what charger or tender do you guys suggest for agm battery?

[Sportster-2001-951C-Stock]

Yep, and I meant to also note I feel if you need to have a constant charge thing going one alternative would be to power the automatic float charger through a lamp timer for a few minutes once a week or something like that.

 

[Seadoobuddy]

Yep, and I meant to also note I feel if you need to have a constant charge thing going one alternative would be to power the automatic float charger through a lamp timer for a few minutes once a week or something like that.

Good idea. I'll search around to find a 7 day timer. Anyone know of a good brand?

 

[DavesNotHereMan]

The only multi day ones I have seen are the outdoor kind used for things like Christmas lights - and they are everywhere right now. I have a weatherproof digital with multiple on / off per day. I think I got it at Home Depot.

Tried to see who makes it, but it's too dark right now. I'll find out tomorrow.


-Dave
Sent from my iPhone using Tapatalk

 

[LouDoo]

I picked one up last year at Walmart, I think, around $15.00, by the time you buy the timer and the battery charger from HF, you could have just bought a battery tender jr. During season I leave a battery tender jr. hooked up and plugged in, for my boat, never had a problem.

Lou

 

[69boss]

I remove all the batteries during the winter and keep them in one place. Every month or so check the voltage, if low charge for a while. It is also easier to catch a marginal battery, the voltage will usually drop faster on it. Going 8 years on 2 batteries and 6 years on another pair.

 

[Sportster-2001-951C-Stock]

Anyway, I keep a few standby battery chargers that must always be charged and ready to go on a timer that pops on once a day for about 10 minutes. Normally the charger quickly goes to float, the indicator light transitions to green from yellow within a minute or less.

So in summary:
Looks like after the charge cycle is complete at about 14.51V, the batterytender 800 floats at 13.33 volts. Otherwise the battery voltage would drop to it's native value (~12.6 for most flooded cells). The batterytender 800 seems to go straight to float mode (13.33) if the battery voltage is 12.7 or greater when power is applied. This is good for me to finally make the measurements so I know exactly what's happening, it helps diagnosing problems.

And I'm convinced b/c the batterytender models take the voltage to 14.51 before going into float mode the AGM battery should receive a full or very near full charge with this strategy. Once the voltage reaches 14.51 it reverts to the 13.33 float mode.

At least that's what I see by measuring the voltages.

So in the case of AGM I think if your charger doesn't take voltage to near 14.5 volts before going into float at around 13.3 then your AGM battery isn't receiving a full charge. This constant float strategy would be acceptable for a flooded cell, 13.8 is about the minimum and 13.2 is really too low to completely charge a flooded cell in my experience. 14.2 will definitely fully charge a flooded cell and it's okay to overcharge (equalize) at 14.5 for a brief period of time as long as the battery isn't receiving that voltage for a long period of time, otherwise the cells will begin gassing, which boils the electrolyte and isn't helping anything except to mix the electrolyte some if it's become stratified. A flooded cell that's in storage and doesn't get moved around can allow the electrolyte to stratefy, thus reaching a voltage that causes brief overcharge outgassing can be beneficial.

That's how I view the charging strategy.

Anyway, I've seen a lot of batteries that die an early age due to overcharging but not as many anymore since most chargers are automatic and thus stop overcharging at some point.

And I've seen a lot of batteries that were defective from the get-go due I presume, to rough handling during transport or some kind of factory assembly issue where the internal connections weren't swaged properly. I've seen a lot of batteries with internal connection problems, and I feel this is a major issue as a battery ages the internal connections become lose.

 

[68ragtop]

I had a tender Jr on my wifes snowmobile since last March. Just took it out of storage last weekend & the battery is in top notch shape! great maintainer for the money IMO

 

[DavesNotHereMan]

I took the HF charger back. No Sweat. I see the battery tender jr on Amazon for $23. Looks good for $13 more than the HF brand. Thanks for everyone's opinion. For a new jet ski owner, like me, this was a greatly informative and helpful thread.


