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

[floatingRyan]

i was just about to throw my battery on for its charge and stumbled upon a line in the manual that says to not use it on agm batteries. It is the cheap harborfreight float charger. Seeing as this one evidently won't work, what do you guys suggest?

Thanks,
Ryan

 

[LouDoo]

I would suggest a battery tender jr. or even better Optimate 4.

Lou

 

[Matt Braley]

Optimate 4 for sure. They are down to $50 shipped, I grabbed a second one.

 

[SabrToothSqrl]

I'm thinking of getting a second. I have a harbor freight job, and it works fine. But in the winter I use it on my boats dual battery setup. So if I need to charge another battery, I have to take the cover off the boat, climb up, pop the hatch. Etc. etc. etc. then hook it all backup.

 

[Sportster-2001-951C-Stock]

An AGM battery requires a little higher voltage to maximize sulfation reversal than an ordinary flooded cell. I think if your charger reaches 14.4V at some point then you can be confident the battery is fully charged and should stop there or soon after, especially as voltage approaches or exceeds 14.8V You need to see 14.4 I think.

The quickest way to shorten the life of a battery is to overcharge it, the 2nd fastest way is to allow it to discharge beyond 50~75%, 3rd mistake is to never charge it to full capacity.

For an AGM as per an manufacturer:

"While in storage, batteries should be boost charged every 90 days or when the open circuit
voltage (OCV) drops to 12.5 volts for a 12 volt battery (6.25 volts for a 6 volt battery). This OCV
corresponds to approximately 75% state of charge. Boost charge batteries using a constant
voltage charger set at 14.4 to 15.0 volts for a 12 volt battery (7.2 to 7.5 volts for a 6 volt battery).
The boost charge should be applied until the charging current falls below 0.5 percent of the
battery’s 20 hour rated capacity (0.5 amps for a 100 Ah battery)."

http://www.amsolar.com/shop/images/Lifelinemanual.pdf

And I'll add, I'm not a believer in leaving any battery on "float" for more than a couple days, there's nothing to be gained aside from a damaged battery (IMO)..

 

[Luv2Camp]

Tender jr for my ski. I tried the harbor freight one for my camper and fried the battery. The voltage ran away on it and was overcharging. I added that to the list of harbor freight things I will never buy again. It is a short list though!

1.) anything battery powered(their batteries suck!)
2.) battery charger
3.) Air hacksaw (have tried them 3 times and burned out all 3 during the first use)

 

[Spimothy Leary]

budget version = tender Jr.
2nd choice is Optimate = twice as much but twice as good.
I hate my battery version = harbor freight

 

[Sportster-2001-951C-Stock]

I added that to the list of harbor freight things I will never buy again. It is a short list though!

3.) Air hacksaw (have tried them 3 times and burned out all 3 during the first use)

Oh snap, then I lucked out a few years ago when I got mine somewhere else! Really haven't used it much but will someday I'm sure.

 

[Spimothy Leary]

I can say one thing about HF, besides the fact that I won't buy their charger.
I absolutely LOVE their color coded deep well sockets...
I haven't cracked one yet, and they are so cheap you don't even get upset if you lose one (unless its the 10mm)

 

[DavesNotHereMan]

So I picked this one up at HF:


And has this warning on the back:


I have a Duralast AGM. Is this thing junk? I can still take it back. Maybe trade it in on that deep well, color coded 10mm? Lol


-Dave
Sent from my iPhone using Tapatalk

 

[LouDoo]

What ever else you say about Harbor Freight, at least in my experience as long as you have the receipt their return policy is great, you can get your money back. If you don't have the receipt they will do an exchange or a credit. If you break a hand tool you can return it for a replacement, of course they replace it with the same piece of crap tool that broke. It's a great source of tools for us back yard mechanics.

Lou

 

[DavesNotHereMan]

Yea. I use the tools with the policy that they are cheap enough and fail, I can toss it and buy another. I bought a polisher and it's still running strong. But should I take that CenTech back?


-Dave
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[LouDoo]

I would.

Lou

 

[Luv2Camp]

I would.

Lou

+2...

Some things are just not worth the savings. Having a fried battery in the middle of your season although not like having a dead motor, still SUCKS!!!

 

[DavesNotHereMan]

You guys' opinion is good enough for me. Woohoo another reason to go to HF again!


-Dave
Sent from my iPhone using Tapatalk

 

[floatingRyan]

i found the battery tender jr on ebay for about 23 bucks. Not really going to break the bank there. Couldn't find at a store anywhere around though which i thought was weird, but oh well.

