# My First AGM Battery - Lasted 10 Months



## Bonesonthebrain (Jan 2, 2020)

Several things do not make sense, an AGM battery is not really any lighter than a flooded cell battery, you sure you have the correct battery? Second, an AGM battery should hold a decent charge for several months no problem, unless there was a draw on it. Do you have a radio connected to it?


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## tcov (Apr 7, 2018)

What brand?


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## NealXB2003 (Jun 8, 2020)

Most agm batteries ive had were slightly heavier than a comparable size flooded battery....


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## not2shabby (Sep 14, 2016)

Y’all might be honing in on my lack of battery knowledge. It’s just a starting battery. No radio. No electronics except for a GPS. I selected it based on cranking amps for my motor, not based on deep cycle or amp-hours or group size. Was that my mistake?

I basically bought the lightest AGM that would crank my motor.

The battery is a Duracell AGM power sports battery.

No radio, in fact it’s on a battery disconnect so I don’t think there could have been a draw on it.


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## Rookiemistake (Jan 30, 2013)

Gotta keep them on a maintainer


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## tcov (Apr 7, 2018)

Rookiemistake said:


> Gotta keep them on a maintainer


I don’t know the tech, but the longest I’ve ever had my AGMs off a charger is probably 1 week maybe. 3+ years in and no trouble. This could be the key.


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## JWT53 (Dec 7, 2021)

tcov said:


> I don’t know the tech, but the longest I’ve ever had my AGMs off a charger is probably 1 week maybe. 3+ years in and no trouble. This could be the key.





not2shabby said:


> Y’all might be honing in on my lack of battery knowledge. It’s just a starting battery. No radio. No electronics except for a GPS. I selected it based on cranking amps for my motor, not based on deep cycle or amp-hours or group size. Was that my mistake?
> 
> I basically bought the lightest AGM that would crank my motor.
> 
> ...





not2shabby said:


> Y’all might be honing in on my lack of battery knowledge. It’s just a starting battery. No radio. No electronics except for a GPS. I selected it based on cranking amps for my motor, not based on deep cycle or amp-hours or group size. Was that my mistake?
> 
> I basically bought the lightest AGM that would crank my motor.
> 
> ...


I have had several AGM batteries that run my trolling motor. You have to charge them….all the time. In the summer when I head north I disconnect the cables, I leave them fully charged. That seems to work……but if you leave the cables attached w/o charging they will loose all their charge. I have never been able to recharge one once it dead. Buyer beware with this brand.


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## NealXB2003 (Jun 8, 2020)

Glad you brought this up. Im in need of new batteries in my little boat. Was considering the duracells for the price point.

I have x2power agms in my big boat. They've been awesome but they are pricey in comparison.


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## Bonesonthebrain (Jan 2, 2020)

not2shabby said:


> Y’all might be honing in on my lack of battery knowledge. It’s just a starting battery. No radio. No electronics except for a GPS. I selected it based on cranking amps for my motor, not based on deep cycle or amp-hours or group size. Was that my mistake?
> 
> I basically bought the lightest AGM that would crank my motor.
> 
> ...


Power sports is a jet ski battery. Have them in my waverunners, should last plenty long and hold a charge for a couple months no problem.


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## jonny (May 1, 2007)

Get yourself a NOCO Genius charger. They have a built in repair mode. Supposedly it can repair them with barely any voltage on them. I went through the same BS with Odyssey once. They blamed me for not using their brand digital charger. Instead of my digital charger.


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## OneMoreCast (Oct 23, 2021)

Bonesonthebrain said:


> Several things do not make sense, an AGM battery is not really any lighter than a flooded cell battery, you sure you have the correct battery? Second, an AGM battery should hold a decent charge for several months no problem, unless there was a draw on it. Do you have a radio connected to it?


A comparable AGM is way smaller and lighter. I got an Odyssey this year and it is about 1/4 the size of the battery it replaced. It weighs about 12lbs and I'd guess my old one was around 50


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## Headhunter (Mar 22, 2016)

Some great comments here And let me add a couple. There are some battery chargers that can recharge a “dead” AGM. Optima makes one but they are hard to find and expensive. You can also try putting your AGM battery in parallel with a flooded battery then connect a charger to both. You might recover the AGM. I have run AGMs for years and the average life span is 7-8 years when you keep them on a good charger. I like Noco and super mania but I just got a boat with a Minnkota precision and that looks pretty cool and does lithium as well.


