Solar Panel Battery Charging And Problems 1998 v70 mostly

[MrAl]

Did you figure out what was drawing the battery down to begin with? Is it just a case of not using the car as regularly as it may like?

Hi,

I think what it really is is that the car isnt driven that much combined with the way they designed the charging system and maybe the battery type.

For one thing what happens is the battery does not charge that well at the alternator design point of exactly 14.00 volts. It needs 14.2 or maybe even 14.5v like some cars have.
It could be because the car is not driven that much so the battery does not get charged as well as if it was driven every day. That makes the battery eventually get even less charged as time goes on because it appears that the battery internal resistance goes up a little and that prevents the alternator from charging the battery as much as it can if the battery was new.

If the charge voltage was more like 14.5v it would charge every time just going to the store and back. That's why i considered adding the 'boost' diode to the voltage regulator. This is an easy mod if you can get your voltage regulator out of the car, but that's something i have not been able to do yet. The alternator is buried in the engine compartment pretty deep, and although i have read it is possible it seems quite hard to do. For one, have to drain some of the radiator fluid.
This is also something that many people have noticed now as i look around the web. I first considered this way back in the 1990's as my Hyundai developed the same problem. I could have done it with that one though the alternator was easy to get out.
The fix is easy, you just have to break the ground connection to the voltage regualtor and insert two diodes connected back to back (antiparallel) and the voltage goes up by about 0.5 volts (Schottky diodes). The diodes are ultra cheap 20 for $5 USD. It fools the voltage regulator into thinking the battery voltage is lower than it really is, so it raises the charging voltage.

So right now i am working on the solar panel solution and i can see that it should work with a few changes.
I'll update when i get more done on it, hopefully today or tomorrow depending on weather.

[MrAl]

Hey Al,

Although the downside to this is will draw down the battery itself, how about this Bluetooth battery monitor:

https://www.princessauto.com/en/12v-blu ... 0008932303

This is about to go on sale here next week for around $40 CDN which is about $30 US. Has some useful storage features which may help with figuring out the charging rate of your battery in different conditions.

Neil.

Hi Neil,

That looks like an interesting device too. A while back i would have paid twice that for a device like that but i read people were having too much trouble with the bluetooth measuring equipment disconnecting and it sounded like a big pain in the neck.

What draw on the battery are you referring too here? Is that the drain due to the measuring/transmitting device? I've gotten the drain down pretty low now around 1ma average, and i can get it even lower once i get everything working.
The thing is, i design this stuff myself, so i can change it as my needs change. For example, i can add current measurements, voltage measurements, door monitors, etc., and that is because the whole thing is designed from the ground up where i can change anything about it.
As far as the battery drain goes, i once designed a refrigerator monitor that monitors the temperature just in case anyone leaves the door open a little. I got it such that two regular alkaline battery cells would last for 2 years. That is possible because you dont have to take readings constantly, and there is a 'sleep' mode on most microcontroller IC chips that allows you to put the device to sleep and that consumes nanoamps or something like that. They call it 'nano power' i think. That's a Microchip microcontroller, the type before Atmel was acquired by them. They make some amazing stuff. The 12F and 16F series flash programmable. They have much newer types out now but my programmer has to be upgraded first.

I will keep that device in mind though in case i can get around to trying one. Right now i just want to get the solar panel working right so i can actually keep the battery alive.

Here is a screen shot of the simplified user interface. I didnt need all that other stuff right now so i simplified it. The four readings are all 12.00v, and that includes the current reading and 3 previous readings. They are all 12.00v because the battery voltage did not change. If it goes down again the one on the far left will go down to 11.99v for example, so they will read:
11.99v, 12.00v, 12.00v, 12.00v
and if it does down again on the next reading they will read:
11.98v, 11.99v, 12.00v, 12.00v
so most current reading on the left, oldest reading on the right. That allows me to check the progress at a glance instead of constantly opening the log file. The log file stores all the readings all day and all night for as long as the program runs.

I want to add solar panel current to the measurement data next because that will allow me to monitor the actual charge current which is also very important. I hope to do that soon. Temperature data will help understand the battery voltage better due to the way lead acid batteries react to temperature.

I'll keep updating this thread as things change and progress is made. I just hope this all works out because this would solve most of my Volvo battery problems.

Oh i almost forgot, i came to the realization that the solar panel does not have to mount on the outside of the vehicle permanently. It only has to be mounted on the outside during the time it is parked in the driveway. Since i monitor the car with a closed circuit security camera, that should be good enough i think.

[volvolugnut]

I think velcro would make good removable mounts for inside or outside of windows.
volvolugnut

[MrAl]

I think velcro would make good removable mounts for inside or outside of windows.
volvolugnut

Hi,

That's an interesting idea, i have used velcro in the past for a lot of things like tying up cords to keep them neat.

The only thing i would worry about is it might make it too easy for someone to unzip and take off with the panel. I dont want to make it too easy. I was thinking something like chain and a padlock or two. What do you think?

[MrAl]

A little update...

