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
4.2 ★★★★★
Based on 11 reviews
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Product Reviews
★★★★★ 5
Great quality
Size: 16AWG -10FT 2Pcs
Worked perfect for my 212 predator mini bike. Easy to install and looks great. High quality product.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on May 4, 2026
★★★★★ 5
Works Perfectly for My Light Bar Setup!
Size: 16AWG -10FT 2Pcs
The Nilight 16 AWG Wiring Harness Extension Kit made installing my LED light bar so much easier. The wires are thick, durable, and exactly the right gauge for a reliable connection. The 10-foot length gave me plenty of room to work with, and everything connected smoothly without any issues. Feels like solid quality, and I appreciate that it comes with a 2-year warranty. Great value and highly recommended for anyone wiring up off-road lights or accessories.
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Reviewed in the United States on October 4, 2025
★★★★★ 5
Nilight 10 wiring
Size: 16AWG -10FT 2Pcs
Great quality brand new condition awesome value super easy to use already had connectors on for easy plug and play
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Reviewed in the United States on April 12, 2026
★★★★★ 4
Easy and clean look
Size: 16AWG -10FT 2Pcs, Size: 16AWG -10FT 2Pcs
Very nice extension wires. Sheath is tough and the connections are tight. Very easy to install. I ended up to tuck in the wires instead of cutting because it was a little long for my application. Works great and had no issues. Pair the wires with my Nilight light pods. You can buy the wire but this was easier and cheaper than getting the wire and sheathing separately.
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Reviewed in the United States on August 18, 2025
★★★★★ 5
Perfect!
Size: 16AWG -10FT 2Pcs
Perfect!
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on April 22, 2026
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