Hacking the solar?

Okay, so I'm reviving an old thread here, but for good reason. Seems that there might be a real possibility the 12V battery is only good for 2-3 weeks of inactivity before it becomes too dead to boot the computer and engage the main contactor for the traction battery.

http://priuschat.com/forums/gen-iii...-17-days-parking.html?highlight=hacking+solar

It seems improbable, but if the 12V battery is really that weak, using the solar panel as a trickle charger sort of takes on a new urgency. So here's what I think the function of that panel ought to have been:

A.) In normal operation, the panel operates exactly as it does now, running the fans to keep the interior cool.

B.) The 12V battery voltage is monitored and the moment it begins to get low, such as after being stored for a week, the panel function switches over and uses all its current to trickle charge the 12V battery.

So then question one, does this make sense? Is it a good use of the panel's voltage? And two, how hard would it be to accomplish?

The charger circuit is readily enough available - been discussed already - and a solid state relay for switching the current from the present circuit to the charger circuit is easy enough. How difficult would it be to rig a battery monitor circuit and use that to drive the solid state relay? Almost seems like the monitor circuit from a commercially available battery tender serves about the same function, right? Only instead of turning on the charger, it could fire the relay and switch the solar panel output from the car to the new charger circuit. When we 'throw the switch', we completely disconnect the panel from the car's built in circuit, so the car will just think it's in the dark and getting no voltage from the panel.

Seems pretty straightforward to me... am I oversimplifying this?

 

I've been mostly not tracking this thread, but a slightly sideways
idea occurred to me the other day: how 'bout hacking the circuit
that the solar plugs into, and be able to power it off the normal
12V of the car?? I'm thinking the overnight camping scenario
where you want to run the fan at a very low level for ventilation,
and given that the panel powers up the fan controller and feeds
it a low-speed control waveform, it would be the semi-obvious
way to do my fan hack in a 2010. Well, if it's got the solar
in the first place.. something else would be needed for cars
without, I guess.
.
_H*

 

If the battery is as weak as some people are saying (only 10 days of inactivity before it needs to be jump started?!?), I'd be pretty hesitant to deliberately run anything off of it overnight. I'm still not buying the 10 day battery theory, to be honest, but if it's true...

 

To be able to run the fan, you have to be at least in accessory mode. In this case, doesn't the 12v battery ultimately get its power from the HV traction battery via a DC-DC converter? If so, then you could probably run the fan an extremely long time in slow speed. At least overnight, and perhaps a whole day.

Yes it can be done and I'm sure someone will soon have a hack to provide the trickle charge from the solar panel. However, if you park your car in your garage while away on long trips, you are out of luck! For you "garage parkers" out there, like me, it's probably cheaper and simpler just to hook up a plug-in battery trickle charger.

 

Where can I find the schematic involving the EV button, and the Motive Battery? Has anyone built a solar charger for the Motive Battery ? I would like to do it, if it does not void my warranty now.

 

I've just discovered this Thread --- but your last post was August, 2009 ~ it is now June, 2010 --- wonder where the followup went?
I have an interest in power a 10-watt ham transceiver ~ while camping across the northern states next month - - TNX, PCV-III

I've just discovered this Thread --- but your last post was August, 2009 ~ it is now June, 2010 --- wonder where the followup went?
I have an interest in power a 10-watt ham transceiver ~ while camping across the northern states next month - - TNX, PCV-III

 

I'm all over this. Did anyone do anything about hacking into the solar or just talk about it? Is there any type of OEM mod that is available now?

Mike

 

I have to admit I have not read every reply. But, I sell solar PV for homes, and the panel on the roof is waay too small even if it covered the whole thing. To get to the 200 watts mentioned earlier, using technology available today Toyota would have had to partner with a company called SunPower (San Jose, CA). the roof size MIGHT be enough to generate 200w at noon.

As for the sunroof (why I bought the option), you can go to Webasto and get a moonroof added to the Prius for way less than the option cost (with pack) from the dealer.

 

My '05 Prius has 85,000 miles on it. I'm thinking about building a solar charger and add-on motive battery setup. Has any one done it? Would
you or anyone else be interested in collaborating on this challenge? I've been disappointed at the lack of progress on the plug-in Prius.

 

There is a user on here called John From Australia, and he has fitted the 4kwh Enginer plugin pack, plus 300watts of flexible panels on the roof, bonnet and rear window. i believe he's getting just over 1kwh per day from the sun - that's about 3 miles of range.

 

I have a 2010 Prius IV. Has anyone determined where the 2 wires that carry the current from the Roof Top Solar Panel come down from the roof into the wiring harness of the car? I too would like to do more with that current. My plan is to charge a sealed 12V battery that I will put in the trunk to power my computer when sitting in the McDonalds parking lot using the free wireless internet access. I hear these horror stories that if the 12V battery in the Prius gets too low, the car won't start.

 

I haven't heard that anyone has actually tried to tap into their solar panel. A comment earlier in this thread describes the general location of the wiring, and someone subscribed to Toyota's TIS to study the wiring.

It seems charging a battery, either a separate 12V, or the car's own 12V might be possible with appropriate precautions.

