Ctek 250S + aux. battery problem

[Lanners]

Did you measure your alternator voltage as well? This is important. As per Kalahari Safari's post quoting Ctek's reply, the CTEk will have switched off if the battery voltage did in fact draw the charging voltage below 13.1V. If it did do this, then their solution makes sense.

But I very much doubt that this is what happened. It is very unlikely that your alternator is too small, old or faulty. My original Defender 60A alternator voltage dropped to 12.9V when hot, and this would have dropped out the CTEK charging circuit. My replacement alternator sorted this. Your alternator should not drop below 13.5V if in good nick. This could also of course happen (volt drop) if your wiring from the primary battery to your CTEK is too thin.

Looking at your wiring, all looks fine at the CTEK chargers - I disagree with HobieDave - your smartpass has been connected correctly. You do not need to connect stuff to the bottom right terminal - you can run it straight off your battery. I would not mess with the wiring before determining your actual fault. I do however agree with him that it would be better for your second aux battery to be in close proximity of the first one. It simplifies and reduces your wiring, and removes the battery from the hot engine bay - batteries hate heat.

I read the CTEK manual again, and learnt something - in my vehicle I actually only need the Smartpass, not both units, as my alternator is a smart alternator, and I do not need the solar controller. Also, something I did not know is that the Smartpass keeps the cranking battery topped up if the aux batteries are charged. A very handy feature, explaining why my starting battery does not lose any charge even if standing for a few weeks.

But more importantly in your case, it states that "The D250SA optimises the charge voltage by increasing the charge voltage at temperatures below 25°C/77°F and reducing it at temperatures higher than 25°C/77°F. The functions is always active." Unfortunately it does not give more details. I assume that it gets this temperature from the temperature sensor, and not from a temperature sensor on it's circuit board.

This is not good news, IMO. I would rather sacrifice some battery life in return for charging up the batteries at a faster rate and knowing that they are fully charged. This also partially explains the problems that I had in the past.

The manual states the following about the temperature sensor in the Smartpass "SMARTPASS 120 protects the battery by switching off charging if the service battery temperature
rises too high". It would be nice if they gave more details.

What would I do in your case?
1. Check the cable feed to your CTEK, and check the input voltage to your CTEK on a hot day with discharged batteries.
2. Trace your temperature sensors. They exit the chargers at the arrows
Attachment 524941
3. Relocate them if necessary.
4. If you are in a jam, and the units shut down and don't charge, short out the 2 connectors between the units. This connects the aux batteries directly to the alternator/starter battery, and does not damage the chargers. I had a cole hersee relay connected across here which I could activate when necessary

Reading more about the temperature sensors, especially from the main charger, I think I would bypass it. I think some testing of the one on the Passthrough would be in order to see at what stage it switches the uit off

Thanks for this Mikemi - sorry I am rejoining the thread quite late this evening!
I did constantly check out my alternator meter during my trip and I never saw it drop below 13.5v so it seems that an underperforming alternator is unlikely to be the issue. My main/cranking battery was replaced a year ago and looks like it is in good shape.
I also had my auxiliary batteries tested and one replaced before my trip so the issue is unlikely to be defective aux batteries.
I think my non-standard setup does need a thorough recheck but I remain convinced that temperature is an issue with a Ctek in normal African summer conditions and your reference to the 25C threshold in the manual seems to confirm this.
Your suggestion about a Cole Hersee solenoid is interesting - will look into it!
Thanks for the clear reference to the temp sensors. I have found the wires coming from these points but I still have to trace where they go in a very congested area.
Thanks!

[Paul Dold]

In very hot ambient temperatures batteries don't seem to perform as well.

Ctek's - I had mine in 50C Kgalagadi temps two years ago and as far as I am aware it operated normally. It was only powering a single fridge off 220V and the alternator to lead crystal battery - no panels. We did not have hot beers!

