This post was submitted as per request for ChrisG and Steve.

My apologies for the (low light)pics ... it was overcast today.

First of all, I should emphasize the not so obvious first: This solar panel installation does NOT tap into the traction NiMH battery ! Instead, it is meant to keep the rather small (in size and capacity) 12V battery topped off.

Now, for the more obvious: My personal HCH-2 actually has two solar panels. One "permanently" mounted at the rear of the car (as shown in the following pic) and another that I have stowed inside which I use on the front dash when I feel like it.


Now for the above, I drilled a hole into the plastic trim and then ran the wiring to the trunk. From the trunk the single wire (+ve) was run past the rear seat into the cabin and then under the carpeting on its way to the fuse box.


Here's another view, this time from the rear right passenger seat. The solar panel is kept in place with double-sided adhesive (10mm) insulating foam and velcro... so that it is not only noiseless and easy to remove, but also slightly tilted to the back.


The following pic (not very clear - I'll take another one at a later time) is the fuse panel. I've connected the RED (+ve) feed from the solar panel(s) to this particular fuse position. If you notice, it is an empty fuse position but any other vacant fuse socket will do. Use a multimeter to make sure you plug it in to the correct fuse contact. In this case, the lower contact is the live rail.
The second wire from the solar panel can be connected to any good ground point in the car. For the rear mounted panel, I found a good ground in the trunk which enabled me to run the single wire (+ve) to the fuse panel.




The following pic shows the dangling connector for the second solar panel, which I mount on the front dash whenever I deem appropriate.




The following pic is a sample of the actual solar panel. I bought quite a few of these at Canadian Tire when they were on sale last year. Pretty good deal I must say. These units will output 40+ mA or more in a sunny day and will also produce good power in cloudy days too




Anyhow, that is all there is for the rather simple install. Does it work? It does for me. As some of you may suspect, it does have a small but measurable positive impact on fuel economy !
If you have a scangauge then watch it work by setting the reading to voltage. Better yet, place a small digital Ammeter (eBay for $20 or less) in series with the solar panel's (+ve) to see the actual current flow. My wife's newly arrived HCH-2 will get a similar install as well - as soon as I get some time to do it that is.

Cheers;

MSantos

 

can you demonstrate any measurable gain in performance, fuel economy or otherwise by installing this?

i dont mean "it seems to do better" but a measured improvement

 

Good question.

It is pretty hard to do just that without making this into a full fledged project of academic proportions... which happens to be something few of us will gain in doing.

However, it is possible to eyeball the benefits by using plain old inference and some calculations based on the trickle effect the solar panels provide to the 12V battery. Is this quantifiable? If anyone is willing to be methodical enough and include all variables then, yes, it is.

Now, a single panel setup is likely to keep the battery drain to a minimum especially if the onboard systems (car off) consume no more current than what the panel provides. In my case, the panels not only replace the power consumed by the onboard systems but also send the surplus to the battery in the form of a trickle charge that spans over 10 hours each day.

Anyway, if you plug a scangauge on your HCH-2, you will be able to tell when the IMA is charging the 12V system and how long those sessions last. These sessions will even occur when the vehicle is ON and in an Auto-stop. With a properly topped-off 12V system the IMA does appear to intervene less often and in smaller durations which by inference means that more of the NiMH SoC will be available for mostly propulsion duties.

Most of us have seen how easily the NiMH SoC is affected by the operation of accessories especially when autostopped and in a warm summer day. Right?
All this solar panel setup does, is reduce the rate of discharge of the 12V battery by supplementing a charge to it over a longer period of time that would otherwise have to come from the IMA's NiMH. In my case, this translates into lesser number of forced regens and hence better fuel economy.


Cheers;

MSantos

 

You can't possibly top my modifications.



I have a prototype on order from Honda.

 

I had the same setup on my previous BMW and it worked quite well
although my solar panel plastic surround melted and distorted shape
is the the Harsh Australian sun or a solar panel that you cant leave in the Sun!


Steve

 

LOL

 

Wow... 2 rotfl in one day. First bwilson and now you.

 

 

It is not too complicated to get an idea about the maximum theoretical savings.

Assume that your solar charger provides 40mA for 10hrs straight, and that it can be completely used to charge the 12V battery.

Remember that:
Watts = I x U and Joules = Watts x seconds

Then: 40mA x 12 V = 0,48W
0,48W x 10 hrs x 3600 sec = 17280 Joules, or 17KJ

The enthalpy of a liter of gas is approx. 33MJ, therefore 17KJ equates to 0,5ml of gas.

Assume that your ICE has an efficiency of around 20%, then it takes 5 x 0,5 ml = 2,5 ml of gas to generate 17kJ of output.

2,5 ml is about 1/2 a teaspoon. That's what you could save, on a sunny day. It would take about 4 years to save 1 gallon of gas in total, so I don't think it makes economical sense to install this solar charger, but I think it makes good fun.

EDIT: Just picked up my HCHII today! After 4 months Japan has finally shipped some to Europe.
Mine is Galaxy Grey with a grey leather interior.

 

this is assuming best case, that the 12v system will TAKE all the charge provided by the solar, this seems very unlikely. so best case is 1/2 a teaspoon. An average case would seem to be a fraction of that.

i would like to say that despite the fact that the benefits may be dubious, its still neat. If someone would just figure out a way to separate the high voltage pack from the electrical system and then charge it I would be happy.