Controlling pellet stove in off grid system

nyoffgrid

Hey all,

I have a tiny off grid cabin in Upstate NY. I have one (1) 24V 200ah lifepo4 battery and I will be installing a new victron inverter charger: PMP242305132. I do NOT have solar panels. I charge my battery with my genset during the night and then use the cabin off battery during the day. Usually my battery goes from 100% to 80% SOC from 8am to 10pm. I have lights, water pump, fan on stove, ceiling fan, and fridge. I also have a ductless as but that doesn't get used too much at all and none in winter. 

I will be installing a pellet stove soon since my wood stove is not enough and I hate waking up at night to feed it. 

I wanted to find a way to switch on my pellet stove before I arrive so my cabin is nice and warm for me. 

I found a way to do this.. By keeping a hotspot and an IR remote blaster - it takes over any IR remote and connects to the internet which then allows you to control the device as if you are there pressing the remote. 

Assuming my battery is at 95% soc or close to it when I leave - I will then kill all usage of the inverter - unplug and switch off whatever circuit breakers I can. I will then leave the outlets "on" via breaker and then the pellet stove, hotspot, and IR blaster will be powered. I will test when I get the pellet stove but I will assume it draws zero power when switched off but we will see. 

I did test both the blaster and the hot spot. The blaster pulls 0.5w while the hotspot pulls 1.2w. 

Questions:

1. assuming the pellet stove draws no power when off: how long should my battery be able to potentially sustain those two items (1.7w total draw)? 

2. Will such low draw (1.7w) cause the victron to shut off and kill power to it? 

3. I read that the victron has several "zero load" modes: Zero load at 11w, Zero load power in AES mode at 8w, and Zero load power in Search mode at 4w. Obviously I wish to keep it at the search mode.. but will that also make it worse for these devices in terms of switching off inveter and killing them? 

4. If my victron needs to be kept at the 11w mode.. then how long can my battery last with those load? 0.5+1.2+11 = 12.7w assuming 95% SOC when I leave? 

5. If such small load is an issue in terms of keeping Victron on.. Then I could potentially hook up both the hot spot and blaster directly to the battery. I will need a step down since they use 5v usc cables but then it will just run well right? I can then set the victron to search mode.. the question is will it kick in fast enough when I try to switch on the pellet stove? I am not sure how the search mode works and if it is possible to "mistime" the switch on with the inverter so it won't give power and keep pellet stove switched off 

Dave Angelini

Sure you can't use propane? No deliveries right?  Much easier with gas millivolt ignitions that do not use any inverter power. You could turn on a low power ceiling fan when there. The stoves I have used for clients have a 40Kbtu to 80Kbtu flame. They have a sealed heat exchanger and low power fan that is adjustable. Really pretty flames and so nice to sit near. Leaning your shoulders against a hot masonry exhaust wall is really nice.

Seems alot safer unattended than pellet. 

Keep it simple offgrid !

SumPower

I have seen several people dissappointed by installing a pellet stove or wood stove as a lone heat source, which I consider a temporary heat source. As you have to be there to tend it to get any long term heat.

Where propane can maintain the heat while you are gone. Set and forget. A millivolt pilot uses very little propane.  LPG is easier to install and maintain than a wood stove or pellet stove.

For heat, I go with the "one source is none" philosophy. I have had two or three heat sources wherever I have lived up north, weather on a boat or in a house.

nyoffgrid

My issue is that I'll need to refill my 30lbs propane tank about eveytime I go Which is a massive pain plus those vent free ones are very unhealthy and thr vented ones cost like a pellet stove. Wood pellet are easier to obtain for me since one trip can last me whole winter. 

BB.

The math assuming 24 volt @ 200 AH @ 95% state of charge down to 20% with a 12 watt load:

24 volts * 200 AH * (0.95 SoC starting - 0.20 SoC "battery shutdown") = 3,600 Watts of "useful" stored energy

3,600 WH battery useful * 1/(12 Watt load * 24 hours per day) = 12.5 Days of 12 Watt load

Probably 12 Watt load (24 hours per day) is just not going to be good for 2 weeks away from cabin--And that does not really account for the load of running the pellet stove for 1/2 day to warm up the cabin and then starting the Genset.

I would suggest looking into remote control of the AC inverter--So d see if your cell phone (Internet?) interface can control the inverter remote ON/OFF and what the standby draw would be for that cell/Internet interface would be...

As we can see--A relatively small load (12 Watts is not a lot of power), running 24 hours per day for days/weeks/month can drain a good size 200 AH @ 24 volt battery bank pretty quickly.

Perhaps the Cell/Inverter interface can be on a DC timer--I.e., only run the remotes for 1-2 hours a day (I.e., 8 am to 10 am) so you can still control the system (deep standby to AC power Hot) and not "use power" for the rest of the 24 hour day.

The other thing to check on is the power consumption of a pellet stove--Not that I have ever used one, but don't (at least some of them) use a red hot heating element to start the pellets on fire (is that 100% on, or only starting duty cycle)--And if there is a fan, that can also be a power consumer too.

Perhaps look at your Genset fuel and possible sharing with heating... Propane genset may be interesting--But an added cost (new Genset) issue.

Or gasoline based RV heaters are something like $1,000 to $1,500 or so (never have used one)--Just a quick link to one here:

https://www.amazon.com/Webasto-Gasoline-Heater-install-9032227A/dp/B01M2ZCWTF

Some ideas...

-Bill

Dave Angelini

nyoffgrid said:

My issue is that I'll need to refill my 30lbs propane tank about eveytime I go Which is a massive pain plus those vent free ones are very unhealthy and thr vented ones cost like a pellet stove. Wood pellet are easier to obtain for me since one trip can last me whole winter. 

The usual reason propane can not be delivered in really rural places is the road quality. 

As for your woodstove, if you feed it with hardwood, a fire, then choked at 10 pm should leave you good coals to start a 6 am fire. 

The vampire loads of bms, search, internet, and pellet have to be tested. Search is often unreliable. 

Good Luck