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Using a PowerMax AC to DC Converter Charger With Battle Born Batteries

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The Powermax PM3-55LK AC to DC Converter/Charger is a fantastic converter/charger that works tremendously well with Battle Born 100Ah 12V LiFePO4 batteries! The most prominent feature of this charger is the ability to manually adjust the charging voltage. This is huge for LiFePO4 batteries because it enables the user to charge their LiFePO4 batteries to the ideal 14.4 V and get the most life and power out of their battery!

Once the charger is adjusted to the 14.4 V, the unit will have the following values for its 3-stage smart charging:

  • Bulk Charge: 14.4 V
  • Absorption Charge: 13.6 V
  • Float Charge: 13.2 V

Follow the steps below to adjust your Powermax PM3-55LK to work with Battle Born Batteries.

Tools required:

  • Phillips Screwdriver
  • Multimeter

Step 1:
Disconnect unit from power and move switch A to the “Adjusted Fixed Voltage”.


Step 2:
Plug charger into AC source. Connect multimeter to positive and negative outputs of charger to measure the voltage.

Step 3:
Use a Philips head screwdriver to gently adjust Switch B until you have a voltage value of 14.4 V on your multimeter.

Step 4:
Once you have achieved a voltage of 14.4 V, unplug the unit and move switch A back to “3 Stage Charging”.

Step 5:
Reconnect battery to Powermax and with your multimeter and plug it back into power. Then measure the voltage at the battery and at the output terminals; these values should be about the same. If the voltage at the battery is significantly lower than 14.4 V, go back to step 3 until the voltage at the battery is 14.4V.

Click here to see the product specifications.

If you have any questions or concerns, please give us a call at (855) 292-2831 or email us at [email protected] so we can help you get out there and stay out there!

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11 thoughts on “Using a PowerMax AC to DC Converter Charger With Battle Born Batteries

  1. I have two Battle Born 100 Ah batteries connected to a PM3-45LK for shore power charging. I spoke with Powermax and we believe the absorption charge is lower than 13.6v. I am seeing the profile start at 14.4v but drop to 13.2v and then 12.8v – the PM3 will also cut out from time to time. We believe Step 4 here may be eliminated and the power supply should be left at the 14.4v fixed voltage – would there be problems doing this?

    Powermax mentioned they will be coming out with a 2-stage charger for LifePO batteries soon.

    1. Hello Pete! Thank you for reaching out. In order to properly charge our batteries a voltage of 14.2-14.6 is required for the bulk/absorption stage. Once this stage of charging is finished you can leave the float voltage at 14.4 without issues. We do recommend that if you are not cycling power out of the batteries (at this higher float voltage) it should be disconnected after 3-4 weeks. A higher float voltage for this amount of time is not good for our lithium batteries. Please let me know if you have any additional questions, and have a great rest of your day!

  2. I replaced my old converter with a PowerMax PM3-lk55 in a 2007 Fleetwood Prowler 240RKS; in doing so I had to remove the plug-in from the cord. I connected the green and white nwires, but i am unsure where to connect the black wire. There are three breakers; a 30/20, a 15/15, and a 20.

    1. Hi Theodore, thank you for your comment. You can give our sales and tech team a call at 855-292-2831 and they can help walk you through the troubleshooting process. Thanks and have a great rest of your day!

  3. Do you have updated instructions for the new BD1260HWL Boondocker BD 1260HWL (60 Amp 4-Stage Converter/Charger Hard Wire) I believe they have a similar adjustable voltage and switch for moving between multi and fixed?

    1. Hi Dave, thanks for reaching out! Our team suggests that as one of the classic Boondocker converters that has the option of 3 Stage output or Fixed Voltage Output, we recommend using the foxed Voltage Output for these converters with the output set at 14.4v. You can see the setting instructions on the second photo of this link here. https://www.bestconverter.com/Boondocker-BD-1260HWL-60-Amp-4-Stage-ConverterCharger-Hard-Wire-_p_751.html#.YHjD1uhKiUk

      1. I recently did this install of the BD1260HWL Boondocker BD 1260HWL (60 Amp 4-Stage Converter/Charger Hard Wire) at a thousand trails campground in La Conner, WA. I met a nice gentleman that had a different Boondocker model and he installed it with a switch that allowed him to shut the converter off and what that does is resets the 3 stage charging and brings the batteries up to voltage. So, since we are buried under a canopy of trees, I left the setting on 3 stage charging opposed to fixed. I just periodically switch the breaker off and on to bring the batteries back up to 14.4 when there isn’t sufficient sunlight. When the sun is out my 400 watts of solar panels can throw 20 amps through my Victron controller, with the absorption voltage set to 14.6 volts and float voltage is set to 13.5. Does this sound like a reasonable solution or should I still consider the fixed voltage recommendation?

  4. We currently need to replace our non functional power converter on our golf cart batteries with a Powermax PM3-55LK. We plan to upgrade our batteries to battleborn – probably 2 100amp hour ones.
    Pete says: that he had issue with this set up using a Powermax PM3-45LK (not sure if this was a typo for 55LK) and was going to go with fixed 14.4V.

    Might this issue be avoided if we were to go to the 60LK or 65LK version of the Powermax PM3?

    How many amps are typically drawn when charging at the bulk, absorption and float level per 100amp hour battleborn batteries?


    1. Hi John, our team would be able to assist with this question if you give them a call at 855-292-2831. Thank you!

  5. I’m getting ready to order 2 12 volt battleborn 100ah batteries for my boat. I have been using a Powermax PM3 30 amp to charge my lead acid batteries during bowfishing trips. Will I still be able to charge both the lithium batteries in the same series connection as before with the lead acid?

    1. Hi Clayton. As long as your able to adjust it to the appropriate settings for lithium as mentioned in the blog above, you that should work just fine!

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