Most decent way to run your 115V essentials out of Prius Prime

That makes sense. I have seen the charge voltage drop while driving, but this only happened when the 12v battery is already fully charged at ~12.8v. If the resting voltage of the 12v battery is lower, it continued to charge at around 14v until it is fully charged as long as the car is on READY regardless of shift being in D or P.

Well, I don't think my PRIME will last 20 hours of continuous drive. I run out of gas before that. Better yet, I will need to take a break long before that 20 hours.

 

I guess you could hit 20 hours if you get gas without turning the car off. Will it let you open the gas tank in Ready mode?

Or using it as a generator or camping in the car. But either way you'll probably be in Park.

 

I don't know what to tell you. The battery's resting voltage is under 12.0V. That's what the voltage reads with a Fluke 88V and Toyota has repeatedly insisted it's normal. I took a picture right now for you.



Then I put the car in READY mode and took another picture.



Then I put some leads on the 12V outlet in the console and drove around the block.



It only dropped to 12.8V today - still not the 14V we see in P even though the battery is at 11.8V. The diagnostic screen read 12.6V, so it's not too far off (±2%).

 

@PiPLosAngeles, I remember your thread a while back about the voltage being low on your Prime. I'm stunned that any dealership would call that <12V resting voltage normal unless the car had been taken on lots of short trips w/o enough time to charge back up. And I gather from your other threads that you drive quite a bit, so that seems unlikely. I don't deny what you're observing. (I've had that happen to me and it's really infuriating.) Your 2nd & 3rd pictures look pretty typical, but that first one is scary. I don't think your situation is normal or typical from all that I've read or experienced.

 

They didn't. Their diagnosis was a bad battery. They ordered one and it was on national backorder. Toyota corporate called me to tell me they were canceling the order and I don't need a battery.

 

What was the reason you took your car to a dealer? Any symptom? If the 11.79v is normal for PRIME's 12v battery resting voltage, then it should not show any ill effect that would prompt you to consult the dealer. And have you tried charging the 12v battery with an external charger?

 

Maybe they won't replace it unless it actually fails. But at 11.8V it seems like it's only a matter of time before it leaves you stranded. The only thing that helps is the lack of a traditional starter. The brake booster pump is almost as bad. It uses something like 40 or 80A when it's running, and it runs as soon as you open the driver's door.

It's crazy that the battery seems to have died so quickly. 4th gen 4runners (2003-2009) came with legendary Panasonic batteries. I replaced my original battery from the factory at 11 years because it was just starting to get slow to crank in cold weather, and sometimes I wonder if I replaced it too soon!

 

I do recommend making the negative connection at the body (such as where the negative battery cable connects there, or to whatever other body ground point is conveniently near the installation), so that the added load gets properly counted. The factory-provided ground points all over the car are typically easy to spot, with usually several white-with-black-stripe wires being terminated at a special bolt.

The discussion of that sensor was here.

Is that a new thing with the Gen 4s and the battery moved back under the hood?

Earlier Prius batteries have tended to have amp-hour figures around 45 or 50 combined with relatively low CCA like 325 or so; that's a combination you'd expect to see in a battery made with relatively few, thick plates and therefore a decent tolerance for deep discharge.

The one I just replaced last winter in my Gen 3 had made it to ten years, and I certainly hadn't babied it; quite the contrary, it had endured a number of unplanned deep discharges at my negligent hands.

The thing about the newly-added sensor in Gen 4 is that it is the first Prius generation able to actually coulomb-count the 12 volt battery. So it knows (assuming you wire your add-ons correctly) not just the battery voltage, but how much charge is in there.

I can see them programming the car to bias the system voltage away from charging the battery when you are using power to move down the road. Seems kind of clever. The idea that they would put a coulomb counter there and then not use it to guide their charging but let the battery go "dead" as you drive seems a bit unlikely to me. Without knowing the details, I'd bet there's a bit more to it than that.

 

The 4th gen is back to a flooded battery under the hood (I guess older gens were AGM), but I don't know if it is built differently than a standard starter battery.

 

The origin of the complaint was that the 12V outlets and the owners manual report that they can supply up to 120W, but they can't even supply half of that before the voltage drops to somewhere around 11V. That was causing problems with my inverter and laptop chargers, which would not operate below 11V. If the voltage drop is linear with current, and 6A drops the voltage to 11V (66W), you can never reach 120W before you pop the fuse.

