4 the whole time. I have gone days without a recharge too.

mxskeeter wrote:

Art are you running Interstate AGM or the conventional batteries? Group size?

Conventional, I couldn’t get the bad thoughts about AGMs out of my head from the Optimas.

gizmoguy wrote:

I have a 36v syatem powered by group 31 northstar batts on a heavy WX2100. Never seen below 50% drawdown and usually only down 25% after a full day. And when I troll I use the Ulterra to steer on settings 3-4 the whole time. I have gone days without a recharge too.

Based on extensive research I did last year on AGM batteries, that is what I am going with when the interstates die. It appears Northstar 27 series outperform most 29 series and some 31 AGMs from other manufacturers.

Mine are Cabelas re-branded Northstar AGM’s. Batteries Plus bulbs also sells a re-branded Northstar. Easy to tell by the case and brass terminal posts. 4 year full replacement warr.

How do you know your batteries are only at 50%. Are you using the inaccurate gauge on the trolling motor?
The optima blue tops are a dual purpose battery. Works great for trolling motors. I have one that’s 10 years old has been in three boats and will run all day long on a 12v 55lb terrova.

Maybe the new ones aren’t any good I don’t know. Longest lasting strongest battery I have owned.

State of Charge-Voltage
Sealed or Flooded Lead Acid battery voltage
100% 12.70+
75% 12.40
50% 12.20
25% 12.00
0% 11.80

AGM Battery voltage
100% 12.80+
75% 12.60
50% 12.30
25% 12.00
0% 11.80

FYI-Discharging batteries below 50% is what shortens there life span. That’s why bigger is better when powering up the old electric trolling motor.