Power Distribution Systems
- Thread starter Mike_H
- Start date
OP
I suppose you may have missed it, but I have a “build thread” about it here too
https://wranglertjforum.com/threads/my-1978-gmc-motorhome.45354/
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.
OP
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...
I don't know either just going off what I've been told. Supposedly the electric awning that I just had installed isn't supposed to be MSW friendly but I've used it 3 times so far. And yes until I'm ready to upgrade I won't be replacing it but when I upgrade to a 3,000 watt inverter I'll go PSW.
OP
OP
I found this guy...
https://www.pysystems.ca/
Lots of information, and it feels like he's legit. I'm also finding more and more on the victron site. They have quite a bit of info there, but its tough to find.
https://www.pysystems.ca/
Lots of information, and it feels like he's legit. I'm also finding more and more on the victron site. They have quite a bit of info there, but its tough to find.
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.
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.
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.
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.
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.
Here's the voltage vs capacity for a lithium battery. (LiFePO4) You can run them all the way down to 12.0v 9% capacity left without damage. Meaning you will get your full 4,000 to 8,000 discharge cycles out of them.
Here's the graph. That's a huge plateau with pretty stable voltage. And, the internal BMS (battery management system) will disconnect your battery before any substantial damage can occur.
The folks at SOK haven't had any failures yet running them down to 90% DOD repeatedly. They are confident enough to warranty their batteries for 10 years.
It seems the fastest way to kill these batteries is to try and recharge them at temps below freezing. Other than that, the built in BMS does a pretty good job of keeping us all out of trouble.
Here is the folks that I deal with. No relationship other than I buy their stuff.
https://www.currentconnected.com/
Browse around on the site. It's pretty cool. I use the 206 amp hour marine batteries without heater or bluetooth. Zero issues so far. My system has a Victron smart shunt that lets me keep tabs on energy flows and state of charge.
https://www.currentconnected.com/
Browse around on the site. It's pretty cool. I use the 206 amp hour marine batteries without heater or bluetooth. Zero issues so far. My system has a Victron smart shunt that lets me keep tabs on energy flows and state of charge.
OP
@StG58 Thanks for the information. Its very helpful. I'm trying to look at worst case, then scale back to reasonable. I can use an absorption fridge and remove most fridge loads off the battery bank and rely on Propane (I have something like a 60 gal tank). The secondary cooler fridge can become an Rtic, etc. I also have a big generator I can fire up As long as I get a decent charger, I can push quite a bit of power and with Lithium, charge those buggers pretty quick. My Genset is 6500 Watts. It was set up to run TWO rooftop units from the 70's...so it will push some power.
I ran my calculations for Ah usage based on an 80% DoD and a 20% reserve capacity. Might be overkill, but better to have more than less, when it matters. Honestly, I only have a teeny tiny little battery now and its never been a problem as we haven't done any dry camping. We do have 80 acres in the UP that I'd like to start using as a campsite though and where I want to camp doesn't currently have power.
I ran my calculations for Ah usage based on an 80% DoD and a 20% reserve capacity. Might be overkill, but better to have more than less, when it matters. Honestly, I only have a teeny tiny little battery now and its never been a problem as we haven't done any dry camping. We do have 80 acres in the UP that I'd like to start using as a campsite though and where I want to camp doesn't currently have power.
OP
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.
Your appliance list is more extravagant than a lot of the little cabins i see around here(ac,microwave). Project wise it can be fun to try and figure everything out yourself,but its a lot easier to get knowledge from people who do it all the time and then start making plans.
The hard part with renewable energy companies is there's a lot of fly by night operations. It can be hard to get good info
Here's a few of the sites I've ben reading a learning about solar.
https://rvblogger.com/blog/rv-solar-panel/
https://www.parkedinparadise.com/rv-solar-wiring-diagram/
https://rvsolarconnections.com/how-to-rv-solar-energy-audit/
https://solarmagazine.com/solar-panels/rv-solar-panels/
https://rvblogger.com/blog/rv-solar-panel/
https://www.parkedinparadise.com/rv-solar-wiring-diagram/
https://rvsolarconnections.com/how-to-rv-solar-energy-audit/
https://solarmagazine.com/solar-panels/rv-solar-panels/
OP
Just want to verify I'm thinking about this correctly. Been looking at schematics from Victron to familiarize my self with all the different components that go into a power system...and they have 50 amp services listed. Since I only have a 30 amp service installed...I had a quick little WTF moment, then thought about ohms law...
If my incoming service is 120v/30 Amp, that is 3600 watts. Assuming I'm dedicating full power to charging batteries, my service will be able to throw 250 Amps at the battery, right? (3600/14.4V DC). Since 0.5C is the common recommendation for charging the lithium battery bank, 250A should support 500 Ah of batteries.
That's more than I'm looking to install, and most of the chargers I'm looking at max out around 120 amps charging...so I should be good with my 30A shore power, but it was curious to me that Victron was listing 50 amp for a camper van even.
If my incoming service is 120v/30 Amp, that is 3600 watts. Assuming I'm dedicating full power to charging batteries, my service will be able to throw 250 Amps at the battery, right? (3600/14.4V DC). Since 0.5C is the common recommendation for charging the lithium battery bank, 250A should support 500 Ah of batteries.
That's more than I'm looking to install, and most of the chargers I'm looking at max out around 120 amps charging...so I should be good with my 30A shore power, but it was curious to me that Victron was listing 50 amp for a camper van even.
OP
Oh yeah. Wire losses can been a big deal when you’re dealing with low voltage systems. Back in my younger days, I played around with car stereo, and upgrading the “big three” (alternator to battery, + batt to PDC, and - batt to ground) was always one of the first things to do.