Deep Cycle Battery Question

[castmaster]

I need to replace the batteries for my trolling motor. I'm looking at getting either the Optima D31M, or one of Cabelas Advanced Angler AGM's.

My question come from trying ot decide which one is best for my needs. The Optima has a reserve capacity of 155 mins and weighs 59.8 lbs. Cabelas AGMs are... 24 series 178 reserve capacity & 53.5 lbs, 27 series 180 reserve 62.5 lbs, and 31 series 205 reserve 84 lbs.

Now on the reserve capacity the AGM's seem better than the Optimas, and I've always been told reserve is the main thing to look at in deep cycle batteries. But I'm guessing there isnt going to be much difference between the 178(24 series) and the 180(27 series) but how about going up to the 205 of the 31 series, is the extra 27 mins of reserve make up for the extra 30 lbs each battery weighs(60 lbs additional between the 2)

I've been running the Evercell batteries, and they only weigh 48 lbs each with 200 mins of reserve, so I'm a little leery of going to batteries where each one will weigh almost as much as both of the ones I have now together!

So just how much difference will there be between a battery with a reserve of 178 and one with a reserve of 205?

Anyone have the Cabelas AGM's, and if so how do you like them? I know the optimas are a quality battery and a lot of tournament guys run the Optima 31 series. So since the Cabelas AGM 24 series has more reserve capacity than the 31 series Optima will it run longer under the same load? IF so I'll go with the Cabelas ones. If I go with those how much longer run time will I find between the 24 series with 178 mins reserve, the 27 series with 180 mins reserve and the 31 series with 205 mins reserve.

[castmaster]

Forgot to add, this is a 24 volt system on a Lund Pro-V 1775 tiller. Batteries run a 60lb thrust pinpoint trolling motor and a pinpoint locator.

[Down Deep]

I can't see spending the big bucks for the exotics. I run Interstate and run the heck out of them. I ran them in my Pro V 1800 with 80lb trolling motor 24 V and never have been able to run them down in a long day of hard running. Most of time I can get two days on them. I use them on my new rig. I average 3 to 4 years on a pair. Save some money and buy more tackle. 170 reserve minutes is a long time when used running a trolling motor.

[Wish-I-Were-Fishn]

IMO extra weight in a boat sucks unless it's fish in the livewell

[walleyewild]

Castmaster,

I have the Cabela's agm batteries in my boat, one is used as a starting battery and the other is for my 55# minkota trolling motor. I would not go back to wet cell batteries. Group 27's should do just fine for you. I would always forget to check the water level in the wet cell batteries and they would only last 2 years. I am going on 4 years with my agm batteries and they are showing no signs of giving up the ghost. I can't kill the battery in a day and if I want can get 2 out of the trolling battery. The batteries are heavy, but worth their weight in gold for run time. When I switched over I put in an on-board charger haven't regretted it one minute. Average life on agm batteries is 400 charge cycles which means I will need to replace them in about 6 years, they won't freeze and you can leave them in the boat all winter. ( I do leave the charger plugged in though).

They do cost more and weigh more but the life expectancy of the battery was the big decision for me. Don't go any smaller then the 27's you will be disapointed in the 24's.

WW

[castmaster]

"Don't go any smaller then the 27's you will be disapointed in the 24's."

Is there really that much difference between the 24 with 178 mins reserve and hte 27 with 180 mins reserve? And if that 2 mins reserve makes a big difference wouldnt jumping up to the 31 with 205 mins reserve be a BIG improvement over the 27 then?

Is there a formula of some sort to figure out what size is needed?

I talk to a number of guides and tourney anglers who LOVE their Optima DG31M's, which have 155 mins of reserve. IF the 24 series AGM has 178 mins of reserve does that mean it will run longer under the same load as the 31 series from Optima?

[walleyewild]

Someone correct me if I am wrong, but I don't look at reserve capacity on a deep cycle battery, what I look at is the amp hour rating on the battery a group 24 batgtery might be about 700- 800 amp hours a 27 would be 1000-1200 and a 31 1400 - 1600. Just guesses on the amp hours but that is really how batteries are rated. The higher the amp hours the longer you'll be able to troll. I am not sure how reserve capacity is measured but someone on here will chime in on that.

[castmaster]

All the batteries I see listed only give reserve capacity, they dont list amp hours. Is there a formula for figuring out the amp hours?

[Hookmaster]

The first set of AGMs I bought from Cabelas were made by Exide. They were 24s and powered a 24 volt 48# thrust AutoPilot for 6 years and a 24 volt 80# thrust AutoPilot for 2. 8 years total and never ran them down in a day. The boat is a Lund 1700 Angler SS. I replaced them this spring with the Cabelas size 24 AGMs. I went with the 24s because of the similar reserve capacity and lower weight than the 27s. I was also trying to find the amp/hour rating but couldn't. I have had no issues with them and power the boat just fine. You may want to call Cabelas technical support to see if they know the amp/hour rating.

[castmaster]

Thanks for the info Hookmaster!

I found a formula on the internet that says it works, as a rule of thumb, for figuring amp hour rating from reserve minutes. You take the reserve minutes, divide by 2, then add 16.

So the 24 series AGM would have a amp hour rating of 105, the 27 series would have an AH rating of 106, and the 31 series would have an AH of 118.5.

How much longer run time will a guy get with the 118.5 amp hour on the 31 compared to the 105 on the 24?

[walleyewild]

Castmaster,

When you hook batteries in series Voltage is additive current is not so series 12+12=24 current remains at amp/hour rating.

If your motor draws 10 amps on high ( that would equal 10 amp/hour) you would get 10 hours out of a qroup 24 and 11 out of a group 31, theoreticly speaking before you have to recharge.

Now there isn't one of us that would run our motors on hogh for 10 straight hours but the 24's will easily get you through a day of trolling with your motor.

I backtroll a lot with a 55# thrust 12v motor it is rare but I have killed my group 27 battery in a days fishing.

If you don't have an onboard charger in your boat, put one in they are worth it. As more resorts have power close enough to their docks recharging overnight is a plus. I have a 100' cord that I keep with the boat to plug it in every night.