Prius as a power source?

[MrK]

I've been reading it for several months, and let me say that I'm extremely impressed with the quality of information available here. This is my first post to Priuschat.

Due to recent storms, much of the St. Louis area was without power for several days. Lowes and Home Depot sold every generator they could get.

I've got a 1500/3000 (surge) watt inverter, and I was wondering if I could hook it up to the 12 volt system of my 2006 Prius. I figure that the high voltage battery would keep the 12 volt system charged and, as the HV battery ran down, the ICE would start and charge it back up. This arrangement seems much more efficient than using a generator, as the generator's engine is always running, regardless of demand. The Pruis would run only to recharge the battery as needed.
Can this be done, or is my understanding of the HV/12 volt system flawed?

[eagle33199]

See http://priuschat.com/I-need-power-outside-...ter-t22351.html for a little more reference

Note that the power outlets are fused (combined) at 15A, Which probably doesn't lend itself to a 3000W inverter too well.

It is definately possible to use the prius to power smaller electronics, like a laptop or a fish tank, but i don't think i would want to try to use it to power standard household appliances.

One possible solution would be to add your own fuse connected to the battery to allow higher current draws, but you'd want to check first on the current draw thats allowed between the hybrid battery and the 12V system. unfortunately, i don't have that info here anywhere

[chogan]

<div class='quotetop'>QUOTE(MrK @ Jul 25 2006, 02:17 PM) [snapback]292076[/snapback]</div>

I've been reading it for several months, and let me say that I'm extremely impressed with the quality of information available here. This is my first post to Priuschat.

Due to recent storms, much of the St. Louis area was without power for several days. Lowes and Home Depot sold every generator they could get.

I've got a 1500/3000 (surge) watt inverter, and I was wondering if I could hook it up to the 12 volt system of my 2006 Prius. I figure that the high voltage battery would keep the 12 volt system charged and, as the HV battery ran down, the ICE would start and charge it back up. This arrangement seems much more efficient than using a generator, as the generator's engine is always running, regardless of demand. The Pruis would run only to recharge the battery as needed.
Can this be done, or is my understanding of the HV/12 volt system flawed?
[/b]

MrK,

Try this URL to see a broad-brush description of how somebody else set this up.

http://store.yahoo.com/yhst-61228970...sinverter.html

If you want to pull up to 1500 watts, connect the inverter directly to the 12 volt battery. You sound like you understand that level of current would fry the cigarette lighter socket.

Another site I saw (but can't remember the reference to) suggested that, due to the small size of the Prius 12 volt battery, get another regular-sized car battery connect that in parallel with the existing Prius battery (jumper cables), and run the inverter from that. That's to give you a little more surge capacity, as the Prius 12 v battey is tiny.

I'm not sure I'd pull 1500 W even then. I'm sure I'd never go over that, because of the following.

I'm not a technical guru, but my understanding is that the link between the traction (big) battery and the 12 volt battery has a limit of about 1500 watts. So that limits the rate at which you can steadily pull current out of the 12 volt battery. I'm not sure whether you'd damage anything if you tried to pull more. But yes, as I understand it (read the invertersrus story), you have the story right. Turn the car on, pull power out of the 12 volt, the traction battery will keep the 12 v up, then the engine will automatically cycle to keep the traction battery voltage up. And you have the quietest generator on the block.

If you follow the priuschat thread recommened in another post, be sure to go to the priups site. It's a hoot. And it has a lot of good technical detail. I think that's the guy who explains the 1500 watt limit in steady current draw from the 12v battery. If you want to pull more than 1500 watts, you need to connect to the traction battery directly. DO NOT DO THIS, but the site's hilarous. The guy ended up wih a system that could power his house (like 18kw or so) by connecting the traction battery to a commercial UPS whose lead-acid batteries were shot.

I bought a 1500 watt inverter for my business, and a full size car battery, with exactly this scenario in mind, but haven't ever had to hook it up to the Prius 12 V battery (which, by the way, is in the trunk, right hand side, under a removable plastic panel, and is about the size of a motorcycle battery.) So I can't say firsthand, but the article on invertersrus looked right to me.

