A/C or DC based electrical system

[Mudhutwarrior]

I run strictly 12vdc for everything including refrigeration which is a Marine unit. The cost of going up in wire size in comparison to availability of parts and equipment justifies spending a a bit more. For AC needs I use a 3k inverter fed by double 1/0 of the battery bank. Overkill yes but ampacity is everything at 12v. Only use LP for hot water and cooking. Small woodstove for heating. A/C is strictly a shore power event. Solar and if needed a wind genny can be raised when boon docking. Not a fan of generators but have a small Honda for back up charging.

Biggest thing is the Alternator. I run a custom 300a unit and upsized all the associated wiring. Even if that fails i can swap in a stock hi output until repairs.
I base my build on commonality of parts. To me that's key.

[john61ct]

Originally Posted by Mudhutwarrior

A/C is strictly a shore power event.

By A/C you mean aircon? If so yes, very realistic.

Did you wire it through the inverter because you thought otherwise?

If I had aircon I'd just have a separate direct shore feed, the charger being the only other shore connection.

[kazetsukai]

Originally Posted by john61ct

If I had aircon I'd just have a separate direct shore feed, the charger being the only other shore connection.

Funny, one of the only things I installed my inverter for was the mini split (240VAC).... With exception of the laptop chargers and TVs (both 110VAC), everything else is 12V/24V DC.

[john61ct]

laptops are DC native , lots of screens these days too

but purity is not a goal in itself 8-D

[Mudhutwarrior]

Originally Posted by john61ct

By A/C you mean aircon? If so yes, very realistic.

Did you wire it through the inverter because you thought otherwise?

If I had aircon I'd just have a separate direct shore feed, the charger being the only other shore connection.

Yes air conditioning.
It is wired only through the shore power panel. I toyed with the idea of dc air conditioning as used in marine applications. Its expensive and would have to be converted from water cooled to air cooled. Not very difficult but not worth it to me. Spent more time instead on moving air around with proper venting. I spend most of my time in the northeast so its not such a big deal. In the hot season I just plan to move from shore power to shore power. Works out very well and doesn't stress the system or require and outlandish build. Had A/C in the coach wired into the inverter/generator and found most often when I really needed it i was on shore power anyways.

[john61ct]

Yes, few run a DC genset, nor invest in the panelage and bank Ah capacity to run aircon off battery.

Maybe 100Ah extra @12V per hour for a small btu unit.

[Mudhutwarrior]

Originally Posted by john61ct

laptops are DC native , lots of screens these days too

but purity is not a goal in itself 8-D

I am not a fan of laptops and DC power supply's for desktops are stupid expensive. I was running a Raspberry Pi for a while but even those need decent power stepped down to usb voltages. Either the power supply failed or it could not drive the Pi. That and most of the programs i run are not linux.

Buddy told me to try the Latte Panda. Not cheap. Around 500 bucks with win 10 installed and you will need to add a drive if you do anything extensive. They will take laptop ssd's. I love it now. About the size of Two packs of smokes side by side. As much power as a midrange laptop. Seperate Wifi and bluetooth antenna jacks included on the board. It has a direct jack for 11-15v so no power worries.

I run mine with a 12vdc 20" monitor and its the best setup for marine or mobile use I have ever run.

If you dislike laptops like I do this is the trick item for RV use and the Wifi jack lets you run a dedicated gain antenna mounted outside along with a gps antenna.

[Iqinsanity]

A 10 amp buck/boost from Amazon is cheap enough. I put one in my car with a dual usb charging socket. I have a "2 amp apple" and "two amp samsung" combo socket now. Had to use resistors to enable the proper signaling for each brand charging port.

You could use the same one to boost to 19v for a laptop or buck to 5v 10amp for the raspberry pi.

[Mudhutwarrior]

Originally Posted by Iqinsanity

A 10 amp buck/boost from Amazon is cheap enough. I put one in my car with a dual usb charging socket. I have a "2 amp apple" and "two amp samsung" combo socket now. Had to use resistors to enable the proper signaling for each brand charging port.

You could use the same one to boost to 19v for a laptop or buck to 5v 10amp for the raspberry pi.

Agreed, My issue is I do a lot of Ham radio and those gadgets are horrible emitters. Won't bother most users but in my application getting one that is properly filtered is very expensive. In Traffic and on 20 meters I can tell whomever is running one nearby.



Using the Panda I have never had any noise issues as its direct 12volt. Don't get me wrong the Pi is a great unit and I just preorderd the Pi4. Seems they over came the power issue with the 3b's, well at least that's what is being reported.

[john61ct]

Yes when radio noise is important stuff this gets way more expensive, and complicated

[nanoplane]

Originally Posted by Mudhutwarrior

I ... For AC needs I use a 3k inverter fed by double 1/0 of the battery bank. Overkill yes but ampacity is everything at 12v. Only use LP for hot water and cooking. Small woodstove for heating. A/C is strictly a shore power event. Solar and if needed a wind genny can be raised when boon docking. Not a fan of generators but have a small Honda for back up charging.

