48 volt question

[Kyfarmgirl]

I have a 48 volt totally DC air conditioner. I am trying to design my system and needed to know if I have to have a 48 volt battery array or if I could run the DC air conditioner off of a 24 volt battery/array.

 

[OffGridInTheCity]

You need 48vdc for the 48vdc AC. Stepping 24v -> 48v will cost efficiency and depending on the AC size you might need significant amps (big $) - which make this even more dubious. Me? with what you've shared so far, I'd suggest 48v battery.

 

[Kyfarmgirl]

Thank you!!

 

[MichaelK]

Is there some really compelling reason why you want to keep this DC air-conditioner? I'm guessing if you bought a new 120VAC air-con at the hardware store it would perform as good or better, and you'd have all the perks a new unit would give you, like remote control, a timer, ect.

Secondly, why are you so hesitant to go with 48V? I think any safety concerns about utilizing higher voltage are grossly overblown. I've operated a 48V system for years now without a single issue. Keep in mind that going from 24V to 48V means you can purchase somewhat lighter, smaller batteries to equal the sample Wh capacity.

 

[chrisski]

going from 24V to 48V means you can purchase somewhat lighter, smaller batteries to equal the sample Wh capacity.

The battery pack will have the same wh if it’s 4s1p, 2s2p, or 1s4p

 

[Kyfarmgirl]

Is there some really compelling reason why you want to keep this DC air-conditioner? I'm guessing if you bought a new 120VAC air-con at the hardware store it would perform as good or better, and you'd have all the perks a new unit would give you, like remote control, a timer, ect.

Secondly, why are you so hesitant to go with 48V? I think any safety concerns about utilizing higher voltage are grossly overblown. I've operated a 48V system for years now without a single issue. Keep in mind that going from 24V to 48V means you can purchase somewhat lighter, smaller batteries to equal the sample Wh

 

[Kyfarmgirl]

I am definitely in favor and he is going with a 48 volt battery bank. I was just curious if I “had” to have a 48v bank. I am so new to this and was just curious.

My reason for using the DC air conditioner is it is on my farm and paid for (money is an issue). It is only 1 year old and (on paper -haven’t hooked it up) is very efficient and does not need an inverter to operate. It has the remote and timer features you mentioned.

Thanks for the thoughts and help.

 

[MichaelK]

Well, can't argue with "new in the box".

I'd say decide on 48V and go for it. It's two days now before the solstice. Gotta get it done!

 

[Just John]

I have a 48 volt totally DC air conditioner. I am trying to design my system and needed to know if I have to have a 48 volt battery array or if I could run the DC air conditioner off of a 24 volt battery/array.

If it uses 48v, then you should use 48v.

 

[QuantumEngineer]

Think about it this way if you are going to use lead acid batteries.
24V System - 4 batteries that are 6V each connected in series.
48V System - 4 batteries that are 12V each connected in series.

It can be confusing with terms like 2s2p, 1s4p, etc., especially if you want to go with lithium because there's lots of ways to get to 48V depending on the batteries and total capacity you want. I had a John Deere eGator that had a 48V system using 8 6V lead acid batteries.

You didn't say which battery type you wanted to use, but if your AC is 48V then it needs 48V like Just John says. Voltage converters are too expensive and inefficient IMO.

We use lots of solar on the farm - 12V, 24V, 36V and 48V. Glad to help out, we are located near Glencoe, KY.

 

[MichaelK]

I wouldn't recommend buying 12V batteries, then wiring them in series. Their amphour capacities are just too limited. Just buy whatever 8, or 6, or 4, or 2V battery you can afford, scaled to your reserve need, then wire them in series to get 48V. Some day you will appreciate the extra capacity.

 

[MisterSandals]

I wouldn't recommend buying 12V batteries, then wiring them in series. Their amphour capacities are just too limited. Just buy whatever 8, or 6, or 4, or 2V battery you can afford, scaled to your reserve need, then wire them in series to get 48V. Some day you will appreciate the extra capacity.

Why not 4x 12v in series (4S)?

Yet you say 8v (6S) or 6v (8S) or 2v (24S) "batteries" are ok? These are unusual from what i've seen.
4x 12v batteries seems like a perfectly reasonable way to get 48v.

 

[MichaelK]

Why not 4x 12v in series (4S)?

Yet you say 8v (6S) or 6v (8S) or 2v (24S) "batteries" are ok? These are unusual from what i've seen.
4x 12v batteries seems like a perfectly reasonable way to get 48v.

In truth, I'm very anti-parallel, when it comes to batteries. The real problem with 12V batteries is their Ah capacity. You can really only get good 12V batteries up to about 150Ah, but by switching lower voltage batteries, you can combine more in a single series string.

Right now I've got a single string of 568Ah at 48V utilizing twelve Rolls 4V batteries. I am very, very happy with the performance of my system.

4 CS 17P | Rolls Battery

www.rollsbattery.com

I'm using three of their 8V batteries for my 24V workshop system.

8 CS 17P | Rolls Battery

www.rollsbattery.com

I love them, except they are too f***ing heavy!

 

[MisterSandals]

You can really only get good 12V batteries up to about 150Ah,

Here in the states, there are LOTS of good 200ah 12v deep cycle battery options.

Amazon.com: Renogy Deep Cycle Agm Battery 12 Volt 200AH for RV, Solar, Marine, and Off-Grid Applications, Gray: Electronics

Amazon.com: Renogy Deep Cycle Agm Battery 12 Volt 200AH for RV, Solar, Marine, and Off-Grid Applications, Gray: Electronics

www.amazon.com

Amazon.com

Amazon.com

...lots more...

I dunno, 4 of any of these would be welcome in my setup if i were to go lead acid.

 

[12VoltInstalls]

I still haven’t told my lead acid batteries they won’t last very long. Or that they have no power.
However, they do work well and were relatively inexpensive. Scaled affordability.

A ‘12V battery’ is sorta already 6 batteries in series. Putting four in series- 48V- wouldn’t bother me at all.

 

[SolarPrep]

Everyone that participates on this site should read the detailed information on the Orion BMS site about the limitations/advantages/drawbacks of hooking up batteries in various manners. It is quite thorough, and would answer many of these questions. And, most likely result in safer installations. Google it for the link.

 

[Just John]

Whatever chemistry you choose, you will need X cells in series to achieve that. Make sure the connections are good. Doesn't matter if they are grouped in 6 or 4 cell packages, you need X cells in series.

 

[JoeHam]

Everyone that participates on this site should read the detailed information on the Orion BMS site about the limitations/advantages/drawbacks of hooking up batteries in various manners. It is quite thorough, and would answer many of these questions. And, most likely result in safer installations. Google it for the link.

If you have a specific article in mind it’s always good form to post a link IMHO.

Google wanders quite a bit.