D250s Dual Appropriate For T6 Bluemotion?

[rtg1200]

Hello all, trying to do research across the forum into whether I can use a CTEK D250S Dual with my 18 plate bluemotion panel van to charge my non factory fitted leisure battery. Sifted thru just about every page of every thread on here but getting a little lost in what I should and should not be doing.

Is it true I can connect the D250S straight to the alternator or can i use a wire that is possibly under the double passenger seat?

If so do i connect it to the solar panel input on the charger or the alternator side?

Do i need to be using a relay so that the charger doesnt take power from the starter battery? Im not using a solar panel, just want the van to charge the leisure battery when the van is running.

if i can use this charger do i need to be earthing to the van or leisure battery? I came across a CTEK diagram that showed the charger earth needs to be to the van body and the battery. but dont want to be getting it wrong

Ideally would like to use the CTEK D250S as i got it off a friend to see if i can make use of it, but if i need to buy something more appropriate so be it.

any help very much appreciated thanks a lot

 

[Martin Gibson]

Not sure about the Ctek or not but i was advised by @travelvolts to use an Ablemail dc-dc charger. Not too expensive,really small,easy to fit and fits the bill perfectly,hope this helps

 

[Deaky]

CTEK will do exactly what you want. You connect it directly to the starter battery, not the alternator. You may have a suitable wire under the seat, you’d have to test it. The CTEK needs a 20a supply and mist be appropriately fused. The solar panel connector to the CTEK. CTEK has a maximum solar input of 23v. Make sure your panels open circuit voltage is no higher than this or you’ll fry the CTEK. The negative connection can be straight to the battery or the van body. It doesn’t matter. You’ll also need a feed from an ignition live in the fuse box to tell the CTEK when the engine is running, you won’t find this under the seat.

 

[travelvolts]

You say 250S? If this is correct this an old model and is NOT suitable for your van. You will need either a 250SA or 250SE, or of course any of the other great DC-DC chargers currently available. Have a look here for more info https://www.travelvolts.net/shop

 

[mmi]

The charging regime of D250S is described on page 12 of the manual ---> http://www.motorcaravanning.co.uk/pdf/CTEK_D250S_Dual_SmartPass Manual.pdf
which reveals that charging starts when voltage reaches 13.1 Volts (and stops at 12.8 Volts at the input). However, there is no feed (or even need) for ignition live as the above mentioned voltage levels prevent starter battery discharge when engine is not running.

Using this default setup the wiring would be as simple as it can get. As mentioned chances are that under the seat might be even a suitable wire. Then just connection (+fuse) to leisure battery and negative connection to the leisure battery or the van body.

Pluses

• Simple wiring
• No extra load when cranking the engine
• Charging starter battery with external charger charges also leisure battery

Minus

• Sometimes delayed start of charging as input (alternator) voltage has to get up to 13.1 Volts before D250S charging kicks in. However, usually this is less than a minute from starting the engine.

Actually my own setup is essentially the above - though in place of D250S I have a CTEK Smartpass alone which actually has the same charge on/charge off properties. Out of curiosity I have been keeping eye on the behaviour of T6 charging regime vs. batteries state of charges to see if there is any room for improvement by adding/replacing by a DC-DC charger.

-----
Interestingly "down under" they are taking advantage of D250S Dual's MPPT charger (which is fed from solar input). The wiring scheme suggests that the MPPT path can use "any" input voltage to create 14.4 Volts at the output (=DC-DC charger, voltage booster...). So then a cut-off relay is definitely needed to prevent discharging starter battery (into leisure battery) when engine is not running.
---> Bainbridge Technologies

If you consider this one I have a few measurements in my mind to support/exclude my assumptions... if you have a multimeter... and interest...

 

[travelvolts]

No, the 250S is not suitable for intelligent alternator application unless you use the solar input. In this case if you also want to fit a solar panel you must fit an external relay controlled by the ignition to select input.

 

[rtg1200]

No, the 250S is not suitable for intelligent alternator application unless you use the solar input. In this case if you also want to fit a solar panel you must fit an external relay controlled by the ignition to select input.

Thanks for the replies everyone. @travelvolts to clarify can I use the d250s powered from starter battery/cable under the seat to the solar input or do you mean I can use solar input with an actual panel and should not be connecting it to the vans battery at all?

It's correct that I have a d250s and not a d250sa or SE here thanks

Edit, not using a solar panel purely want to charge from the van while driving

 

[rtg1200]

The charging regime of D250S is described on page 12 of the manual ---> http://www.motorcaravanning.co.uk/pdf/CTEK_D250S_Dual_SmartPass Manual.pdf
which reveals that charging starts when voltage reaches 13.1 Volts (and stops at 12.8 Volts at the input). However, there is no feed (or even need) for ignition live as the above mentioned voltage levels prevent starter battery discharge when engine is not running.

Using this default setup the wiring would be as simple as it can get. As mentioned chances are that under the seat might be even a suitable wire. Then just connection (+fuse) to leisure battery and negative connection to the leisure battery or the van body.

Pluses

• Simple wiring
• No extra load when cranking the engine
• Charging starter battery with external charger charges also leisure battery

Minus

• Sometimes delayed start of charging as input (alternator) voltage has to get up to 13.1 Volts before D250S charging kicks in. However, usually this is less than a minute from starting the engine.

Actually my own setup is essentially the above - though in place of D250S I have a CTEK Smartpass alone which actually has the same charge on/charge off properties. Out of curiosity I have been keeping eye on the behaviour of T6 charging regime vs. batteries state of charges to see if there is any room for improvement by adding/replacing by a DC-DC charger.

