Need Help Charging AGM Battery From Home AC Power

[PowerNS]

the maintenance charger you already own @1 amp will only maintain a 120ah battery, Period. the battery charger you propose to buy is only 4 amps and will take a sometime time to recover a 120ah battery, you can spend your money how you like. if you want a closet of inadequate parts for project$ long since forgotten

Your saying it will take SO long to charge my battery with the 4 amp charger that I will forget about my project?
Please, LOL

[Logan005]

the maintenance charger you already own @1 amp will only maintain a 120ah battery, Period. the battery charger you propose to buy is only 4 amps and will take a sometime time to recover a 120ah battery, you can spend your money how you like. if you want a closet of inadequate parts for project$ long since forgotten

[PowerNS]

First of all, it never came with an owners manual, and I can not locate one, otherwise, I would not be asking here.

This charger says it can charge batteries up to 120aH. My battery is 100aH. Does it not fall into the category of what the charger says is acceptable?

I guess our definition of "damage" differs quite a bit, to me, damage means the battery will FRY, and a possible smoke show will ensue.

Sorry I don't understand simple "grade 4 math".

[Sunking]

Yes, but that doesn't answer my question.
Will the batter be damaged in any way if I use too low a charger such as the 4A charger I'm thinking about buying, or, will it simply just take longer to charge?

Already answered that. If the AGM Minimum Charge Current requirement is not met, your battery will never be recharged fully. The Oxygen/Hydrogen gasses will not recombine. Lead Acid batteries MUST BE FULLY CHARGED after any use. If not the plates will sulfate and death is around the corner. I would call that damage.

Again check your owners manual.

[PowerNS]

Yes, but that doesn't answer my question.
Will the batter be damaged in any way if I use too low a charger such as the 4A charger I'm thinking about buying, or, will it simply just take longer to charge?

[Sunking]

Do you mean that part of the batter might not get charged at all and ruin the battery if I don't charge with enough amps, as opposed to what I thought, that it might just take longer to charge??

Here is the crux of your challenge. Consult your battery owner manual. AGM's have a minimum charge rate specified in hours. For example C/4. What that means is C = the Battery Amp Hour capacity, and the number is the Hour rate.

Doing a little 4th grade math Amp Hours = Amps x Hours Doing some very simple 4th grade math and we know Amps = Amp Hours / Hours. So let's say you have a 100 AH battery and the manufacture says it must use a minimum C/4 charge rate. How many amps is that? 100 AH / 4 Hours = 25 Amps

Ok let's turn it upside down. Let's say you have a 100 AH battery and a 4 amp charger. What is the Hour rate? Well the answer is right in front of you. Hours = Amp Hours / Amps. So 100 AH / 4 Amps = 25 Hours or C/25. Easy Peazy

So why do AGM's have a minimum charge rate? Because they use recombination of oxygen/hydrogen, and it takes a minimum charge rate to recombine Oxygen and Hydrogen back to water. They can also be charged to fast. If charged too fast electrolysis exceeds recombination which will cause the battery to vent and go into thermal runaway. Is C/10 enough charge rate for your battery. BTFOOM read your owners manual and see what it requires. Most likely C/10 is enough, but very doubtful C/25 is enough.

You really have no choice. Its physics

[Logan005]

I would always plan to have some headway, no point in starting with a charger that struggles to get and maintain your precious batteries, only to decide to expand and have to buy the charger you should have bought to begin with.

[PowerNS]

you want to be able to maintain the batteries you plan to use. if you under do it you could cost yourself an entire battery bank. my samlex 2415 cost more than I wanted to spend., but boy am I glad I did.

Do you mean that part of the batter might not get charged at all and ruin the battery if I don't charge with enough amps, as opposed to what I thought, that it might just take longer to charge??

[Logan005]

you want to be able to maintain the batteries you plan to use. if you under do it you could cost yourself an entire battery bank. my samlex 2415 cost more than I wanted to spend., but boy am I glad I did.

[PowerNS]

Actually, I just found the 10A version of this charger, and it is actually way out of my price range:

http://www.amazon.ca/NOCO-GEN1-Waterproof-Battery-Charger/dp/B003JSHQW0/ref=sr_1_fkmr0_1?ie=UTF8&qid=1456948163&sr=8-1-fkmr0&keywords=NOCO+Genius+GEN+Mini+1+On-board+Battery+Charger

[PowerNS]

Not here in Canada you can't!

[Sunking]

I think this is the charger I'm going to purchase:
http://www.canadiantire.ca/en/pdp/no...-0111937p.html

I know it's only 4 amps, but it has all the features i need to make a power box, and it is good for this type battery, and can be left connected permanently, which is what I want.
The price is right also, at $89 bucks, for under $100 there aren't many options that have the features i need it to have.
It says it has pure sine wave DC output, and charges 2X as fast as regular chargers are, so I'm guessing it won't take too long to charge this battery and keep it charged, will it?
Do you think this charger will charge this 12V 100aH battery over night?

What do you think??

Awful lot of money for a small trickle charger. For half that money you can get a 10 amp charger that runs circles around what you selected.

[PowerNS]

I think this is the charger I'm going to purchase:
http://www.canadiantire.ca/en/pdp/no...-0111937p.html

I know it's only 4 amps, but it has all the features i need to make a power box, and it is good for this type battery, and can be left connected permanently, which is what I want.
The price is right also, at $89 bucks, for under $100 there aren't many options that have the features i need it to have.
It says it has pure sine wave DC output, and charges 2X as fast as regular chargers are, so I'm guessing it won't take too long to charge this battery and keep it charged, will it?
Do you think this charger will charge this 12V 100aH battery over night?

What do you think??

[Sunking]

So does that mean I should take it off the charger now, it's been on that trickle charger for 2.5 hours now.
I don't want to fry or explode my battery!!

If the charger in question is a 1 amp charger, then you can leave it connected practically forever to a 100 AH battery. If the battery is deeply discharged, it will likely never get fully charged with a 1 amp charge. Leave it connected until you see a voltage on the battery of roughly 14 volts. Just keep in mind that could be a week or more.

[SunEagle]

So does that mean I should take it off the charger now, it's been on that trickle charger for 2.5 hours now.
I don't want to fry or explode my battery!!

I would not be worried about frying your battery if that charger has only been on a few hours.

I was thinking if left on all day or longer you might have a problem. Most trickle chargers will not over charge a battery in short time periods but if left totally unattended could result in a cooked battery.