CTEK Dual Battery Setup

[coulter6]

CTEK D250S dual charger & dual battery install.

I really like the CTEK D250S DUAL charger and the way it will charge your service battery and maintain the starting battery. The stock alternator is not set up to charge a deep cycle battery. You'll get some charging, but eventually the deep cycle will not be able to maintain a charge. They must be maintained by an external charger of some type. CTEK propaganda: “The D250S DUAL charger obtains its energy from DC sources such as alternators, solar panels or wind power and optimises this power to meet the charging requirements of different battery banks. The D250S DUAL automatically selects the best connected DC energy source (of 2) for the purpose and switches between these energy sources to achieve high efficiency multi-stage charging. “

I run a Norcold MRFT40 fridge and needed a way to keep the battery charged when on the road. Decided on the CTEK D250S DUAL charger that uses the truck’s alternator and external solar. I ran a dedicated 8ga wire to the back of the truck and put in a 12v plug. Put in a dual battery system. Finally, I bought the Renogy 100W solar suit case from the group buy.

Here’s the detail:

I have a 2015 so I had to deal with the smog pump. I bought a relocation kit from [MENTION=96749]enginerd4ni[/MENTION] here on the site. This is a substantial bracket! Thanks enginerd4ni for the chance to install it.

Installed:

Bud Built Dual Battery Tray installed:

Battery installed.

I ran an ARB wiring kit (8ga wire) from the second battery to the driver rear. Removing the kick plates weren't to bad, although I did buy a simple panel removal tool kit to make it easier.
Working the wire though:

I didn't get a pic of the center kick panel between the driver front door and rear door, but you'll need to removal the seat belt bolt to get the panel off. Not a big deal.

The forward kick plate; you can see the bolt to the right of the wires that secures the panel.

Where the wire goes through the rubber grommet from the engine side. I put wire loom on each side of the firewall. At first I was going to run a single 8ga wire (shown here) and ground the plugs to the frame at the end, but decided to use the ARB dual wire kit to have a ground directly to the battery.

I used a Blue Sea fuse box to complete the run. You can see the dual ARB 8ga wires here.

Wire through the engine compartment. I ran out of black loom and had to use blue. Brightens up the compartment don't you think.

 

[coulter6]

The CTEK D250s has one weakness: it’s rated to only 50°C and IP65. I didn't feel comfortable mounting it inside the engine bay but it needed it to be close to the batteries for shorter wire runs. Using enginerd4ni methodology, I put it in front of the radiator but behind the grille. Seems to work great so far and gets cool air. Since I have an 85 Amp deep cycle battery, I felt I didn’t need the additional of the CTEK SmartPass for extra charging power. I did leave room on my bracket for one if I ever needed to add one.

Rough cut of the bracket.

CTEK D250S in position.

Wiring it up.

Got the Renogy 100W solar suitcase with controller. I got it with the controller in case I wanted to charge a battery without using the CTEK. I modified the Renogy wiring so I could by-pass the intragal controller to use the CTEK.

I got 2 25ft AWG 10 Double Layer MC4 PV Solar Cable Extension from Amazon, cut them in half and made an extension cord.
https://www.amazon.com/gp/product/B00Q2OFG2A/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

Put a Mar-Lan trolling motor connector in the grill to connect the panels to the CTEK. Also from Amazon.
https://www.amazon.com/gp/product/B00434SEKC/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1

It works.

 

[Swarty]

Nice work!

The CTEK D250s has one weakness: it’s rated to only 50°C and IP65. I didn't feel comfortable mounting it inside the engine bay but it needed it to be close to the batteries for shorter wire runs. Using enginerd4ni methodology, I put it in front of the radiator but behind the grille. Seems to work great so far and gets cool air. Since I have an 85 Amp deep cycle battery, I felt I didn’t need the additional of the CTEK SmartPass for extra charging power. I did leave room on my bracket for one if I ever needed to add one.

That's a clean build.
Newb question:
Won't it get hotter near the radiator when you aren't moving? Why not inside the fenders near the air intake?

 

[coulter6]

That's a clean build.
Newb question:
Won't it get hotter near the radiator when you aren't moving? Why not inside the fenders near the air intake?

When I was planning the project, I placed wireless thermometers in the engine compartment in various locations to measure the heat build up. The location I chose was the coolest area by far - even when parked. I guess inside the fenders would be a good place. I like my location because it's easy to get to and close the the batteries. CTEK requires cables to both the starter battery and the service battery. This shortened the cable runs.

 

[Swarty]

Good to know!

When I was planning the project, I placed wireless thermometers in the engine compartment in various locations to measure the heat build up. The location I chose was the coolest area by far - even when parked. I guess inside the fenders would be a good place. I like my location because it's easy to get to and close the the batteries. CTEK requires cables to both the starter battery and the service battery. This shortened the cable runs.

Nice job measuring it's always a crap shoot on what areas get hot under the hood.

 

[DannyLlama]

Thanks for the write up! Updated it in the Dual battery thread.
Where do you plan to mount the solar panels? Anywhere on the roof rack?

