CTEK D250SE - why do I need one?

[Trialmaster]

There is a tremendous amount of information posted by some very knowledgeable people on here. I have a Trialmaster, which as we know is fitted with a CTEK SMARTPASS 120S.

There are threads discussing the fitment of a D250SE, with detailed explanations on how to fit it.

My question is why would I need a D250SE if I am not going to add a solar panel? My expectation is that the Smartness is designed to manage both batteries. Therefore, in my circumstance why spend £300 on fitting one, unless it is to prevent the Starter battery draining unnecessarily? Hopefully, someone can help me out here.

 

[Kruegerruda]

If I have understood the posts correctly: The 250 SE charges the secondary battery optimally and keeps it in the best condition. Interesting for people with cool box or other consumers. And of course for the solar panel option.

 

[AnD3rew]

If you aren’t looking for solar input capacity and not looking for future lithium potential then you probably don’t need one. In theory it should improve the way it charges the second battery. I don’t know if this has been definitively proven for the Grenadier yet. INEOS appears to he claiming (indirectly and confusingly) that they have it all covered in their software, but that is also yet to be definitevely proven in real life and so far trust in their software has taken some blows. If you don’t think you need it at the moment then hold off and let the community build the experience. You can add anytime

 

[MarkH]

The Smartpass is not a smart charger and relies solely on what voltage the alternator is outputting. Typically it won’t charge the service battery to 100%. This is not optimal if running a fridge as you want to get back to 100% asap while on the move so it's ready for the next night's (or two) usage, e.g. you might only drive for 1 hour to the next camp. The EFB 105Ah service battery is not large in terms of running a fridge so the more you fall behind the harder it is to recover to 100%, and the more chance you have of the fridge cutting out while camped.

The 250SE 20A is a smart charger so will get the service battery back to 100%, and quicker. It does this by creating a load on the starter battery which signals the alternator to continue outputting at a higher rate, this in turn helps the Smartpass to stay in the game so you then get the two charging sources combined. The Smartpass can also create a load but only when the service battery is low as there's little internal resistance, but once this rises the Smartpass cannot boost the charge like the 250SE can to overcome the resistance, so the alternator can reduce its output.

Bottom line is, with the 250SE you are using a smart charger with the correct bulk, absorption & float stages to recharge the service battery, as you should do with any lead acid battery. The Smartpass is just a 'dumb' bulk charger. Any decent 4wd setup running a fridge usually incorporates a DC2DC smart charger like the 250SE or the Redarc and Everdrive DC chargers etc.

Ctek themselves will tell you to add a 250SE if running consumables and that the Smartpass is more suited to a larger battery bank or a lithium battery - it can output up to 120A when needed. In the Grenadier the Smartpass is overkill for such a small service battery and you could easily get away with just using the 250SE, or a Redarc, Enerdrive etc. But Ineos have used it because it's a convenient solution for a dual battery setup in this scenario. It parallels the two batteries for charging and allows integration with a smart DC charger. It can also trigger the service battery to maintain the starter after engine stop and provides a Start Assist function which links the two batteries if the starter has run too low for engine start. This can happen when running devices off the 12V outlet in the boot or other outlets such as the USB sockets or roof outlets. The Smartpass also features a protected load terminal for consumers (e.g. fridge).

Ineos would see no requirement to include a smart DC charger like the 250SE as they expect each user might have different requirements, e.g. some may have large fridges and other consumers so prefer to run 40A or 50A DC chargers. The Smartpass will pair with any brand of DC charger.

 

[Trialmaster]

Thank you all, especially @MarkH your explanation is very clear and concise. MY conclusion, is I don't need one this very minute, but should add one in the near future.

 

[Logsplitter]

Thank you all, especially @MarkH your explanation is very clear and concise. MY conclusion, is I don't need one this very minute, but should add one in the near future.

I’ll be testing my vehicle out for six months before I commit to changing anything. I’ll be running a fridge attaching 2x 100w solar panels with inbuilt mppt controllers when parked up and using a Victron smart charger when at campsite’s with mains power. That should be a good test of how the Grenadier dual battery system with SMARTPASS 120s work. I’ll keep you all informed as of mid September

 

[Trialmaster]

I’ll be testing my vehicle out for six months before I commit to changing anything. I’ll be running a fridge attaching 2x 100w solar panels with inbuilt mppt controllers when parked up and using a Victron smart charger when at campsite’s with mains power. That should be a good test of how the Grenadier dual battery system with SMARTPASS 120s work. I’ll keep you all informed as of mid September

I am sure we will all be looking forward to your overlanding updates and whether we need a D250SE.

In the meantime I have asked a friend who has a laser cutter to make the plate with the diagrams provided by BAS.

 

[Logsplitter]

I am sure we will all be looking forward to your overlanding updates and whether we need a D250SE.

In the meantime I have asked a friend who has a laser cutter to make the plate with the diagrams provided by BAS.

I’m awaiting reports from others regarding the D250SE. If it is of benefit I will get one and fit. I’ll make my own plate up

 

[Trialmaster]

I see they are around £260 from Amazon.