Ctek d250se charger help
Submitted: Wednesday, Sep 21, 2022 at 17:05
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Savannah480
I have fitted a cteck d250se charger to my camper trailer which has two 100ah agm batts in parallel (200ah), vehicle is a Toyota LC200 2011, so not a smart alternator.
With the vehicle running and supplying approx 13.7 v to the cteck, the amber “service battery” light cycles on and off (approx 7 secs on and 3 secs off) with resulting voltage and current fluctuating up and down.
As an experiment, I disconnected one batt at a time and the light was normal (constant) for both single batts.
It appears that it can’t handle two batts but can handle one. The literature says it is good for 40-300 ah.
There is no fault light showing.
Not sure whats going on, any suggestions please.
Reply By: Nomadic Navara - Wednesday, Sep 21, 2022 at 18:54
Wednesday, Sep 21, 2022 at 18:54
What size cable do you have between the tugs battery and the D250SE? If it is too small you will have problems.
AnswerID:
641696
Follow Up By: Keir & Marg - Wednesday, Sep 21, 2022 at 19:46
Wednesday, Sep 21, 2022 at 19:46
I suspect PeterD is on the right track(as usual). A little more information from you might help here. I'm also assuming the Ctek is (correctly) mounted in the camper. When you say the vehicle is supplying 13.7V to the Ctek, where is this measured? My suggestion is that you firstly measure the voltage at the vehicle battery with the engine running. Then, with one battery in the camper connected to the Ctek, measure the voltage at the INPUT to the Ctek. Lastly, connect both batteries to the Ctek and again measure the voltage at the input to the Ctek. If there is any difference in the voltage with these last two measurements, then there is clearly a voltage supply problem to the Ctek when it's drawing a high current (i.e charging two batteries). I would suggest you need at least 6mm2 cable for both the positive supply and earth return between the Ctek and the tug battery. In addition, this supply should not run through a 7-pin flat plug as the pins cannot handle the current. Either use 12-pin flat socket and plug (which have larger pins for high current devices) or separate 50A Anderson connectors.
Hope this helps, Keir
FollowupID:
921003
Reply By: Savannah480 - Wednesday, Sep 21, 2022 at 20:37
Wednesday, Sep 21, 2022 at 20:37
The wiring from the starter batt to the ctek is 10mm2 and through an Anderson plug and it is all mounted correctly. The 13.7 v was measured at the d250se alternator input terminal. When tested with a single batt it was 13.7v steady, but with both batts connected and the service light cycled on, the voltage dropped to about 12.7, then recovered back to 13.7 when it cycled off. It appears to be overloaded with both batts and cycles off, but is ok with one batt (either batt).
AnswerID:
641698
Follow Up By: bellony - Wednesday, Sep 21, 2022 at 22:52
Wednesday, Sep 21, 2022 at 22:52
Just a random thought but make sure the Air Con is turned off while taking voltage measurements. On our LC100 the voltage varies quite a lot when the air con cuts in as the idle speed increases and the Alt likes that.
FollowupID:
921005
Follow Up By: Gronk - Monday, Sep 26, 2022 at 22:24
Monday, Sep 26, 2022 at 22:24
10mm2 wire is a bit on the small size for charging 2 batteries.
16mm2 is the usual minimum size, but bigger the better.
FollowupID:
921041
Reply By: qldcamper - Thursday, Sep 22, 2022 at 04:28
Thursday, Sep 22, 2022 at 04:28
Have you measured the current flowing into each battery whilst it is charging?
If the batteries are in a low state of charge it may or may not be normal if the combined current is at or above the units max rating, read up on its over current protection.
Without reading the specs 12.7 should be more than enough to run the unit as over comming voltage drop is what they are designed to do. Eg, the redarc will operate down to 9ish volts until the supply batterys standing voltage gets down to a pre determined low voltage cut out.
Where did you buy the unit, if from a sparky ask them but if from a large retailer you will be lucky to find anyone with the knowlege to help you.
AnswerID:
641701
Reply By: Gbc.. - Thursday, Sep 22, 2022 at 05:30
Thursday, Sep 22, 2022 at 05:30
It isn’t a charger problem. You’ve proven that by isolating the batteries. They easily have the capacity to service those batteries. It may just be in desulphate cycle for a while or more likely your cable needs beefing up. 10mm is good for 10m electrically which is a 5m run so anything past your drawbar is stretching it. I’ve had cteks for 15 years and whenever there has been problems it was never the charger at fault even though that is the first place we look.
AnswerID:
641702
Reply By: Savannah480 - Thursday, Sep 22, 2022 at 08:55
Thursday, Sep 22, 2022 at 08:55
Hi everyone, thanks for you help. I found the problem. It was a loose negative connection at the shunt. Nut tightened and I have a nice steady service battery light.
Thanks again.
AnswerID:
641704
Follow Up By: Keir & Marg - Thursday, Sep 22, 2022 at 19:27
Thursday, Sep 22, 2022 at 19:27
Glad you found the fault. The CTek doesn't start charging until it's getting at least 13V, and shuts off if the voltage drops below this level as it thinks the engine in the tug has been turned off. So, with the loose connection at the shunt, the input voltage to the Ctek dropped below 13V and it shut off , then turned on again as the voltage rose, hence the cycling.
Keir
FollowupID:
921014
Reply By: Member - DOZER - Sunday, Oct 09, 2022 at 18:38
Sunday, Oct 09, 2022 at 18:38
I would recommend you look at a charge fuse diode, which will take the voltage up to 14.1, for the cost of the fuse/diode, it increases safety margin and allows faster charging of main batteries too.
Ive used one in my 2012 200 for some time now. The alt in these is not a smart alt but it is temperature compensating, meaning it backs off as motor heats up.
AnswerID:
641828
Follow Up By: Nomadic Navara - Tuesday, Oct 11, 2022 at 00:53
Tuesday, Oct 11, 2022 at 00:53
DOZER, what you are saying only applies if you are charging batteries directly from the alternator. The OP is using a DC-DC charger. He will not benefit from using your fiddle.
FollowupID:
921190