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## ReelBoi (Dec 17, 2020)

So I have odyssey batteries and a noco on board charger. I charge them every time after use for about 10hrs or so. But then I unplug it so I don’t overcharge. Are others leaving that plugged in the whole time until next use? I avg about 1 outing every three weeks in the winter.


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## Headhunter (Mar 22, 2016)

Leave it plugged in


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## not2shabby (Sep 14, 2016)

ReelBoi said:


> So I have odyssey batteries and a noco on board charger. I charge them every time after use for about 10hrs or so. But then I unplug it so I don’t overcharge. Are others leaving that plugged in the whole time until next use? I avg about 1 outing every three weeks in the winter.


I’ve heard with a good smart charger you leave it connected all the time. They won’t overcharge, I guess.


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## NealXB2003 (Jun 8, 2020)

Mine stays plugged in all the time, unless there's thunderstorms in the area. I'll unplug it to avoid power surges and brown outs.


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## Smackdaddy53 (Dec 31, 2012)

not2shabby said:


> I’ve heard with a good smart charger you leave it connected all the time. They won’t overcharge, I guess.


A NOCO genius will not and there are plenty of other float chargers on the market. I’d do as suggested and use one to try to repair the battery. Interstate will also do this for you if you take them the battery.


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## g8rfly (Oct 9, 2011)

Smackdaddy53 said:


> A NOCO genius will not and there are plenty of other float chargers on the market. I’d do as suggested and use one to try to repair the battery. Interstate will also do this for you if you take them the battery.


Specific to these duracells (I bought mine at sams club) - I had zero luck with multiple good repair charges getting these repaired under similar circumstance. Still worth a shot but just sharing my experience. Buy from Sams club next time they have a pretty easy no hassle warranty replacement, but its only 18 months. And, get a maintainer.


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## Half Shell (Jul 19, 2016)

Can someone post a link or tell me what AGM is comparable to a lead acid but half the weight? Although, I'm skeptical of the quality of an AGM with half the weight, I have never seen it and I'm interested.

Mine stays plugged in 24/7 (usually). Powermania charger into a GFCI outlet in the garage.

Ok... now I see... Duracell Power Sports battery.


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## Smackdaddy53 (Dec 31, 2012)

g8rfly said:


> Specific to these duracells (I bought mine at sams club) - I had zero luck with multiple good repair charges getting these repaired under similar circumstance. Still worth a shot but just sharing my experience. Buy from Sams club next time they have a pretty easy no hassle warranty replacement, but its only 18 months. And, get a maintainer.


I have dual Duracell AGMs in my diesel and have had no issues. It stays on the NOCO for 7-8 days straight while I’m at work. I’ve never let them have a chance to be severely discharged.


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## coconutgroves (Sep 23, 2013)

I have an AGM and it goes for up to 3 months without use or recharging. I do not put a maintainer on it when not in use, I just put a charger on it before a trip to make sure it is full. Never had an issue.

Get yourself a new one and just periodically charge it. All of this other stuff seems like overkill.


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## anytide (Jul 30, 2009)

lithium iron phosphate,, never look back.


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## 35spline (Mar 21, 2020)

I got 10 years out of the Odyssey batteries, starting and trolling.


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## Surffshr (Dec 28, 2017)

I feel like I’ve been doing this wrong. Ran AGM starters for years without ever charging or plugging in. That said, I do have cut off switches on all batteries to prevent draining them.


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## TR. (Sep 28, 2019)

I replaced my interstate trolling motor batteries with Duracell AGM in March of last year. I keep them on a 1 year old mine kota charger/maintainer 24/7. The batteries have maybe 50 days of fishing on them. i have never run them down past 25% until a few weeks ago. A solid morning of use and they crapped out, down to zero. I normally wouldn’t run them that low but I was in a no motor zone and against a tide so I drained them to get out. they had been on the maintainer for two months without use. I charged them and used them for another 7 days straight and they seemed to do better, however nowhere near the interstates. Perhaps I got a bad battery, not sure, but I would never buy them again. They were never even close to the interstates, and they were the same size/group etc.


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## Fairweather (Aug 17, 2020)

Half Shell said:


> Ok... now I see... Duracell Power Sports battery.


