Christophe Delpuech has been here from the very start, in 2011, and it is an understatement to say he knows the portable power market inside out. In charge of purchasing and sales, he is the first link in the chain: he decides which products make it into the catalogue and which never will. Needless to say, his opinion carries weight, and a manufacturer does not easily sell him a marketing pitch.
His method is known to the whole team: every charger, portable power station or generator he considers listing goes through a punishing test, pushed to the limit of its capabilities. Repeated charges, borderline power draws, behavior once the battery is warm, real accuracy of the advertised watts: Christophe looks for the gap between the spec sheet and reality, because that is always where the nasty surprises hide. With more than 75 product tests to his name, he has developed a rare instinct for spotting, within minutes, a device that will not live up to its promises.
His favorite line, repeated to the brands' sales reps, sums up the spirit of the house rather well: we don't want your best-seller, we want your best product. It is his buyer's choices, demanding and sometimes unpopular with suppliers, that guarantee the coherence of the catalogue and the trust of readers. The same filter applies on Au Frais, where he steers the selection of portable and fixed air conditioners as well as air purifiers with the same uncompromising eye.
Married and a father of two, Christophe recharges his own batteries out in nature: a tireless hiker, especially attached to the Gorges du Tarn, where he often tests in real conditions the runtime of a power station or a cool box during long family outings. A fairly logical way, for him, to check that a product holds up far from any power socket.
Several years after launch, the Delta Pro remains a technical benchmark: efficiency measured at around 85 to 91 %, mains recharging that beats its own claim. But two realities change the picture today: a history of backup-mode failures worth knowing about, and new-unit availability that has become highly uncertain in France.
Published on August 30, 2026 by Christophe
The only product on the market that plugs directly into an already-installed solar inverter, the Zendure SolarFlow 4000 Mix AC+ targets an unprecedented use case, but its measured efficiency on a pre-production unit remains clearly short of the announced 90 %, and real-world hindsight is still sorely lacking on this manufacturer's very first model of its kind.
Published on August 29, 2026 by Christophe
With 4 MPPT trackers and up to 2000 W of solar input, the EcoFlow Stream Ultra features the widest configuration in its range, but it receives a harsh grade in an electromagnetic compatibility test and keeps feeding surplus power back to the grid even with a full battery, a design choice the manufacturer stands behind.
Published on August 29, 2026 by Christophe
This brand-new balcony battery promises 96.1% efficiency, but the real figure comes in around 79%, one of the widest gaps in the category. Its smart mode sometimes charges from the grid during off-peak hours even when sunlight is available, a counterproductive behavior rather than simply a lack of finesse.
Published on August 29, 2026 by Christophe
This large AC-coupled battery delivers on its efficiency promise (83 to 85% measured, a good score for this type of coupling) and its backup switchover in under 10 milliseconds, but its "5-minute installation" only covers the storage part: unlocking the full 3500W requires an electrician and a dedicated outlet, for several hundred euros of extra work.
Published on August 29, 2026 by Christophe
This DC-coupled balcony battery delivers on its efficiency promise, with real-world conversion measured between 90 and 93 %, consistent with the manufacturer's own figures. But it carries the heaviest software-reliability baggage of any product in this category reviewed to date: failed updates, random BMS resets, and at least two complete hardware failures documented within weeks.
Published on August 29, 2026 by Christophe
This DC-coupled balcony battery delivers on its full-power efficiency promise, about 89% measured, but drops sharply below 150W, the most common situation on a balcony. Its real documented weakness is not the power electronics but the WiFi and firmware, with a recurring charging-lockup bug, and the multi-module extension suffers from a charge imbalance between stacked units.
Published on August 27, 2026 by Christophe
This balcony micro-inverter delivers well on its main promise, a measured efficiency of 93 to 94% close to the stated 96.7% and genuinely independent MPPT trackers, but its documented weakness is not energy production: it is the reliability of the WiFi and monitoring app, which regularly loses connection without affecting the conversion itself.
Published on August 27, 2026 by Christophe
This two-in-one Samsung power bank delivers on its basic promises, a confirmed 25W on a single USB-C port and a weight matching the stated 222g, but wireless charging stays capped at 7.5W against competitors reaching 15W, and the three-device mode drops all outputs to 7.5W each.
Published on August 27, 2026 by Christophe
This carbon-fiber power bank delivers on its most visible promise, a measured weight of 288 to 291g for 20,000mAh, but its real-world efficiency remains uncertain: the available measurements diverge sharply, between 40% and 74% of rated capacity depending on the protocol, and its price can double depending on the buying channel.
Published on August 27, 2026 by Christophe
This 99Wh LiFePO4 power bank returns between 88 and 90% of its rated capacity, a very good result, but its second USB-C port caps at 45W while the first alone reaches 100W, and an intermittent contact fault recurs across several separate reports on the main port.
Published on August 27, 2026 by Christophe
This compact 10,000 mAh power bank returns close to 82% of its rated capacity, an excellent result, but its actual recharge caps at 35W where the spec sheet claims 45, and its combined output across multiple ports drops to just 15W in total.
Published on August 27, 2026 by Christophe
Updated on July 29, 2026