The D250SE (CTEK Part No. 40-315) is a DC to DC fully automatic charger that’s designed to charge a Service Battery and is powered by the alternator/starter battery. With dual inputs the D250SE is also solar compatible (a standard solar controller is not necessary). The D250SE charger supplies up to 20A of power to any 12V lead-acid or lithium service battery from 40–300Ah. It also works if the starter battery and service battery are different chemistries, for example if the starter battery is lead/acid and the service battery is lithium. (Note: a service battery may also be called an auxiliary/aux battery, house battery, secondary battery, or backup battery.) This is a great charger for our V1 and V2 Lithium Deep Cycle Batteries.
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Description
CTEK D250SE 12V Smart Charger 20AThe D250SE (CTEK Part No. 40 315) is a DC to DC fully automatic charger thats designed to charge a Service Battery and is powered by the alternator starter battery. With dual inputs the D250SE is also solar compatible (a standard solar controller is not necessary). The D250SE charger supplies up to 20A of power to any 12V lead acid or lithium service battery from 40300Ah. It also works if the starter battery and service battery are different
Dual Inputs
The D250SE CTEK Charger has dual inputs and can charge the service battery from the alternator or a solar panel or both. The charger is designed to work with smart alternators and can still operate if the alternator is shut off but the vehicle has access to solar or wind power. So it can use power from the alternator, solar panel, wind power, or any DC power source can be used through the solar input port (within voltage spec). The D250SE can also charge the service battery from the solar input and the alternator in parallel using its built-in regulator to save fuel.
Optimum Charge
Continuous charging while the vehicle’s on the move means the batteries are fully charged in the shortest possible time. The built-in temperature sensor compensates for hot or cold conditions to prevent the battery from overheating or overcharging, so it always gets the optimum charge.
When the service battery being maintained is fully charged, the D250SE will automatically redirect overflow charge power to top-off the starter battery. The D250SE can maintain a stable output up to 20A to vehicles fitted with smart ECU controlled alternators.
LITHIUM
5-Step Program
- Accept*: Tests if the battery can accept charge. This step prevents that charging proceeds with a defect battery. (*Step 1 for lead/acid is Desulphation)
- Bulk: Charging with maximum current until approximately 90% battery capacity*. (80% capacity for lead/acid.)
- Absorption: Charging with declining current to maximize up to 95% battery capacity*. (100% capacity for lead/acid.)
- Float: Maintaining the battery voltage at maximum level by providing a constant voltage charge.
- Pulse: Maintaining the battery at 95–100% capacity. The charger monitors the battery voltage and gives a pulse when necessary to keep the battery fully charged.
Video about D250SE Charger
Specs
- CTEK PN: 40-315
- Input: 11.5–23V, 25A
- Output: Max 14.4/14.2/14.7V, 20A max
- Back-Current Drain*: Less than 1Ah/month
- Ambient Temperature: -4°F to +122°F (-20°C to +50°C)
- Battery Types: 12-Volt WET, EFB, Ca/Ca, MF, AGM, GEL, Lithium (LiFePO4, Li-Fe, Li-iron, LFP)
- Battery Capacity: 40–300Ah
- Insulation class: IP65 (splash and dust proof)
Shipping Notes
- Free Standard Shipping on $100+ Orders to the USA.
- Except Preorder products are shipped in 48 hours.
- Delivery to the USA:
- Standard Shipping : 3-10 business days
- If time is of the essence, please consider selecting expedited delivery for faster service.
Exchange/Return Notes
- We offer a 30-day return/exchange service after receiving.
- Final sale items are not eligible for returns or exchanges.
- To process your return/exchange, please contact us at [email protected]
- Please click here for more details>>> Return & Exchange Policy
4.4 ★★★★★
Based on 1092 reviews
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Product Reviews
★★★★★ 5
Great pillow, but the cooling effect depends on the cover
Color: Blue-ice Plus, Size: King(Pack of 2)
I really like this pillow overall. It’s comfortable, supportive, and feels well made. When you use it without a pillowcase, it definitely feels cool to the touch and does what it claims in terms of that initial cooling sensation.
