David Baillie

John Weiland wrote:

larry kidd wrote:It got down to about 20f last night and I never insulated or heated the batteries. Lost power about 2:30am took till about noon to get the cells warmed up to about 35f or 2c and got power back online. Spent the better part of the day after that wrapping the cells with heat tape for pipes and put insulation under and over , still need to go back and insulate the sides. Used 30 feet of heat tape with a 90w draw. It has it's own thermostat on at 35 off at 50 if I remember correctly.

Living where we do in the central US just below the Canadian border, an experience like this is what causes me to hesitate on diving into LiFePO4.  I probably will anyway and just keep the investment small to modest.  Wife is still tooling around the farmyard with recent ~10 degree F using lead-acid batteries in a Polaris Ranger EV and we are grateful for the robustness of the time-tested tech, even with the known power deficits of these batteries in cold weather.

There was mention recently of Canada leaning more towards solid-state/sodium ion technology, partially because it may be a less expensive battery to produce, but also in large part due to its greater resiliency to cold temperatures.  Still that battery too will use a battery management system (BMS) and one hopes these don't turn out to be a weak link in the technology.  Larry K, I always wondered if a seedling heating mat would be enough to prevent severe temperature drop in such situations.  CLearly if the location is too cold and the batteries unprotected, the BMS will do best to shut down the battery.  But in situations where the batteries are housed in an insulated container of sorts, a seedling mat seems to be designed to produce low temperature, low wattage heat to the item(s) sitting on the mat.  Perhaps this would be a safe solution for many out there?   Also a question for those having installed LiFePO4 batteries going back a decade or two:  Have you experienced or heard of situations where either the cells or the BMS itself failed causing need for battery or cell replacement? If the BMS goes bad and the cells are otherwise good, can the BMS be replaced (assuming a battery case whose contents can be accessed) fairly easily?  Thanks!

John there is Lithium and then there is lithium... Most of the server rack type assemblies are available with a built in heating mat. It is a little annoying though as it will only power up while the batteries are charging and cannot be used in an off grid discharge only scenario. I have taken to oversizing my insulating boxes by 6 inches on all sides and incorporate a 300 watt heater with a blower. Even with the extra troubles lithium is worth it. The greatest advantage is rate of charge. Traditionally you would limit your array size to match the ideal rate of charge of a lead acid battery since the rest was "wasted". Now we can oversize the array so that you can grab 100 percent of available sun on those days where the sun comes out hard for short amounts of time. Also all that extra time running a generator for absorb charging is also a thing of the past. So the little power you use heating the box is worth it. I would suggest sticking to a company that has distribution and available spare parts like all high cost tech items. I like the units that do closed looped communication with the inverter so you get a real time temp reading and balanced charging. The cheap drop in replacements without comms have not been doing well long term. As to Sodium they are starting to show up but are in their early adopter high cost unknown specs days so I'll wait for now.
Cheers,  David

Jackie Lei wrote:Yes, LiFePO₄ batteries really are a big step up. I’m also planning to upgrade, I’m looking at a 16 kWh LiFePO₄ battery for my home loads. The price is surprisingly low, just a little over $1,200. A friend recommended this battery manufacturer to me since I’m not very familiar with LiFePO₄ products myself.

This is the battery I’m considering. 16KWHCould you help me take a look and let me know if the lifespan can really reach 10 years?

that battery will probably make the cycles it advertises but when you purchase a low cost battery straight from the manufacturer like that you have no way of knowing if it will be supported if something goes wrong. If you live in an area that enforces certification of batteries you might not be able to use that one. As long as you understand those points its specs look good.

David Baillie wrote:

John Weiland wrote:I'm hoping to piece-meal together a small system that would be expandable in the future for more off-grid power.  Initially, I was hoping to school myself by focusing on two essential items of the homestead-- the furnace (propane) for winter and the well pump for water.  As you might expect, non-winter months are not so crucial.  Even if the well becomes inoperative for a period, livestock watering can be done from the river near the house.  

I've already dabbled a bit with 12V-powered inverters for producing low-wattage 120V AC power.  What I'm envisioning for the current project is a 48V inverter/charger (Magnum Energy being one brand of interest) that would keep batteries topped up while grid-power is active, but be able to switch over to powering the furnace motor (120V) and well-pump (220V) if grid-power goes down.  A side angle here is the fact that I'm preparing to convert a 36V golf cart to 48V soon and this likely will involve several (3-4?....more?) 48V/30Ah LiFePO4 batteries.  Clearly one can get larger individual batteries, but I'm interested in keeping individual battery weight as low as possible so that they can be used in the golf cart (solar PV panel roof) in summer and shuttled easily to the basement for winter.

