Originally Posted By: wrcsixeight
So your standing in the basement, near some copper plumbing. You know there is pressure in them pipes, and somebody upstairs turns on a fawcet.
You can hear water flowing through the pipes, BUt is is the watermaker in your fridge, or is someone filling the bathtub.
Voltage is electrical pressure, but it does not tell one how much water is flowing through Dem pipes.
Get a digital Ammeter.
Defining 'Current' by voltage alone, is not wise.
Get one of these, or one of the many different clones available. Place it inline on the charger output paying attention to the load and source sides. The battery is the load when charging, the charger the source.
https://www.amazon.com/RGBZONE-Power-Ana...ds=gt+power+130
With it you can see:
voltage
Amperage
Wattage
Peak amps
Peak watts
Minimum voltage
Amp hours
Watt hours
and possibly time since it first got powered up, depending on the clone chosen.
Much Much much more revealing than voltage alone.
Revealing as to what the charger is doing, or not doing, and what the battery is accepting at the voltageit is being held at by the charging source.
Most AGMS specify a float voltage, at 77f, of 13.6v. There are exceptions, but too low a float voltage held for a week is worse than disconnecting the fully charged AGM, if indeed it is fully charged.
I have a Northstar AGM. If I float it at 13.5v for any amount of time, while still running other DC loads on the battery, then I boost voltage back upto 14.7v, well if the battery was being kept fully charged, amps would quickly taper to very little percentage of capacity, but 13.5v does not do this. 13.6v does.
13.5v while running DC loads and it takes X amount of time for amps to taper back to 0.5% of capacity or less at absorption voltage, indicating the battery even while being held above its fully charged resting voltage, was getting discharged by the DC loads at too low of a float voltage.
I'm not quite sure how this works but it is observable and repeatable and very obvious as I have an ammeter, and can easily change voltage by twisting a dial, while watching a voltmeter, and ammeter.
Get an Ammeter, or you are basically blind.
And as far as determining the efficacy of any charger, use a hydrometer. The hydrometer on a flooded battery is a battery polygraph. The green light on the charger is meaningless, indicating only that the charger has dropped to float or stopped. Float does not equal full. The green light does not equal a fully charged battery.
Trust if you want, but I recommend verification. I have a schumacher sc2500a charger, that back when the display still worked, would throw out the green light, but my wattmeter inline would indicate the battery was still being held at 14.7v, and still accepting 5 amps. This is very far from being fully charged, this is still hours away from being fully charged.
With AGMS verification of full charge can only be done with an Ammeter with the battery at absorption voltage/ ~14.5v. Float voltage amperage is nearly entirely meaningless, unless the battery is accepting a lot of amperage at float voltage, this would indicate the battery is NO where near fully charged.
Get an Ammeter.
That is great info. Kudos to the poster.
If you don't remember all of it remember this:
"Voltage is electrical pressure, but it does not tell one how much water is flowing through Dem pipes.
Defining 'Current' by voltage alone, is not wise."
They used to teach this in 7th grade science. By high school physics it was that and Ohms Law, AC and DC, etc.
I kid you not, I know engineers who ask me to wire their garage or room addition because they can't do it. Software engineers who can't handle a DMM for basic functions, etc
