Frequently Asked Questions
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To fully charge up a wet cell battery, most battery manufacturers suggest 2.35 volts per cell or 14.1 volts (for a 12V system). However, this varies depending on the manufacturer, temperature, and type of battery – Lead Acid, Gel Cell, Lithium
The amount of time it takes to charge the battery depends on many factors, such as capacity of the battery, the amount the battery has been discharged, the gauge of wire connecting to the battery, and the size of the charger. Considering these variables, charge time can range from 2 to 24 hours.
The selector switch allows the user to change the charging mode from “standard” 3 stage charging to fixed mode charging. Please see the User Manual for information on how to use the selector switch.
No. To keep the unit cool, PM3 converter / chargers feature proportional fan control. The fan will run only when needed and at the speed necessary to cool the unit.
The fuses on the PM3 provide Reverse Polarity Protection should the unit be connected to the battery incorrectly. If the fuses are blown, verify proper battery installation before replacing the fuses. Always replace the fuses with the same type and rating fuse.
Fuses used for the DC circuits are determined by the manufacturer. Always replace with same type and size as the original.
220-240V systems require a specific PowerMax unit. 220-240V units are clearly identified on the label as 220-240V and are available in a variety of amperages.
The PM3 can charge any battery type, Lead Acid, Gel Cell, or Lithium batteries in 3 stage or fixed mode charging. PowerMax also has specific units with 2 stage charging for Lithium if required by the battery manufacturer.
The battery will draw amperage out of the converter. The converter provides only the amount of amperage the battery requires. In an RV application, amperage is supplied to the RV load first, then the remainder goes to the battery. Reducing the RV’s electrical load, sends more amperage to the battery allowing it to charge faster.
No. The converter will accept AC input and convert it to DC voltage to operate your equipment.
The converter is a constant current device. This design will hold current (amperage) constant while reducing voltage as loads increase. The converter may be in Bulk Charge Mode but due to the high amperage draw, you may only see voltages in the high 12 VDC range. As amperage is reduced, the voltage will climb. Wire length, loose connections, or battery isolators can also affect the voltage that reaches the battery from the charger / converter. Keep all wiring connections tight and keep wiring distances to a minimum.
Hydrometers can give you an accurate reading of the state of charge of each battery cell, however a good voltmeter can safely give you an accurate reading of the battery state of charge. The following is a gauge you can use to check your battery in a rested state.
• 12.63 – 100%
• 12.45 – 80%
• 12.27 – 60%
• 12.09 – 40%
• 11.91 – 20% (Avoid allowing your batteries to get below 20% capacity).
Yes, however batteries MUST be the same brand and type (preferably the same age as well). Adding more batteries will provide longer use of DC appliances when not on shore power. But using multiple batteries may reduce the converter’s battery charging efficiency.
Yes. Multiple PowerMax converters / chargers can be wired together for ‘Series’ or ‘Parallel’ charging. By combining multiple PM3 units together, you can increase either the output voltage or the amperage of the PM3.
Charging in Series multiplies the output voltage by the number of chargers you are using. For example: Two PM3 chargers with an output voltage of 13.4VDC connected in series would provide an output voltage of 26.8VDC with no effect on amperage.
Parallel combines the amperages of the DLS units with no effect on output voltage. For example, two PM3-35 chargers connected in parallel, would provide 70 amps at a continued 13.4VDC output.
No. Please contact PowerMax Tech Support to help identify the problem. If the converter is under warranty, PowerMax will replace the unit.
The PowerMax converter serial number is located on the label next to the fuses.
Whenever a 12V battery has reached 13.8 to 14.1 VDC and remains there for any length of time, it will “gas”. Some gassing is good, but if left in this condition for a long period of time, it can boil, start bulging, and ultimately ruin the battery. Additionally, a short in one of the battery cells or an old battery with a very high leak inductance can cause the charger to put full current into the battery, causing the battery to boil and become a safety hazard. When plugged into the shoreline or grid power for long periods of time, the best way to maintain your batteries is to have a charger that will “float” your batteries at an appropriate level (13.4 to 13.8 volts for 12V batteries).
The ideal operating temperature for most batteries is 78 degrees F. High temperatures can cause the battery to self-discharge faster. Cold temperatures slow down the self-discharge but decrease the output capacity of the battery. At 0 degrees F. a battery will only have 50% of its capacity at the ideal operating temperature of 78 degrees F. Caution: A battery that has been 80% discharged can freeze and burst at 18 degrees F or below.
Cold temperatures require a higher voltage to charge the battery up to the 100% level. Battery charging voltages should adjust according to the ambient battery temperature to ensure a full charge in colder temperatures and to ensure that the battery does not overcharge in higher temperatures.