Checks to see what is being charged
This applies not only to solar panels, but also 'on board' and external/portable battery chargers.
First of all you'll need a test meter. Its now possible to purchase a cheap test meter, usually digital for about £5 - absolutely crazy as I was initially paying ten times that when they first came on the market. Try your local cheapo shop or somewhere like
www.maplins.co.uk
IMPORTANT On your meter, there are usually several options for measuring electrical thingies! Voltages (the potential difference of two test points) on vehicles are DC (direct current) which will be indicated by either 'DC' or a short horizontal line over the top of a dashed line. AC (alternating current) is what your house is fed with from the central electricity generating company. Current is Amps (A or mA - milliamps), again there is probably a choice of two options, AC and DC. These are measured by connecting your meter in series with your load and supply. With cheap meters, they are not usually capable of measuring anything more than an Amp or so, so avoid this. By the way, if you connect your meter across the battery terminals whilst the meter is set to measure current it will be fit for the bin after its gone 'POP', unless it the meter has been equipped with a separate terminal. Finally most meters have the option to measure resistance (Ohms) which is normally indicated by an upside down horseshoe symbol (well its upside down to me as the luck runs out of horseshoes if nailed up the wrong way!). The resistance test is how well two items are connected together, therefore the connection between a battery terminal and the lead connected to it should be zero ohms, if it does have a resistance it will generate heat and breakdown, also it will cause a loss in voltage. Again it should be noted that your meter will probably die if you connect it across a voltage whilst set on ohms.
1. First make a note of the battery voltages with no engine running and no solar panels or chargers running, plus check everything is switched off, small interior lights won't hurt .
2. To establish whether your batteries are isolated when parked up (the most common and recommended situation), carry out an voltage check first. This is done by having one test meter lead on the + (positive) terminal on one battery and the other test lead on the + terminal of the other battery. Ideally you should have a zero reading (like as if the meter is not connected to anything). providing you have a zero reading, reset your meter to measure resistance/ohms and do the same test again. This time you should have an open circuit reading of maximum ohms (like as if the meter is not connected). If you do have a low resistance, you have got a problem where your house equipment is also going to drain your vehicle starter battery. Its probably worth reversing the test leads to see if you get a different reading, in this case there is probably some electronics involved in the connections between house/leisure and vehicle starter batteries.
3. Then start your engine and take another set of voltage readings. These should be higher than the first. If not you've got problems! Next stop your engine, and plug in or switch on your solar panel (I'll state the obvious, and say this should be done on a bright day - not at night!), check your battery readings, these again should be higher than your first initial readings, however you may find that the readings are only higher on one battery. This will indicate what is being charged by your solar panel. It is a possibility in some cases that no increase in voltage is detected (especially if your solar panel is connected via the cigarette lighter socket) until the ignition switch is turned on (providing the panel is powerful enough), in this case I recommend a rewire of your circuits. After the test, and before proceeding to the next stage, isolate or turn off your solar panel.
4. This test is similar to the solar panel test, but using an onboard battery charger. Check your charger/hook-up is connected and switched on, then check the battery readings, which again should be higher than the first initial readings. It will also indicate which batteries are being charged. This test also gives the opportunity to check any switching options for charging on any auxiliary electrical panels in you vehicle so that you understand exactly what they do when you operate the switches. After the test, and before proceeding to the next stage, isolate or turn off your solar panel.
5. As a final check, I would use a normal battery with flying leads and crocodile clips. Connect the charger up to your vehicle battery and power up the charger. Take the battery readings, in most cases there will be an increase in voltage only on the vehicle starter battery, however if there are special circuits on your vehicle, you may find there is an increase in voltage on your leisure/house battery. I would also try this test again by connecting the battery charger to the leisure/house battery to see if there is any back feed or leakage!
Obviously if you have any strange results from your tests that don't really comply with the above, it would be best to post them here so we can work through them together. By all means email me (especially if your not sure), but do also post your questions here (minus any embarrassing bits) so others benefit from the knowledge/experience. Hopefully all the above makes sense, but as I tell my students if it doesn't make sense or I have made errors, let me know so I can put it right.