AGM Battery Charger

[ghostvet]

Hey guys and gals...

So I just replaced my alternator with an 85amp. But, now my AGM battery is dead. Of course, I don't have the right battery charger available to me.

So, a couple of questions. I do have a bench AC/DC transformer, in which I can adjust voltage (and I think amperage- I don't recall at the moment). Can I use this?

Also, of all the myriad of chargers out there, what is the best, most practical one to use? I see some at like $40, and all the way up to $400. They all claim to do everything. I don't want a cheap piece of crap that will damage the battery or that I will have to replace. I want something I can use to start the bike if I need it, but also to just charge it normally. I already have a battery tender, but of course that won't charge the battery.

I am on my way to Sears and Walmart, etc to look around (after I take my daughter to a Dr appt). I can check your answers on my phone in the meantime.

Thanx!

[wingman12]

good afternoon, I have two AGM battery chargers, they are both maintainer type not trickle. Battery Tender is a very good maintainer type of charge, you have to request the one for the AGM battery. around $65.00 you can find online for a little less. My favorite is from PulseTech Products, this one not only is good for liquid acid, maintenance free and AGM, it is a pulse charger that also Desulfates any lead acid battery. This one is around $100.00. I will also let you know if the battery is not good.

[WingAdmin]

Hey guys and gals...

So I just replaced my alternator with an 85amp. But, now my AGM battery is dead. Of course, I don't have the right battery charger available to me.

So, a couple of questions. I do have a bench AC/DC transformer, in which I can adjust voltage (and I think amperage- I don't recall at the moment). Can I use this?

Also, of all the myriad of chargers out there, what is the best, most practical one to use? I see some at like $40, and all the way up to $400. They all claim to do everything. I don't want a cheap piece of crap that will damage the battery or that I will have to replace. I want something I can use to start the bike if I need it, but also to just charge it normally. I already have a battery tender, but of course that won't charge the battery.

I am on my way to Sears and Walmart, etc to look around (after I take my daughter to a Dr appt). I can check your answers on my phone in the meantime.

Thanx!

A Battery Tender absolutely will charge a battery...just very slowly (over the course of a day or two). It has the limitation that the battery can't be stone cold dead to begin with.

As far as a charger, I would get one that has the ability to limit current. Ideally one that has a setting to charge at 2 amps or 6 amps maximum. Let it take a base charge for an hour or two from that, then hook up the Battery Tender and let it sit until it's fully charged and float charging it - and leave it connected when you're not riding. Doing this will have your battery lasting for many years.

If the battery is brand new, you should be able to charge it to full using just the Battery Tender. Charging slower at a low current is far easier on the battery (and extends the life) much more than a fast, high-amperage charge. The battery might take 20 amps initially if it is really low, but allowing that kind of current into it is going to sulfate plates and severely shorten its lifespan.

A Battery Tender Jr. will charge and maintain an AGM battery just fine. Their Battery Tender Plus is specifically meant for AGM batteries that has a different maximum absorption mode.

[ghostvet]

At Wal-Mart...

This one SEEMS to be the best and can be used to start my vehicles too.

$69.99

No products here mentions de-sulphiting.

Thanx!

[ghostvet]

Actually, this one DOES mention de-sulphiting on the end panel, so it looks like I will be getting this one maybe.

[harvey01]

I realize you are looking for an instant answer so you can get the battery charged and the bike running.

This may not be the best answer. As Wing Admin notes a Battery Tender Plus charger is one of the best on the market. And will get the job done but will take 4-8 hours to charge your battery. As he notes this is a good thing!

I would urge you to go to the Yuasa website and download their Technical Manual. This deals with different batteries, how to check them, and how to charge and maintain them. Yuasa does have some chargers available, I just have had great experience over the last 20 years with Deltrans Battery Tenders.

[ghostvet]

Sorry, I forgot to mention the battery voltage is very very low.

I was reading up on the AGM batteries, and apparently that is why many chargers won't charge it, because it is very low and they cannot sense it or something like that

[ghostvet]

I have a Battery tender JR.

I set the new charger on recondition. It takes 24 hours. I will check back tomorrow.

Thanx all!

