Emergency power/medical equipment

[Manooti]

I’m new to this and been doing a ton of reading. I understand how the panels should be arranged and picking up 4-6 300w panels next week. Have a mppt controller on the way and I’m stuck on batteries. Trying to maximize usable hours and compensate for cloudy days for 2 refrigerators and medical equipment. Oxygen for dad and my insulin. Pretty crappy situation.

How would the batteries be wired to get 24v and between 400-600ah? 48v is ok too but trying to maximize the ah over 12v.

I saw the wiring diagrams for one bank in series parallel but is it possible to wire 2 banks and which way to wire 2 separate banks?

I’ve seen so many wiring diagrams my math is starting to look like hieroglyphs lol

 

[rmaddy]

Are you asking about individual battery cells or are you asking about prebuilt batteries?

 

[Manooti]

Are you asking about individual battery cells or are you asking about prebuilt batteries?

Prebuilt would be easier and look nicer lol.
I could go diy but don’t have the tools to solder cells or if there’s another way I haven’t found yet, maybe.

 

[rmaddy]

The answer depends on what you have. If your goal is a 24V 400-600Ah battery bank then how the batteries are connected depends on the voltage and capacity of the individual batteries. Do you have 12V or 24V batteries? What is the capacity of each?

 

[rmaddy]

You should also have a look at chapter 3 in the Wiring Unlimited document:

Wiring Unlimited

Wiring Unlimited is a great resource that covers many many common topics and questions relevant to DIYers. It is a free E-book from Victron Written by Margreet Leeftink. Check it out! Download

diysolarforum.com

 

[Manooti]

No batteries yet. Don’t want to make a mistake without asking for guidance. It’s first setup and when we lose power we’re screwed. We lose power every season. The longest we lost power was for 3 weeks. Other than that we lose power every other week it seems like. Sometimes for an hour sometimes all day and or all night.

No cell service here also so we use WiFi calling for our phones.

We also get stuck from storms. We have a 6 mile road to get down to main road then maybe 1/2 mile to see a gas station. Trees down all the time, ice storms, 1 inch of snow on this road and your fishtailing all the way down lol

 

[Manooti]

Checked out the pdf posted. I understand the series/parallel but confused on connecting banks together. Or I’m missing something

12v,10kwh @833ah
8-9 in parallel

24v,10kwh @416ah
2s4p

48v, 10kwh @208
4s2p

Is my math right? I read lifepo4 can’t be connected in series so that limits my options. Considering the 50% dod with agm or lead acid I’ll have to double those numbers…

For the 4s2p that means 4x2 for 8 batteries 2 banks? I’m overthinking this. There’s gotta be an insiders trick to batteries lol

 

[rmaddy]

Is my math right?

If you had 8 12V 104Ah batteries then your math is basically correct. You could make a single 12V bank (using 8S) that would be 832Ah, a single 24V bank (using 2S4P) that would be 416Ah, or a single 48V bank (using 4S2P) that is 208Ah.

I read lifepo4 can’t be connected in series so that limits my options.

That's only true of some LiFePO4 batteries. There are many that can be put in series. Just make sure whichever batteries you get specifically state that they can be put in series enough to meet your needs. There are some 12V that can be put in series up to 24V (2S). Some 12V that can be put in series up to 48V (4S). There are some 24V that can be put in series up to 48V.

Keep in mind there are also 24V and 48V LiFePO4 batteries so you don't necessarily have to put batteries in series to get what you need.

For the 4s2p that means 4x2 for 8 batteries 2 banks?

If you connect 8 12V batteries in 4S2P then that gives you 1 48V battery bank.

 

[Short_Shot]

I’m new to this and been doing a ton of reading. I understand how the panels should be arranged and picking up 4-6 300w panels next week. Have a mppt controller on the way and I’m stuck on batteries. Trying to maximize usable hours and compensate for cloudy days for 2 refrigerators and medical equipment. Oxygen for dad and my insulin. Pretty crappy situation.

How would the batteries be wired to get 24v and between 400-600ah? 48v is ok too but trying to maximize the ah over 12v.

