Please explain 12V system to me--how to keep battery charged while using accessories?

Thanks Elektroingenieur for looking up the rav4 wiring. I guess the temperature correction, if it exists, must be done another way. The notion that it used a thermistor in the 12v current sensor assembly came from here: trav4|battery_temperature_sensor_circuit-438. Here it is stated that the rav4 current sensor uses Hall effect: toyotaguru|rav4-car-features|battery-current-sensor. (Sorry, I am not permitted to include links or 'sneaky URLs' here). I know that these are 'generic' sites, but the Hall effect sensor seems to be accepted by rav4 hybrid owners who know something about electronics.

Here is the part, but I can't find 'FIG 84-01':



I still don't follow the argument that current will flow through the chassis instead of the wires in the return circuit. I thought electricity followed the path of least resistance. But I am not an elektroingenieur. I think it will not matter which wiring option is used if the accessories draw only a few mA. But from my experiments I think it could matter a great deal if the accessories drew close to 1A (then to avoid battery overcharging you really want the sensor to read only charge current, IF I am correct about the design purpose of the sensor).

 

Apologies, you are right. I had to look at a diagram to understand it:


I also understand now that the LIN bus can be multiplex, so it can request current and temperature status over the same wire.

 

Good work doing the diagram and answering your own question.

That's the sound bite that's drilled into everybody's head, but the less sound-bitey way to put it is that it follows all the available paths, in inverse proportion to their resistance. (Doesn't roll off the tongue quite the same way, but has the advantage of being true.)

Wires are very conductive, but so is a thousand pounds of sheet metal.

 

Yes, "I feel you, Homie" the best solution to energy need is to integrate living with transportation energy need. Only then, can we optimize for lowest demand and highest comfort in all possible situations. I am planning to retire on Hawaii Island. I plan to bypass the extremely expensive Diesel powered electricity system there. I will use Photovoltaic Panels ( on a sun tracker) and Wind Turbines...to provide enough electricity to exist comfortably. The abilit
y to turn my Automobile into a backup generator would add an additional layer of security to my existence while ensuring I consume the minimum to keep things going. What do you think?

 

Since this thread was revived, I might as well add my grain of salt regarding the generator. I would assume that the Prius with its emission control system would be more environmentally friendly than a small generator with a basic carb and muffler.

 

The Prius is certainly is far more lung- and life-friendly, with vastly lower carbon monoxide emissions. As for other environmental factors, I believe it is less clear.

Almost nobody installs sun trackers anymore. Those were for the old days when solar modules were very expensive, so it paid to get as much energy out of each individual module as possible. Today, solar modules are cheaper than the tracking hardware, so for a given budget you can harvest more total energy by deleting the trackers and putting that money into extra modules on fixed mounts.

Fixed mounts are also more reliable and far lower maintenance than trackers.

 

Well, with a 2-Axis tracker I can increase my Sun-Hours per day from 4 to over 8 thus doubling my production. Using top quality REC Alpha Pure panels and a cheap Eco-worthy tracker makes good sense from an economic standpoint in this application despite the "conventional wisdom" I often hear quoted. But, thanks for the reply.

 

I'd like to see a description of your particular situation, such that a tracker could double your production. Eco-worthy claims only a 40% increase:


PS. I just ran some figures through NREL's PVWatts calculator. For my location without any tree shade interference, a 2-axis tracker could collect about 37% more annual energy than a fixed open-rack mount at the best tilt angle. Roof mount gets a little less than an open rack, I'm guessing for temperature and cooling reasons. With tree shading, I believe the tracking gain will be significantly less, based on my particular tree locations.

For Kailua-Kona in Hawaii, PVWatts figures that a 2-axis tracker will collect 33% more than the best-tilt fixed open rack.

 

https://photos.app.goo.gl/ARHG9imfaWMBvDMf8

Take a look at the data for Ainaloa in the above linked screenshot. The difference between 4.8 and 8.3 Sun-Hours/day is nearly, sort of, almost double if you squint a little. in any event, considering the location and cost of transport of fragile photovoltaic panels vs a solar tracker that costs about as much as one PV panel (REC Alpha Pure 420 watt) I think it is all well worth it in a place with VERY EXPENSIVE electricity like Hawaii.

 

What is your source for that?

So you were misrounding. That is a 73% increase, not a doubling.

NREL's PVWatts calculator shows significantly lower boost. This a 1 kW system, standard panels and input typical parameters, for a fixed open-air rack tilted 15 degrees:



... 1-axis tracking:



... and 2-axis tracking:





I compute the boost from 1333 to 1740 as just a 31% boost, far short of you initial doubling claim, or even the 'corrected' 73%.

 

My source? Why Hawaii All Cities | TurbineGenerator

I was glad to have the info because I have plans to move out there for retirement. You will see other places in the table with the same sort of measurement figures .....all with the same latitude. However, I'm pretty sure the figures are lower across the board for Ainaloa because the rainfall is so excessive there. On the dry side of the Island (see Captain Cook) the latitude is the same as Ainaloa with vastly less rainfall. (Thus more sunny days). My plan is to expand as needed: adding 4 of the 420 watt panels to each tracker. The Trackers can ship via surface freight (cheap and slow) but the PV panels need to go Air Freight (expensive but better handling). The NREL calculators are good, but really can't take all the variables into account. As always "your mileage may vary"

 

Unfortunately, that page doesn't show any source references. The rest of the site doesn't give me any confidence of it being a match for NREL's calculator.

