12v or 24v or 48v
- Thread starter Natgreen
- Start date
Help Support Van Living Forum:
highdesertranger
R.I.P HDR
- Joined
- Apr 4, 2012
- Messages
- 22,892
- Reaction score
- 87
I am assuming you mean for your house electrical not your vehicle. I have worked on a few 6v and 24v vehicle systems but no house systems. all I can tell you is it's a pain in the ass not being able to jump off of other vehicles. highdesertranger
I dont know of anyone using 24 or 48v house batteries. I have heard of stationary off grid applications that use 24 36 and 48v batteries because they use wind turbines. I dont recall why those were preferable. I think it had something to do with the only turbines available that were reasonably priced used AC and it was more efficient to convert it to 36v DC.
But nowadays there are lots of 12v wind turbines on the market so maybe that's a thing of the past like 6v car batteries as HDR mentioned.
But nowadays there are lots of 12v wind turbines on the market so maybe that's a thing of the past like 6v car batteries as HDR mentioned.
B and C
Well-known member
I think it might have to do with voltage drop over distance. A house setup is much larger than a van or trailer. With the higher voltages comes increased cost to down convert it for use.
Right. This is what I wanted to get opinions on. My understanding is that it is actually cheaper and provides more power. By the way, let's assume we are talking about a RV application. You do need to buy an inverter to change it from let's say 48v to 12v but it provides much more power. I haven't really looked into much beyond that. Wanted to get some opinions to see if it's worth pursuing
Oh. I totally spaced. A big advantage would be if you were say using a 48v to 120v ac inverter to power household appliance would be that it doesnt draw as many amps. So a huge load would have less puekert effect if using lead acid batteries.
Let me elaborate. A 500 watt load @ 48v would draw 10.42 Amps.
At 12v a 500 watt load would draw 41.7 amps.
The larger higher current drain means you would have less usable capacity in a lead acid storage battery because a 120 Ah battery isnt rated at 120 Amps for 1 hour. Its rated at a discharge of 1/20 of its capacity for 20 hours or 6 amps.
A 40 amp load is huge on a 12v lead acid battery and even though you would thing you could get 3 hours of 40 amp drain on a 120AH battery you cannot. Only 60Ah is usable so 1.5 hours youd assume but again no.
A 40 amp drain is going to cause puekert effect which I cant remember how to explain properly atm to cause it to run for only a few minutes before its depleted. A lower amp drain will allow longer running time so 48v is more efficient for heavy loads.
Let me elaborate. A 500 watt load @ 48v would draw 10.42 Amps.
At 12v a 500 watt load would draw 41.7 amps.
The larger higher current drain means you would have less usable capacity in a lead acid storage battery because a 120 Ah battery isnt rated at 120 Amps for 1 hour. Its rated at a discharge of 1/20 of its capacity for 20 hours or 6 amps.
A 40 amp load is huge on a 12v lead acid battery and even though you would thing you could get 3 hours of 40 amp drain on a 120AH battery you cannot. Only 60Ah is usable so 1.5 hours youd assume but again no.
A 40 amp drain is going to cause puekert effect which I cant remember how to explain properly atm to cause it to run for only a few minutes before its depleted. A lower amp drain will allow longer running time so 48v is more efficient for heavy loads.
I hope that makes sense.
Let's say you're building out a trailer because you're a traveling auto body mechanic and need to use welders and grinders that are high wattage. It makes more sense to take 4 12v 120Ah lead acid batteries and connect them in series to get 48v 120ah than it does to connect them in parallel and get 12v 480Ah.
Strictly beacuse you need the lower amperage drain on the batteries so they have a longer duty cycle.
Alternatively if you're building a trailer because you're a traveling nomad using small loads it makes more sense to have a 12v 480ah battery than a 48v 120ah battery.
Let's say you're building out a trailer because you're a traveling auto body mechanic and need to use welders and grinders that are high wattage. It makes more sense to take 4 12v 120Ah lead acid batteries and connect them in series to get 48v 120ah than it does to connect them in parallel and get 12v 480Ah.
Strictly beacuse you need the lower amperage drain on the batteries so they have a longer duty cycle.