[Die SwartKat]

Thanks for this Mikemi - sorry I am rejoining the thread quite late this evening!
I did constantly check out my alternator meter during my trip and I never saw it drop below 13.5v so it seems that an underperforming alternator is unlikely to be the issue. My main/cranking battery was replaced a year ago and looks like it is in good shape.
I also had my auxiliary batteries tested and one replaced before my trip so the issue is unlikely to be defective aux batteries.
I think my non-standard setup does need a thorough recheck but I remain convinced that temperature is an issue with a Ctek in normal African summer conditions and your reference to the 25C threshold in the manual seems to confirm this.
Your suggestion about a Cole Hersee solenoid is interesting - will look into it!
Thanks for the clear reference to the temp sensors. I have found the wires coming from these points but I still have to trace where they go in a very congested area.
Thanks!

We are dying to know this. Please revert once you've found where they are located.

[Kish2604]

My electronics knowledge is rather basic, but yes there are cables from the cranking/main battery to the Ctek unit at the back of the vehicle, from the Ctek unit to the adjacent aux battery and then also back to the additional aux battery in the engine bay. Not sure if this complex wiring system would contribute to charging problems? I am not sure what a temp sensor looks like - but have unsuccessfully searched for it.

I would think that your overly complex set up with cables running back and forth is partly where the problem lays, Voltage drop over the cables going back and forth and unknown diameter would also compound the problem. This is apart from the temp sensor location for the ctek probably hidden in a corner somewhere.

If i were in your shoes i would set up my system differently, The primary aux battery in the engine bay would run on a simple NL solenoid. The short cables between main and aux battery would lower the voltage loss. Power from this battery can be run to a distribution box at the rear for ancillary's like lights/small inverter etc.

The ctek and smart pass connect directly of the main battery via cable to its location in the rear and that will feed the secondary 105ah aux battery. Your pv panel can then be connected to the ctek to supplement the secondary battery as well when your standing in the sun. If the need exists you could add a second panel to your first one to give a bit of fat in your generation capacity.

NL spec sheets says "Average power draw of 2.5amps/12v is measured with a typical fridge-freezer temperature setting in an ambient temperature of 32 degrees at low-speed. Actual power consumptions may vary considerably with ambient temperature, thermostat settings and frequency of use. Power consumption will increase during periods of surplus available power (Turbo mode)"

Using this 2.5amps and adding another 80% extra draw due to climate takes you to a current draw of 4.5amps/hr so you should use approx 45amps for 10hours between usable PV sunlight. this should take your secondary aux battery to about a 55% soc before the panel starts working again. You will now have the other battery as spare capacity in the event of poor weather limiting generation during the day.

The other alternative is to put both batteries in the rear and run both in parallel of the ctek and simplify the wiring. Ultimately i think you should consider chatting to another installer.

[ekkekan]

Power from this battery can be run to a distribution box at the rear for ancillary's like lights/small inverter etc.

Would the long run to an inverter at the back not cause a high voltage drop ? Normally it is quite clear to keep the battery to inverter run below 1-1.5m. 12V amps is nearly 20 times the 220V amps.

[Kalahari Safari]

Correct, if the alternator voltage in fact drops below 12.8V, causing the CTEK to switch off. That is why I asked for the alternator voltage. I would be very surprised if this was the case.

If however it was the case, then it would be very easy to wake up the alternator by shorting the input and output terminals on the CTEK thereby connecting the aux battery directly to the alternator.

I wouldn't as the Ctek is supposed to boost the voltage to 14.1V and by shortening the terminals you would only achieve a partial charge of the Aux batteries. Apart from potentially destroying some internals on the Ctek.

[mikeml]

I wouldn't as the Ctek is supposed to boost the voltage to 14.1V and by shortening the terminals you would only achieve a partial charge of the Aux batteries. Apart from potentially destroying some internals on the Ctek.

In the above scenario would you rather choose no charge, or un-boosted alternator charge?

