Community Forums

TomL8345 · 01-31-2025, 11:03 AM

I recently purchased a new to me TT that is older (35+) but still in good shape. I have replaced the suspension, axles, and tires, resealed the roof and I am now refurbishing the interior and modernizing some of the systems.

I will be doing some boondocking for a week at a time. I am replacing all the lights in the trailer with LED and I plan on adding USB/12V outlets in more of the trailer as well.

I am looking at adding 400w of solar, mppt controller, and a 12v 100ah LiFePo4 battery (maybe 2). Do I need to do anything with the converter that came with my trailer? It is a Magnetek TU-740-2 converter, 120v 7.35A, 12v 40A, Avg Charge Rate 4A.

Finally, I am a CPAP user, and I am trying to design my system to accommodate that usage. I have two machines: one is a 12V 6.65A, and the second is 24V 2.5A. Do you have any thoughts about how to use the 24V machine without adding an Inverter? I'm thinking about using a 12V to 24V step up converter and just plugging that into a 12V outlet.

Thanks in advance,
Tom

Persistent · 01-31-2025, 11:34 AM

A Magnetek converter/charger is very old technology. It does not regulate well and may cause electronic devices to miss behave. It may boil your lead acid battery dry. It charges very slow. You should replace it especially if you are going to run a CPAP on it.

I recommend a 35 amp 12 volt converter/charger or larger. It would be good for a 100 amp hour lead acid battery. Check out etrailer.com They give good advice.

A pair of 100 amp hour lithium batteries would be better. A new lithium capable charger and solar controller would all work together well. They may not cost more than paying for AGM lead acid batteries.

I got 5 days of dry camping using a pair of 100 amp hour AGM lead acid batteries. However, 400 watts of solar charging will quickly charge a 100 amp hour battery. At least that works if you are camping in the Desert South West.

CPAP
My wife uses a 24 volt CPAP. She got a power brick and cord that plugged into a 12 volt cigarette lighter socket. It does not power the humidifier.

Vintage465 · 02-04-2025, 09:35 AM

It sounds like you're on the right path. However you choose to install conductors for the solar, I would size them for a possible future upgrade. As mentioned you will need to upgrade your converter to something lithium campatible. I upped to a Progressive Dynamics. With 2-100ah lithiums you have enough battery bank to run your C-Paps....and possibly the humidifiers if you turn down the setting a bit. I have a Resmed 24v unit and a Phillips 12v unit we run off our battery bank and we run our humidfiers....but I do have 400ah of Lithium. With a little searching you can find converters that will plug into 12v outlets(cigarette lighters)for 12v and 24v. Also, I ran a dedicated #12 conductor to power my C-Paps. Humidifiers create a fair amount of load and a 16 or 14 gauge would not likely keep the peace.

Triangle Drifter · 02-05-2025, 08:42 AM

When it comes to drycamping for more than a day or two water capacity and battery bank capacity are top priority. Water being absolute top importance. Once it is gone, it is gone.

RV_Lee · 02-06-2025, 06:23 PM

100ah is fine for a rig that goes from RV park to RV park and will be enough for an overnight stay at a rest stop but is nowhere near enough for boondocking. 200 might do if you have sun everyday. Aim for 300-460.

SafariBen · 02-06-2025, 08:54 PM

You don't mention any electrical use besides the LED, USB, and CPAP machine, so I'll assume the CPAP is the main electrical load. I would go to 24V just to use the more efficient CPAP. 24v solar will be cheaper and more efficient than 12, the battery will be the same price per KWH, and will possibly be more reliable than two parallel 12's. You'd have to ditch the converter.

If you stayed with 12V, the converter would be fine with Li, it wouldn't fully charge to balance, but the solar would easily do that. Balancing is not needed every week, or even every month.