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Topic: Fancy power system (Read 399 times) previous topic - next topic

Fancy power system

I'm happy to report that our new lithium bank has been working great on our U295.

I pulled the old 8Ds out of their bay, cleaned it up, and turned it into the "power bay" for inverters and charging hardware.  Here's the rough layout, about halfway through the installation:



The battery bank is a set of 8x EG4-LifePower4 server rack batteries at 5.1kWh each, or about 41kWh total at 54V.  The batteries are arranged vertically in the center forward section of the main basement storage bay, just aft of the little hole that (used to) hold the old inverter and where the aux air compressor is located.

The batteries connect to a 10kVA inverter/charger as well as a standalone pair of 5kW adjustable chargers (one yellow one is shown in the picture).  The inverter is a 240V European model, so it feeds an autotransformer that recreates the 120V-120V split phase that the house distribution panel needs.

The inverter now powers the entire coach, and the forward-aft wiring between genset, old inverter bay, and engine batteries has been changed around.  Now, the coach batteries feed the big engine and the generator constantly (no boost/merge solenoid).  A 12V power supply makes house 12VDC from the inverted AC.  And a set of 12V battery tenders keep the engine start batteries as well as our toad's battery charged independently.

The genset in this coach is a Powertech 10KW.  My experience with Powertech gensets in coaches is that their theoretical power rating is not sustainable in conditions where you'd want it most (hot), so I have it wired directly to the yellow chargers and set them to deliver 6kW of charging. 

We squeezed 2kW of solar on the roof with five, 400W panels snuck in around the various protrusions.  I used superstrut VHB taped to the fiberglass this time, to make it a little easier to unmount the panels for maintenance and to minimize the roof profile while still keeping a good air gap below each panel:



Most everything that has telemetry available is integrated into one MQTT network, maintained locally on the coach LAN (so we can see everything even when we have no internet) and also mirrored to the cloud when a connection is available.  Grafana makes for a great, flexible way to build custom dashboards.  I have this one running on an LCD above the dash:



...and smaller displays with just tank and energy levels on smartphones embedded into the wall in the bathroom and bedroom.

U295's blend of excellent basement height, pretty clean roofline with no sidewalls to shade panels, and substantial cargo capacity make it easy to turn this coach into a boondocker's dream.  We're seeing consumption on warm days of around 25kWh (with air-conditioning on and off throughout the day) and the solar can make up about half of that, so we have 3 or 4 days before we need to turn on the genset or find an outlet.

When we do get to an outlet, a regular 15A 120V is fine most of the time -- that's enough for 34kWh a day, more than we consume.  In fact, I'm thinking of leaving my heavy 50A cord at home after this trip, because even the 30A one is more than enough.
1997 U295 36' WTBI

Re: Fancy power system

Reply #1 –
I would love to add a 5kW, 48V alternator to charge while underway.  There certainly seems like there's enough room in the engine bay to fit one.  Or five.  :-)

I don't have much experience with engines and modifying things, but I imagine I could get someone to help me build a mounting bracket and then just use a longer belt with extra tensioners or whatnot. 

It might even be enough to render the genset moot.
1997 U295 36' WTBI

Re: Fancy power system

Reply #2 –
How are you getting data to Grafana.  Can it pull data from 1708 or 1939?  Curious.

Jerre
Jerre and Kathy Griffin
2003 U320 4220 Special
Build # 6207
2022 RAM Laramie 4X4 EcoDiesel
2002 Country Coach Magna 37 Tag- Forever Coach-Died in fire 7/23
1997 Country Coach 32 Intrigue-No slides-Wonderful

Re: Fancy power system

Reply #3 –
Quote from: nebster –
I would love to add a 5kW, 48V alternator to charge while underway.  There certainly seems like there's enough room in the engine bay to fit one.  Or five.  :-)

I don't have much experience with engines and modifying things, but I imagine I could get someone to help me build a mounting bracket and then just use a longer belt with extra tensioners or whatnot. 

It might even be enough to render the genset moot.

Upgrading the alternator or even going to duals is not a huge stretch. Many coach buses have 24-volt systems witch easily support larger inverter systems. 24 volts and up also allow for 240 volt industrial and forklift battery chargers. Many smaller RV's now get equipped with large lithium battery banks, dual alternators, and solar in an attempt to go full electric and not have a generator. I have worked on some with dual 400 A/H batteries, 3,000 watt invert/chargers, and 340 A/H dedicated alternator with advanced control These will support a roof top AC, electric 2 burner stove and even electric water heater.
Dennis Haynes
Bohemia NY
2008 Nimbus 342 SE Carlyle
Build #6475
Motorcade #19148

Re: Fancy power system

Reply #4 –
Quote from: DaBus –
How are you getting data to Grafana.  Can it pull data from 1708 or 1939?  Curious.

[Several MQTTs] > Telegraf > InfluxDB > Grafana.

I would imagine you could build a J1708 extractor (I don't have any J1939 on my engine's computer) and publish through another parallel set of MQTT topics, in the same way, yes.

I happen to have a Bluefire app for that, although it would be pretty nice to have it all converged.  (I'd also like to consolidate the microair easytouch into one control plane, but they are proprietary.)  There is about a two-second latency before things land on grafana with my setup, so some engine data would be a little slow.  And my old engine only publishes a few bits onto the 1708 bus anyway...  it's missing a lot of the valuable pressures and temperatures that would be helpful to pre-diagnose an impending issue.
1997 U295 36' WTBI