[Bluewaterhooker0]

I have a Battery Tender Plus that I used to recharge my AGM last January when my alternator bit the dust. Now, my battery wasn't stone cold dead, but if YOUR battery is that dead, it's probably toast anyway. They don't tend to fully recover from a total discharge. My son-in-law just had that issue a few months back with his new to him, VTX1800. He left the key in the on position overnight. Next day, dead as a door nail. We attempted a charge, but to no avail. I told him that even if it took a charge, he would be headed for problems in the near future, anyway. From all I have read (that's a LOT), these small MC batteries are not able to handle the charge rate that an automotive charger can put out. I believe you are limited to 1.25 - 2.00A maximum. The lower number, actually being better for the longevity of the battery. These batteries only have a total of something like a 20ah capacity. Hook that up to a 25A capable charger, and you are by design, rapid charging your battery, and lead-acid or AGM (which are another form of lead-acid) batteries don't like that. As has been suggested, you are looking for a rapid solution to, what should be, a long slow process. You may indeed succeed in charging quickly, but at the expense of, at minimum, deteriorated battery life. But as I said, if your battery is truly dead, as in won't even light a light bulb, you are most likely looking at a new battery. I learned a long time ago, with automobiles, when you have a battery problem once, you will have more problems in the near future, and they are never convenient. So, rather than spend the money AND be inconvenienced to greater or lesser extents, I'd rather just spend the money without being stuck somewhere, not of my choosing.
The Battery Tenders are highly regarded on many forums. I have the Plus model for its higher output, full charge capability, temperature compensation, and nicer charge indicator lights, as well as AGM compatibility. And, no, I don't work for them.

[ghostvet]

Voltage was down to 5.6vdc

About the only thing this a charger does NOT have is a low amp charging. I wanted that, but then I focused in on the anti-sulphite feature and I forgot about checking for 2amp charging.

I figure I can either-

A- Use this charger, while I am with it (not walking away and forgetting it) to give it just enough voltage to get the other battery tender to kick in. I think that is like 10vdc.

B- Use the bench AC/DC power supply and put about 12vdc into the battery- IF I am able to control the amperage. I just do not recall if it has Amperage control on it or not.

[Bluewaterhooker0]

This might be handy

http://www.yuasabatteries.com/pdfs/TechManual_2014.pdf

http://www.yuasabatteries.com/videos.php

I read in one of their discussions about hitting the battery with 20V for 5 minutes, to push it into a chargeable state. I don't think they specified the amperage.

[ghostvet]

Electronics question...

How easy it is to build a resistor to reduce the amperage to 2amps so if I have to charge in the future using this or another device, I can just put it on the cables?

Thanx!

PS- When my boy was little, he couldn't produce the "th" sound, so he would just say "HANX", so HANX!

[ghostvet]

PS- When my boy was little, he couldn't produce the "th" sound, so he would just say "HANX", so HANX!

To which, we would reply "Helcome" lol

[WingAdmin]

Electronics question...

How easy it is to build a resistor to reduce the amperage to 2amps so if I have to charge in the future using this or another device, I can just put it on the cables?

Thanx!

PS- When my boy was little, he couldn't produce the "th" sound, so he would just say "HANX", so HANX!

You can't really use a fixed resistor, as the value of the resistor would have to change as the internal resistance of the battery changes, which itself changes based on the state of charge of the battery, temperature of the battery, phase of the moon....

There's two ways chargers regulate current:

- By having a transformer that is only capable of producing x amps, it knows it can not send more than x amps to the battery

- By having an active current monitoring circuit that adjusts the output voltage to maintain a constant current as the resistance of the battery changes. Some of them have switchable current taps that allow it to step current capability up and down, but that's way above what is needed for a motorcycle battery.

[Scooter363y]

The agm style battery is a very strange beast. If not using a dedicated "agm" battery charger strange things exist. If the agm battery is very low a regular battery charger won't charg it. You have to fool the charger into giving it a charge by tricking it into thinking its a regular lead acid battery. So the next time you are trying to charge your agm battery with a regular charger and it's not charging take a known good 12 volt battery (lead acid) run some jumper cables to the agm and momentarily touch the cables to the corresponding terminals with the charger attached. This will momentarily "fool" the charger into thinking its charging a regular battery and will continue to charge the agm battery. As always wear protective gear when working with batteries.

You can reduce the current of a battery charger just use an old turn signal. Put alligator clips on the end of the wires and clip it in series with the hot/ positive leg. Plus you will have a light to indicate that charging is happening

Scooter