CTEK D250SA dual smart battery to battery and solar 12v charger

This is indeed a fine piece of equipment and if you need it it justifies the price. In any case I know of no other piece of kit with these capabilities. If you don't need all of these features you could save money buying a dedicated solar panel charger and/or more solar panels.As described it is best thought of as a device for optimally charging a 12V battery with currents up to 20A from a separate 12V source. The "dual" refers to two input sources, one of which is meant for a generator/alternator and the second from anything else. The first input will not take power from a 12V battery connected to it, but will only take power when the alternator connected with it is generating enough volts to charge (i.e. both the battery you bought the 250S dual to charge --can be called a service battery-- and the battery connected directly through the alternator, not through the 250S dual --usually a starter motor battery to start the engine for the alternator). This ensures that the "starter" battery (if you have it wired up like that) is not drained and will be able to start the engine. An additional nice point is that if the "service" battery is fully charged and there is power from solar panels (see below) the "starter" battery is kept topped up as well as the "service" batteryThe second source can be used for solar panels and the efficiency when the sun is shining is impressive, but my panel was under-powered to make it work well in cloudy conditions. Or you can connect another 12V source and it will take power form this even at voltages slightly under 12V (so you can use a 12V battery on this input if you don't mind it being discharged. This is why I now need this kit). Note that the negative connection is common to the two inputs and the connection to the battery to be charged (usually "service" battery). The positives from the two sources and to the "service" battery make up a total of four and while they are clearly labelled as in the review above, read on for my sad story.WARNING. The instruction leaflet does state that you must not connect 12V in reverse polarity, but this is not given prominence. One night I though I would use the easily connected thumb screw terminals to connect my "service" battery to a light. As nothing else was connected I did not expect current to pass through the 250S dual. Unfortunately in the dark I connected it the wrong way around and it died. I emailed Ctek to say I thought they should make this more obvious but never heard from them so for some years have been using a cheaper lower powered solar panel regulator to keep my battery trickle-charged.Now that I need faster charging I have bought a new one. The instruction leaflet does not make this warnaing prominent.

I bought this to keep a leisure battery charged while on a two week camping trip. It was easy to install once I'd routed some 27A cable to the rear of the truck where the battery lives.My fridge was running continuously, lighting in the evening and chargers during the night. The C-Tek performed faultlessly and I never once needed to worry about draining either my starter or leisure battery. Yes it's more expensive than other options, but you get what you pay for.

An excellent piece of equipment. Provides optimal charging and maintenance of your camper battery from both solar and alternator using a Max Power Point Tracker algorithm - much more efficient than a cheapo Pulse Width Modulated charge controller. Plus providing you don't have (or have removed) the split charge relay in your vehicle this will charge the vehicle starting battery from the solar panels once the camper battery is full. If you need to handle higher charging amperage from the vehicle alternator you can add a "Smart Pass" unit to this too. I run this in parallel with a 10 amp CTEK AC to DC charger and they seem to play nicely together (a previous Ring intelligent charger got confused and would think the battery was faulty)

Excellent charger. Simple installation and seems to work really well. Smart charges my 2x 100AH leisure batteries on my campervan as I'm driving and will allow me to hook up solar panels when I don't have a hook up. Did a lot of research and there really isn't much out there which does this job and has sufficient charging current to fast charge larger batteries. You get what you pay for I guess.

Used in my horsebox to keep leisure battery and starter battery charged via solar and alternator. Easy to install and so far has been working great for the past 2months. Prior to using the CTEK the starter battery would drain over a period of 10days....this kit has put an end to that.

Been in charging circuit for 18 months now. Works perfectly in B2B charging system with 2 x 100w solar panels into Varta 230 Ahr battery in our motorhome. Used year round with occasional lay ups of 4-6 weeks & no probs so far.

I had two of the Ring DC30 chargers which didn't work so I thought I would try this charger instead and very pleased that i did as it is a far better charger and was about the same price. Just wish i had gone with this one in the first place.

