TIL the importance of AC vs. DC

[u/jasoncbus]

PNW for the summer, worst I saw was 2 full days of clouds. Not too bad. House battery just barely survived a 3 day onslaught of ZERO sun on the panels.

I was running my fridge on the AC outlet, full time. Plus and extension cord for miscellaneous. What a lesson. Don't do that lol. Today I got up a 6am and ransacked my electrical and now every swing d...utility is on D.C.

With it somewhat cloudy my battery ran up to 100 around 2pm. I fear I may have done some damage to the power station. But, lesson learned.

Don't be me, use D.C. for EVERYTHING!!!

[u/pyroserenus]

AC has its place, mostly big and fast loads. DC gets progressively better the lower your sustained power needs are. In short use it for cooking and as needed for things that can't run on DC. 12v fridges on the other hand are called 12v fridges for a reason.

Commiting to 24/7 inverter usage isn't ALWAYS bad, but it requires a totally different set of planning and usually isn't a great approach for a van.

[u/jasoncbus → u/pyroserenus]

No shit haha. Learned that when I woke up to sub %30 battery after 3 days / nights.

You're right about AC having its place. When I first started this leg, I had to cut some metal, and the power station handled it very well. I was surprised. So I wrongly assumed to just leave on the A.C. for anything that would take it.

Now I have a montra - turn it off. I have an electric bed frame for back problems. It's on A.C. It can take D.C. but I'd have to actually know what I'm doing to get the exact cable for it so as not to set my van on fire. So, from now on, the bed frame is on a "turn it on, then turn off" setting.

[u/xgwrvewswe → u/jasoncbus]

Getting the right cable is easy. You just need to know distance, both ways negative and positive, ampere demand, voltage of the battery. There are charts and tables that will tell you the exact gauge of wire and the most important part, what fuse.

[u/cr0ft → u/pyroserenus]

If the ultimate source of power for whatever it is is DC batteries, there will still be a wild amount of amperes running over DC to provide power to the household current appliances. If you're on shore power that's another matter.

[u/goonie284]

Yeah, inverters are inherently inefficient, good you found out now instead of in the winter when there would be way less sun to recharge the battery. Was it a lithium battery? If so it’s no biggie to almost fully drain but if it’s a lead acid battery it can shorten the battery life to drain below 50%.

[u/jasoncbus → u/goonie284]

Lithium. I went with a big power station because I'm too dumb to wire up an actual system. Or lack of patience / focus, I guess.

I'm actually happy I found out, though. Now, I'm looking forward to squeezing in a propane generator and enjoying the cloudy days and fall foliage in the North East here soon. Seriously looking forward to that. Never been.

[u/midgaze → u/jasoncbus]

The propane generator is really nice for those times when you're running a power deficit. Running the generator for a few hours a couple times a week keeps things going. I have a Honda EU2200i with the Hutch Mountain propane conversion kit, and it works great. I get about 20kWh from a 20lb tank of propane (pre-conversion, somewhat less gets into the batteries.)

The amount of power (kWh) you get from a tank of propane is higher if you can run the generator close to its max rated load, as the generator is more efficient at high loads. Maybe 50% higher at 90% than at 25%. Also, cheap generators tend to overheat and shut down when you try to run them close to their full rated load for any length of time, because they are liars. Honda generators are not cheap, but they do what they claim to do and will serve you for years.

If your AC -> DC charging system is too small to load the generator fully, you might be able to get away with a cheap generator, but you'll be paying more for propane.

[u/ParkerFree → u/midgaze]

I also have a Honda generator, the EU200i with a propane conversion kit. I live in the PNW, and it saves me every winter. Currently running completely off AC, but like OP, moving more to DC in my new build.

[u/HeavenDecker]

Everyone is generally correct. Just want to clarify things as an electrical engineer.

Inverters are NOT overall efficient. 1. They burn power with no load. E.g. 3000W inverter idle is 60w 2. They PEAK efficiency at 90%. And that peak is, ideal conditions, typically around 40% to 80% of its rated capacity, For example to charge my ebike 690 wh, it took 1000wh of battery. That is 70% eff.

Small loads will be worse.

There is a reason inverter have remote on/off.

Minimize AC at all costs. I actually would love to create more DC devices not generally available: PC LCD (get portable ones), ebike charger (possible DCDC 12-48v).

[u/Gunnarz699]

Good inverters are very efficient. "Power stations" less so. This is more of an argument to have a DC-DC charger or a small backup generator.

