Doesn't the PV panel have a series diode on the output? If a normal Si diode (not a Schottky) the reverse leakage should be almost unmeasurable. If there isn't a diode (which I think would be unusual if designed for battery charging) then you could add one. But the charging current you'd get from a north-facing window would be tiny. Did you measure it? If you use something cheap like phone or UTP wire, the 50 metres to s south window needn't cost much, and you're only looking for a trickle charge, are you not?
Some Schottkys have a lot of reverse leakage, but I think you could usually add another normal Si diode in series without much affecting the few milliamps of trickle charge which would be needed to offset the battery's self-discharge.
In Winnipeg car parks for employees, customers, etc. were often fitted with sockets on poles into which you could plug your car's block heater so that the engine remained well above freezing. Which also made it easier to start. Of course that was before all the disasters the West has suffered. Don't know about nowadays.
Another requirement (unfortunately) is that this needs to be doable by SWMBO'd with or without the assistance or the kids, hence the electric start in the first place...
This single cylinder open frame diesel set isn't exactly "whisper quiet". B-)
Needs to be a near "fit 'n forget" solution. Something that needs to be done evry three months or WHY probably won't be.
That is an alternative, if I can find a suitable charger. I think I have a constant voltage power supply somewhere that could be "adjusted on test" to give say a < 50mA charge rate. Enough to replenish the self discharge in a few hours but not enough to dry the battery if the timeswitch fails to on.
Any idea what current it sits at once charged? Need to balance enough current to keep it charged against finger growth against "cooking".
Until I knock a hole in the garage wall and connect a pipe to the "silencer" outlet autostart/change over isn't required. It's also only a 2 kVA generator, enough for fridges/freezers/heating but not the kettle!
What poor site to navigate. Left menu drop down drops down over the menu. Pages with multiple products on don't tell you the basics of what a given product is. Not even something like "Autostart controller, 20 kVA, single phase".
Ah yes, the "spare" 2 kVA UPS has those to connect the battery pack to the electronics.
Still trying to KISS though, as conditions maybe pretty bad when wanting to use the genset. Getting the heating running with a real blizzard(*) going on outside is a high priority. Anderson connector are quite chuncky but the cables which are stiff at 15/20C are really not going to be very flexible at 20+ degrees colder. A small strap or bungee could replace the tiddly fiddly wing nuts and angle that hold the battery onto it's tray.
(*) Above 30 mph sustained windspeed, "Near Gale - F7" with visibilty less than 1/4 mile. Drifting and/or falling snow builds up pretty rapidly out of the air flow. Out in a blizzard is not pleasant up here, windchill is likely to be below -20C, the wind does snatch away anything lightweight, the snow does hurt on impact and sting because it'll still be well below freezing.
It does and the measuring bit is what I can't remember the details of or the circuit. The LED and it's series resistor might be after the diode...
ISTR (badly) a few mA at 0.5 Hz or slower.
This is true. Cat5 uses 8 * 24 SWG wires. 24 SWG is nearly 0.25 mm^2 so paralleling two pairs gives about 1 mm^2. 1 mm^2 has a resistance of about 19 mOhms/m so 50 m is about 1 ohm or 2 ohms there and back.
2 ohms and 10 mA is 20 mV, not worth worrying about.
However any route to get south facing is really really tortious. B-(
But I might be able to expose the panel better without quite so much bother. The panel is KISS compared to time switches, chargers, etc.
I have two car batteries on the go. Both have been abused in the past by being let go flat in the car whilst we were on a long holiday abroad. Both have been brought back to life by a trickle charger and at the moment I have one on charge and the other in the car. When one battery starts to lose charge due to infrequent short journeys (especially over winter) I swap them over.
Been doing this for 2 or 3 years now and both batteries seem to be holding up.
The charger is an AccuMate which is claimed to be good both for maintenance charging and recovering deeply discharged batteries.
So perhaps a good quality maintenance charger, and a heating strip/pad linked to a thermostat wrapped around the battery to prevent freezing, could keep your battery alive.
Dontcha tink Dave that there come a time when living in one of the highest and remotest places in the UK might loose its appeal and you might be well advised to come down from that mountain to a lush green valley;?....
Well even Dave's remote hilltop isn't quite as cold as Sweden and I don't think Volvo owners have had to do that. And yes before anyone gets wound up by that anything chemical does depend on temperature for its speed of reaction....
But IIRC this battery which is on its last legs isn't quite out in the open more in an outhouse and a bit of lagging around that with polystyrene foam would keep the worse of the weather out and a simple home brew float charger would keep it topped up..
We've dome quite a few of these over time a simple power transformer, bridge rect one smoothing cap one reg current and voltage limited and adjustable, been is use some 15 odd years.
Don't know. Just set it to 13.8 volts and leave it at that they work fine and we've been making them and doing that for some 15 odd years now and never had a problem. The current is limited by the size of the reg they come in three sizes we just use the 7.5 Amp ones....
Yes not that good but no worse than a lot of others, but very good and well thought out units all the same:)...
The one we have looks at the Oil pressure light and when thats off it knows the genny is running but if it came on while the genny is running it shuts it down and tells you it has a a fault condition etc plus its programmable for such as start attempts and lots of other useful features:)...
I very much doubt it. My Will has instructions for cremation and releasing my ashes to the wind across our in-bye. And if the Parkinsons starts to get to the stage where I'm not functioning well enough and fail to do a Cilla I have the option of doing an Oates.
More like 350mV at 100mA on a 10 amp diode. You wouldn't be gaining very much over an ordinary silicon rectifier diode in this case, especially since the reverse leakage current is several orders of magnitude greater than an equivilent rated silicon diode. The high reverse leakage isn't an issue in smpsus where they offer a reduced forward volt drop on 3.3 and 5 volt supplies (450 to 500mV at their forward current rating).
Each silicon PV cell produces an open cct voltage of about 700mV which drops to around the 550mV mark at optimum loading. I think these panels have 30 PV cells in series (mine, afaicr, produced a peak open cct voltage of about 22v) so the inclusion of a cheap silicon diode makes very little difference to the charging rate. Admittedly it loses just over 1 PV cell's worth of voltage on load but, with 30 or so, that's neither here nor there in such a simple solar cell charger as this.
Such 30 cell panels are standard for 12v Lead Acid battery based systems. The use of a smart solar power controller will hold the voltage to around the 17 volt mark to maximise the power transfer into the 12v battery. Converting 17v down to 13.8v at an efficiency of 90%[1] produces a higher charging current than simply letting the battery directly bog the panel's voltage down to 13.8v.
At 90% efficiency you'll see almost an 11% boost in charge current versus perhaps a 2 or 3 percent increase over the optimum 17v output current by letting the battery load the voltage down to 13.8v. The output impedance of solar panels is quite high creating an almost constant current between the optimum 17v and the 12.5v almost flat battery condition.
[1] 90% efficiency is a conservative estimate. Efficiencies for these controllers is probably more like 95 to 98 percent for 12 and 24 volt systems respectively. At 95% efficiency, the gain is even higher (17% more current on the 13.8v output compared to the 17v input current from the panel - around a 15% net gain over a direct connection to the battery).
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