CTEK D250S Solar Charge Controller/Dual Battery Isolator Review

coolfeet

Mark Keeler
I bought an ARB 60 liter fridge freezer and knew little about powering it. I bought a CTEK D250 S dual battery isolator to charge an 80 ah Lifeline AGM battery while driving. It worked fantastic for 3 out of 4 weeks on a camping trip to British Columbia. On the way back, it would not keep my battery charged. The battery was sulfated and would not charge above 12 volts. I used a portable CTEK charger and de-sulfated the battery and was on the road again.

BatteryBox.jpg

On my next 4 week trip, I added a 160 Watt solar panel on the roof of my Ford E350 van. Battery still would charge above 12 volts. I ran the fridge/freezer off the 12 volt socket and turned it off when not driving. A Lifeline battery dealer in the Bay Area de-sulfated the battery and I was operation again.

With the battery working again, I added an $18 battery monitor from Amazon that provides real time battery volts, amp draw, and watts. Foolishly, I planned another 4 week trip and did not bother to check if the CTEK was bulk charging over 14 volts. Found out the hard way on a road trip to Alaska. It never charged above 12 volts!

BayiteBatteryMonitor.jpg

When I returned home, I contacted CTEK and Leo, the technical service/warranty person told me to send the unit back for repair. Two weeks later, a brand new unit appeared at my door step!

While waiting for the CTEK to return, I bought a cheap 30 amp PWM charge controller on eBay for $16 delivered. It's a 4 stage charge controller that bulk charges at 14.5 + volts. It has a built in battery meter that is within .1 volts of my cheap battery monitor. It charged my Lifeline battery to over 13 volts. I carry this as a back up incase my CTEK craps out. I bought a back up battery too.

The Real CTEK D250 S Story

I am no expert when it comes to solar. As soon as I connected the CTEK, it went to work. Within a day, the onboard MPPT charge controller was pushing 14.5 + volts into the house battery. While driving, the CTEK boosted the alternator voltage to 14.5 volts and continued charging the battery. When finished charging, it maintains a float volt of 13+ volts.

We dry camped from Friday afternoon at 2 PM until Sunday afternoon (46 hours) and the battery never went below 12.58 volts. I was parked in partial shade.

After a frustrating 2 years with a malfunctioning CTEK D250S, I am a true believer with this functioning unit. For about $250, I think it's a fair price because it's both an MPPT charge controller and dual battery isolator. It's
simple to connect to both the battery and solar panel.

I did not connect directly to the starting batteries. An electrical engineer friend along with my 14 year old son read the wiring diagrams from my shop manuals and connected the CTEK D250S directly to the fused 12 volt trailer auxiliary battery charging circuit using 12 awg wire. The CTEK is rated at 20 amps. No need to wire directly to the battery with heavy gauge wire and fuses.
 
Last edited:

Micklethepickle

New member
I bought an ARB 60 liter fridge freezer and knew little about powering it. I bought a CTEK D250 S dual battery isolator to charge an 80 ah Lifeline AGM battery while driving. It worked fantastic for 3 out of 4 weeks on a camping trip to British Columbia. On the way back, it would not keep my battery charged. The battery was sulfated and would not charge above 12 volts. I used a portable CTEK charger and de-sulfated the battery and was on the road again.

View attachment 419054

On my next 4 week trip, I added a 160 Watt solar panel on the roof of my Ford E350 van. Battery still would charge above 12 volts. I ran the fridge/freezer off the 12 volt socket and turned it off when not driving. A Lifeline battery dealer in the Bay Area de-sulfated the battery and I was operation again.

With the battery working again, I added an $18 battery monitor from Amazon that provides real time battery volts, amp draw, and watts. Foolishly, I planned another 4 week trip and did not bother to check if the CTEK was bulk charging over 14 volts. Found out the hard way on a road trip to Alaska. It never charged above 12 volts!

View attachment 419051

When I returned home, I contacted CTEK and Leo, the technical service/warranty person told me to send the unit back for repair. Two weeks later, a brand new unit appeared at my door step!

While waiting for the CTEK to return, I bought a cheap 30 amp PWM charge controller on eBay for $16 delivered. It's a 4 stage charge controller that bulk charges at 14.5 + volts. It has a built in battery meter that is within .1 volts of my cheap battery monitor. It charged my Lifeline battery to over 13 volts. I carry this as a back up incase my CTEK craps out. I bought a back up battery too.

The Real CTEK D250 S Story

I am no expert when it comes to solar. As soon as I connected the CTEK, it went to work. Within a day, the onboard MPPT charge controller was pushing 14.5 + volts into the house battery. While driving, the CTEK boosted the alternator voltage to 14.5 volts and continued charging the battery. When finished charging, it maintains a float volt of 13+ volts.

We dry camped from Friday afternoon at 2 PM until Sunday afternoon (46 hours) and the battery never went below 12.58 volts. I was parked in partial shade.

After a frustrating 2 years with a malfunctioning CTEK D250S, I am a true believer with this functioning unit. For about $250, I think it's a fair price because it's both an MPPT charge controller and dual battery isolator. It's
simple to connect to both the battery and solar panel.

I did not connect directly to the starting batteries. An electrical engineer friend along with my 14 year old son read the wiring diagrams from my shop manuals and connected the CTEK D250S directly to the fused 12 volt trailer auxiliary battery charging circuit using 12 awg wire. The CTEK is rated at 20 amps. No need to wire directly to the battery with heavy gauge wire and fuses.


I know this is many years later. How did everything work out? im thinking about doing the exact same of wiring to the trailer power instead of running up to the engine bay on my 17 tacoma. I wanna keep it as pristine electrically for now.

-Mike
 

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