AGM Chargers

[five]

I was under the impression you need to have a certain charger or a certain setting in your charger if using  it with AGM batteries.  There's a poster on another forum who insists AGMs work fine on 'normal' chargers.  Anybody have the straight skinny on this?

[desertdeals69]

If the charger does not have a AGM setting, use the flooded setting.  They are very similar.

[dickandlois]

Five! AGM Batteries have there place, but they do require conditions different form other type batteries.

Check out this link.

  http://batteryuniversity.com/learn/article/absorbent_glass_mat_agm

Rich.

[wolfe10]

Rich,

From the article: " As with all gelled and sealed units, AGM batteries are sensitive to overcharging. A charge to 2.40V/cell (and higher) is fine; however, the float charge should be reduced to between 2.25 and 2.30V/cell (summer temperatures may require lower voltages)"

2.40 times 6 cells = 14.4 VDC (bulk charge mode)

2.25 times 6 cells= 13.5 VDC (float low side)

2.30 times 6 cells= 13.8 VDC (float high side)

These numbers are very close to regular wet cell batteries, so if no AGM setting on a smart charger or smart inverter/charger, wet cell settings work fine.

[dickandlois]

Brett, good point. I do have one question.

With the charging current of 130 to 160 amps from the alternator and 100 to 150 amps from many of the inverter changers. With this current level is heat created from this charging level create temperatures detrimental to a sealed battery.

Rich.  

[wolfe10]

Rich,

Remember, amps available does not necessarily mean amps in.  Voltage is controlled, which therefore controls amps.

And, AGM's because of lower internal resistance do not heat as much as wet cell batteries (should be mentioned in the article you cited). That is why they can accept a higher charge rate than wet cells.

[dickandlois]

2 minutes ago, wolfe10 said:

Rich,

Remember, amps available does not necessarily mean amps in.  Voltage is controlled, which therefore controls amps.

And, AGM's because of lower internal resistance do not heat as much as wet cell batteries (should be mentioned in the article you cited). That is why they can accept a higher charge rate than wet cells.

Thanks Brett, One is never to old to have there knowledge base refreshed and you are correct!  I did not take the difference in internal resistance into consideration and I have not run across anything published that really covered the internal resistance.

Rich.

[five]

Thanks guys.  These things are high dollar and I want to be sure I get my 'high' dollar's worth.