-Dave
Sent from my iPhone using Tapatalk

 

[soccerdad]

+1 I just added it to my Christmas wish list! Funny how EVERTHING I asked for has something to do with this hobby..... Where is that addiction thread...

 

[68ragtop]

I wanted to add that, like sportster & other mentioned above, I also do not normally leave maintainers on small power sports batteries. Nothing really to gain, unless you battling a parasitic draw & don't want to disconnect the battery. My 97 XP was that way. leave it sit for 3-4 weeks & the battery would be under 11.5V & barely turn over. just started plugging it in after I realized it was happening.

On the snowmobile I mentioned above, it has a 5 year old battery that was drained dead last winter. I figured I would be replacing it soon so I turned it into a guinea pig this past summer & didn't care what the Jr would do to it. I was actually surprised that it is in good shape after being connected for 8 months straight.

 

[jammin777]

the main reason i use the battery tenders is that i'm bad at remembering to manually charging them on the off season
i usually put the tender on the ski a couple days before i ride just to make sure.

 

[Sportster-2001-951C-Stock]

the main reason i use the battery tenders is that i'm bad at remembering to manually charging them on the off season
i usually put the tender on the ski a couple days before i ride just to make sure.

Yes, for my boat I just leave it all hooked up with the 12v cord hanging out of the tarp connected to the tender mounted on the wall then every so often I'll walk by and plug it in to AC and watch the light on the tender just to see how long it takes for the tender to go into float mode.

Last winter each time I plugged it into the AC, the tender light turned green right away. I did this about once a month b/c I didn't know if the battery would slowly leak down by itself. I was pleased to see the battery was holding it's charge quite well and didn't need recharging, so this spring I was more confident the battery was in good condition (b/c it held it's charge well all winter).

If the battery had required a long time to recharge each time then I probably would've replaced it, b/c a battery should be able to hold it's charge voltage for at least a month, that's my expectation.

The battery in this boat is always disconnected from my MPEM during storage and especially during charging. This boat came equipped with a rotary battery switch to easily allow me to disconnect it from the boat's electrical system. Fortunately many boats have an integrated battery switch these days.

Note: The tender I'm using in this case is the "batterytender 800", and the battery in the boat is a 650CCA flooded cell cranking battery.

Owners manual PDF for this particular charger:
http://www.gen-tech.net/fullpanel/uploads/files/product-info-waterproof-800.pdf

 

[Sportster-2001-951C-Stock]

Nothing really to gain, unless you battling a parasitic draw & don't want to disconnect the battery. My 97 XP was that way. leave it sit for 3-4 weeks & the battery would be under 11.5V & barely turn over.

I think in this case by leaving the battery connected to the jetski you forfeit the opportunity of knowing which side of the system presents the parasitic drain. A parasitic drain internal to the battery can reveal a defective battery if the rate of decay is rapid.

By disconnecting the battery (I suspect you actually did, for troubleshooting purposes) you can isolate the source of the parasitic drain from the battery and thus determine if the battery itself is defective (a possible warranty claim).

 

[jammin777]

last summer after a ride, if it sat for 2 weeks, when i put the battery tender on it the red light would be on for about 2 hours then turn green, not sure if thats normal or not being a AGM battery, however, we have a tester at work that will tell you how many cranking amps it has left, the specs say 325 cca and the tester read over 600 cca! whats that all about? wierd.

 

[Sportster-2001-951C-Stock]

Exactly, battery chemistry and construction will shift saturation voltage by a few tenths of a volt. I'd wager seadoo's regulators weren't calibrated to fully charge an AGM battery.

Whats truly baffling though is how batteries most often puke their guts right about a month after warranty fully expires, just like a clock runs out of spring.

 

[jammin777]

what really baffle me is why the tester reads almost twice the rated cca. any idea? sorry about derailing the thread.

 

[Sportster-2001-951C-Stock]

I think it's largely b/c these batteries are conservatively rated. Figure they might sit in a store room for several months and also must make it to the end of the warranty period still able to crank a motor over.

