can a 48v lifepo4 run a 48v DC to 110v AC inverter?

[needWheels]

I was wondering if I somehow managed to get a 48v inverter like they use for windmills and solar panels if I could run it on my lifepo4 for post-hurricane emergency use and how long a 20ah pack could run a load of a few hundred watts at 90% efficiency?

(Will those kinds of inverters handle the 53-55v starting voltage?)

I guess if a pack is a theoretical 1000 watt hours, at 100% efficiency a 300watt draw should last a little over 3 hours?

Is that math right?

 

[frodus]

Yeah, sounds about right.... if the inverter DRAWS 300W on the input, it should last a couple 2-3 hours.

 

[needWheels]

Yeah I am thinking I might run a TV + DTV converter box for a few minutes but mostly just run a box fan and a few lights, charge batteries, etc. Hopefully I could get the draw down to less than 200 watts which would give 5 hours or so.

If I can get the draw down to 100 watts I could make it overnight with a fan and a light or so.
I wonder if the battery + BMS can safely run 10 hours continuously without radically killing it's life due to heat.

In the poor person's version of this I might just try to get a 5A DC to DC coverter and run a couple of 5V bicycle headlights and some kind of small USB fan. Now that little load could run 24 hours in theory, if the cells can discharge that long.

Just imagine, 10 years from now people might have 5kwh batteries + inverters wired right into their house for a couple hundred dollars if electric cars advance the technology enough to become super cheap.

 

[gogo]

It might happen the other way around with all the smart grid development and on-site energy generation.

 

[needWheels]

Yeah if you mean local solar/wind (geo?) at each house instead of relying on the grid.

With the few news segments I've seen on PBS about power grid distribution problems for all these wind farms, local power for neighborhoods seems like a really good idea.

But batteries still need an exponential drop in price for it to happen. No other way to store solar.

 

[needWheels]

I just realized I have a small box fan (1 foot) that has a 12 volt input.
But it comes with the old style power brick that is a transformer from 110v.

If I use a 110v to 12v switching power cube from an external hard drive enclosure, I wonder if i can run it directly off the lifepo4 pack like people use the 5v cubes to run led lights. Hmm. That would be only 10 watts or so.

Can I run multiple mini-switching power cubes from the pack at once? One 12v and two 5v ?

 

[RTLSHIP]

needwheels, you live in a Hurricane zone? I'm in S FLA

 

[needWheels]

Not really directly in a hurricane zone but every couple summers we get winds/rain strong enough to knock out power in some areas and I happen to live in part of a loop that loses power for a few days before they get around to fixing it.

It's weird because our street lights will work but all the apartments don't have power.

I think I am going to try the mini-switching power cubes and just run a couple 5v lights and a 12v fan. Hopefully I can get 24 hours out of that and then I can ride my bike somewhere where there is power and charge it up again.

 

[RTLSHIP]

Of course, we get Hurricanes in Florida, but I live very close to a Hospital and they typically get power restored
ASAP. I've never tried running 48 v through a 12v dc to 110 v ac inverter. I have an 200 watt inverter (400 w surge) in my car and use it to run a fan to supplement the a/c. You can experiment with it right now and determine if it works, but you are risking a busted inverter or a blown fuse? You should have alot more wattage
because of the 48 v

 

[needWheels]

Oh no, I'd never even try to put 48v DC into a 12vdc to 110vac inverter, sounds dangerous.
48vdc to 110vac inverters are far more expensive than 12vdc and there has to be something serious to that.

But as far as efficiency, I think I will do much better with the little switching power supplies.
There's 1000 watt hours in a 48v 20ah pack and I am fairly certain I can get 24 hours of lights and fan out of it.

I'm not too worried about the fridge because I don't eat meat so there's nothing too valuable in there, it would just be more annoying than a huge loss.

 

[RTLSHIP]

I know they sell 48v dc to 110v ac inverters. But pricey? Just keep your frige light. 12 v inverters are cheap and canbe run with Ebike SLAs

 

[needWheels]

I know they sell 48v dc to 110v ac inverters. But pricey? Just keep your frige light. 12 v inverters are cheap and can be run with Ebike SLAs

Not for a full day they can't. If my math is right:
A 500 watt fridge could only have it's motor on for two hours total at 100% efficiency on a 1000watt pack.
Since only 90% efficiency is possible and a fridge cycles 4 times an hour supposedly, and a 12ah SLA is really only 12ah at 0.2C, your SLA would last maybe for a one hour cycle (4 times on) tops.

 

[frodus]

I know they sell 48v dc to 110v ac inverters. But pricey? Just keep your frige light. 12 v inverters are cheap and can be run with Ebike SLAs

Not for a full day they can't. If my math is right:
A 500 watt fridge could only have it's motor on for two hours total at 100% efficiency on a 1000watt pack.
Since only 90% efficiency is possible and a fridge cycles 4 times an hour supposedly, and a 12ah SLA is really only 12ah at 0.2C, your SLA would last maybe for a one hour cycle (4 times on) tops.

90% efficient 48V inverter? I haven't seen any with that high of an eff..... (not saying you're wrong, but that seems pretty high).

 

[RTLSHIP]

I do not expect you to run a frige with an inverter. For that I'd recommend a generator. What I meant is go light on the perishables foods in case there is a power outage. This way you have less food loss etc.

 

[gogo]

I've seen a claim of 88% efficiency for a 48V 2500 Watt inverter.

http://www.serious-sounds.com/Items... POWER INVERTER 2500/5000 W 48V DC TO 120V AC

 

[frodus]

wow, thats pretty high for something that's boosting voltage and creating a "sine" wave.... sounds like a good product then...

I doubt that its greater than 88% at peak power though.

 

[dogman dan]

If you had a Dc converter, such as ebikes ca sells, you could then have 12 DC avaliable, and use many of the 12v items designed for trucks and campers, such as fans, etc. Regular inverters would work on the 12v to run a tv box and the tv to see the news. I have a similar problem where I live, but since I have a house and yard, I can easily fire up a generator when summer storms knock out power for a few hours.