I saw the wiring diagrams for one bank in series parallel but is it possible to wire 2 banks and which way to wire 2 separate banks?

I’ve seen so many wiring diagrams my math is starting to look like hieroglyphs lol

If you are using this for a fridge AND medical equipment, I would suggest (if the budget allows) using an isolated DC to DC charger and a separate battery/inverter for the medical hardware itself. The solar and main battery will still provide power for everything but it will protect your lifesaving gear.

Its fairly standard in medical electrical to isolate these things for many reasons, including eliminating nasty feedback. Granted, this is less important for home equipment designed for the home environment, but if you can afford it... I wouldn't mess around with something that involves my life.

It also provides extra redundancy.

Just a suggestion. Not mandatory by any means. You could split up the system half and half (making it all 12v, but splitting the power demands of inverters), or add a somewhat cheaper lead acid for the medical side.

 

[Wellbuilt]

What type of air Machine are you running
I run 2 air concentrators for my son the draw a lot of power .
I think the use up 750 watts I know 2 of them use up most of a Honda 2200 watt genarator .
You will need a large system

 

[Manooti]

All good information here thank you. The dc to dc might be over my head. Haven’t even looked that one up yet lol.

Ok the toughest question to ask, which would be the best budget wise way to go? Just spent roughly 2k on dads oxygen concentrators portable and stationary. So low on funds. They had him on a waiting list, none available so I just bought them.

Got a quote from a company and they want me to buy 2-48v batteries at $5.5k.
Not sure which way to go about this.

 

[Short_Shot]

All good information here thank you. The dc to dc might be over my head. Haven’t even looked that one up yet lol.

Its almost exactly the same as a solar controller, except the input goes to another battery. There are isolated, and non-isolated versions.

The non-isolated versions connect the negatives of both batteries together while the isolated version uses two different negatives.

 

[Short_Shot]

Regarding the batteries, if you have the technical ability you can build your own battery pack BUT the lead time might be a challenge and theres a learning curve just to order good ones.

48v is very expensive because you are essentially buying 4x 12v batteries for each one, and we all know those prices.

 

[Manooti]

What type of air Machine are you running
I run 2 air concentrators for my son the draw a lot of power .
I think the use up 750 watts I know 2 of them use up most of a Honda 2200 watt genarator .
You will need a large system

No stickers on units but I ran the meter. Stationary one is between 280-390 watts. The portable one is not bad at 25-45 watts

 

[Wellbuilt]

I would get some back up .
I have tanks to use if the power go’s out.
But a tank Dosent really last to long I think 3 hours max .
I mite just look into a Honda generator
My son started on one air unit on low and a few years later he was on high
Now I’m running on 2 units at 75% but he need more are if he gets winded .

 

[Wellbuilt]

O wow that not bad if he can use the portable units if the power go’s out .
I have a big air tank for emergency use
It’s 24” around and 50” tall I’ve never used it

 

[Manooti]

O wow that not bad if he can use the portable units if the power go’s out .
I have a big air tank for emergency use
It’s 24” around and 50” tall I’ve never used it

Yeah I understand. Crappy situation. Dad has copd from construction. Doing whatever I can however I can. The portable ones are awesome. They gave dad some tanks but the tanks ran out before we left the doctors office. At least with portable unit can use dc or A.C. it just isn’t a constant flow.

I’m gonna look at maybe building some batteries.

I might if screwed up before I even start building. The controller I ordered is a positive ground. I didn’t even know they did that. Not too big a deal right?

 

[Wellbuilt]

For medical equipment I would get tier 1 equipment
I would try to stick with negative ground
You will need to keep your inverter on grid power and it will switch to inverter and battery if the grid go’s down like a upc

 

[schmism]

here is a link to a dual fuel propane inverter generator.

https://www.amazon.com/Champion-Power-Equipment-200961-Ultralight/dp/B08L45W2V9

add a Jackery solar generator and have reliable backup power at a fraction of the cost of a solar setup.

 

[Wellbuilt]

I really like the champion equipment , but not to produce air to breath.
There is just to many cheep parts that break or need attention while I’m dealing with the problem the boy would be turning blue .
Honda makes the best generator equipment in the Business .