As luck would have it my inverter failed a few months after that and I replaced it with a cheap Chinese one that has real sine wave output and doesn't care that the car is feeding it 10.5V.

 

The only drawback is that the lower voltage means voltage sag at the outlets will take the voltage well below 12V long before you reach their rated 120W. If you max them out at 10A you're only going to get somewhere around 10.5V (in my car anyway). Happens in both outlets, but a little less in the front console outlet.

 

Sweet!

edit to add: Rats! Currently unavailable and not known when it will be.

 

I think it is being replaced by a new 1200W model: BESTEK 1200W Power Inverter. Not much difference in price or specs compared to the 1000W model OP's link.

I have a 7500W portable dual fuel generator with a whole house hook up and a manual transfer switch set-up for the prolonged outage. Our SUV also has a 120V outlet that came standard with the car. Although I don't know how good that outlet is. I have not used it yet.

 

Thanks!. That's not a pure sine wave inverter, though. I found a boat-load of those on Amazon and they are much less expensive, but I'm not sure I want to run some of my stuff on one. Then again, for the price, it might be worth a try. Now that I've thought about it and read up a bit, I think I'll not risk a MSW inverter. The risk isn't worth it for me. I might want to add an inline breaker to make sure I don't go over 1,000 watts, though.

Edited to reverse a tentative decision.

 

Oh, I see. How important is it to have a pure sine wave? The link on OP's inverter says none of those appliances listed can be used on a modified wave. My portable generator is not a pure sign wave, but so far I have never had any of our house appliances including many of the electronics listed on the table like computer and TV not working on the "dirty wave" generator power. What would happen if I keep using those appliances on "dirty wave" power?

 

I think I'll just repost this, having no great ideas to improve it.

In my experience, "modified sine wave" is one of those terms like "100% juice with added ingredients".

You look at the output, it's essentially a square wave, except it rests at zero a little bit between half-cycles.

The closest it ever gets to a sine wave is there on the back of the box, where somebody from the art department drew a sine wave next to it.



It'll usually run hand tools sort-of, but they'll sound weird and buzzy and may run unstably, especially if they contain their own electronic motor controls, as more hand tools recently do.

I would be quite cautious about trying to run laptop/phone/etc. chargers from one, because most of those things are switch-mode power supplies in their own right: they try to regulate their own output by rapidly cutting in and out from the supply coming in. The interaction could be weird when that incoming supply itself is abruptly cutting in and out, rather than varying smoothly.

I think I've got something like three old MSW inverters lying around that I haven't used in years, but also haven't taken to Goodwill or the Re*Store because I don't relish inflicting them on anybody else.

Back in the day, true sine inverters were a lot more expensive than MSW, but the price gap has narrowed enough now that I don't see much of an argument for MSW.

 

If your generator is a rotating physical machine, without the inverter intermediate stage on many newer systems, I can't image it being anywhere near as dirty as an MSW inverter.

 

Modified sine wave does work with switch mode power supplies (half the things on that list). They will run hotter and might not last as long as a result.

I bought this pure sine inverter a while back, but haven't used it much yet. I hate poorly designed electronics, and this seems to be an actual reputable brand. I bought it from Amazon Warehouse, so it was cheaper than the list price.
https://www.amazon.com/gp/aw/d/B002LGEMOQ/

 

I've been a satisfied Xantrex customer, with smaller models in that same lineup. (2kW is about twice the max I would ever put in a Prius, off the 12 volt system).

One nice thing is they have a telephone-style jack that can be used for both a remote on/off button, and an inhibit circuit based on ignition being on or off. I ran a telephone cord from the inverter to an RJ11 breakout board and wired up the inhibit circuit to the little VCM-06 module I was using to control other things, which turns ON only when the car is READY, and turns off an hour after the car does. I ran the remote switch and status-LED circuits forward to the dash.



One caution, I let the magic smoke out of my first Xantrex by running a variable-temperature heat gun. Full power of the gun was 1500 W, which I knew was too much, but I had it set below 4 on the dial, and the Xantrex does have overload detection that normally shuts it down safely. But of course the heat gun control used high-frequency switching, drawing pulses of too-much with an average value of not-too-much, and that behavior managed to kill the Xantrex without triggering its overload detection.

Xantrex doesn't offer any repair service or internal parts for the PROWatt SW line, so if you do something dumb like that and let the smoke out, it's effectively done for.