Half Shell, are you saying you saw where the AGM Power Sports battery is half the weight of a flooded lead acid battery? I looked at their spec sheet for both Power Sports starting batteries and deep cycle batteries, and it looks virtually the same as a FLA battery. I might have missed something, though. I'm interested because it's about time to replace my trolling motor battery.


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## 35spline (Mar 21, 2020)

Fairweather said:


> I'm interested because it's about time to replace my trolling motor battery.


Time to look in to Lithuim.


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## Half Shell (Jul 19, 2016)

Fairweather said:


> Half Shell, are you saying you saw where the AGM Power Sports battery is half the weight of a flooded lead acid battery?


No, I was quoting the OP in his original post where he stated he cut the weight in half. I then looked at his batteries online and there are some very light batteries but according to the website, these small "power sports" batteries are for starting jet skis, snowmobiles, etc. 

Their Marine AGMs intended for outboard use are the same AGM specs and the weight you're used to seeing. I know the difference between AGM and flooded lead acid batteries but I don't know the difference between these power sport batteries and regular AGM. With the size and weight of them and still using AGM design, there is just no way the PS vs normal AGM is apples vs apples


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## not2shabby (Sep 14, 2016)

Half Shell said:


> Can someone post a link or tell me what AGM is comparable to a lead acid but half the weight? Although, I'm skeptical of the quality of an AGM with half the weight, I have never seen it and I'm interested.
> 
> Mine stays plugged in 24/7 (usually). Powermania charger into a GFCI outlet in the garage.
> 
> Ok... now I see... Duracell Power Sports battery.


AGM is absorbed glass mat. They’re a little different than flooded batteries, based on what I understand. They’re completely sealed, so you can mount most of them in any orientation. That are also less susceptible to damage with shock/vibration.

I was able to get 400+ cranking amps out of a 17 pound battery. My old marine battery was 35 pounds.


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## Smackdaddy53 (Dec 31, 2012)

not2shabby said:


> AGM is absorbed glass mat. They’re a little different than flooded batteries, based on what I understand. They’re completely sealed, so you can mount most of them in any orientation. That are also less susceptible to damage with shock/vibration.
> 
> I was able to get 400+ cranking amps out of a 17 pound battery. My old marine battery was 35 pounds.


Buy the same one and keep it charged up is my recommendation.


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## not2shabby (Sep 14, 2016)

Smackdaddy53 said:


> Buy the same one and keep it charged up is my recommendation.


Thanks amigo. Good to see you around here. I’ve been gone a while!


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## Smackdaddy53 (Dec 31, 2012)

not2shabby said:


> Thanks amigo. Good to see you around here. I’ve been gone a while!


I’m around! Same here brother.


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## Foxtrot Juliet Bravo (11 mo ago)

My bay boat recently sat on lift for 21 months , construction project on property. No power …. Lead acid batteries. Charged prior to putting up. Battery switch on & tm plugged in. I think its all about good wiring & “ bleed oft “. I was planning on jumping it oft w jumper box. Not needed , turned key & guages popped on . wth . Motor fired oft on second try ! 2014 E tec 200 HO No ethanaol ,startron & stabil 360 , full tank. maintenance pays oft guys … Lets go fishing ,boys !


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## Half Shell (Jul 19, 2016)

not2shabby said:


> AGM is absorbed glass mat. They’re a little different than flooded batteries, based on what I understand. They’re completely sealed, so you can mount most of them in any orientation. That are also less susceptible to damage with shock/vibration.
> 
> I was able to get 400+ cranking amps out of a 17 pound battery. My old marine battery was 35 pounds.


We all know AGM is an absorbed glass mat but it has the same chemistry as flooded batteries, it just uses the absorbed glass mat to store the electrolyte in a dry state rather than a liquid state. There are a million articles on this so need for anyone to state all the advantages and disadvantages to it.

What I would like to know is why choose a power sports battery to start an outboard when it is specifically not marketed for that purpose? Then if the answer is "amps is amps and it should work", then why did it not and die in 10 months?

If it was lack of charging which can be avoided and people are having success with PS batteries, then this is viable and cheaper alternative to LiFeP04 at least for weight concerns (but still not performance). The question seems to remain is a PS AGM suitable for a boat and if so why do they not market it as such and why did it fail.


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## m32825 (Jun 29, 2018)

How many horsepower do jet skis have? Seems like a battery that starts them should work for starting a similarly sized outboard.