 

[Seadoobuddy]

Yea. I use the tools with the policy that they are cheap enough and fail, I can toss it and buy another. I bought a polisher and it's still running strong. But should I take that CenTech back?
-Dave
Sent from my iPhone using Tapatalk

I bought the same one last May from HF. It's on my battery as we speak since Oct 28th. It's in Fl and I'm in Michigan.......it that an oops on my part. Brand new AGM from Advance in Oct. My wife stayed down there for another week after I left and did check on it.....it was cycling from charging to just on and not charging (green light & yellow light).

 

[Luv2Camp]

Yea. I use the tools with the policy that they are cheap enough and fail, I can toss it and buy another. I bought a polisher and it's still running strong. But should I take that CenTech back?


-Dave
Sent from my iPhone using Tapatalk

I bought a polisher last year from HF. Polished my truck, my Seadoo, the sides of my boat and my Son's Mustang after I repainted it and burnt the polisher out. I am going to give the polisher from HF another try though

 

[DavesNotHereMan]

I bought a polisher last year from HF. Polished my truck, my Seadoo, the sides of my boat and my Son's Mustang after I repainted it and burnt the polisher out. I am going to give the polisher from HF another try though

At the risk of a thread hijack, I know there are two models of that polisher. 1 burns out the brushes quickly and the other one supposedly lasts longer. I got the one that supposedly lasts longer, but I forgot what the model is. If you go online, I think it is described in the ratings area. I have polished my boat (Donzi 21 LXR) stem to stern with a cutter pad and two finer polishing pads for the last two years. I plan to use it on the SeaDoo in the spring.


-Dave
Sent from my iPhone using Tapatalk

 

[DavesNotHereMan]

I bought the same one last May from HF. It's on my battery as we speak since Oct 28th. It's in Fl and I'm in Michigan.......it that an oops on my part. Brand new AGM from Advance in Oct. My wife stayed down there for another week after I left and did check on it.....it was cycling from charging to just on and not charging (green light & yellow light).

And it's working correctly with no problem?

I bought this in Oct from the specials newspaper they send out. It was like $10 on sale.


-Dave
Sent from my iPhone using Tapatalk

 

[Strizzo]

i only use battery tender brand float chargers, which are supposed to be good for AGM batteries. i have two for the skis, and bought one for my dad's mustang last time i was up there after i had to wait for the battery to charge so i could take it out on a nice day.

 

[jammin777]

i use a battery tender plus with a agm battery and just leave it on all winter for the second winter now. i also have a battery tender plus dual port for my 2 rv batteries which are also left on all winter. pretty much fool proof imo.

 

[Sportster-2001-951C-Stock]

I bought the same one last May from HF. It's on my battery as we speak since Oct 28th. It's in Fl and I'm in Michigan.......it that an oops on my part. Brand new AGM from Advance in Oct. My wife stayed down there for another week after I left and did check on it.....it was cycling from charging to just on and not charging (green light & yellow light).

That must be an extremely long extension cord you have? I think if I was going to leave it connected all the time I'd probably set up some sort of timer to charge it maybe 30 minutes a week or something. That way it would be pretty hard to overcharge in about any circumstances and probably save a ton of electricity.

Not that I think HF chargers are junk b/c I wouldn't know without evaluating one myself. The batterytender jobs are switch-mode power supplies, I think they're 2-stage, and the ones I've used all seem to be rock solid. I keep a few batteries on timer chargers that pop on a few minutes each day, I could probably could extend that out much longer.

 

[Sportster-2001-951C-Stock]

i only use battery tender brand float chargers, which are supposed to be good for AGM batteries. i have two for the skis, and bought one for my dad's mustang last time i was up there after i had to wait for the battery to charge so i could take it out on a nice day.

I just measured a batterytender 800 on a 350CCA battery with a 100W load applied momentarily to drag voltage down and the charger popped on right about 12.45 volts and charged a few minutes till voltage reached about 14.1~14.2 volts then went back to "float". I don't think any current flows until battery voltage reaches under 12.5 then the charger pops on and charges up to 14.1ish then pops off again.

I ran that same test again using a different (perhaps more accurate) meter and this charger popped on around 12.7 and then popped back off at 14.5

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 future problems.

 

[69boss]

And I'll add, I'm not a believer in leaving any battery on "float" for more than a couple days, there's nothing to be gained aside from a damaged battery (IMO)..

That is very good advice. Don't trust the float chargers. Besides the possibility of being hard on batteries had one short out. Could have lost everything in the gargae because of it.

Might also add that HF had issues with poor fuses.
http://www.topspeed.com/cars/car-ne...se-fuses-defective-and-dangerous-ar42923.html


I purchase stuff there from time to time but usually items that I don't expect to last or use much. Can't beat the little LED flashlights for a couple dollars.