What battery voltage 24 or 48 volts ?

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win0911

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Sep 18, 2020
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Which battery voltage (24 or 48 volts) is more suitable to have 3500 kw per day?
 

Korishan

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48V is generally better than 24V because it's easier to work with, the components are about the same price, and you get a longer save running time.

Easier: because the wiring required is smaller. The higher the voltage, the smaller the wire is required. You can effectively use almost half the size wire for 48V than with 24V

Inverters for 24V or 48V are about the same price. If anything, the 48V may be cheaper as the internal components can have smaller wires to handle the switching. This is especially true for Analog based inverters (these have huge transformers instead of banks of Mosfets)

Safer run time: This is the operating voltage. It takes longer for the 48V to go from fully charged to cutoff voltage than a 24V system would. The voltage range of most Lithium-Ion is 57.4 - 49V, so there's about 8V of working voltage. Whereas 24V is 28.7 - 24.5V, or 4V range.

This can be negated by have more in parallel. So for the same 'capacity', you can have either a 14s50p or 7s100p. These two systems would be about the same in capacity. However, the 7s could handle current surges better because of the higher cells in parallel, not because it is 24V.

In the end, it's usually recommended to go with 48V over 24V unless your particular application requires the 24V arrangement, such as you already have the equipment, or installing into an existing system that uses 24V.
The kW usage per day doesn't really make the determining factor.
 

Redpacket

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Feb 28, 2018
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Korishan's info above is good.
If you are only using about 3.5kW/day, your usage sounds lower & a 24V system might suit better for other reasons.
With 24V systems, the battery & BMS parts are a bit simpler but wire sizes go up (due to higher currents at 24 vs 48V for same power out).
24V may be better for a mobile system, eg RV use.
If you might grow your usage, 48V is definitely better & less loss.
 
Last edited:

paddy72

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Nov 17, 2021
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You could also go for 36V if you find suitable charge controler and inverter. Generally i would tend to go higher in voltage to lower the current and save on cables and connectors. Do you mean 3.5 kWh per day or 3.5 kW max. power? 3.5 kW means 100 Amps on a 36V system, which is quite a lot and need thick cables.
 

OffGridInTheCity

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Dec 15, 2018
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1,862
Korishan's info above is good.
If you are only using about 3.5kW/day, your usage sound lower & a 24V system might suit better for other reasons.
I went 14s88p (48v nominal) for a 13kwh DIY 18650 battery bank for my 7 x 14 trailer. This works nicely with MPP Solar 3048LV. In 24hrs in colder weather we burn 5-7kwh between all-electric cooking and mini-split for heat.

With 24V systems, the battery & BMS parts are a bit simpler but wire sizes go up (due to higher currents at 24 vs 48V for same power out).
7 sense leads instead of 14 and maybe a bit cheaper and agree that wiring is smaller for 48v of the same power.

24V may be better for a mobile system, eg RV use.
This is what prompted me to comment :) 48v works just fine in a trailer. I did an 120vac -> 12vdc @ 80 transformer... so all power goes thru the AC distribution center for centralized monitoring and it works great for the 12v sub-system. I even run the 12v Husky power-hitch-jack from it. They also make many varieties and amp levels of 48vdc ->12vdc converters.
 

cak

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Mar 14, 2021
Messages
93
Both are great and could work for you. Generally I see 48vdc being used more in home sized systems and 24vdc used more in "portable" rv type systems. In my case I live in a small off grid cabin that already had some 24vdc systems so I stuck with that and have found it easier to find cabin/rv type appliances or DIY PCB components for 24vdc stuff. once I started looking for 48vdc appliances they got much more expensive(but also generally higher quality). I am running almost the whole cabin off 24vdc with strip LED lights and DIY dimmers, Anderson PP plugs for accessories, 24vdc Freezer and fridge, 24vdc to USBC PD for phones and laptops and it has been easy to find everything that works well at that voltage. All my higher load stuff like the induction burner, electric oven, blender, ice cream maker, desktop computer I run off the AC inverter. A lot of the DC stuff I couldn't find 48vdc versions. Of course most of the DC stuff is fairly low power usage so it wouldn't be too hard to have the main battery bank 48vdc(or I have considered even higher) and then have a buck converter to supply 24vdc throughout the house or at point of use.
 

win0911

New member
Joined
Sep 18, 2020
Messages
7
48V is generally better than 24V because it's easier to work with, the components are about the same price, and you get a longer save running time.

Easier: because the wiring required is smaller. The higher the voltage, the smaller the wire is required. You can effectively use almost half the size wire for 48V than with 24V

Inverters for 24V or 48V are about the same price. If anything, the 48V may be cheaper as the internal components can have smaller wires to handle the switching. This is especially true for Analog based inverters (these have huge transformers instead of banks of Mosfets)

Safer run time: This is the operating voltage. It takes longer for the 48V to go from fully charged to cutoff voltage than a 24V system would. The voltage range of most Lithium-Ion is 57.4 - 49V, so there's about 8V of working voltage. Whereas 24V is 28.7 - 24.5V, or 4V range.

This can be negated by have more in parallel. So for the same 'capacity', you can have either a 14s50p or 7s100p. These two systems would be about the same in capacity. However, the 7s could handle current surges better because of the higher cells in parallel, not because it is 24V.

In the end, it's usually recommended to go with 48V over 24V unless your particular application requires the 24V arrangement, such as you already have the equipment, or installing into an existing system that uses 24V.
The kW usage per day doesn't really make the determining factor.
Korishan thanks for the clarification.
 
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