Schumacher ElectricSolar Battery Charger and Maintainer with Solar Charge Controller, SP-1500, Water Resistant, 15 Watts, 12 Volt, for Motorcycle, Power Sport, Car, Truck, and Marine Batteries

I bicycle to and from work most days, but must have access to a vehicle should I need to go meet with customers across town, or to avoid the road dangers on my route from inclement weather. Accordingly, I park my 2000 Odyssey at work. Unfortunately, the battery will slowly discharge if the car is not driven, and on several occasions, I have needed a jump start.I thought I was so smart when I bought a small, Shumacher solar panel to trickle charge my battery (via the 12V power outlet. However, I failed to do enough research. It turns out that at night, this particular solar panel would allow current from the battery to run in reverse, thereby draining the battery. Your voltage off the solar panel varies significantly, depending on the intensity of light to which it exposed. Apparently, the voltage from the solar panel can run from around 3V to around 19V or 21V. At the low end, you get reverse current through the solar panel if the car battery is charged reasonably well; at the high end, your voltatge across the battery is not all that healthy for recharging/trickle-charging the battery. (You want your charging source to be running at 13-14 Vdc.)Bottom line - if your solar panel does not have a voltage regulator/charge controller, you need one.The Schumacher SPC-7A provides that capability at a reasonable price. It will handle up to 7 amperes coming off a solar array, and it will give you an indication of whether you are generating a charge, and it will warn you if you have a low voltage (below 12 V) coming off the solar panel. It has standard, 12V line plugs to connect to the solar panel output, to connect to your charging line for a 12V battery (either battery clamps or a 12Vdc power plug). there is a third ouput cable for an alternate load device.I have found that the low voltage indicator (an LED) is useful for ensuring that the solar panel is positioned properly. I just orient the solar panel so that the low voltage light goes off, and then I know that I am getting a useful trickle charge.My fault for chosing a trickle charger without a charge controller. But this modestly priced device got me back on track.

I used it for several months and it worked well until it started overhearing. I'd give it 3 stars.

I have not used this very long, so may update my rating later. I wanted to post some information that may be helpful to others.Luckily when hooking this up I used my multimeter to verify everything first because it appears the connection to the battery is backwards from most other systems. I had bought a battery tender cable hoping to use that to connect to my battery, but the polarity was reversed. Trying to determine who was wrong I found this info on Wikipedia about the SAE 2 pin connector. The SAE website wanted me to pay for the specifications.Wikipedia: "This connector is typically used for applying a maintenance charge to a vehicle battery. The polarity of the connector, when installed in a vehicle and attached to a battery, is always such that no short circuit will occur if the exposed terminal were to touch the vehicle chassis. In most vehicles, this means that the exposed terminal connects to the negative terminal of the battery. Conversely, the positive terminal on a battery charger is exposed, to mate with the concealed one on the vehicle side.Although there is a risk of short-circuiting a battery charger, the risk is minimal and often mitigated by the circuitry of the battery charger itself. On the other hand, the short circuit current of the lead-acid batteries installed in vehicles is sufficiently great, that a short circuit could result in a fire or explosion. The priority is therefore given to avoiding short circuits of the vehicle battery, rather than of the charger."So it appears that it is Schumacher who is wrong. The exposed metal pin coming from their charger should be positive, but you can see, even in the pictures here, that it is negative. This just goes to show that you should always double check everything before hooking it up.This is easily remedied by cutting an extension cable in half and splicing it back together backwards, but that kind of defeats the whole reason some people bought this in the first place, so they wouldn't have to do any wiring.

Many people complaint reverse polarity of the cables on the charge regulator but in fact it does NOT matter. The real culprit is the cable polarity of the solar panel. Cable is the combination of several wires. To explain, first we need to clarify: red wire does not mean that it must be positive, rather if it connects negative on the circuit it can be negative. On my unit all red wires connect to + on the charge regulator. Second same idea applies to the SAE connector, I call them black (black plastic) and silver (silver metal, the naked end) -- either one can be positive or negative depending on where it connects.That said, since the solar panel is energy giving, its cable polarity will determine the polarity of all the cables downstream. As many of us buying third party solar panels, we need to first use a multi meter to determine the cable polarity of the panel. Picture 1 shows positive voltage and picture 2 indicates negative voltage (minus sign under DC) when I reverse the leads. Picture 3 shows wires are properly labeled as positive vs negative. Second be sure when solar panel's SAE connects to the SAE of the charge regular, positive wire must attach to the positive in the regulator circuit. The SAE on my panel needs to flipflop so picture 3 also shows the new connections with blue wire connectors.To confirm if there is current going from the panel thru the regulator to the battery, a positive voltage should show on the multi meter when its leads are attached to "battery" SAE on the regulator. In this way the 12V battery will be properly charged.

Muy bueno

Ok I'm not sure I'm going to write this properly cause I'm not to knowledgeable in solar anything. All l know without this part there is no control on the fluctuating temperature. Yes it works in the shade but the temperature is no where near stable without this piece. YOU NEED THIS FOR SOLAR BATTERY CHARGER!!!!!!

V.R. , pour charger la batterie.

Parfait

I purchased this solar charger controller for a compatible product from the same company. It worked for 2 months then failed to operate and caused my car battery to totally discharge at the time in the middle of WINTER leaving me without a vehicle for a period. I subsequently returned the product to Amazon for a replacement which came in a few weeks. This time the controller did not appear to work properly and demonstrated similar characteristics i.e., the LEDs did not light and there was no current being provided to my car battery although the solar panel emitted over 15v when not connected and almost 13v when connected. No voltage was measured at the battery connections and when connected to the battery, no increase in the battery voltage observed after a significant amount of time. I was warned by other purchasers and I did't heed the warnings. Due to personal health issues and the Covid situation I failed to do anything about this until I could check it out agin in warmer Spring weather. Now Amazon will not allow me to return it for a GOOD replacement after sending me a defective item! My fault for not dealing with it at the time but extenuation circumstances.