Alternatively if you're building a trailer because you're a traveling nomad using small loads it makes more sense to have a 12v 480ah battery than a 48v 120ah battery.
I'm not an expert and I know that more batteries in the bank reduces the puekert effect but I'm not certain of the numbers. But in theory that 10.42 amp load would run for 5.75 hours with a usable 60Ah of capacity on a 48v system not accounting for losses in efficiency as some energy is wasted by the inverter. Also as the 120Ah battery is rated for 6 amps drain per hour over 20 hours and 10.42 amps exceeds that there is puekert effect to consider which I dont know how big a bite that would take. But 900 watts of solar assuming the bank wasnt discharged much at all the AC would be running off of the solar. It's all dependant upon how long you're using the Air conditioner.
All that I can say for certain is that a 40 amp load is gonna take a massive bite out of a 12v system. A 10 amp load is gonna take a bite but lesser so out of a 48v bank but both will be effected by the puekert effect and both would need the watt hours consumed to be replaced.
Watts are watts. 1000w at 120v AC is 1000w at 12v DC and the same at 48v DC the variable is the voltage and amperage.
All that I can say for certain is that a 40 amp load is gonna take a massive bite out of a 12v system. A 10 amp load is gonna take a bite but lesser so out of a 48v bank but both will be effected by the puekert effect and both would need the watt hours consumed to be replaced.
Watts are watts. 1000w at 120v AC is 1000w at 12v DC and the same at 48v DC the variable is the voltage and amperage.
Pleasant Travels
Well-known member
So if I'm understanding this right;...you only get as many watts out of of either a 12v, 24v or 48v system as you put in,...but the higher volt system is more resilient to amprage draw than lower volt. Seemingly, since even lower draw electronic devices can function on a higher voltage system, why does anyone put up with a low volt system at all? What is the benefit?
Pleasant Travels said:
That is the takeaway. The benefit is that for low drain appliances 12v is super efficient. There are many many many 12v appliances on the market. And many 12v inverters for household appliances. But if you were ONLY ever using high loads there would be fewer losses on 48v but very few appliances that worked with it.
Also if the same number of 12v batteries were connected in parallel instead of series and you used low drain appliances you would have more time between charges before you damaged your batteries.
More time between charges with smaller loads 12v
Less time between charges with larger loads 48v
Seeing as how the sun only shines at max efficiency for 4 or 5 hours a day if the sun is cooperating 12v makes more sense.
If you need massive loads and can charge even when the sun isnt shining 48v
A wind turbine runs at night. Makes sense as it can recharge in the dark. 48v makes sense more expensive inverters though.
If you rely on the sun and need to get the longest time between charges factoring in cloudy days 12v with more reserve Ah makes more sense. Also 12v appliances are numerous and cheap.
As I understand it lithium systems while more expensive upfront than lead acid systems and more complex do not have the same puekert effect limitations as lead acid. Also they recharge more quickly and efficiently than a lead acid system.
Considering that you had a solar only lead acid 48v system you would need significantly more solar and likely a secondary charging method such as wind turbine as well as generator to replenish the watt hours used in a day to refill one days usage of high drain appliances.
As I said I'm not an expert. I havent worked with anything other than 12v and havent dealt with many of the issues other users have.
I was able to keep my head above water running solar. Only just.
Considering that you had a solar only lead acid 48v system you would need significantly more solar and likely a secondary charging method such as wind turbine as well as generator to replenish the watt hours used in a day to refill one days usage of high drain appliances.
As I said I'm not an expert. I havent worked with anything other than 12v and havent dealt with many of the issues other users have.
I was able to keep my head above water running solar. Only just.
If you look on amazon you can find 48v pure sine wave inverters but they are pricey. Also I found a 48v to dual USB phone charger but it was nearly $60! You definitely CAN find 48v adapters but I dont see that being feasible for mobile unless you have to run high draw loads. Like in a food truck, or a mobile welding shop, etc. Much more doable to change your habits and use gadgets geared towards mobile living.
A hot logic mini instead of a crock pot. Butane stove instead of induction cooktop etc.
Now if you were building a self sustaining island off of the coast of south america..... that's a different story.