NREL's calculation for this site is based on 30 years of historical weather data at Hilo, 14 miles away. NREL shows a 31% gain from 2-axis tracking, whereas your link shows a 73% gain at Ainaloa (vs only 25% gain at Hilo). Is there really that much a difference in cloudcover patterns between Ainaloa and Hilo that a fixed rack PV system collects the same energy in either place, but a tracking system collects 38% more energy in Ainaloa than in Hilo? This would require that Ainaloa have far less cloudiness during the early morning and late afternoon, but far more cloudiness mid-day, than Hilo.

I also see your chart showing a 32% gain from 1-axis (6.3 hours equivalent) to 2-axis (8.3 hours) tracking at Ainaloa. I don't understand how this is even geometrically possible, given that a 1-axis tracker should never be off-point by more than 23 degrees (at summer and winter solstices), and the cosine of 23 degrees is always within 10% of unity. In contrast, it shows a 3% gain for Hilo (5.8 and 6.0 hours), a much more believable figure.

Separately, based on basic calculus applied to the geometries involved, I find any tracking gain greater the π/2 (or 1.57) to be very suspect. This is the theoretical gain limit at the equinoxes in a vacuum, absent any possible clouds or other weather. While the seasonal solar tilt could allow a greater gain because the sun is up more than 12 hours in summer, the increased atmospheric attenuation at low angles has far greater impact, reducing the achievable gain. Since your chart shows a gain of 73%, greater than the 57% of that theoretical π/2 yardstick, I very strongly suspect that your chart has a data error.

Then why does your chart have exactly the same figures for Ainaloa and Captain Cook?

Note also that your chart shows lower solar collection for fixed-tilt and 1-axis configurations for Ainaloa than for the adjacent entries of Aiea and Anahola, but higher 2-axis results. These should be screaming red flags for possible data errors.

Online, I'm seeing prices of $330 for those PV panels, and $560 for that tracker, without shipping to Hawaii. At those prices, you'll need to put 6 panels (1118 x 1730 mm frames) onto each tracker (2900 x 2900 mm brackets) for the tracker to come out even. Though because I don't have shipping cost figures, I'll necessarily need to let you refigure this cost breakpoint with such costs included.

 

Since this is a Prius forum let's keep the conversation to that. If you two want to talk about solar please take it to dm or a solar forum thanks.

 

Newbie request declined.

On one hand, sorry for the thread drift. That is a very common happening here, there are very many interesting topics that come up and deserve discussion, but don't get properly moved to their own separate threads. Mea culpa.

On the other hand, this is a very common happening here. There is a huge mass of not-directly-Prius materials here on PriusChat, and has been since its inception. If you don't like this solar discussion being on PriusChat, then you are in for massive problems with all the other not-directly-Prius stuff here, unless you learn to just pass over the materials you feel aren't relevant to you.

If you need a more formal topic policing, take it up with the owner or moderators. They are the only members with standing to make your requested policy or practice change.

 

No problem I've reported your disrespectful and pedantic post to the mods as you wished. And you have all the power to not post irrelevant topics. It's called being respectful. No the topics that come up do not all bare discussion here, again this is a place for discussions about the Prius. Keep it on topic. It's really not that difficult. I can show you how to use the DM function if you like.
Funny because you were so concerned a few posts ago about lowering community standards yet here you are doing your best to achieve just that. So the rules don't apply Senior members? You would think if anything people who have been around here longer would know the rules better and follow them, not try and use them to their own advantage. People use these forums to help them with their vehicles with relevant information about the car. Not for people to go off on a tanget everytime they think there's a chance for them to try and show off how smart they think they are to everyone.

 

@fuzzy1 is one of the most even tempered, patient guys here.

What does DM stand for again? PM would be Private Message.

anyway, carry on burning bridges.

 

DM and PM are the same thing. Either way fuzzy knew what I was talking about and responded by disregarding my request and childishly saying if I don't like it report him. His responses in no way showed patience or an even temper. This is also the second time being disrespectful in response to my posts in the past few days. So he already established a pattern very quickly, and continues to site the age I've been in the forum as an excuse. First time shame on you.......
Sorry I fail to see what bridges are being burnt when the responses have absolutely nothing to do with the topic at hand and when they do respond to me they are passive aggressive and unhelpful anyway.
Again all of this is still off topic. It's already difficult enough getting information on these cars sometimes so it's helpful having a place that actually talks about the car. Imagine trying to find information to fix you electrical system only to find pages of information about solar panels. Somewhat frustrating don't you think?

 

Where do you think you get off joining a twenty-year-old forum and dictating new rules to the people who have liked it just the eclectic way it is for pretty much the whole time?

 

Respect is earned, not given.

Minus one on the respect scale.

 

Staying on topic is literally the main basic rule of just about any forum. What's the point of having topics and threads otherwise? Besides that I wasn't dictating anything it was a simple, nice request that was responded to like a child. If the response was something nice like well that's not what we really do here, would have been a different issue.

And being respectful of others is the second rule of any forum.

Everything is context, like how you are only showing my response, not his two responses before that calling my posts trite. So again -2 on the respect scale before that response even happened. So if respect is earned im simply responding to them like in being responded to in kind.