Will a 7 stage 10amp charger work with 120AH AGM battery

I use a 5 amp charger on my 100 amp battery without problems. It only takes longer.

I'm no expert but I would say he is correct the minimum recommendations I have read is to have 10amps of charge per 100ah. The bigger the charger the faster it will recharge the battery which is good for short trips and if you run the battery down low you can get the power back into it faster which is better for it. That's the basics you can get into the technical reasons why but that bores me. Also they say a 100ah battery will take approx 30amps of power so you are limmiting it with a 10 amp charger bigger is better. In my 4wd I have a 40amp charger looking after 2 x 105ah batteries it works well I don't have a 240v charger I have no need for one.

I tried your link came up error is it a 12v car charger or house 240v

G'day Myles,
I have 3 different chargers I use & sometimes use the 2 amp smart charger on 1 of my 120AH batteries when the others are used elswhere. Fully charges it but just takes longer.
For longevity of batteries best to charge at no more than 10% of battery capacity. So thats 12 amps for your 120AH.
I use a 16amp when using Gennie so its quicker. Bit over the 10% rule but battery is still fine after years of use.

Cheers
Stu.

Mynance - You're spot on with your perception about the sales "pump up". A 7 stage 10 amp charger is quite suitable for your 120AH battery.

I use a simple old 4 amp taper charger mostly, I'm never in a hurry to charge batteries - charging lead-acid batteries fast is not an ideal way to treat them, due to the potential for gassing, and increased battery temperature.

Correct charging voltage is more important than high amperage charge rate.

Pulsing chargers are most effective at keeping lead acid batteries in good condition.
I use an Infinitum Battery Desulphator when charging, it greatly assists in combatting battery sulphation and short life.

Cheers, Ron.

A higher amp charger will get a battery up quicker but for longevity low and slow is best. Also remember a battery only takes what charge it needs - if it only needs 2amps it will only take that even if a total of 20amps is available.

I have had a supercheap 12 amp smart charger for 15 years and it works fine.

Also dont post links direct to the site as they do not work - yours doesn't.

In the menu box there is a post link option - use that and all would be good

LIKE THIS

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Hi Myles,

Yeah, the salesman is 'mistaken'. A 10A charger will adequately charge your 120Ah battery.
If your battery is discharged to its lowest safe level (80% SOC) then it would take maybe 4 hours to bring it up to full charge. But as you are using it solely as a maintenance charger at home then this should be fine.

A reservation I would have about this charger is that although it is promoted to be suitable for a variety of batteries, "GEL, Lead Acid, AGM & MF Calcium", good practice requires each of these to have a different voltage for the finishing value. This charger has no adjustment provided for these voltages. "One size fits all" is old-style and not good. Do not be fooled by statements such as "Charger automatically senses and adjusts to battery type". Not possible! And do not be impressed by expressions of the number of "Charging Stages". There are only 5 "Real" stages possible at most. Any additional quoted "steps" would be "sensing" only, not charging stages.
There was a problem with your Supercheap link. Here is another link.

Jaycar on the other hand offer a well-made 10A charger that does have settings for these different battery types. Jaycar 10A charger. Although it costs a little more at $139, I would consider it to be much better value.

There is also the "Kickass" (Australian Direct) at $109 but it also has no provision to adjust for differing battery types.

EDIT:
Perhaps I should expand on the "battery types end voltages". These are only small differences and are only of consequence if the battery is going to be left on 'float' for an extended time. If the charger is only used to bring the battery up to full charge, then a basic charger with a non-adjustable 'end voltage' is adequate. Most are set to suit flooded calls.

One other thing Myles.
One of my chargers (jaycar brand) has a setting for 6 or 12 amps. If the outside temp is 30C or over the thermal overload cuts in on the 12 amp setting. It does have a fan but it just can't get rid of the heat.
Nothing wrong with Jaycar gear as I have many items purchased there just wanted to warn you about that.
My Oz Charge will work at 16amps even on a 40c day. Something to ask about with the charger you purchase.

Cheers
Stu

As others have indicated, it will be fine - and perfectly adequate unless you are in a gut-busting rush to replenish the battery.

Basically an up-sell attempt. Their 15A charger is currently twice the sale price of the 10A (both are SCA "house brand"), so their profit would be way better on the 15A unit. "Just saying ...".

For AGM charging I am reading more and more that .2C is the preferred current. For a 120aH battery that equates to 24a charging. I would have no issues using either charger, but would buy the best I could afford every time.

First up I wouldn't buy a supercrap charger. Why? Because they are cheap knock off models from china and having bought other electronic stuff from this mob I have learnt my lesson. 10 amp will do the job well. If your battery is not a top quality like Ritar, Powersonic , Fullriver etc. the your battery is probably closer to 100amp hr than 120 amp hr. 10% is a generally accepted figure for longevity. Save a few more dollars and get a quality charger that you will look after and use for many years.. Rmember...the poor man pays twice. Good luck.

I'll just add most chargers are built to a price, this generally means when the battery is low and charger is working at 100% output to bring it up to fully charged it will be running hot.

Heat is not good, it stresses internal components, most failures I have encountered in switch mode power supplies over a long working career have been caused by heat stress, ie dried out electrolytic capacitors, dried out heat sinking grease causing switching transistors/IC's to fail.

A small say 5A will charge a 150Ah ok but will take around 18 hours to bring it up to 100% SOC from 50% SOC, a 15A charger will take around 5.2 hours. If you are going to be deeply discharging the battery I would be going with a the higher capacity charger to keep run times and heat stress down. If your only keeping it topped up then it doesn't matter.

I suggest that it is insufficient to consider charge amps in isolation from voltage.
The charge voltage offered will very often limit the amps accepted by the battery, irrespective of the amps available.
An alternator is a common example.
Despite 100A +/- being available, actual charge rates are typically not excessive because the voltage is relatively low at around 14.4V.
The same battery fed by the same alternator but at 15V would be a whole different story. The charge rate would be very much higher and damage would likely occur quite quickly.
Different battery chemistries are best charged (and floated) at different voltages, so for mine, every battery charger whether it be 240V or solar should have adjustable voltages in order to treat the battery as the manufacturer intended.
After that is achieved, the more amperage available, the faster the battery will be charged, within the limits of the battery size and chemistry.
Cheers
Peter
OKA196 motorhome

As for the ethics of the salesman, on checking the charger manufacturer recommends:

6A unit for upto a 65Ah battery .

10A for upto a 100Ah battery.

15A for upto a 150Ah battery

So salesman was recommending the correct unit as per the manufacturers literature.

mynance
Apart from battery charging, Will a defibrillator work on a salesman? Answer: No it won't, because they don't have a heart.