AGM Battery Charging

To maximize the life of your Chrome Battery brand battery, it is important that it is properly charged. As with all

lead-acid batteries, both over- and under-charging a Chrome Battery AGM battery will result in shortened service

life. The best protection from improper charging is the use of a quality charger and routinely

checking that the charger current and voltage settings are maintained.

 

Please read the following instructions before using your battery.

 

Charger Inspection

The charger cabling should be insulated and free of breaks or cuts. The cable connectors should be

clean and properly mate with the battery terminals to ensure a snug connection. The charger’s AC

cord should be free of breaks or cuts and the wall plug should be clean.

 

Charging Guidelines

  • Fully charge batteries after each use.
  • Charge in a ventilated area as gasses may be released through the pressure relief valve if the

batteries are excessively over-charged.

  • Never charge a frozen battery.
  • Ideal charging temperatures: 32°F – 104°F (0°C – 40°C).
  • Charging Characteristics

    If the charger has a setting for AGM, use this setting to charge your Chrome Battery AGM battery. To maximize your

    battery life a voltage regulated charger with temperature compensation is strongly recommended.

    VRCIUU.jpg

  • The initial charge current is recommended to be set at I1= 0.25 X C20 (Imax= 0.35 X C20) in order to fully charge the batteries within a reasonable amount of time.  It can be set lower, however please be aware that charge time will increase so make sure the batteries have enough time to fully charge before being put back into service. Chrome Battery AGM batteries have a low internal resistance allowing them to be charged at a higher current, therefore faster, than conventional flooded/wet batteries.

     

    Bulk stage – the charger should deliver the initial current I1 until the voltage limit U0 is reached.

     

    Absorption stage – the charger should maintain the voltage U0 until the current tapers to I2.

     

    Float stage and termination – the charger can maintain the current I1 indefinitely or until the charger is shut off or unplugged.  This stage is ideal to maintain battery state of charge.

     

    Make sure the temperature compensation is programmed as specified in the graph above (-4mV/°C/cell or -2mV/°F/cell) or manually adjust the voltage setting for temperatures varying from 25°C (77°F).  As the temperature decreases, the voltage should be increased and as the temperature increases the voltage should be decreased. The profile in this graph can be used with or without the float stage.  Without the float stage, recharge can be terminated based on time (this will need to be determined as it will vary with depth of discharge and charge current) or percentage recharge (~105%-110%).

  • excessive over-charge.  See figure below for the recommended constant current charge profile.

     

    CCCIUI.jpg

     

    Bulk stage – the charger should deliver the initial current I1 until the voltage limit U0 is reached.

    Absorption stage – the charger should maintain the voltage U until the current tapers to I2.

    Termination – If the charger can be programmed, the charge should terminate when the voltage stops

    increasing over time. This is called a dV/dT termination. The charge should terminate when the dV/dT

    is equal to 2.5mV/cell/hour.

    The charge time in the final phase should not exceed 8 hours and the total charge time should not

    exceed 20 hours.

    The percentage recharge should be between 105%-110%.

  • Charge Voltage Quick Reference

     

     

8 thoughts on “AGM Battery Charging

  • Hello,

    Great article. You have mentioned that the current “can be set lower, however please be aware that charge time will increase so make sure the batteries have enough time to fully charge before being put back into service”. Is there is a “rule of thumb” for a minimum suggested current, based on the CA parameter? Is it safe to charge a 20 AH battery with 1 A? Would it damage the battery?

    Best Regards,

    Alex

    • Thanks for your comments, with regards to the charging question of whether or not it is safe to charge a 20Ah battery with a 1amp charger it would be more than fine to do this, however if the battery was fully discharged it would take about 20 hours to fully charge the battery. A slower steady charge is alot easier on the battery than that of a fast rapid charge. However if it was me I would probably use more of a 4 to 6amp charger on a 12V 20ah battery it is a good middle point not to slow and not to fast. Let us know if you have any additional questions or concerns we would be more than happy to assist.

  • Hi there.
    I came to the site because I own a Chrome Pro YTX9-BS battery. Unfortunately, I do not understand the instructions that are included with the battery nor this article, above. My battery is discharged to less than 8 volts and I would like to charge it but, am not sure how to safely proceed.
    I have access to a 12 volt charger that is capable of 2 amp or 10 amp charging. Please inform me of how to safely charge my battery. If you would also suggest a maintenance charger appropriate to this battery also, so that I never discharge it this drastically again ?

    • We are not to sure you will be able to revive this battery, however the best way to charge this is to have your 12Volt charger set at 2amp setting it should take about 4 hours to fully charge up this battery. It should top charge out at 13.4Volts then drop down to 12Volts once a load is applied.

  • Thank you, Brittney.
    Fortunately, it read above 10 V’s this morning. I do have it on a charger the same as you instructed above. In the event that I do acquire another or this one does revive,would also suggest a maintenance charger appropriate to this battery also, so that I never discharge one this drastically again ?

  • Yes we would suggest a float or maintenance charger for your battery that way it will not drop that low again. We have a 1amp and a 4amp smart charger that is affordable that would do great with this type of charging maintenance.

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