Questions arise around sizing the inverter/charger and battery bank for powering the furnace fan and the well-pump.  The furnace is less of an issue as it should be readily powered by an inverter of 4000-6000W (pure sine wave, peak surge watts nearly double the running watts). If memory serves me, the house well pump was ~2/3 - 3/4 hp submersible running at 220V and while the running amps/watts aren't terrible, the starting amps may be up in the 20s to low 30s.  So I'm more concerned about making sure the well pump won't trigger a system shut-down due to either batteries or inverter (or both) being under-sized.  A parallel string of 4 batteries each at 48V would yield 120Ah with internal BMS's sized for golf-cart amp surges (80 - 100A per battery...typically double that for short spike surges).  As finances allow, I would be integrating solar energy into the system as well as part of the expansion.  Input on this vision and design is most welcomed...  Thanks!

John the magnum is currently discontinued. If you want to stick to the older transformer based units like the magnum then a samlex or victron would do it for you. If you are going lithium choose an inverter meant for them like the lux or sol ark type. I am liking lux these days.

Well John, Michael is right about inrush current. If you are using a 3/4 Hp pump you will want to oversize the inverter. Older transformer units had better surge capability but they have not moved on to the new standards for meeting UL 9540 rules for using Lithium Batteries. In some areas of the world that does not matter. Here in Ontario I have to meet all the latest standards. So, Michael suggested the 6048 which is a good unit but you would want to substitute a 10kw all in one inverter as a subsitute if you wanted to go for the transformerless units. I would also invest in a 3/4 horsepower pump with a soft start like a grundfos pump.
Cheers,  David

John Weiland wrote:I'm hoping to piece-meal together a small system that would be expandable in the future for more off-grid power.  Initially, I was hoping to school myself by focusing on two essential items of the homestead-- the furnace (propane) for winter and the well pump for water.  As you might expect, non-winter months are not so crucial.  Even if the well becomes inoperative for a period, livestock watering can be done from the river near the house.  

I've already dabbled a bit with 12V-powered inverters for producing low-wattage 120V AC power.  What I'm envisioning for the current project is a 48V inverter/charger (Magnum Energy being one brand of interest) that would keep batteries topped up while grid-power is active, but be able to switch over to powering the furnace motor (120V) and well-pump (220V) if grid-power goes down.  A side angle here is the fact that I'm preparing to convert a 36V golf cart to 48V soon and this likely will involve several (3-4?....more?) 48V/30Ah LiFePO4 batteries.  Clearly one can get larger individual batteries, but I'm interested in keeping individual battery weight as low as possible so that they can be used in the golf cart (solar PV panel roof) in summer and shuttled easily to the basement for winter.

Questions arise around sizing the inverter/charger and battery bank for powering the furnace fan and the well-pump.  The furnace is less of an issue as it should be readily powered by an inverter of 4000-6000W (pure sine wave, peak surge watts nearly double the running watts). If memory serves me, the house well pump was ~2/3 - 3/4 hp submersible running at 220V and while the running amps/watts aren't terrible, the starting amps may be up in the 20s to low 30s.  So I'm more concerned about making sure the well pump won't trigger a system shut-down due to either batteries or inverter (or both) being under-sized.  A parallel string of 4 batteries each at 48V would yield 120Ah with internal BMS's sized for golf-cart amp surges (80 - 100A per battery...typically double that for short spike surges).  As finances allow, I would be integrating solar energy into the system as well as part of the expansion.  Input on this vision and design is most welcomed...  Thanks!

John the magnum is currently discontinued. If you want to stick to the older transformer based units like the magnum then a samlex or victron would do it for you. If you are going lithium choose an inverter meant for them like the lux or sol ark type. I am liking lux these days.

Aaron Yarbrough wrote:

David Baillie wrote: Lithium is a game changer as well as you can get full array production since they have low resistance to charging unlike lead and you don't waste time at the high voltage low amperage low production absorb stage. It has forced solar designers to change their ways as we now maximize panel numbers due to low panel costs as our first priority. On the down side you are usually best to repanel completely so you can maximize your strings and the all in one inverters are terrible at lead acid charging as they lack a proper 3 stage charging profile.

We woke up with no power a few weeks ago. One our 6V FLA batteries had a bad cell I think. Fortunately, I had recently received a lithium battery kit and was almost finished assembling it so we we didn't have to limp along for long. The difference between the FLA battery bank and the Lithium Phosphate one is amazing. We're still getting summer temperatures here(two months out from the winter solstice) and I'm running two mini splits, a convection oven, an induction cooktop two fridges and it seems like I can't run the battery out of power. Then with 2-3 hours of full sun it's back to 100% charge. I ordered more solar panels which I will still install but it definitely appears like the weak link of my system was my battery.

 

Yup, the use case for lead is shrinking all the time. It has proven to be a game changer for many people.

