Very, very cool...thank you.
Now is the time for me to install a good system. I have the access and I need batteries, anyway. Looking at a few of the cost comparisons of AGM vs LiFePO, it’s silly to not install lithium, if you can swing the up front cost. Even that isn’t terrible now, I’m seeing quite a few brands (Epoch, kilovault, SOK) coming in around 600 bucks for a 12V, 100’ish Ah battery.
I’m going to get the system set up for future expansion into solar, but I don’t have any plans to do that yet. So…design leaving room for the solar controller and making sure the inverter/charger has an input for it.
I’m also looking to get a DC/DC charger to run off the engine alternator. My running electrical load isn’t all that high (carbureted engine, no pcm) so I have quite a bit of overhead on the 100 amp alternator installed too.
I totally get it and agree with you 100%. I've figured out I can fit 4 of the Lion UT1300 batteries on my battery tray. They have a lot of good reviews and have been recommended to me by a few people. It's swinging that initial purchase but I'll save up for them.
I only have a 1200 watt inverter right now and it's a modified sine wave which from what I understand can have issues where you really want a pure sine wave inverter. And to run my whole coach I technically need two 3,000 watt inverters. $$$$ All just takes time to do.
Yes a DC/DC charger is on my list too.
I think the modified sine wave thing is a bit overblown. Everyone says the pure sine is better for electronics and whatnot, and I'd say if you were buying fresh, go pure sine...but I don't know that I'd replace a modified sine wave inverter, just because. If you think about the electronics that the internet says are an issue (computers, phones, TVs), most of them have their own inverters (the brick on you laptop cord, for instance) to convert to DC anyway, so the MSW inverter isn't going to affect that.
But, what do I know, I'm just a mechanical engineer...
Those numbers look to be in the ball park, if a little high. Remember that with lithium battery technology you can run your batteries waaay down there and still get over 12 volts out of them. Find the power curve for the batteries you want and check it out. They fall off a cliff at some point, but it's usually around 90% + DOD.
Looking at your energy budget... Your refrigeration numbers could be a little high, except on really hot days, or days where you are in and out of the fridge a lot. We don't use the microwave, an electric coffee pot, or the TV(s) that much if at all out boondocking.
Our 27' trailer has essentially the same setup you have. I think the lowest we've ever pulled the batteries was about 85% DOD. (15% left + another small emergency reserve) That took just shy of four days. We have a theoretical capacity of 412 amp hours. Hope that helps.
You don't want to run them below 20% for the most part though right? And above 90% if you want them to last.
Your needs don't seem that different to an off the grid solar home. Or tiny home. Mainly size and packaging issues. Might be worth consulting some companies specializing in those fields for panel and battery expectations?
My father just got done adding solar to his house. It has an all in one controller that maintains the lithium batteries and switches between the grid,panels and generator(during a winter power outage) by itself.
He bought some cool frameless panels that are laminated to glass. Just 4 holes you use to mount.
View attachment 418100
Probably not as impact resistant as aluminum framed panels but lightweight for their size.
Anyway,the nice thing about an all in one programmable controller
Is the ability to add or remove components and change how you manage batteries without a bunch of different modules.
Yeah, kinda sorta. More like an adventure van. I'm not looking to go "grid-free," per se. Just trying to give myself options to do some dry camping, in case I need to stay at Rustic national forest campgrounds and the like. I don't want to run my generator all the time, just to have some light to read by.
As a side bar note: Use the appropriate wire gage on both the negative and positive sides of your charging circuit. Make them as short as possible. I'm losing 30% or more at the battery because of the wire gage that Airstream used to wire in my converter/charger.