| Some tips and hints
on how to vastly improve the battery charging efficiency of almost all
Portable Folding Solar Panels. Almost all supplied portable folding solar panel kits have serious flaws, and although most will still work in their manufacture supplied configuration, they will be operating at far far less efficiency than they could, and should! So with some extra knowledge, and just bit of tinkering and maybe adding some quality good sized cable, the folding solar kits out-put and charging efficiency can be vastly improved. Firstly the cable that runs between the solar panel and the battery.. Almost all portable solar panels come supplied with cable that is grossly undersized for the job it needs to, here the electrical resistance over distance is a huge problem and will almost always cause a substantial throttling back of the solar panels available battery charging current! It is always best to keep the leads to/from the solar panels as short as possible, noting that the longer the cable, the increasingly more the electrical resistance is and the increasingly less current that will be flowing, and the only way to overcome this throttling back through electrical resistance is to either shorten the cable, or increase the cables copper core size. Just like increasing the size of a water pipe to allow for higher flows, it works just the same with electricity and cable size. I recommend that cable anything up to 2meters in length then twin 6mm auto cable (4.59mm²) should be fine, however anything over that and it would be well worth stepping up to 8 B&S twin cable (8mm²). The next tip, and very very important. But first, why do we have a solar controller/regulator? Well the voltage coming from the solar panels is up around 17V under load (it needs to be this high for various good reasons), and that 17V if left unchecked would grossly overcharge your battery and destroy it very quickly. So the job of the solar controller/regulator is to regulate the solar panels charging current into the battery, so that the battery charges as quickly as possible, as fully as possible, and safely without overcharging or damaging the battery. It is very true that for the best battery charging performance in every case, it is much better for the solar panels solar controller/regulator to be mounted as close as practical to the battery that it is charging. This is because all solar controller/regulators (yes each and everyone of them) are designed by their manufactures to be mounted as close as possible to the battery that they are charging, and for a very good reasons! You need to understand that during the main charging phase the solar controller/regulator simply links the panels directly to the battery (just like turning a switch on), and then monitors the battery voltage so it can do it's regulation thing when the battery voltage gets high enough, but of course to do this properly it really needs to know the correct and actual battery voltage, at the battery! So with the regulator being mounted near the battery, and with such a short cable run between it and the battery, it gets almost no voltage drop at all, and the solar controller/regulator can read a true and correct battery voltage. However is the case of folding solar panel kits it is common for the solar controller/regulator to be mounted close to the solar panels, normally glued on the back of the panels, or mounted on a leg, and as I've just pointed out this is not ideal, and this is just about the worst possible place for them to be mounted in most cases! It is the worst possible place because the solar panels are putting out up around 17V under load, and if the solar controller/regulator is at the solar panel end, and with all that electrical resistance over distance to the battery, it will more easily see the much higher voltage of solar panels first, and think that the battery has a much higher voltage (more charge in it) than it really has, and so it will shut off the charging of the battery long before the battery is fully charged. So with smaller inadequate cable not only do you get a throttling back of the charging current, causing wasted energy and slow battery charging, but also with the solar regulator/controller stopping the charging prematurely as well! I have proven many times that changing to good sized cable, and putting the solar controller/regulator close to the battery can increase the folding solar panels efficiency (as supplied) by between 200% and up to 500%. Also a little about the solar regulators........... Many of the solar regulator/controllers supplied with these portable solar panels are of a very poor quality, and almost all so called MPPT (Maximum Power Point Tracking) solar controllers sold and attached to these panels are a hybrid MPPT/switch mode/PWM (Pulse Width Modulation), and a very poor one at that! Most true quality MPPT solar controllers of 20A or more will cost in excess of $500, and these are really only viable and practical for larger systems to be of a cost effective benefit. Testing of some of these hybrid ones have shown that they perform no better than basic standard solar controllers, and in some cases they have proven to perform worse than the most basic ones. Just be aware! Having said all that, the majority of the supplied solar controllers will do the basic job required, keeping in mind what I have already mentioned about wire size and regulator positioning, so I'm not suggesting having to replace all these solar regulators, just be aware of what you really have, and may NOT have (MPPT etc). Also for quick and easy connect and disconnect of solar cable, I advise the use of Anderson plugs.
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