Sheldon Caulfield wrote:Hey all! I'm in a mad rush to install my new woodstove before the winter.

This is going in my unfinished basement, and you'll see in the attached photo that there are some soft mini split/heat pump tubes and cords strung across the top of the wall directly above the wood stove.

I'm having someone in for the final inspection in a weeks time so that I can safely burn, but it's $350 for the inspection so I really don't want to fial and have to book another one.

Does anyone think those tubes would be a problem? Additionally, are there any other glaring problems you guys can see around the stove that I'm blind to? (Except for the fact that the stove isn't hooked up to the chimney of course, lol)

Based on the wett inspections I've had done for clients everything looks good. Is the horizontal pipe leading to the chimney going to be double walled? If not you will want to double check your clearances to the Minisplit tubing. I assume your floor is concrete? If so you are good as you need 18" of non combustible floor in front of the stove.  Good luck on the Wett inspection.
CHeers,  David

Miikee Mike wrote:Hi folks. I was very confused by all those heavy electronics videos when i wanted to learn about Voc Isc and Bypass Diodes so i made a video that uses easy water analogies to explain it. It has a follow up video at the end screen going into reverse biased and forward biased Bypass Diodes and strings. They're just meant to get some ideas across. Feel free with feedback or questions.
YouTube

I've always liked the water analogy for explaining power to people. I usually use pressure for voltage, flow for amperage, and volume for watts... Its not perfect but it gets the point across to  people.
Cheers,  David

Crinstam Camp wrote:

David Baillie wrote: I would suggest then disconnecting the light circuits from the larger panel if possible and powering them using plugs.

Exactly how would one go about powering circuits from a separate inverter without disconnecting them from the main panel???

I'll let you look that up. I suggest you not do that with a portable floating neutral inverter for safety reasons.

Crinstam Camp wrote:

David Baillie wrote:I would suggest you look into low wattage LED bulbs then. The conversion efficiency on any inverter will be at its absolute worst in the first 20-30 watts. What are you lighting up? I've had good success with the USB based low wattage bulbs.  Your conversion efficiency will be much better stepping down in DC from 12 to 4.5 than stepping up from 12 volt to 120ac. Or any of the 12 volt led lighting out there. At the scale you are talking conversion will kill you. All that depends on your application of course.
Cheers,  David

I assume you meant to say low wattage DC bulbs?

Most of our lights are all double bulb fixtures with a 1 watt LED in one side and a pull switch socket with 2 Watt LED in the other. Just wandering through and turn on the switch and the 1 watt comes on, need more light? Pull the cord and the 2 watt comes on.

We aren't going to run new lines for DC lines to power the lights.

Our lights are all going to be on their own 12v bank of two 100Ahr batteries and 300 watts of panels. The little amount we will lose with a inverter is small, I just want it as small as possible lol

It started because we aren't supposed to hook 6 of our batteries in parallel for some reason that I'm still not clear on lol

I figured instead of just letting them sit here until we got two more we might as well use them.

But when I started thinking about it, I realized how much better it would be.

If the other bank drains, or the main inverter takes a dive, we're left in the dark. This way that doesn't happen.

Plus we have three 100 watt panels, that we were using as our main ones until we got the new 200 watt panels, that are now just sitting here along with the charge controller we had then. This way it all is still getting used.

Much clearer now. I would suggest then disconnecting the light circuits from the larger panel if possible and powering them using plugs. Your main house loads will be bonded neutral all small inverters are floating neutral and will usually overload or fry if plugged into a full house panel. In the case you describe any pure sine inverter will do efficiencies will all be about the same. Stick to pure sine though as lots of leds have fancy step down electronics in them that don't play nice with modified sine.
Cheers, David

Crinstam Camp wrote:

David Baillie wrote:

Crinstam Camp wrote:I'm looking for the most efficient 100 watt inverter (12vdc to 110vac) I can find.

Any suggestions?

Just generalities. Make sure its a pure sine wave inverter for efficient energy conversion and smooth running of your devices. Modified sine can heat up transformers and fry certain battery chargers on tools. I like the small wattage Victrons for durability; they have a 250 watt unit. Samlex is another good small inverter brand, renogy is so so, then you get into the take a chance ones on amazon.
Cheers,  David

All it will be powering are 1 and 2 watt LED bulbs up to a maximum of 40 watts in total. The normal would likely be closer to 6 to 10 watts

I would suggest you look into low wattage LED bulbs then. The conversion efficiency on any inverter will be at its absolute worst in the first 20-30 watts. What are you lighting up? I've had good success with the USB based low wattage bulbs.  Your conversion efficiency will be much better stepping down in DC from 12 to 4.5 than stepping up from 12 volt to 120ac. Or any of the 12 volt led lighting out there. At the scale you are talking conversion will kill you. All that depends on your application of course.
Cheers,  David