Some Advice Please Guys & Gals, with this COVID19 and we cant drive

[Motorhead]

Caroline,

Just to point out that the alternator needs to be putting out at least 13-14 volts (ideally between 13.8 and 14.2 volts) to charge the battery effectively, so I would assume that a charger/conditioner would need to be doing the same? I would imagine that when it's not charging the open-circuit voltage would be about 12 volts.

Jeff

 

[carolinewoodley]

Hmm, interesting little note in the manual that I missed before. In the section on "battery monitor mode" it says that the most accurate measure of the battery charge level is in the morning before charging starts. It says "Accuracy improves once the battery has cooled to room temperature and has not received further charge for at least six hours or more", so it does seem to indicate that the LEDs in monitor mode are at best only a guide. Presumably during the day the battery heats up due to both sunlight falling on the car and the charging process so perhaps looking at the LEDs in the evening when it is still hot is not a good way to check the charge levels. Unfortunately I'm not usually awake before sunrise these days [] so I probably won't be able to go and check but I'll take their word for it!

 

[Twinfan]

Change of plan my end, Caroline. After a few sunny days my battery is still on red/amber on the monitor at night and the car says it's at a low 11.9volts. During the day when the panel is active it only ever seems to be in monitor mode, so I don't think it's been charging the battery at all

I'm wondering if using the negative post is the problem. The charge controller seems to think the battery is fully charged when the sun is out so I've moved the crocodile clip to the negative terminal instead, and this seems to trigger the charging cycle. It's showing the same red/amber now the car is in the shade so I think it's just the charge system that isn't triggering correctly.

I'll check it several times during the day tomorrow and see what the monitor is registering at this time in the evening and report back...

 

[carolinewoodley]

That's odd as I definitely have mine connected to the negative point on the chassis (as per the picture of a black crocodile clip on the chassis member), and it has definitely been charging. Last night the monitor showed amber not red/amber and this morning the solar LED was flashing (which indicates charging) and the green LED was lit showing it was in maintain mode. I didn't bother even to take the panel out of the car, I will check it again tonight but it certainly seems to be charging for me. I don't want to connect direct to the battery's negative terminal as I was told when I bought the car that might damage the in-built battery monitor.

Have you checked whether the solar LED is flashing during the day? According to the manual this means the controller is receiving electricity from the panel and then the LED colour gives an indication of whether it is in SAVE (red, i.e. charging from almost flat), CHARGING (amber, i.e. charging from some charge) or MAINTAIN (green).

I have had the panel outside the car on most occasions though and I did notice it wasn't charging much when it was inside. I just thought today I'd leave it inside and see if it still ends up in maintain mode tomorrow morning. If not I'll probably take the panel out and try to find a permanent spot for it (not on the car bodywork) whilst I've got the car charging during the lockdown.

To be honest, it has taken longer than I'd expected to charge given how sunny it has been and the otherwise ideal south facing location of the panel, so I think it is definitely losing a lot via the window glass and was much better when I had the panel outside. Do you have tinted glass by any chance? That would probably make a difference to how well it can generate electricity inside the car.

 

[Twinfan]

The panel is definitely active as the red LED is flashing all day but it's always in maintain mode, which can't be right if the car is currently showing 11.9V and the status is red/amber on the monitor.

Connecting directly to the battery must be OK given the charger is supplied with the permanent connector system, I can't imagine the Porsche electrics still be affected. I'll see how it goes tomorrow.

 

[Twinfan]

Hmm, bit of trial an error this! So the sun came round this morning and with the panel active it was still showing "maintain", which can't be right.

So I unhooked the panel and moved it to the dashboard to get maximum sunlight and switched the negative crocodile clip back to the charging post as instructed, making sure I connected up the clips first and then plugged in the panel last to complete the installation. This seems to have triggered a charging cycle as the indicator was red at first and it has now moved to amber. Whether it was the moving of the panel or the order of re-connection I'm not sure.