[chogan]

MrK,

Better also read this:

http://priuschat.com/lofiversion/index.php/t13502.html

Particularly the part about, if you blow the 100-amp fuse on the 12-volt side, the car won't run. That guy seems to have done the correct and cautious thing, which is to put a 60 amp fuse in line with the inverter. If that fellow's correct, then trying to draw 1500 watts may be asking for trouble. I swear I've read people who've drawn more than that, but I believe I'd be cautious about the load.

[MrK]

<div class='quotetop'>QUOTE(chogan @ Jul 25 2006, 01:13 PM) [snapback]292111[/snapback]</div>

MrK,

Better also read this:

http://priuschat.com/lofiversion/index.php/t13502.html

Particularly the part about, if you blow the 100-amp fuse on the 12-volt side, the car won't run. That guy seems to have done the correct and cautious thing, which is to put a 60 amp fuse in line with the inverter. If that fellow's correct, then trying to draw 1500 watts may be asking for trouble. I swear I've read people who've drawn more than that, but I believe I'd be cautious about the load.
[/b]

[MrK]

Thanks to all for the prompt response. I see that I'm not the first to think of this.

Just to clarify, I wasn't thinking of using the cigarette/power sockets; I intended to hook up directly to the 12 volt battery with jumper cables. In fact, having read that the 12 volt battery is 'undersized', I was considering wiring around it to a deep cycle battery or a full-size car battery, just like chogan suggests.

I wasn't aware of the 100 amp fuse that must be protected, and while I believe it's a very good idea to put a smaller fuse in-line, I question the need to do so. My rationale is that I'll be drawing down the battery, and the Prius will try to keep it charged. If I were to be using as much power as my inverter can put out, it seems to me that my battery will eventually run out of juice because the Prius may only charge to one-half or one-third the level of usage. It's not clear to me how pulling power directly from a battery would cause a fuse not in the circuit being used to blow, as the Pruis can only charge to a given level. Not that it can't, I simple don't understand why it would. But then, better to be safe than sorry. I'll put a smaller fuse between the Pruis battery cables and the inverter.

Again, thanks for all the coaching. I really appreciate it. It's this kind of response that makes Priuschat such an asset.

[jdenenberg]

<div class='quotetop'>QUOTE(MrK @ Jul 25 2006, 04:58 PM) [snapback]292179[/snapback]</div>

Thanks to all for the prompt response. I see that I'm not the first to think of this.

Just to clarify, I wasn't thinking of using the cigarette/power sockets; I intended to hook up directly to the 12 volt battery with jumper cables. In fact, having read that the 12 volt battery is 'undersized', I was considering wiring around it to a deep cycle battery or a full-size car battery, just like chogan suggests.

I wasn't aware of the 100 amp fuse that must be protected, and while I believe it's a very good idea to put a smaller fuse in-line, I question the need to do so. My rationale is that I'll be drawing down the battery, and the Prius will try to keep it charged. If I were to be using as much power as my inverter can put out, it seems to me that my battery will eventually run out of juice because the Prius may only charge to one-half or one-third the level of usage. It's not clear to me how pulling power directly from a battery would cause a fuse not in the circuit being used to blow, as the Pruis can only charge to a given level. Not that it can't, I simple don't understand why it would. But then, better to be safe than sorry. I'll put a smaller fuse between the Pruis battery cables and the inverter.

Again, thanks for all the coaching. I really appreciate it. It's this kind of response that makes Priuschat such an asset.
[/b]

The 150 amp fuse (not 100, I believe) is in the charging line to the 12v battery (from the Prius HV inverter - actually a DC-DC converter). That's where your power to the external inverter comes from, not the toy 12v battery (which would be discharged and ruined quickly if asked to supply high current). The best reference on this is Bob Wilson's work on using the Prius (2001-2003) as a 1Kw UPS.

http://hiwaay.net/~bzwilson/prius/priups.html

If you want more power you need to connect directly to the traction battery as in:

http://www.priups.com/

by Richard Factor.

