Choosing Between The Redarc 25 amp or 40 amp Model For A 2018 RAM Promaster 1500

Question:

I have a 2018 RAM Promaster 1500. The dealer service department couldnt tell me if it was a variable or SMART alternator, but, did say it was 180 AMP. How do I decide between the Redarc DC to DC battery 25 amp or 40 amp charger? Does it have to do with the size of my alternator or the size of my auxillary batteries? I am looking at purchasing a LiFE po4 , 100Ah battery, but would like to add an additional battery down the road, for possibly a total of 200 or 300 Ah. Which Redarc unit should I purchase - 25 or 40 ? Also, so I understand correctly that the input for solar on the Redarc Unit can accept unlimited current but has a max output 40 watts? If the unit greenly s solar over alternator Im okay w that, however, wont that sometimes be a longer charge time than from my running alternator? Lastly, can I use any solar panels or is it proprietary panels in some way? I greatly appreciate your informative videos.

asked by: Cathy C

Expert Reply:

Your 180A alternator will work fine with any of their BCDC models. Whether you need a 25, 40 or 50A model will depend on the size of the battery bank you’re planning to charge. If its between 75-200Ah the # 331-BCDC1225D model will be fine but if its greater than 200Ah either the # 331-BCDC1240D or # 331-BCDC1250D will work best to replenish the battery bank faster.

Yes, the BCDC can accept unlimited solar Watts/ Amps but its output is limited by the model chosen (i.e. 25, 40 or 50A).

Yes, the BCDC is a simultaneous charger so it will always accept charge from solar first and then top up from the vehicle's alternator. In the case the # 331-BCDC1240D model is able to output up to 600W of solar so its unlikely you will carry this much solar. Therefore, it will seek power from the alternator if the vehicle's ignition is on. However, when the vehicle's ignition is off it will pull as much power from solar as possible. It will take longer to recharge using solar power for sure. The speed of charge from solar will depend on the number of solar panels connected to the BCDC. For the # 331-BCDC1240D , if 600W of solar panels are connected and the sun is shining bright you’ll get 40A of charge going into the auxiliary battery. Anything less than 40A from solar and the BCDC will pull power from the vehicle's alternator too.

Unregulated nominal 12V solar panels are to be connected to the BCDC. The panels must have an open circuit voltage of 32V or less.