ctek d250s error

If it is charging the batteries fine off of the solar input why do you not take the lead off of the input from the vehicle and place that on the solar input and see what it does. The unit should run fine if all is correct as I run both my solar and input from my car into the solar input via a selector relay. It may be that the 5amp laptop supply to your solar input is dropping its voltage as soon as the system tries to place it under load as the batteries are so flat. Maybe bring the batteries up to full charge via 240 v charger/generator if available.

Tim,

Sounds like you have "cooked" the solar circuit on your D250S.
Separate the batteries and try the charging process on each one at a time, to identify if one battery is faulty.

Using a laptop power supply on the solar input port doesn't sound like a good idea to me. This circuit employs an MPPT solar controller and the "regulated" input the power supply is providing is different to that which an unregulated solar panel would be providing.

Does the charger work OK on the battery bank when operating from the Alternator input? i.e. are both batteries reaching full charge?
If so the solar charging capability has been compromised by use of the power supply on the solar port.

Well I charged the service battery on a 240v charger and then reconnected the service battery to the ctek and all seems fine again. The laptop power supply still connected - I think that's a red herring.

Hi Tim,

having watched the sequence of the lights, I'm pretty sure that's caused by the batteries over-loading the 19V supply through the ctek.
Computer power supplies momentarily switch off their output to protect themselves against too much current draw.
The ctek reacts to this by releasing its grip waiting for the voltage to recover, before opening the throttle again and the cycle repeats.

Of course when the batteries are reasonably charged, they gradually lose their appetite for charge and at some point the charging current will fall within the power supply's rating which then works smoothly.

There are other MPPT regulators such as the Victron MPPT75-15 which have an adjustment for max current. On these you'd, select a current which can be sustained by the power supply indefinitely for smooth and thorough charging - no more power supply hiccups when the SOC is low.

Regards, Peter
Battery Value Pty Ltd

Hi Tim,
unfortunately I know nothing about the ctek, but you're moving on thin ice when connecting a power supply to its input because it's not designed for this.
The fact that it now puts on this flicker show even with solar panels connected doesn't sound good at all.
If it keeps doing this with solar panels after double and triple checking all connections on the input and output side I'd get it checked out.
Also make sure the common negative connection for solar, battery, and input is in good nick.
What wattage are your panels?

The first thing you need to remember is that "Smart Charger" is a sales term ...... these electronically controlled chargers are far from smart and can be confused.

Lets start with the MPPT regulator ....... it is designed to load down the solar panel till it achives the maximum amount of power out of it at any given time ....... so it will load down the source ( should be a panel) till the just voltage drops and the current does not ... or something similar ....... so it's going to push your laptop power supply in to or to the verge of overload ......... how the laptop power supply will respond is anybodies guess ..... it may foldback current limit or or may shut down momentarily.

If it shuts down the MPPT reg will them slacken its grip on the PSUs throat and it will come back to life ...then the MPPT reg will strangle it again ...... this may be one explanation.

The other MPPT reg may not be big enough or it may not be as aggressive..... thus may run.

If you want a simulated solar panel you will need a regulated power supply and a series resistance to mimic the solar panel behaviour ....... one of the solar gurus may be able to tell you what this series resistance needs to be .... it could be quite high. ... and a resistor capable of copping the full output of the PSU

Pretty much all of these "smart chargers" can be confused when they are presented with something on their terminals that is outside what they are programed to deal with. ... they may do strange things or simply shut down.

well known issues are.

Strange and out of spec voltages or behaviors on their inputs
Batteries at very low or very high states of charge
Batteries that do not show a healthy charging behavior

so give it what it expects to see ...... it might run.

cheers

Just to close this off .... once I gave the ctek a break from the laptop power supply, and reconnected 'regular' solar panels it seems to be back functioning normally.

What stumped me was when I switched from the laptop supply to the solar it exhibited the same behaviour ... but I guess I didn't give it sufficient time to think/reset itself.

And heres a plug for battery value AGMs, I've got 2 (I think 95ah) AGMs wired in parallel in my camper box - they are now over 5 years old, and still holding 12.95V when fully charged. I'm sure there is nothing too defining in that claim, but I'm happy with the service I've had, and continue to enjoy from them.

Other than the self inflicted trouble reflected in this thread, I have to say I've also enjoyed the 'set and forget' arrangement with the ctek too.