Good luck and have spare fuses in your kit.

JeffD

[htmlspinnr]

<div class='quotetop'>QUOTE(jdenenberg @ Jul 26 2006, 06:36 AM) [snapback]292526[/snapback]</div>

The 150 amp fuse (not 100, I believe) is in the charging line to the 12v battery (from the Prius HV inverter - actually a DC-DC converter). That's where your power to the external inverter comes from, not the toy 12v battery (which would be discharged and ruined quickly if asked to supply high current). The best reference on this is Bob Wilson's work on using the Prius (2001-2003) as a 1Kw UPS.

http://hiwaay.net/~bzwilson/prius/priups.html

If you want more power you need to connect directly to the traction battery as in:

http://www.priups.com/

by Richard Factor.

Good luck and have spare fuses in your kit.

JeffD
[/b]

The fuse on my 2004 is 100A - just looked under the hood. Note the reference/layout on the fuse/relay cover - the 100A DC/DC is the fuse we're concerned about.

[tochatihu]

I have a 1000 watt modified sine wave inverter hard-wired into my 2001 Prius, and (am at least one) person who added a 60 amp fuse to sacrifice itself before the Prius' 100 amp one blows. You are absolutely dead in the water if Toyota's fuse opens. It is rather costly to replace and must be unbolted under one of the engine compartment fuse boxes. So this is an area to stay away from if at all possible.

Fuses are apparently somewhat tricky because they vary in terms of how fast they open at different levels of overload. ANL fuses (such as I have added) are quite sluggish according to the specs I have seen; this is why I chose a 60 amp which at first appears to be small. This fuse has never blown for me, but I don't use quite as much power as Bob Wilson does for example.

Presumably all inverters of the 1000 watt or so size class have internal fuses but I am somewhat conservative when it comes to the Prius electrical system. When you are pulling big amps from there, don't be also running the headlights, HVAC fan, or any other big 12 volt loads.

If you decide to install a big inverter, make sure its power and ground leads are as short as possible and not smaller than 6 gauge wire. Better still 4 gauge.

[nerfer]

<div class='quotetop'>QUOTE(MrK @ Jul 25 2006, 03:58 PM) [snapback]292179[/snapback]</div>

Thanks to all for the prompt response. I see that I'm not the first to think of this.
:
I wasn't aware of the 100 amp fuse that must be protected, and while I believe it's a very good idea to put a smaller fuse in-line, I question the need to do so. My rationale is that I'll be drawing down the battery, and the Prius will try to keep it charged. If I were to be using as much power as my inverter can put out, it seems to me that my battery will eventually run out of juice because the Prius may only charge to one-half or one-third the level of usage. It's not clear to me how pulling power directly from a battery would cause a fuse not in the circuit being used to blow, as the Pruis can only charge to a given level. Not that it can't, I simple don't understand why it would. But then, better to be safe than sorry. I'll put a smaller fuse between the Pruis battery cables and the inverter.
:
[/b]

I'm not an expert, but the load (watts) depends on both volts and amps. The batteries are being charged to a particular voltage, like you say, but that doesn't control the amps that are being drawn from it, so you can definitely overload the battery draw if you don't limit that aspect with a fuse. This is particularly true for controlling surges, since most equipment needs a momentary blast of power to get started, then keeps running at a lower wattage. And it is in the circuit (from what I've just recently read but it makes sense), since the power comes from the gas, to the ICE to the main traction battery (at intervals) where it's stored. Then from the traction battery thru the DC->DC converter (and the internal 100 amp fuse) to drop it to 12V where it keeps the aux battery charged, which is where you likely have the inverter attached. From the aux battery it also has other paths, to the A/C, lights, stereo, a 15-amp fuse to the cigarette lighter, etc. Add them all up and you better use less than 100 amps, hence the safety measure of using a 60-amp fuse on the inverter. 60 amps * 12v = 720 watts peak. If you make sure you turn off all accessories beforehand, you could probably use a 75 amp fuse (do they sell that size? I haven't shopped for anything that big before) for 900 watts.

Interesting thread.