Plus, I kinda wonder if your tester wasn't calibrated a little off, those CCA numbers can be all over the place with just small errors in calibration. Was it a high quality professionally calibrated carbon pile tester or one of the new pulse types? Were you also able to test any other batteries to confirm the calibration of the tester?

I do know a big advantage of the AGM type batteries is their ability to deliver a large jolt for a longer period than the flooded cells typically can, and they also can be charged at a faster rate.

And I think it's not necessarily a bad thing if the seadoo doesn't top charge the AGM, that's a better alternative as opposed to grossly overcharging and forcing one to vent. Figure you're going to give it an occasional topping charge anyway, so you should be good to go IMO.

 

[jammin777]

yes it is a good quality hand held tester and seems pretty accurate (tested several batteries) otherwise just hard to believe that my battery test 600 cca testing it several times. lol! it must be a darn good battery then.:hurray:

 

[Seadoobuddy]

I think it's largely b/c these batteries are conservatively rated. Figure they might sit in a store room for several months and also must make it to the end of the warranty period still able to crank a motor over.

Plus, I kinda wonder if your tester wasn't calibrated a little off, those CCA numbers can be all over the place with just small errors in calibration. Was it a high quality professionally calibrated carbon pile tester or one of the new pulse types? Were you also able to test any other batteries to confirm the calibration of the tester?

I do know a big advantage of the AGM type batteries is their ability to deliver a large jolt for a longer period than the flooded cells typically can, and they also can be charged at a faster rate.

And I think it's not necessarily a bad thing if the seadoo doesn't top charge the AGM, that's a better alternative as opposed to grossly overcharging and forcing one to vent. Figure you're going to give it an occasional topping charge anyway, so you should be good to go IMO.

Talking about calibration of a meter, mine reads low in volts. Does anyone know of a shop that can recalibrate it? I checked one shop locally and he wanted $65. It's a $89 craftsman that I paid about $59 (on sale) back in 2006 -07. thanks....

 

[Sportster-2001-951C-Stock]

I guess in that case the reference batteries were in poor condition or undercharged.

In the case of the 350CCA @ 0*F AGM battery, it should test out to ~555A at 65*F, so it seems to be better than spec by ~50Amperes (I'm assuming 65*F was the battery's ambient, actual temp unknown).

At 85*F the 350CCA battery should flow 573A

http://www.bgsoflex.com/ccatemp.html

 

[Sportster-2001-951C-Stock]

Talking about calibration of a meter, mine reads low in volts. Does anyone know of a shop that can recalibrate it? I checked one shop locally and he wanted $65. It's a $89 craftsman that I paid about $59 (on sale) back in 2006 -07. thanks....

Yeah, we used to have to send our voltmeters in for periodic ISO9001 recertification. Seems like our meters weren't recalibrated but they were compared to a calibrated reference and the result was a pass/fail test where fail = toss the old one and replace with new.

 

[jammin777]

I guess in that case the reference batteries were in poor condition or undercharged.

In the case of the 350CCA @ 0*F AGM battery, it should test out to ~555A at 65*F, so it seems to be better than spec by ~50Amperes (I'm assuming 65*F was the battery's ambient, actual temp unknown).

At 85*F the 350CCA battery should flow 573A

http://www.bgsoflex.com/ccatemp.html

so are you saying they rate the cca at 0*f? i didn't know that. it was probably around 90*f when i tested mine.
the tester we have at the shop will tell you the cca as well as good, charge and retest and bad battery meaning a bad cell.
in turn i tested the battery in my wife's Tahoe and failed the battery at 365 cca when it was suppose to be around 700 cca along with others so it seems to be working alright. thanks, i just learned something new

 

[Sportster-2001-951C-Stock]

Correct, if not specified it's assumed the CCA is given at 0*F Note the calculator also allows for changing the specified CCA temp as well.

Many batteries are spec'd at two temps, 0*F and 32*F