It's a nice sunny day again today so I'll see what the monitor says tonight when the car is in shade again, but hopefully it will have moved to at least amber only on the LEDs.

 

[carolinewoodley]

I wonder if you just had a dodgy connection before? I did try to make sure the croc clips were well seated on their respective positions when I connected mine up.

Having said that last night after the panel was in the car all day (rather than outside) the LEDs in monitor mode showed red and amber again, rather than amber only the night before, so today the panel is out and I will see this evening if that pushes it back to amber in monitor mode. TBH with the drain on the battery from the alarm I am not expecting it ever to show green overnight with no charge coming in from the panel, although this is just a hunch rather than any direct knowledge on my part!

Personally I do think the charger is working, and in charge mode it is accurate as to whether it is maintaining or charging; I think the issue may be either that the LEDs are not that accurate in monitor mode (as the manual itself admits, albeit a bit obliquely!), or that the constant drain from the alarm when not charging simply pushes the voltage level down. Or maybe simply a combination of both?

 

[Motorhead]

Yes, I was wondering if you had a dodgy earthing connection Dave. Mind you, croc clips are usually sufficient to bite into the surface, although it might be worth cleaning the earthing post thoroughly to ensure a good contact.

Caroline, I don't think the alarm pulls much current (30mA perhaps?), and the system doesn't go into current-save mode until 7-days as I recall.

Jeff

 

[carolinewoodley]

Even a small drop in current would affect the voltage though wouldn't it, assuming the resistance of the circuit is the same? I don't remember much about my school physics these days, it's way too long ago [], but I do remember V=IR so a drop in current would lead to a drop in voltage proportional to the resistance in the circuit surely? And the manual seems to imply that the LEDs measure voltage in monitor mode so it wouldn't surprise me to see that a small current drain from the alarm in monitor mode is enough to push the voltage down enough for the amber or amber/red LEDs to light?

Of course I may be missing something obvious here, and those with more knowledge than me about car electrics are welcome to put the record straight [], but it doesn't seem unreasonable to me for the voltage to drop when the alarm is drawing current.

 

[Motorhead]

I think we need an input from an electronics engineer Caroline (sorry, I'm a mechanical engineer), although I'm sure it's more complicated than you're assuming since a control unit is involved which is monitoring the battery charge condition and adjusting the charge voltage accordingly while still maintaining the alarm.

Apologies if that sounds as though I know what I'm talking about..!

Jeff

 

[AndrewCS]

I assume that the kit came with ring terminal connections (pp their website info).

If so I`d use these in preference to the clips, given the low charge rate you want the best possible connection … and use the separate negative `post`.

 

[Twinfan]

The problem withe ring/pigtail clips is that you risk disconnecting the battery fitting them and/or damaging the battery clamp bolt when you remove the nut which aren't designed to be removed. You can modify the rings to be "C" shaped instead and loosen the nuts just enough to slide the clip onto the bolt, but you still risk disconnecting the battery or damaging the nut/bolt - they can be quite hard to shift!

I was considering fitting the ring clips but have decided to stick with the crocodile clips for now. I'll be completely removing the charger once the lockdown is over, and for the odd time I may want to use it in the future the crocodile clips will be fine for my use.

 

[carolinewoodley]

I think we need an input from an electronics engineer Caroline (sorry, I'm a mechanical engineer), although I'm sure it's more complicated than you're assuming since a control unit is involved which is monitoring the battery charge condition and adjusting the charge voltage accordingly while still maintaining the alarm.

Apologies if that sounds as though I know what I'm talking about..!

Jeff

I very much agree, I'm sure basic O level physics isn't enough in this case to work out what's going on! I did wonder how much effect the controller unit must have, but I really don't know anything like enough about it to be able to work it out myself. However I am sure Optimate will have tested it with a large number of different cars and charging scenarios (I would guess, including one where the car itself has a battery monitor) and would not have released the product if they weren't confident it would work in the vast majority of cases.

