Quick verdict
Two triple-layer fibreglass fire-retardant bags, 5.5 by 3.5 by 2 inches, with a fold-over hook-and-loop closure that restricts airflow, for charging and storing small lithium packs: drone and RC LiPos, hedge trimmer and drill packs, camera batteries. Tenergy is an established battery maker and these are the standard hobby precaution. Each bag takes one tool pack or a couple of hobby cells; the fold-over flap passes a charger lead. They contain a failure; they do not prevent one.
Strengths
- Triple-layer fibreglass contains heat and flame from a failing cell
- Fold-over closure restricts oxygen to the fire
- Two bags for charging and storage
- Sized for tool packs and hobby LiPos
- From an established battery brand
Weaknesses
- Small; a large pack does not fit
- Fibreglass sheds fibres with age; handle with care
- Containment only; smoke still escapes
The overall YardToolLab Score is out of 100. Section scores are out of 10.
A Safe Place to Charge
Small lithium packs charge on kitchen counters and workshop benches every day, and almost all of them are fine. The one that is not takes the bench with it. A fire-retardant bag is the hobby world’s answer, and Tenergy’s are the standard small size: triple-layer fibreglass, 5.5 by 3.5 by 2 inches, with a fold-over closure, two to a pack.
This review is based on the maker’s specifications and on how LiPo safety bags are used generally. We have not evaluated these bags ourselves, and no bag makes a battery safe to charge unattended in a living space.
What It Does
Fibreglass does not burn and three layers of it insulate. A cell that fails inside the bag heats the bag, not the bench, and the fold-over flap limits the air that feeds the flame. The fire burns out inside. Smoke and gas still escape, so charging happens where they can disperse and a detector can sound.
Using It
Drop the pack in, run the charger lead under the flap and press it closed. Set the bag on tile, concrete or a metal tray, away from paper, fuel and curtains. For storage, cap the terminals, bring the pack to half charge and leave it in the bag on a shelf.
Size
One compact tool pack, a 2 Ah drill or hedge trimmer battery, or two or three drone or RC LiPos. A 5 Ah pack is a squeeze and a LiFePO4 car battery needs the large bags. Two bags charge two packs at once or keep one for storage.
Tenergy
An established battery and charger maker whose bags have been the hobby default for years. The fibreglass sheds fibres as it ages; handle it by the flap and replace it when it frays.
Who Should Buy It
- Drone and RC hobbyists charging LiPos.
- Anyone charging tool packs in a wooden shed or on a bench.
- People storing a few spare packs over winter.
Common Owner Complaints
Too small for big packs. It is the small bag; buy the large one for those.
Technique Tips
Fold the flap over the charger lead rather than leaving the bag open, so the closure does its job of limiting air. Charge on a metal tray or a ceramic tile with nothing within a foot. Set a timer for the charge so a pack is not forgotten on the charger overnight, which is the common thread in most battery fires. Inspect packs before bagging; a swollen pack goes to recycling, not the charger.
Storage
For winter, bring packs to about half charge, cap the terminals and put them in the bags in a cool room. Check them every couple of months and top up any that have dropped low.
Alternatives to Consider
The HulkGoo large bag for LiFePO4 and pack collections. A metal ammo can with a vent hole. A ceramic tile and distance, which is the minimum.
Verdict
For a few dollars, two fibreglass bags make charging small packs a contained risk instead of an open one. Charge on a hard surface, flap closed, detector nearby.
Full specifications
Tenergy 2-Pack Fire Retardant LiPo Battery Charging and Storage Bags, 5.5 x 3.5 x 2 Inches FAQs
One compact tool pack such as a 2 Ah drill or trimmer battery, or two or three hobby LiPos. A 5 Ah pack is tight; a LiFePO4 car battery is for the large bags.
Put the pack in, run the charger lead out under the fold-over flap and press the flap closed. Charge on a hard surface away from anything flammable.
It does not burn and it insulates. Three layers hold the heat of a small lithium fire inside the bag until the cells are spent.
No. Vented gas escapes. Charge where it can disperse and a detector can hear it.
