K8MEJ
Owner, Off-Grid Power Systems
Apologies if this isn't the right sub-forum for this question. I'm new here.
I'm planning for an off-grid solar + LiFePO4 + inverter/charger system for my travel trailer with the new system running a nominal 24v. To power my existing 12v accessories (tongue jack, electric brakes breakaway system, 12v accessories running from existing DC fuse block) with a 24v-12v DC-DC step down converter. I am a ham radio operator that likes to operate when I go camping myself or when performing STEM demonstrations for Scout events. Consequently, I need to build a system that generates as little radio frequency interference as possible. That's challenging when you consider that the charger & inverter circuitry are both switch-mode power converters and so is a DC-DC converter. All switch-mode power supplies generate a lot of harmonics that create havoc on the HF ham bands. There are FCC Part 15(b) Class B certified, which are supposed to be well filtered to limit the amount of RFI generated. Based on this, I have two questions for the collective intelligence here:
1. Does anyone know of a 24v-12v DC-DC converter that is well filtered for RFI? I can't find anything in the 40-60amp range that holds an FCC Part 15(b) Class B certification. If you have experience with a DC-DC converter that is RFI quiet please let me know.
2. If I build such a system, is there any concern with the low-current 12v power supply coming in to the camper from the tow vehicle via the 7-pin connector? In other words, can the 24v-12v converter handle another 12v power source on the 12v side of the converter?
Thank you in advance,
Ed Jones
P.S. The Xantrex Freedom SW 3024 is the inverter/charger I plan to use because it carries the FCC certification. I am planning to use one or two Morningstar ProStar MPPT 40amp solar charge controllers because they also carry the FCC certification and I have found several discussions where hams say they are RFI quiet. I can't find any solid ham-friendly advice on inverter/chargers. I'd love to use Victron everything, but their MPPT SCC's are known to generate a ton of RFI junk. Their Multi-Plus inverter/chargers hold no FCC listings and I can't find any evidence they are RFI quiet or not.
I'm planning for an off-grid solar + LiFePO4 + inverter/charger system for my travel trailer with the new system running a nominal 24v. To power my existing 12v accessories (tongue jack, electric brakes breakaway system, 12v accessories running from existing DC fuse block) with a 24v-12v DC-DC step down converter. I am a ham radio operator that likes to operate when I go camping myself or when performing STEM demonstrations for Scout events. Consequently, I need to build a system that generates as little radio frequency interference as possible. That's challenging when you consider that the charger & inverter circuitry are both switch-mode power converters and so is a DC-DC converter. All switch-mode power supplies generate a lot of harmonics that create havoc on the HF ham bands. There are FCC Part 15(b) Class B certified, which are supposed to be well filtered to limit the amount of RFI generated. Based on this, I have two questions for the collective intelligence here:
1. Does anyone know of a 24v-12v DC-DC converter that is well filtered for RFI? I can't find anything in the 40-60amp range that holds an FCC Part 15(b) Class B certification. If you have experience with a DC-DC converter that is RFI quiet please let me know.
2. If I build such a system, is there any concern with the low-current 12v power supply coming in to the camper from the tow vehicle via the 7-pin connector? In other words, can the 24v-12v converter handle another 12v power source on the 12v side of the converter?
Thank you in advance,
Ed Jones
P.S. The Xantrex Freedom SW 3024 is the inverter/charger I plan to use because it carries the FCC certification. I am planning to use one or two Morningstar ProStar MPPT 40amp solar charge controllers because they also carry the FCC certification and I have found several discussions where hams say they are RFI quiet. I can't find any solid ham-friendly advice on inverter/chargers. I'd love to use Victron everything, but their MPPT SCC's are known to generate a ton of RFI junk. Their Multi-Plus inverter/chargers hold no FCC listings and I can't find any evidence they are RFI quiet or not.
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