This should be done with a charge controller such as one of these:
KINTREX SPC0601 Solar Charge Controller – 7Amp, 100 Watt, Digital LED Display | Solar Panels
SunForce Products Inc. - Charge Controllers - 7 Amp Charge Controller
and not by simply tying the panel directly to the battery, or through a simple diode.

Charge controllers protect the battery against overcharging, protect against the battery discharging through the panel at night, reverse connections, etc.

Bigger charge controllers operate in stages depending on battery state of charge and can use techniques like pulse-width modulation, so the load on the panel and the charge current to the battery is not constant. I'm not sure if these small units do this too. Pulsing might cause problems with the car's ventilation controller deciding how much power is available to run the fan. It might help to not use the fan and a battery charge controller at the same time.

It also is probably a good idea to make sure the charge controller is (automatically) disconnected from the car's battery whenever the hybrid system is on (having the hybrid system charging the battery in parallel with a solar charger might not be a good idea, as they might interfere with each other and potentially damage one of them - the Prius manual does say the battery should be charged only with the hybrid system off).

Usefulness might be limited to keeping the charge up on the 12V battery while the car is parked for an extended time (in this mode, the charge controller would likely only place a small load on the panel to maintain charge), or might also be useful if accessory loads are used while the hybrid system is off.

Charging capability might also be helpful to get started in an emergency if the car's battery runs down (either from something being left on, from not being driven, or when it expires due to age). I wonder if the several amps available from the panel could recharge the battery sufficiently to start the car in a reasonably short time (if I follow my safety precaution above of not having the charge controller connected with the hybrid system on, the panel's current could not be used directly to start the car).

It does seem Toyota has gone to some trouble to try to keep us from discharging the 12V battery... accessory outlets are turned off with the hybrid system off; accessory mode automatically turns off after a period of time to protect the battery, the smart key system turns off after 5 days, headlights turn off automatically, so adding a solar charger may be unnecessary for all but the most extreme circumstances.

 

Reviving this thread, some years ago... I learned there is limited juice we can get from the solar panel, the battery trickle charger seem nice but we need to invest on the battery controller to connect to the battery... But I think everybody here have the hope to use it for the main battery, to at least charge one bar or two when leaving your car on your work parking lot without shade for the complete day. That way we can use some electric motor when almost reaching your parking place.

What about the regenerative brakes? Are they just like a dynamo? if that is the case there should be some controller already to get the different voltages obtained from braking, so the conversion of the pv cell voltage to something usable for the main battery probably could be more simple than we imagine.
Am I totally lost?

 

After seeing all that has been looked into, it seems the only alternative use for my solar roof is to help identify my car from the other 5 red ones at work.

 

I just made a webpage explaining the installation of my solar controller to charge my secondary battery...
Prius Solar Cell as battery charger

I hope it can help others who wants to do the same mod.

 

Interesting. After learning the cheapest thing you can find on ebay may not be the best, maybe you have a good setup. I hope exposing all the electronics in the car (not just the battery) to over 15V didn't harm anything assuming you tested this on the battery while installed in the car. Maybe not, it's only a little high (even when the car is not ready, some things like the SKS are still on).

Did you install any on/off switch, or are you always charging the battery?

Will you be able to confirm how this works out concerning:

• Does the solar ventilation still work normally?
• Is there any radio interference with this installed? Toyota claimed they didn't use the solar panel for powering the car or charging batteries because it caused radio interference. I guess you should check FM, AM, and satellite too if you have that.
• Does this solar charge controller prevent overcharging the battery (float chargers normally do; trickle chargers normally don't, I don't know what's customary for solar charge controllers)? Overcharging would not be good for the life of the 12V battery, especially if you're doing this on a daily basis.

 

Hello Gary. I appreciate your comments and feedback. I have a switch installed to the line coming from the solar cell for disable it when needed. I read someplace that the current produced is enough for charging and for the vent, I am still pending to test that when correct temperature is out and there is plenty sun. If vent is not turning on I may turn my switch off on summer, unless I leaved my car out for many days.
in regards interference, I normally setup an am station from mexico in the morning which normally is affected even by cellular calls, and no problem noticed yet. Also, when car is turned on, there is higher voltage on the car than the threshold of the controller, so at that time it is on open circuit condition. I consulted several solar forums and it seems the morningstar brand is very recognized. Overcharging on batteries is detected with a higher voltages at the battery.

Nexus 7 ?

 

OK, thanks for sharing.

All sounds good with the morningstar charge controller, but I would still like to hear how having this solar charger on affects the solar ventilation, in full sun, and also other conditions like with the sun lower in the sky. The solar ventilation slows then stops as the sun fades away, I guess this might happen sooner if you are also using the solar charger? Or I wonder if the solar charger pulses on and off or anything that might make the ventilation also start and stop. It would be better if we can use both at the same time, because if I leave the car parked for a long time in a sunny airport lot where battery charging would be helpful, I would still like to have the solar ventilation keeping the car cool.

 

You only need the car cool when returning from your flight, not all the week

Nexus 7 ?

For me, yes, but if I have things stored in the car I still like to avoid it overheating, and it can't hurt the car's interior to avoid being baked in the heat.

Still with the vent, it is hot to leave items on the outdoors, more inside the car.

Nexus 7 ?

look also at this post, this guy used a stepdown converter instead of a solar controller... also have some information about when the vent triggers with voltages and amperes....
Solar Panel Mod charger | PriusChat