[Kish2604]

Would the long run to an inverter at the back not cause a high voltage drop ? Normally it is quite clear to keep the battery to inverter run below 1-1.5m. 12V amps is nearly 20 times the 220V amps.

Fair point taken!

[Lanners]

We are dying to know this. Please revert once you've found where they are located.

Found the temperature sensor - it was coiled up between my second aux battery and the metal body of the vehicle, which is in a closed off box next to the back drawer system. So it was not being subjected to engine bay heat issues but could easily have registered temperatures higher than 25C in a 36C ambient temperature environment.

[Hendrik du Toit]

Yes, your sensor placement wont protect the battery from boiling but still think the slow charging is mainly due to to the below:
1) ctek cutting down due to high outside temp
2) NL compressor running continuously due to high outside temp
3) Running two batt of one ctek eg if the ctek reduce charging amps down to eg 8A, fridge is taking 4.5A, you have 3.5A effective charging, which are split between two batteries.
Im going to see if i can do a few test this weekend to see whats the impact on the charging rate on the ctek if you play around with the sensor temp..

[Bloutrein]

I have a CTEK 250. I have 2 batteries in my bakkie of around 200Ah. They run two 40l Engel fridges. I have been on 5 trips over the last 4 years where temps have been in the higher than average range. Two of which had temp. over 40'c for a week on end. Everything worked fine to the degree you would expect.

Let's state the obvious first. Most of this has been mentioned already but bear with me:
When temp gets high fridges struggle. A far greater load is put on all energie sources. At 39'c fridges rarely shut off.
The most important thing is to try and stay ahead, beacause once you fall behind the only answer is 220V.
100w solar panel is about half the size you need. So start there.

The installation looks very complicated and a bit unpractical. As faultfinding seem to be very difficult.
As with alot of things, the simpler it is, the better it often is. Remember, the more connections and plugs
and extensions and routings through little holes you have, the more likely something is to corrode, get loose
or get damaged by all the vibrations on nice roads like that of the Kgalagadi. Even the smallest connection that
is not working properly could render a great setup useless.

With the CTEK as well as the smartpass installed, charging should be fast. Especially if the batteries are at a low state of charge, they wil accept
a lot more charge.

Put everything close to each other. Cuts down on voltage drop, amount of connections and possible damage in unreachable places. Check the sensor for any damage and put it on the battery. If the sensor is not faulty then everything should work according to the specs you have given. I think the fault is somewhere in the installation. Loose wire or connetion or something like that.

[Die SwartKat]

I have a CTEK 250. I have 2 batteries in my bakkie of around 200Ah. They run two 40l Engel fridges. I have been on 5 trips over the last 4 years where temps have been in the higher than average range. Two of which had temp. over 40'c for a week on end. Everything worked fine to the degree you would expect.

Let's state the obvious first. Most of this has been mentioned already but bear with me:
When temp gets high fridges struggle. A far greater load is put on all energie sources. At 39'c fridges rarely shut off.
The most important thing is to try and stay ahead, beacause once you fall behind the only answer is 220V.
100w solar panel is about half the size you need. So start there.

The installation looks very complicated and a bit unpractical. As faultfinding seem to be very difficult.
As with alot of things, the simpler it is, the better it often is. Remember, the more connections and plugs
and extensions and routings through little holes you have, the more likely something is to corrode, get loose
or get damaged by all the vibrations on nice roads like that of the Kgalagadi. Even the smallest connection that
is not working properly could render a great setup useless.

With the CTEK as well as the smartpass installed, charging should be fast. Especially if the batteries are at a low state of charge, they wil accept
a lot more charge.

Put everything close to each other. Cuts down on voltage drop, amount of connections and possible damage in unreachable places. Check the sensor for any damage and put it on the battery. If the sensor is not faulty then everything should work according to the specs you have given. I think the fault is somewhere in the installation. Loose wire or connetion or something like that.

This!!!