-----
Interestingly "down under" they are taking advantage of D250S Dual's MPPT charger (which is fed from solar input). The wiring scheme suggests that the MPPT path can use "any" input voltage to create 14.4 Volts at the output (=DC-DC charger, voltage booster...). So then a cut-off relay is definitely needed to prevent discharging starter battery (into leisure battery) when engine is not running.
---> Bainbridge Technologies

If you consider this one I have a few measurements in my mind to support/exclude my assumptions... if you have a multimeter... and interest...

Thanks for the info, so you're saying if I connect the d250s to the starter battery/under seat cable I need a relay to stop the charger taking power to charge the leisure battery when the van isn't running? So the charger won't know when the volts go down enough to recognise the van has stopped? Not 100% sure on where the relay goes or how it works is it in place of a fuse on a fuse box?

 

[mmi]

Thanks for the info, so you're saying if I connect the d250s to the starter battery/under seat cable I need a relay to stop the charger taking power to charge the leisure battery when the van isn't running? So the charger won't know when the volts go down enough to recognise the van has stopped? Not 100% sure on where the relay goes or how it works is it in place of a fuse on a fuse box?

Actually two different possibities.

(1) To run D250S as originally intended by CTEK (though not perfected for so called smart alternators). No relays – just fused connection into under seat cable. I would say worth to give a try and see if that works also for you. If not then a D250SA/SE would be just a drop-in replacement (+wiring for the ignition feed).

This setup definitely won’t drain your starter battery. Only drawback might be the delayed start of leisure battery charging (due to so called smart alternator scheme) – although I have kept eye on that two years but not seen that happening when running van “stand-alone”. However, if you would have a solar panel or some other external power source that would confuse this setup somewhat. Of course there is a possibility that T6 charging setup is different for Nordic countries (as mine is) and that would obviously flush out the suitability for your purpose.
​

(2) Or a bit more complicated - as described in https://www.baintech.com.au/can-i-use-a-ctek-d250s-dual-in-a-vehicle-with-a-smart-alternator . Here you definitely need a relay to prevent starter battery discharge when engine is not running. Otherwise the connections are the same.

​

The difference between these two is that as (1) is ultimately controlled by van's smart charging scheme the charge state of leisure battery might be slightly less than in setup (2) or using proposed modern DC-DC-chargers. But if it's noticeable or measureable is not that obvious as charging acceptance efficiency significantly drops when battery state of charge gets above 80-85% - in plain words - to top up a lead-acid battery above that quite a few extra hours of driving are needed.

 

[Pauly]

Option 1 just doesn’t charge the leisure battery, if the vehicle battery is charged then as soon as the alternator drops the voltage down (a few minutes of driving) the CTEK will shutdown and stop charging

 

[rtg1200]

Option 1 just doesn’t charge the leisure battery, if the vehicle battery is charged then as soon as the alternator drops the voltage down (a few minutes of driving) the CTEK will shutdown and stop charging

Could that not be worked around by using the solar plug in side of the d250s charger, so that the charger takes power from regen braking and whatever power isn't going into the starter battery?or am I reading that totally wrong?

 

[Pauly]

Yes you can but would need a relay to shut the supply off when engine isn’t running or it will continue to charge until batteries are equalised or engine batt is flat

 

[rtg1200]

Yes you can but would need a relay to shut the supply off when engine isn’t running or it will continue to charge until batteries are equalised or engine batt is flat

So the charger can't work out when the engine is running thru what power is being put to it? Does a relay do automatically what a switch would do manually?

Sorry for the daft questions just trying to get it straight in my head

 

[Pauly]

As its the older S model the alternator input is not designed for the fluctuating voltage a smart alternator puts out and will cut out the charge when the output voltage of the alternator drops (as per my comment above)

If you are using the solar input to deal with this fluctuating voltage then the unit will not care if the engine is running or not (as it thinks it is being fed by a solar panel) and will harvest energy from the engine battery at all times 24/7 hence the need for a relay to cut the power supply when the engine is not running

The newer ctek units (D250 SA or SE) have been modified to work with modern smart alternators and the units have an extra input for an ignition live so it knows when the engine is running and acts accordingly

 

[t0mb0]

It might be slightly erratic starting as it will have to wait for a sufficiently long high voltage to get started, but I assume that once it gets going the current draw should keep the alternator high (maybe until the battery charge gets high and the current drops)? If this is the case, given you've already got it, I'd just stick it in and see how you go - stick a plug in voltmeter to check it's keeping the alternator on. If it's really not working well enough, you can get something else and stick that in.

 

[rtg1200]

understood thanks for the help gents very much appreciated, ill do some homework on the relay and give it a try

 

[travelvolts]

The official line from Ctek for this model was to connect to the solar input using an ignition controlled relay. Connecting to the alternator input will not work. I am wondering how you have come by this unit as they haven't been produced for around two years now?

 

[oldiebut goodie]

Ideally would like to use the CTEK D250S as i got it off a friend to see if i can make use of it, but if i need to buy something more appropriate so be it.

any help very much appreciated thanks a lot

 

[rtg1200]

correct come from a friend he thought it may be useful. do you sell the relay i need to make it work @travelvolts?

 

[travelvolts]

You can use any 5 pin change over relay, readily available from places like Halfords. Or, I could supply you with a complete wiring kit with the relay included.