The only other variable is whether a 20W panel is really enough for a car like the Cayman with I am guessing a pretty high capacity battery, but as it seems to be maintaining during the day I am pretty happy it's fine. I guess the proof of the pudding will be if I leave it five or six weeks and then try to start it.....! []

It would be interesting to find out though what is going on with the monitor mode - if there are any electronics engineers out there with a knowledge of the Cayman electrics it would be interesting to hear their views.

 

[AndrewCS]

The problem withe ring/pigtail clips is that you risk disconnecting the battery fitting them and/or damaging the battery clamp bolt when you remove the nut which aren't designed to be removed. You can modify the rings to be "C" shaped instead and loosen the nuts just enough to slide the clip onto the bolt, but you still risk disconnecting the battery or damaging the nut/bolt - they can be quite hard to shift!

I was considering fitting the ring clips but have decided to stick with the crocodile clips for now. I'll be completely removing the charger once the lockdown is over, and for the odd time I may want to use it in the future the crocodile clips will be fine for my use.

The positive battery clamp connection on my 981 CS incorporates an additional connection, utilising a standard bolt / nut. The clamp bolt / restrictive nut is not touched - disturbed when connecting my c-tek with the `ring`.

I had assumed that the 982 was the same …

 

[Twinfan]

I think you might right, I seem to recall an extra bolt on there. Where would the negative ring go though?

 

[AndrewCS]

I think you might right, I seem to recall an extra bolt on there. Where would the negative ring go though?

If same as the 981 … there is an open M8 `threaded socket` on the nearside top mount. I enlarged the M6 ring to suit and used a short M8 bolt to secure.

 

[Twinfan]

Thanks Andrew.

Well after a full day in the sun yesterday my battery has now dropped to red only on the monitor, so clearly the panel solar panel isn't doing enough. For today, which looks like it'll be sunny again here, I've moved it to outside the car as a last attempt to get it working. The windscreen must be attenuating too much sunlight for an effective charge, which is what Caroline has found. At the moment it seems that these solar chargers aren't really suitable for a modern car.

We'll see how today goes though...

 

[AndrewCS]

Omitted to credit `Ray` for this info … he posted some time back in a `charger` thread.

[attachment=C-TEK Connection a.JPG]

 

[carolinewoodley]

Thanks Andrew.

Well after a full day in the sun yesterday my battery has now dropped to red only on the monitor, so clearly the panel solar panel isn't doing enough. For today, which looks like it'll be sunny again here, I've moved it to outside the car as a last attempt to get it working. The windscreen must be attenuating too much sunlight for an effective charge, which is what Caroline has found. At the moment it seems that these solar chargers aren't really suitable for a modern car.

We'll see how today goes though...

Hi Twinfan, did having the panel outside work better? Mine does seem to be keeping it on "maintain" now whenever the panel is charging (inside or outside the car) although I must admit I have not looked at the charge levels at night for a couple of days. But it was definitely not on maintain for the first couple of days so I think it's working. I am currently in a "routine" of putting the panel out early in the morning and then putting it back in the car overnight and with the current sunny weather it seems to be fine.

However I'm not yet confident enough that the charge is enough to put the car back into the garage for a couple of weeks (i.e. a few days out charging and then back in the garage for a couple of weeks), which is what I really want to do ultimately as it's getting really dusty and the gap between the windscreen and the bonnet is slowly getting filled with leaves/petals and other sundry natural debris sitting outside!

 

[Twinfan]

I must admit I gave up on the solar charger and dug out an old mains Optimate I used to use on my motorbikes. As it's been dry I've run an extension lead out to the car from my garage and had it hooked up since lunchtime yesterday but it's still showing "charging". I suspect the battery was pretty low and as the charger only trickles at a low rate it's going to take some time to get it up to near full charge again, probably sometime tomorrow.

My plan is to get it up to 'maintain' via the mains charger, then re-install the solar panel on my dashboard and see how it gets on in the hope it can maintain the battery for a while, or at least significantly slow the rate of discharge, once it's up to charge again...