Lead acid vs agm

[Pickwicked Basser]

What’s the pros and cons of lead acid vs agm other than price for trolling batteries? All I’ve ever had was lead acid and I’ve been thinking of swapping my trolling batteries to agm while Sams has them on sell if the benefits outweigh the cost difference.

[jc2bg]

I am no expert, but the basic difference is that lead acid batteries lose charge strength gradually, while AGM retains full strength for a longer period and then flatlines when the charge is gone. The kind of use you typically encounter for your trolling batteries may determine which type is better for you. And of course, AGM don’t need water added. On the advice of my dealer, I run AGM for cranking battery—because I want full strength to crank the big motor, and because I have a jump-start module on my boat—but use lead acid for trolling batteries because a gradual loss of power gives me a heads-up that I may need to keep an eye on battery condition to get through the day. I also run 3 trolling batteries, which makes the cost differential greater between the 2 battery types. With 36 volts, I am unlikely to ever deplete my trolling batteries in one day’s fishing, so the AGM as a trolling battery has no advantage for me, other than not adding water once a year.

[bgibson]

I am no expert, but the basic difference is that lead acid batteries lose charge strength gradually, while AGM retains full strength for a longer period and then flatlines when the charge is gone. The kind of use you typically encounter for your trolling batteries may determine which type is better for you. And of course, AGM don’t need water added. On the advice of my dealer, I run AGM for cranking battery—because I want full strength to crank the big motor, and because I have a jump-start module on my boat—but use lead acid for trolling batteries because a gradual loss of power gives me a heads-up that I may need to keep an eye on battery condition to get through the day. I also run 3 trolling batteries, which makes the cost differential greater between the 2 battery types. With 36 volts, I am unlikely to ever deplete my trolling batteries in one day’s fishing, so the AGM as a trolling battery has no advantage for me, other than not adding water once a year.

I agree and have the same set up for the same reasons.

[CatFan]

AGMs are lead acid batteries. The difference is that the electrolyte on an AGM is absorbed into a glass mat between the plates instead of being free to flow around the plates. That's both an advantage and a disadvantage.

Because the electrolyte can't flow freely, it takes more plates to produce high current for starting. An AGM of the same capacity as a conventional flooded cell will weigh about 10% more than the flooded cell.

An AGM has lower internal resistance which reduces self-discharge and results in more efficient charging.

An AGM is much more resistant to sulfation, which kills battery capacity. An AGM will generally have longer cycle life than a conventional flooded cell, but how many cycles and the difference between the batteries depends on how you are using them.

As a cranking battery on a bass boat, AGMs are hard to beat. Because of the way they are made, they can supply cranking power and reserve capacity for running electronics and pumps while fishing and they recharge faster when running the outboard.

For trolling applications, the advantages aren't as strong. If you fish a lot, fish in curcumstances where you can't recharge every day, often fish long days where you deeply discharge the batteries or are otherwise rough on batteries, then AGMs may be the best choice. The sale on the Dekas at Sam's tilts the scale toward them. Other AGMs at about 3 times the price of flooded cells are probably no bargain for TM use.

[L.Roberts]

AGMs are lead acid batteries. The difference is that the electrolyte on an AGM is absorbed into a glass mat between the plates instead of being free to flow around the plates. That's both an advantage and a disadvantage.

Because the electrolyte can't flow freely, it takes more plates to produce high current for starting. An AGM of the same capacity as a conventional flooded cell will weigh about 10% more than the flooded cell.

An AGM has lower internal resistance which reduces self-discharge and results in more efficient charging.

An AGM is much more resistant to sulfation, which kills battery capacity. An AGM will generally have longer cycle life than a conventional flooded cell, but how many cycles and the difference between the batteries depends on how you are using them.

As a cranking battery on a bass boat, AGMs are hard to beat. Because of the way they are made, they can supply cranking power and reserve capacity for running electronics and pumps while fishing and they recharge faster when running the outboard.

For trolling applications, the advantages aren't as strong. If you fish a lot, fish in curcumstances where you can't recharge every day, often fish long days where you deeply discharge the batteries or are otherwise rough on batteries, then AGMs may be the best choice. The sale on the Dekas at Sam's tilts the scale toward them. Other AGMs at about 3 times the price of flooded cells are probably no bargain for TM use.

This is spot on. One other thing....if you have AGM batteries you have to have a charger capable of charging them.

[texasbass1]

CatFan, thanks for the battery info. You always provide clear explanations about batteries and their nuances.

[wmitch2]

I've always run AGM's for Trolling and starting for the convenience of never having to add water, the cleanliness of no acid burn off, and the warrantee. I've also been running a Troll Bridge, which charges the Trolling batteries when the big motor is running, on this latest boat Works like a charm !! Last 4 day trip, I never plugged in the charger after a day on the lake, and had plenty of battery all day, each day !! PLUS, if my starting battery is low, it will automatically "borrow" juice from the TM batteries to get me running ! I have a standard DuoPro Ranger charger and have never had an issue with charging the AGM's either

[joe3buck3]

I have three lead acid batteries in my boat (2 TM, 1 Starter). They work fine but when they die I will replace with AGM because of the very tight battery compartment. It is a real hassle to check the water level on the last TM battery because it is positioned in the very back of the compartment with no way to get to the top of the battery except to remove the starter and 1st TM battery then slide the last battery out. AGMs are maintenance free and can even be laid on their sides if need be.