This isn't really a HCH2 specific topic but I couldn't decide where else to put it. So please bear with me.

Browsing through my weekly stack of flyers, i came across "dash-top solar panels" that can be plugged into the 12V socket in your car and charge the battery. I was wondering if this is at all useful for Hybrids?

- The solar charge would go to the 12 V battery so less energy from the ICE or IMA charge would be used to top it up.
- If the car is left out in the sun for a while ... would the charge then flow down to the IMA battery once the 12 V battery is topped up? [I know I'm treading into phev terrain here]
- If the charge doesnt flow through to the IMA battery ... what happens when the 12 V battery is topped up? How does the solar panel system deal with the generated energy?

If you drive your car I'd doubt it'd do much good. Not sure about the overflow thing.

this may be useful.

i killed the 12v battery in my 07 HCHII and it would not start. The IMA battery was nearly fully charged, but the car was not capable of starting. This would lead me to believe that the 12v system is isolated from the high voltage system entirely. This makes sense to me, you almost certainly cannot charge the high voltage pack through the 12v system.

I do have the technical manual and could track down all the wiring, but thats an awful lot of work.

on a side note, if nothing is using the power the cells are collecting then they will just sit there. meaning that if you put the solar cell out in the sun and there is nothing connected to it then it will just sit in the sun and get warm, which is precisely what they do when they are being used.

if you find a way to tap into the high voltage pack to charge it please let me know.

In order to charge the IMA battery, you would need much more than just a 12v solar panel. You would need a DC/DC converter to raise the 12v to the level of the IMA (144V for a HCH-I) and you would need to know where to connect this voltage source to. Can't just connect it to a NiMH battery without some kind of Heat/Current/Voltage protection circuitry.

It can be done but not without some re-engineering.

I believe that in the HCH-I, the IMA battery is used to start the engine by way of the IMA motor. The 12v battery/starter would very rarely be used. I've owned my for 2 years now and it is parked outside in the cold NE winter and the 12v starter has never had to kick in.

Presumably correct. however see below:


Nope. If you plug a solar panel to the power socket then no charge will be delivered to the 12V battery. This is because the accessories power circuit is interrupted by a relay that only closes when the key in the ignition and on position I.

I do have an Eliminator solar panel (Canadian Tire) that charges the 12 volt battery but this is because I pugged it directly into the 12V power lines that can be tapped in the fuse panel.

Charging the IMA battery pack requires intrusive engineering. It can be done, but it would require care much care so that it does not damage any of the exiting circuits & modules. Also the IMA circuit is totally disabled whenever the key is off the ignition. Because of this, the BCM module can not be used to regulate the IMA battery charge and you must find another regulation mechanism that can co-exist with the car's native systems when they are on.

It is unlikely that a small solar panel will cause an overcharge situation for your 12V battery. Unless it is a 5W or larger panel the charge you get can be equated to a trickle charge which is of no danger to the battery.

However, if you have a higher wattage panel then you'll need a charge regulator (also found at canadian tire or another store).


Cheers;

MSantos

Yes, but the 12v battery is seldom discharged too much after driving a while.
No, in most hybrids the 12v energy can't directly flow back to the "Main" battery. It tends to flow the other way.
It can tend to overcharge the 12v battery. The excess energy should be dumped and this requires a "smart" charging module that will behave in a manner similar to that of a Battery Tender or Float Charger.

Note that these small solar units don't generate much electrical power as they have a small surface area and have poor conversion efficiency.

JeffD

I used a solar charger on my HCH I. I ended up burning out some kind of relay so that my 12 volt would no longer maintain a charge! That is what the dealer told me anyway. They are usually pretty good in diagnosing problems.