Oh, I don't think that's overkill .. on mine, I have a 3KW inverter that can output 9KW peak... I sized the wire for that 4/0 Battery wires to bus bars (1/4" x 1" copper) and 3/0 to the inverter..

I run my AC off the inverter but it's only a 9K BTU mini-split that draws less than 700W. My cooktop is a two element induction unit that will draw up to 2KW max. My hot water tank has an electric element but also has two heat exchanges, one will be connected into the engine coolant system and the other will be connected to a solar hot water heater that will go on the roof. The electric element will be power managed to only draw power when power is available and when it makes sense to do so.

I do expect to carry a small generator to support recharging the batteries when there's no sun.

[john61ct]

That is not in line with how I roll, but your rig your choice.

A LFP bank would make good sense there, getting a lead bank back to true 100% Full (as per endAmps) every few cycles will likely be a real chore when living off grid.

[nanoplane]

So, my battery bank is 4 x 220AH AGM.

So far, running the heat pump for 12 hours per day (9am to 9pm), I'm fully charged back to 100% by about 10AM each day when the sun is shining. If it's a gray day, it does take the whole day to get back up. I haven't got much of the rest installed yet. (wish I had more time to work on it, but... priorities.)

[john61ct]

Originally Posted by nanoplane

I'm fully charged back to 100% by about 10AM each day when the sun is shining.

Very likely you are naively taking the word of your charge source.

Even those costing thousands need to have AHT adjusted, by default drop to float way too early.

100% Full is defined by endAmps, if not spec'd by your batt maker use .005C,

You need to use an ammeter right at the batt post, and calibrate until "most days" the stop-charge (Float transition) point occurs only **after** endAmps is reached.

Or maybe .01C with AGM if you really are hitting it almost every day.

Even without any concurrent loads and .5C charge current available,

this will take a minimum of 6-7 hours from when the SC starts putting out significant current. IOW that 10am bit is a fantasy.

If you don't get there at least a couple days per week, bank lifespan will be greatly shortened.

Some SCs trigger stop-charge based directly off the BM's shunt reading, which of course is ideal, but costs more.

[Iqinsanity]

Originally Posted by Mudhutwarrior

Agreed, My issue is I do a lot of Ham radio and those gadgets are horrible emitters. Won't bother most users but in my application getting one that is properly filtered is very expensive. In Traffic and on 20 meters I can tell whomever is running one nearby.



Using the Panda I have never had any noise issues as its direct 12volt. Don't get me wrong the Pi is a great unit and I just preorderd the Pi4. Seems they over came the power issue with the 3b's, well at least that's what is being reported.

Yeah, it could be expensive idk if the power wires actually carry the radio waves. If not then you could faraday cage the buck/boost.

[nanoplane]

What I'm going on is the indications on the trimetric battery monitor that monitors the current shunt directly. It's calibrated based on a full charge from the solar and/or Inverter based 4 stage chargers I use in my system. The Trimeric does monitor charging and discharge current automatically.

Note that in it's current usage for sunny days, I don't use more than about 15% of the charge, so that 10am thing corresponds to 120 AH or so. It was cloudy yesterday so this morning at 7:30am, I have about 70% left.. Clouds again for a couple of days so I may need to turn shore power back on to charge things back up... Although it's been running only on Solar for about a month now.

I have three charging sources, all of them 3/4 stage charging systems:
- Solar: two Midnite Solar Classic mppt charge controllers
- Inverter: up to 100A charging off shore power
- Sterling Battery to Battery smart charging system (charges when the Engine is running).
All of these are configured with the same charging parameters for AGM batteries based on the Mfg recommendations.

[john61ct]

OK, Bogart makes great gear, looks like a great setup wrt hardware.

So for an 800Ah bank, you are saying that charge current has tapered to what, 4A before your charge sources drop from CV/Absorb target V to Float?

What model batteries, how old?

What time's the solar start putting out decent current this time of year?

[nanoplane]

Originally Posted by john61ct

OK, Bogart makes great gear, looks like a great setup wrt hardware.

So for an 800Ah bank, you are saying that charge current has tapered to what, 4A before your charge sources drop from CV/Absorb target V to Float?

What model batteries, how old?

What time's the solar start putting out decent current this time of year?

The batteries are now about a year old or so, got them all at the same time. They're ExpertPower BLMFM12_200.

What would you call significant? At 9AM this morning on a cloudy day, I was pulling about 35A @13V from solar. This was enough to run the Mini split for heating (outside temp 60, inside 72) and provide about 4A for charging. Right now (2pm), it's still cloudy, but brighter. I'm pulling about 45A with 14A going to charging and the rest running the inverter and AC.



I haven't measured / tracked the charge current, I configured the Midnite Solar Charge Controllers for the 880 AH capacity and just let it go ... I'll see if I can set up some tracking

[john61ct]

Even the fanciest SC needs to have setpoints customized, none work well with defaults.

Keep lengthening AHT setting until your ammeter at the bank shows a 4A or so taper while still at absorb.

That is the objective measure of a Full bank.

[Camalot]

I'm an electrician.

Dc before the batteries ;)