Please report back after some months of usage, especially regarding the heat.

The other concern I would have is in a head in collision, might pose a safety concern?

 

[coulter6]

Thanks for the write up! Updated it in the Dual battery thread.
Where do you plan to mount the solar panels? Anywhere on the roof rack?

Please report back after some months of usage, especially regarding the heat.

The other concern I would have is in a head in collision, might pose a safety concern?

I use an AirTop RTT, so there's no room to permanently mount a solar panel. I got the Renogy portable suit case 100W panel. Carry it the cargo area and deploy it when I get to camp. Here's the setup before the install, but you get the idea.

Head on collision is a concern but with 2 batteries & wiring up front, anything could happen.

I'll let everyone know how it works. So far over the last 3 weeks, the charger has kept the service battery fully charged with daily driving and no noticeable degradation of performance. Service battery has been at 12.6V-12.7V every time I checked. Time will tell.

 

[enginerd4ni]

Thanks for the write up! Updated it in the Dual battery thread.
Where do you plan to mount the solar panels? Anywhere on the roof rack?

Please report back after some months of usage, especially regarding the heat.

The other concern I would have is in a head in collision, might pose a safety concern?

My setup survived the summer heat of Big Bend NP and is still working flawlessly so I would expect Bob's to do the same! It is hot near the radiator but when the vehicle isn't moving, the fan kicks on pulling air through the heat exchanger and reducing the temperature in front of it where the D250S resides. If I end up having any issues, I'll let everyone running the CTEK know.

For safety, yes, front end collisions are a big risk. I mitigated with inline fuses just before reaching the batteries. Bob, what did you do?

 

[enginerd4ni]

Oh yeah, I really like your Mar-Lan trolling motor connector. That is a really nice solution for quick connections!

 

[DannyLlama]

For safety, yes, front end collisions are a big risk. I mitigated with inline fuses just before reaching the batteries. Bob, what did you do?

In doing some research on the WWW I came across this and thought I would reference it for general information

Finally talked to someone at CTEK. They said you do not need an inline fuse between the battery and CTEK at all and it's recommended you don't use one. Kind of surprised me.

We ended up wiring positive from start battery to CTEK in bed (next to house battery) and house battery positive to CTEK as prescribed by CTEK. Then we earth grounded from frame to house battery and then to CTEK from house battery post. Couldn't see a reason to earth ground the CTEK on its own, just run off house battery ground post. The starter batter remained OEM setup for ground. Does anyone see an issue with the ground?


Brett C.
IronworksTactical.com - owner

Wiring the CTEK D250S - Page 2 - Expedition Portal

 

[enginerd4ni]

In doing some research on the WWW I came across this and thought I would reference it for general information


Wiring the CTEK D250S - Page 2 - Expedition Portal

Interesting. Page 24 of the CTEK user manual lists "Fuse Recommendations" of 30A if using the D250S alone or 150A if using the Smartpass. I can see how an undersized fuse could jack with the charger's sense voltage and perceived current capacity. Perhaps that is why the D250S uses 20A but asks for a 30A fuse and the Smartpass uses 80A but asks for a 150A fuse.

I haven't seen any performance issues by having the fuses (I use 150A because I am running the Smartpass as well) and I like having the peace of mind knowing a short won't likely burn down the house.

I wonder why a CTEK person would say to not use fuses?

 

[DannyLlama]

Interesting. Page 24 of the CTEK user manual lists "Fuse Recommendations" of 30A if using the D250S alone or 150A if using the Smartpass. I can see how an undersized fuse could jack with the charger's sense voltage and perceived current capacity. Perhaps that is why the D250S uses 20A but asks for a 30A fuse and the Smartpass uses 80A but asks for a 150A fuse.

I haven't seen any performance issues by having the fuses (I use 150A because I am running the Smartpass as well) and I like having the peace of mind knowing a short won't likely burn down the house.

I wonder why a CTEK person would say to not use fuses?

Interesting... It may have been a one off phone call with a not so knowledge CTEK Rep. Worth further investigation? Maybe not.

Thanks for sharing your information

 

[coulter6]

For safety, yes, front end collisions are a big risk. I mitigated with inline fuses just before reaching the batteries. Bob, what did you do?

I installed a 30amp fuse at each battery coming from the CTEK. Also fused the 8 gauge wire running to the dedicated fridge plug.

Each fuse within inches of the batteries.

 

[raptore]

Have you monitored the voltage, of your second battery, over the year to track if the ctek is keeping up? I ask b/c since it's 20amp capable and if you happen to camp for a while with the second battery depleted fairly well, it would take a while to fully charge the second battery?

 

[coulter6]

I've checked the second battery periodically over the last year and found that the CTEK keeps up very well. Never had the 96A battery fall below 12.4 amps. I also add a 100W renogy foldable panel when I sit in one place for awhile.

 

[teotwaki]

The CTEK 250 has three internal 30 Amp fuses, one on each DC port: alternator, solar panel and the "service" battery. Found this out when I repaired my CTEK after a couple of the MOSFET switches and one fuse blew out