What to use AGM or wet cell batteries on a Yamaha 225 ox66

I don't know the reason for the warning but it would worry me to try the AGMs.
The charging profiles for AGMs are different than flooded cells and that may be the issue.
I will see what if I can find an explanation.
 
I talked with my local Grady White dealer when installing new batteries in the late fall/early winter of 2023 and asked about the AGM style, of which they said they'd just recommend the standard wet cell batteries for a few different reasons. The first was the vibration, in that the AGM batteries don't do very well with waves, bouncing up and down, vibration and so forth. The second was the cost in that at the time, the AGM batteries were considerably more than the standard wet cells. Which goes along with the third issue, and that is the AGM batteries typically only last 3-4 years or so before needing to be replaced. This is just what my local GW dealership said, though I did go with an Interstate brand 24M-XHD battery, and the AGM version of what looks like the same battery still appears to be around $100 more at the minimum.
 
AGM's are nice - they resist vibration better and generally last longer than regular flooded batteries. But of course this comes at a cost and only the buyer can determine if it's worth it. SOME newer engines require AGM's because of the stability of the battery and because they can power more sensitive electronics being as they are more voltage stable and usually have a higher amp-hour rating.

But, their initial charge profile is higher (voltage) than regular flooded batteries. I suspect this is where the recommendation to not use them is coming from since maybe the older 2-strokes can't support that - at least at low RPM's? You could still use AGM just fine - but they probably won't last as long as they generally would.
 
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I am going on my 3rd season with AGM's in my 228. I have a 2001 ox 66 225 and it works just fine, no issues.
 
DennisG01 said:
AGM's are nice - they resist vibration better and generally last longer than regular flooded batteries. But of course this comes at a cost and only the buyer can determine if it's worth it. SOME newer engines require AGM's because of the stability of the battery and because they can power more sensitive electronics being as they are more voltage stable and usually have a higher amp-hour rating.

But, their initial charge profile is higher (voltage) than regular flooded batteries. I suspect this is where the recommendation to not use them is coming from since maybe the older 2-strokes can't support that - at least at low RPM's? You could still use AGM just fine - but they probably won't last as long as they generally would.
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If I understood the video correctly, the initial charge voltage on the SX motors is higher than the max spec for AGM. That overcharging kind of cooks the battery and can lead to a shorter life span. It seems like the motors will be OK, it's just that the agms will age faster.
 
seasick said:
If I understood the video correctly, the initial charge voltage on the SX motors is higher than the max spec for AGM. That overcharging kind of cooks the battery and can lead to a shorter life span. It seems like the motors will be OK, it's just that the agms will age faster.
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I didn't watch the video, but AGM's require MORE voltage. I don't know the charging ability/specs of the older 2-stroke charging system... but logically :) if it's good for regular LA, then it must be a lower charge rate?

I always thought the 2-stroke charging system was not as adequate at low RPM's compared to an alternator. Am I wrong on that?
 
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I should have bought battery manufacturer assest as i ruined at least 2 wel-cell batteries every year,
till i replaced them with AGM's in 2016 and from then i just replaced dead wet-cells with AGM's, but not a dead AGM.
I can't recall any outboard manufacturer who does clearly allow AGM batteries, most write about wet-cells and only them, same as for LiFePo's btw.
There is no reason to not use AGM's on a boat and they have only many advantages over wet-cells and price came down substatially and at least here in Italy a quality brand AGM is about 30-60$ more than same size, same brand wet-cell.
  • AGM has a much lower elf discharge and can be stored in a cool place for 6 months without recharge
  • AGM, same as Gel have a much higher vibration and shock resistance as wet-cell
  • AGM does not loose acid nor do cell plates become exposed due lack of acid
  • AGM under normal circumstances don't produce hydrogen
  • AGM are in every car with start/stop system
  • AGM charge faster than wet-cells
Problems of AGM batteries are
  • higher production cost
  • AGM batteries cannot tolerate overcharging or deep discharging, which can significantly shorten their lifespan.
  • ts capacity gradually diminishes over extended usage cycles
  • Compared to other advanced battery technologies, it has a lower energy density, resulting in larger volume and more occupied space

Regarding the above mentioned problems:
  • i never had any problem with quality AGM's, Varta, Bosch and a lot of Optima nor did they lasted less than wet-cell
  • They get charged in my (some of them very old) cars, trucks, tractor, backhoe and boats without obvious overcharging
  • It may be that wet-cell last a few years longer under optimal conditions, but they are often achieved
  • the usual 96Ah or 100Ah i use has exactly same size as a wet-cell of same Ah
My Venture 34 had 2 BlueTops for house and 2 Yellow Tops for starting the twin DF300AP and there was not the slightest problem with them in 5 years. They got killed when i was back in Sardinia by someone who turned on the batteries - probably to wash the boat - and left battery switch on. Thats why i don't want that the boat is washed when on the dry and usually pull the batteries and take them home.
My 306 Canyon has 3 two year old AGM's and no problem the last summer and 120 hours, same as my dive rib.
All boats had no land power nor solar charging, only charging was eith engines on or when in my home nd on a charger.

All of my NOCO Genius and G3500 charger have Cold/AGM setting and switch automatically to it.
However, for a new charger i would buy the model with AGM setting even if i am not sure if there is a substantial difference.

Chris
 
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Thank you, I appreciate all your comments I decided to keep the AGM batteries and give them a try.
 
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