Redodo 12V 40A DC-DC with MPPT
#9 in DC-DCFull review
For budget van and trailer builds that want alternator and solar charging in one cheap box. Specs are thin, so pick it on price rather than features.
Amazon $165.99$165.99
2.4/5
For owners of small lead-acid or lithium banks who want a sealed, set-and-forget charger that also keeps the starter battery topped up. Bigger lithium banks need a higher-current unit.
- 20 ACharge current
- 12 VBattery
- 2 yearsWarranty
Check price at Amazon$404.85
Price checked October 22, 2026. As an Amazon Associate we earn from qualifying purchases.
Pros
- Charges from the alternator and solar together, with an MPPT solar input
- Tops up the starter battery automatically once the house battery is full
- Works with smart alternators and is sealed to IP65
- Simple to set up: one button picks lead-acid, AGM or lithium
Cons
- Only 20 A, so a 100 Ah battery takes about 5 hours of driving from flat
- About $20 per amp, several times the cost of budget chargers
- No app, no custom voltages and a two-year warranty
How it scores
The rating comes from 4 measured or published factors, each scored 0-100 against fixed reference points for its type. How we rank explains each one.
Specifications
| Model number | 40-315 |
|---|---|
| Charging | |
| Type | DC-DC charger with MPPT solar input |
| Charge current | 20 A |
| Battery voltage | 12 V |
| Lithium profile | Yes |
| Custom profile | No |
| Temperature sensor | No |
| Inputs | |
| DC input range | 11.5 to 23 V |
| Smart alternator | Yes |
| Monitoring and build | |
| Bluetooth | No |
| Load output | No |
| Water resistance | IP65 |
| Dimensions | 192 x 110 x 65 mm |
| Weight | 1.5 lb |
| Warranty | 2 years |
Alternatives in this type
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