Excellent piece of kit. Purchased as a quicker means of charging my leisure battery whilst driving but I have also noted that it works much better as a regulator for my solar panel than the regulator that was fitted on installation. So - highly recommended.

Set this up in my off grid overland pickup. It charges two 6 volt (linked for 12 volt) batteries and maintains the system well. In the middle of winter here so waiting to see how well the solar input works but from all the readings on use by other overlander's I think this is a good buy.

Gesucht war ein Ladegerät, dass meine Blei-Säure-Starterbatterie und meine AGM-Versorgerbatterie in meinem Campingbus über Lichtmaschine läd inklusive Trennrelais für den Stand plus zusätzlicher Speisung über ein 100 Watt-Solarmodul auf dem Dach, möglichst in einem Gerät.Das Ctek D250S Dual kann's und legt zu meiner Überraschung noch einen drauf: Im Handbuch steht, dass die maximale Ladespannung 14,4 Volt ist. Das wäre zwar etwas zu wenig für meine Optima Blue Top AGM, die optimalerweise 14,8 Volt Ladespannung braucht. Hätte ich wegen der vielen anderen Vorteile in Kauf genommen. Aaaaber: Das Ctek läd die AGM mit optimalen 14,7 Volt und die Starterbatterie mit vorgesehenen 14,4 Volt! Entweder habe ich eine neuere Version oder das Gerät ist intelligenter als die Handbuchverfasser. Somit fällt ein Ladebooster für AGM-Batterien auch noch weg, ein extra-Trennrelais gleich mit.Solarpanel noch angeklemmt, fertig.Ist die Versorgerbatterie voll, wird bei längerem Stand über Solar die Starterbatterie mit Erhaltungsspannung mitversorgt.Einziger Wermutstropfen: Es fehlt das Solar-Kino. :-)"Jaaaa, ich hab wieder 0,00034 Volt mehr. Der Zeiger bewegt sich... Wow!"Dafür gibt's hier aber Volt/Amperemeter für 16€, in 20 Minuten eingebautund für den Ctek fünf Sterne und klare Kaufempfehlungfür diese Versorgungssituation (Campingbus – 2 Batterien – optional Solarpanel)(Im Bild zu sehen ist der testweise provisorische Aufbau ohne Solarpanel. Das Trennrelais ist nicht mehr nötig)

Straightforward works well use it with a 120 watt solar panels on yakima roof rack just wish it were a hybrid model capable of wind turbine too, updated 9/27/2105, charger is working great after I resolved a problem, that is proper grounding, battery neg to neg on charger, and also from charger to chassis, prior to that the circuit did not complete properly and I thought the charger was defective. It's working like a champ, that is a Wynter 45 fridge/freeze mounted in the rear of an Xterra, I leave on 31 degrees all the time, always have cold drinks, able to buy that great deal where it needs to be cold; until I get home, leftovers after a bbq, you get the idea. Using with an Optimata Yellow Top.

Previously I used a solenoid to separate the starting and deep cycle battery but could never get it to charge correctly, even after a full day of driving. This product simply fixes it. For further details on the topic do a search on youtube for "4xoverland deep cycle charging". Very satisfied with this product.

Ordered 2 of these, installing flexible solar panels on top of a 2004 TRD Tacoma and a 2007 Tundra, with aux batteries. This all in one box is the ticket. Was able to screw it into the side of the truck bed with sheet metal screws. I did not get the smart pass, since I only have one 108aH battery for 200w of solar panels for each truck. It will be powering a fridge and occasionally a laptop and charging phones etc. I can read the incoming voltage with my voltmeter and it regulates the incoming solar voltage, and outputs a charging voltage to the battery, and isolates the starter battery from the system when alternator not running. A nice, magic, all in one box. Read the manual so you know that it is not reverse charge protected!