[u/cr0ft]

An inverter loses something like 20% efficiency by converting, and then converting back inside the appliance just adds to that. So yeah, if you're running off batteries, don't do househould current.

[u/fflis]

How did you take an AC fridge and start running it on DC. Yes a 12v fridge is more efficient, but that’s a whole different appliance.

What did you actually change over to DC?

[u/Lost_soul_ryan → u/fflis]

Depending on the type of fridge, a lot of them can run off either. For instance my Iceco will work off either.

[u/Prestigious_Yak_9004]

I usually turn my inverter off for the night. The food is still cold in the morning in the fridge. Works fine for me. I wouldnt trade the inverter in for anything. I have a lot of stuff I like to run with it. Most of it is quick loads. I also have a small generator to do a quick bulk charge and take a shower with the hot water heater if I want to or need to. Love it.

[u/Prestigious_Yak_9004]

Always check the idle power consumption power of an inverter before buying it. If it’s over 30 watts look for another. There is also standby mode which can be as low as 10 watts if memory serves. Some of them have an adjustable wake up setting.

[u/kdjfsk]

A/c has its place.

I carry a lot of power tools. I dont like all the proprietary 12v batteries that fail. 12v, or even 18v or 24v, is just going to be a way less powerful tool than a 120v tool. Why use a shitty 5ah battery when i can be tapped into a 200ah battery? Yea, the inverter has some inefficiency, but its not that big of a deal for something that i domt use as part of a daily routine.

Also, imo, its good to have other means of charging than solar. Theres lots of options. Small wind generators are a thing. Propane/gas generators, shore power from a friendly home, or a campsite, ev charge station adaptor, etc. Be flexible. Parts break and fail. Having suboptimal backups and alternatives can ease the situation until you can get the main squeeze repaired.

[u/fflis → u/kdjfsk]

I mean if you told me I could only have a single drill, I’m choosing the 12v Milwaukee hammer drill, not a giant 120v sds Bosch.

I think if you told me I had to use all cordless or all corded tools for the rest of my life, I would choose cordless.

[u/kdjfsk → u/fflis]

And you'd be without functional tools as soon as the batteries fail, as they commonly do. those things are consumables.

I have a bin that is something like 18"x18"x24", and i have half a dozen corded tools in there, along with the associated bits, blades, and discs. Size isnt an issue. There are huge corded power tools, sure, but there are also corded power tools smaller and more powerful than 12v cordless equivalents. Particularly the Bauer stuff from Harbor Freight is great. The smallest or second smallest of each type always does the job for me, and average price is like $40 per tool. The whole bin of tools cost less than what you can spend on one 12v milwaukee battery...not even a tool, just the battery... and i dont have to worry about them becoming obsolete.

[u/fflis → u/kdjfsk]

I’d love to see you perform a household function like hanging blinds or repairing a fence, mounting a tv using a plug in drill vs me with a little M12 cordless.

Will I need a new battery in 5 years? Ya probably. But this isn’t your nicad battery from 1999 that’s always dead when you go to use it. It’s always charged, it’s super light weight, powerful enough to drill and drive tapcon screws in cement. It does it all and it’s easy to grab and super portable.

[u/kdjfsk → u/fflis]

I’d love to see you perform a household function like hanging blinds or repairing a fence, mounting a tv using a plug in drill

Gosh, im flattered? All of this is completely trivial. I'm not even sure what you're trying to imply. Cord length?? First, I don't use them around a house, so a 25' cord is more than plenty for me, but longer cords exist for homeowners, and almost every garage has a few of them.

It’s always charged, it’s super light weight, powerful enough to drill and drive tapcon screws in cement. It does it all and it’s easy to grab and super portable.

Yea, i can say all the same for the 120v stuff. Except the 12v batteries aren't always charged, they're charged until they're not and have to go back on the charger. I have way more capacity in my house battery bank than the pocket size cordless battery. Also, unlike the 12v, i can run much longer off of power stations, all day on generators using gas or propane, or infinitely off of shore power as long as civilization exists.

Cordless is a lie anyways. You still need an outlet for a charger, so all the ectra steps and costs are just a scam anyways. Skip the nonsense, and just plug into the outlet to begin with.

[u/xgwrvewswe → u/kdjfsk]

I have had no problems with my Ryobi setup. I have 18V batteries that are 11 years old and still work fine.

[u/shickenphoot]

General rule 12v 85-90% efficient 24v 92-95% efficient 48v 94-98% efficient Quality matters

Dc is not always better. Replace my dc fan with an ac fan and it used less power and was quieter