Ctek 250sDual Power Light not steady

Just rang the people I bought my Ctek from, the reason the light blinks is that the voltage has to be over a certain level. Once I started the car the voltage level increased and everything worked beautifully.

I had a similar problem, but the CTEK power light was fickering rapidly, rather than blinking and the charger was not charging. Temperatures were up to 42c, so I though it may have been just a bit hot, but checks on subsequent trips where the outside temperature was as low as 17c showed the same result. I redid all connections and cleaned up all terminals, and it has been OK since, through about a dozen check points. So in my case, it looks suspiciously like it may have been a crook joint. I still check it on each stop though...

Cheers
Greg

I don't think the unit and battery have to be wired to the chassis. The important thing is there must be a good ground connection between the negative terminals of both batteries and the D250S negative. A good connection can be either via the chassis or a heavy cable of at least the size of the positive one.

The power light indicates enough voltage to power the charging. Possibly what was happening was there was sufficient surface charge on the starting battery to initiate charging. When the float charge reduced to the level the charger ceased working the power light went out. With the load removed from the starting battery the float voltage would recover somewhat and the cycle then recommenced ad infinitum until you disconnected the unit.

As per the reply from PeterD, whenever I stop the engine the Ctek continues to charge the second battery until at some point the voltage of the starter battery drops low enough for it to cut out, but I have also seen it flickering rapidly at times when it is at that "in between" state of charge and have never worried about it - accepted it as "normal".

However if you are not getting a good solid power light and the second battery charging when the engine is running I would suggest (in a similar light to PeterD) that you may not have good enough connections either on the Earth or 12V supply to the Ctek from the starter battery, or maybe not heavy enough cable to prevent too much voltage loss by the time it reached the Ctek - the Ctek can drag up to 20Amp on initial charge of the second battery so if your cable or connections are not good enough you may be losing too much voltage at the Ctek itself.

Heavy cable (at least 6 or 8 B&S depending on distances involved) and good solid terminations are essential for both source to Ctek, and Ctek to second battery - whether you use the chassis earth or not will not matter as long as those connections are good and clean as well.