However, once you put a pillowcase on it, you can’t really feel the cooling effect anymore. I’ve tried multiple different pillowcases made from different materials, and none of them really let that cool feeling come through.
That said, I still love the pillow itself. It’s comfortable and supportive enough that I’m keeping it. Just keep in mind that the cooling feature works best without a cover, which isn’t ideal for everyone.
Overall, a good pillow — just manage expectations about the cooling effect once it’s covered.
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Reviewed in the United States on February 17, 2026
★★★★★ 5
Cooling and holds shape.
Color: Blue-ice Plus, Size: Queen(Pack of 2), Color: Blue-ice Plus, Size: Queen(Pack of 2)
Very nice pillow for the price is also holding up well and holding shape very cool and comfortable to the touch. Best pillow I found in a long time.
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Reviewed in the United States on April 28, 2026
★★★★★ 5
Best Pillow Ever
Color: Blue-ice Plus, Size: Queen(Pack of 2)
Best pillow ever. Although it still gets "hot", it does take longer to get "hot". I love this pillow. I was buying a new pillow almost every 3 months. Other pillows would either remain rock hard or go flat. I was concerned at first when reading the description as I though the memory foam would be big pieces. They are soft fluffy pieces. I had to remove almost half of the foam to get the pillow to what works for me. I have not had to put any filler back in. Maybe in a couple of more months I may have to put a bit more in, but it is holding it's shape and not going flat. I do fluff it every night. This helps. I am a stomach sleeper. I have bought the expensive purple pillow and hated it so much I gave it to my daughter. This QUTOOL Pillow is the best! I bought a 2 pack. Have not used the other pillow yet, but I feel I may actually go years for once without having to buy a pillow as I have the 2nd one set aside if the first one gets to a point in need replacement. I have bought Dollar Store pillows. I have bought $300 pillows. None of them even come close to this pillow and the way you can adjust this pillow for you. The pillows came in a white mesh like bag. I keep all the unused "stuffing" in this bag. I have it hanging in my closet and I just fluff the bag once a month to keep the filling fresh so it is ready if and when I need it. Coming from someone who has trouble staying asleep, neck issues, a stomach sleeper who hate those flat pillows manufacturers think stomach sleepers like but actually hate, buy this pillow. Just buy it. Best Pillow for a picky person like me. Buy 2 or more so if you have to stay at a hotel, you can take your own pillow.
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Reviewed in the United States on June 15, 2025
★★★★★ 4
Slippery Pillow
Color: Blue-ice Plus, Size: Queen(Pack of 2)
Nice and cooling but it’s so slick my pillow sheet doesn’t want to stay on.
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Reviewed in the United States on May 14, 2026
★★★★★ 5
Foam Mattress NEEDs Foam Pillows
Color: Blue-ice Plus, Size: King(Pack of 2), Color: Blue-ice Plus, Size: King(Pack of 2)
10 stars!! Quality foam, structure & price. Best bang for my buck.
HRV, readiness & total sleep score metrics increased drastically this week. See screenshot :)
Support:
Molds and cushions every crevice under my neck and above shoulders. So comfy
Size:
Adjustable loft but king length is perfect to hug and rest your head. Love love love. The 1st 2 nights were uncomfortable with pillow as is, first night I was up at 3am half asleep pulling foam out but wasn't enough. The second night at 2am I pulled out more stuffing. I was getting frustrated.. my Oura ring showed both nights I was awake every hour. Not good. Before the 3rd night I pulled enough to fill the bag the 2 pillows arrived in. Boom -8hrs sleep and for the first time ii years I achieved 17% Deep sleep. Huge.
Weight:
Perfect weight with adjustment. Squishy and molds to b the contour of my neck and shoulders
Softness:
Like the baby bear.. just right.
Comfort:
Very comfortable after removing 30% foam in both pillows. I actually now have enough to make a 3rd pillow, replace old foam, or adjust OGs, Still to early to measure.
If you have a foam mattress that contours your body but not your head you'll end up with neck and/or back pain from head being elevated- not sinking/molding the body into a foam mattress.
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Reviewed in the United States on July 1, 2025