I got the panel installed on the roof temporarily.
The results were pretty good, much, much better than with the panel inside the car. I saw voltage levels that were very promising, much higher than before. The voltage was over 13 volts at some times when before i was lucky to see 12.35 volts.

I still have to see what happens with cloud cover though. Today we had mostly sun but some clouds rolling in now and then, and you could see the voltage drop when that happened. So it still remains to be seen how well this will work out in the long run, but it looks much more promising now. I know it will have to make some difference as today it charged up pretty well and the voltage was pretty low last night ... lower than it had been in some days now.

Oh i tried to measure the parasitic drain current. I got a different clamp meter that works down to lower current levels. The problem is, even with that clamp meter it's hard to get accurate results with currents below about 50ma. The best i can figure for now using that meter is between 5ma and 40ma drain. I'll have to check it better at some point. With the solar panel though it may not matter anymore i'll have to see how that goes over several weeks. When summer hits it may change too because the leaves on the trees may block out more of the sunlight. I am hoping the insolation level goes up in summer though which may compensate. This time of year in this area it is only around 65 percent of maximum.

[MrAl]

Little update...

I measured the current from the panel during full sunlight and the voltages at the OBDII connector and the battery and found that the voltage drop indicates that the wire size is around #22 AWG. I had hoped it would be #16 but no luck it cant be that good. Too bad, but i got my own wire and am planning to install it soon, going from the battery to the interior of the car, so i wont have to depend on the OBDII wiring anymore. Cant wait to get it installed i have been putting this off for years now. Lucky for the good weather lately though.

Oh i looked at the panel strength too because it is now on the roof of the car at an angle so it picks up the sunlight better.
I was able to calculate the total force on the panel in a 100 mph wind or driving 100mph in a calm wind. The total force is about 50 pounds force and the mounting materials are rated for 600 pounds force (max). So technically i could drive down the road at 60mph and have no problem, but i am planning to take it off the roof anyway when i go out. That's especially if i go on the highway, which i almost never have to do anyway. I did have to buy the new mounting materials though which added to the cost quite a bit.

[tomvv11]

I have the same question. Why are you farting around with solar charging if the problem is that your battery is not holding a charge or is not being charged by the car? If you are having trouble starting the car there are the starting circuit and/or the state of tune to consider.
The only thing that would draw the battery down legitimately would be a quartz clock or something else with a tiny motor. Any other drain would be a minor short to ground somewhere that could be time-consuming to track down without a schematic, a multimeter and a logical approach.

[scot850]

tomvv11, Al has been down all those routes. It would appear from what he has told us the drain is in the 10-40? mA level. My car drains at the 45-50 mA level and after 2 weeks it is getting too low to start the car. I have checked the car out, the dealer has checked it out and all is normal other than the radio will always draw a tiny bit to maintain memory, and in my case the aftermarket Viper immobiliser/key fob system draws the rest. Normal should be in my experience 10-20 mA in a 98 or earlier P80 unless there is a drain.

Al has complications in like me he also does not drive a whole lot these days so the car can sit for longer periods of time. Particularly in the colder weather we have experienced, when you don't run the car for 15-20 minutes or more, you can draw down the battery faster than the alternator can replenish. He also due to where he lives, cannot run a power cable to the car for a trickle charger so is trying to find a way to maintain his battery which is good.

Hope that helps.

Neil.

[MrAl]

tomvv11, Al has been down all those routes. It would appear from what he has told us the drain is in the 10-40? mA level. My car drains at the 45-50 mA level and after 2 weeks it is getting too low to start the car. I have checked the car out, the dealer has checked it out and all is normal other than the radio will always draw a tiny bit to maintain memory, and in my case the aftermarket Viper immobiliser/key fob system draws the rest. Normal should be in my experience 10-20 mA in a 98 or earlier P80 unless there is a drain.

Al has complications in like me he also does not drive a whole lot these days so the car can sit for longer periods of time. Particularly in the colder weather we have experienced, when you don't run the car for 15-20 minutes or more, you can draw down the battery faster than the alternator can replenish. He also due to where he lives, cannot run a power cable to the car for a trickle charger so is trying to find a way to maintain his battery which is good.

Hope that helps.

Neil.

Hi Neil,

Thanks for the breakdown of what has been happening on my end with the car.
Yeah it is probably due to the fact that i dont drive much anymore that's probably the main issue. But i cant see driving the car around town just to charge the battery either (ha ha). That is just unreasonable and a waste of gas. $30 the other day only got me about half a tank.

So today if the weather permits (looks bad though) i will try the fishy wirey thing and see if i can get it through that tube in the firewall. I think i might be able to based on the replies i have been getting. If not, i am prepared to drill a couple holes for tie wrap and run the dang wire through the door jam probably on the passenger side. I dont open that door much anyway and these doors have a nice thick rubber grommet running around the door which does not harm the wire (i tested that already). I would prefer to go through the firewall of course.

[scot850]

As the guys have said Al, there are some spots that a wire can be fished through which saves drilling holes and potential for water entry to the car. I wish you good luck!

Neil.