A hot logic mini instead of a crock pot. Butane stove instead of induction cooktop etc.
Now if you were building a self sustaining island off of the coast of south america..... that's a different story.
Mrcap
Well-known member
In all practicality it is easy to source 12v components and now you see a good amount of 24v inverters and other components and it is cheap to step dc voltage down from 24-12.
Higher voltages beyond these are not normally cost effective. Higher voltage is often used off grid when long wire runs get very pricey so the higher voltage pays off.
I have a 24v 3000w inverter and was surprised at how small the wire sizing requirements were.
Sometimes higher voltages are used to accommodate some of the voltage sizes of batteries that are coming onto the used market like the Tesla modules used in 24v systems.
Sent from my iPhone using Tapatalk
Higher voltages beyond these are not normally cost effective. Higher voltage is often used off grid when long wire runs get very pricey so the higher voltage pays off.
I have a 24v 3000w inverter and was surprised at how small the wire sizing requirements were.
Sometimes higher voltages are used to accommodate some of the voltage sizes of batteries that are coming onto the used market like the Tesla modules used in 24v systems.
Sent from my iPhone using Tapatalk
My understanding of why 12 volt dc in vehicles is common today is that in the 1950s when automobile engines became bigger and had higher compression the starter motors were struggling to turn them over, so the industry switched to 12 volts to try provide more torque. Also doubling the voltage helped power more accessories. Today there is talk and some movement towards 48 volt dc auto systems. As someone stated earlier watts are watts. In many applications the reason for higher voltage is the ability to use smaller gauge wire. Voltage and amperage for a given wattage being inversely proportional. It is possible that the auto industry may someday switch to a higher vo!tage. As they did in the 1950s.
Perhaps in time. Or perhaps not. Diesel vehicles perhaps. I dont foresee gasoline vehicles standing the test of time. With the increased reliability of electric vehicles and the increasing scarcity of crude oil I'd imagine that in 100 years only a rich man could afford to even buy the fuel for a gasoline vehicle.
I believe many semi trucks with sleeper cabs use 24 and 48v as a lot of the fancier ones have fridges and microwaves.
I believe many semi trucks with sleeper cabs use 24 and 48v as a lot of the fancier ones have fridges and microwaves.
Gypsy Freedom
Well-known member
- Joined
- Jun 30, 2019
- Messages
- 329
- Reaction score
- 2
Pleasant Travels said:
yes, pretty much. as several have said, watts is watts.
if you have a 5kilowatt hour battery bank. it makes no real difference in storage capacity
for example 4 run of the mill 220 amp hour golfcart batteries can be assembled as 12 volt or 24 volt banks
at 12 volts they would make a 440 amp hour bank, with a nominal voltage of 12.7 they would be around 5.5kwh
at 24 volts they would make a 220 amp hour bank, with double the nominal voltage 25.4 they would also be the same at just about 5.5 kwh
they would both have the same capacity. the puekert effect would effect them both the same. where it would be different is if the bank size in kwh was different. for example, if you dischage a battery in 5 hours you will get less out of it than if you discharge in 20 hours. you can look these numbers up for any quality deep cycle battery. they are usually published in the 100hour, 20hour and often in the 1,5 and 10 hour rates. if you have the same size battery bank in kwh and discharge it with the same load in watts it does not matter what voltage the batteries are at, the rate of discharge will be the same.
the difference you get is( and the benefit from) higher volts, is lower amps for the same load. when you go from 12 volt system to 24 volt system you cut the amps in half for the same load. when you cut the amps in half, you can pretty much cut the wire size in half for a similar voltage drop.
another benefit can be that some solar charge controllers are rated for say 50 amps but capable of running 12v or 24 volt. in that case a 24 volt system could handle 2 times the solar on the same charge controller
in my case i had victron 50 amp controller and when i went to 24 volts i was able to double the amount (in watts) of solar that way i save a few hundred $ by not having to buy another charge controller
people "put up with" the low 12v systems because that is what is common. you can find most anything you need locally to fix a 12v system. you can find tons of 12v appliances. so for the run of the mill rv with a few hundred watts of solar 12v makes sense and saves money