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## NealXB2003 (Jun 8, 2020)

Jet skis don't have bilge pumps, navigation lights, or depth finders. Even though a power sports battery may start my outboard, it wouldn't have enough reserve capacity for all of my other needs.


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## not2shabby (Sep 14, 2016)

Half Shell said:


> We all know AGM is an absorbed glass mat but it has the same chemistry as flooded batteries, it just uses the absorbed glass mat to store the electrolyte in a dry state rather than a liquid state. There are a million articles on this so need for anyone to state all the advantages and disadvantages to it.
> 
> What I would like to know is why choose a power sports battery to start an outboard when it is specifically not marketed for that purpose? Then if the answer is "amps is amps and it should work", then why did it not and die in 10 months?
> 
> If it was lack of charging which can be avoided and people are having success with PS batteries, then this is viable and cheaper alternative to LiFeP04 at least for weight concerns (but still not performance). The question seems to remain is a PS AGM suitable for a boat and if so why do they not market it as such and why did it fail.


I think that sums it up pretty well. I think a lot of ‘marine’ batteries are deep cycle, but a PS battery doesn’t have to be. Motorcycles, 4 wheelers, jet skis, etc. don’t need deep cycle, they just need amps to crank. I’m guessing mine failed because it wasn’t on a charger or maintainer. I will give it another try, I think.


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## TR. (Sep 28, 2019)

anytide said:


> lithium iron phosphate,, never look back.


I have been looking at switching and came across this article during research and figured I would share the link:



https://diysolarforum.com/threads/ampere-time-200ah-lithium-any-reviews.11161/page-4



way too techy for me but it did compare a couple of brands I was looking at So figured I would share.


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## WatermanGB (Jan 25, 2019)

If you go AGM buy an Odyssey 8-10 years service life. A little more money but cheaper in the long run. Keep it on a battery tender trice charge.


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## not2shabby (Sep 14, 2016)

WatermanGB said:


> If you go AGM buy an Odyssey 8-10 years service life. A little more money but cheaper in the long run. Keep it on a battery tender trice charge.


 I've heard great things, but I never looked at prices until today. Ouch. Nearly $300 for the one I would go with.


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## Mako 181 (May 1, 2020)

Put one in my Harley. 
Sucked !
Went back to stock battery.
Got to keep on trickle charge. 

Not For Me


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## Headhunter (Mar 22, 2016)

Best bang for the buck. Duracell AGM at Sam’s or Battery plus. Used them going on 7 years now.


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## Wayne Serpa (Nov 4, 2019)

not2shabby said:


> Last year, I replaced my flooded marine battery with an AGM. Cut the weight in half with plenty of cranking amps for my 70 2-stroke. I was warned that you can't fully discharge an AGM or it will be dead-dead. As part of the battery warranty, they say you can't let it drop below 10v or the warranty is void.
> 
> I was running the boat weekly when I didn't get out on the water up until Christmas. Holiday travel and other projects got in the way, so I didn't run it for about 6 weeks, and I don't have a battery maintainer or smart charger. I went to start it this week and the battery was dead. I put it on a charger, got it to 8.5v and it was 5.8v the next morning. Took it back to the shop and they obviously said it was my fault and there's no warranty coverage.
> 
> ...


You can put a charge back on that AGM by hooking a charger to a battery with 12 v and then hooking cables to the AGM it will charge a dead AGM every time 0


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## mt hwy (Mar 18, 2021)

Yep, you got to get the voltage above a certain level, and then the battery should start accepting charge. And then the 'repair' process some newer chargers use is a de-sulfating process which cleans the plates. I've got a 9 year old Deka Marine Master traditional flooded lead acid (heavy) which still works great and fully charges after 3 months of sitting in a hot garage - put it away fully charged. In a different boat, I have three Odyssey PC 1200 AGMs (38 lbs and ~ $300 each) - two for the TM, one house/starter - onboard Pro Mariner charges all three and works with AGMs, always fully charge after use, I don't leave it plugged in after charging, and battery switch in 'OFF'. The newest pricest option I see is a lithium-ion 24volt (30 lbs) to replace the two PC 1200s for the TM, but at $1,100 ... nahhh, what I have works great.


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## not2shabby (Sep 14, 2016)

Thank you all. I picked up a noco genius 5 And let it run the repair process. So far it appears to have worked great! The guys at batteries plus said the AGM could not be recovered.


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