I have a TOMO model power bank and use it with reclaimed 18650s. It holds up to 4 cells, easily slides open so serves as a 18650 battery charger as well. has two USB outputs and mini USB input. It's not super rugged, but has LED display for each battery to show power level.
I have the TOMO "V8-4", it's actually a pretty old product. I found an old piece of paper which i kept for its written contents but I am cleaning the room and it's really time to toss it. Before doing so, i am transferring the data, here we go, now for our common
records:
- my (empty/filled?) TOMO unit has a standby current draw of
14.8mA. I can't remember how i measured such a small current, probably not with my USB doctor. We don't know if this constant energy consumption also goes into the 4 batteries.
- my notes say "steady-state" (funny enough i am geman but i do take notes in engrish lang) but i cannot tell if i really meant that the battery voltages will reach a steady state, i.e. a constant value no matter how long you leave the TOMO connected to MiniUSB input power.
- in any case, my Samsung 18650 reached "steady-state" slot1 slot2 slot3 slot4:
4.197V 4.217V 4.183V 4.214V
- and my NCR-GA reached "steady-state" slot1 slot2 slot3 slot4:
4.199v 4.220V 4.185V 4.216V
For the voltage measurements i apparently took each cell out and quickly measured with my DMM duh.
These numbers tell us that there is no perfect 'cross-consistency' (i.e. consistency across slots), which doesn't matter because the product is just a cheap stupid powerbank, and that each slot charges consistently to the same end voltage respectively, no matter which 18650 battery i throw at it.
Somewhere else i noted down at which low voltage the TOMO ceases to operate, supplying USB output power. And how long it takes to charge up a set of 4 depleted batteries in the TOMO. I lost the notes, all i can remember is that it takes ages, maybe 9hrs or so depending on the battery capacity.
Off the top of my head what i like or dislike about the V8-4:
Likes:
+ made out of unbreakable/uncrackable type of flexible plastic. the product doesn't feel solid or rugged but i have the feeling that the construction would absorb drops on concrete or ceramic tiles. no worries about dropping the product on the floor.
+ independent slots, informative display
+ works. good energy conversion efficiency. not very good but good.
Dislikes:
- the USB ports are cheap, high contact resistance, and hold the USB cable plugs very very loosely. in consequence, the USB output power isn't reliable or steady and drops considerably after few usages. In theory the port could deliver 2A, and it does so on its very first day fresh out of the box, but the more often you use the port, you will never get the 2A again, only because of the mechanical degradation of the cheap USB port which was too loose to begin with.
Do i regret having bought it back then, years ago? - No. I try to live without regrets. So i try to take things easy and remind myself not to regret (small) mistakes. So no. No regrets here.
Would i buy it again today, if i needed another unit or a new powerbank? - No. There is a
newer model out on the market. Or i would try something else, maybe a powerbank made out of aluminum.
Imho the TOMO is a product that you buy once in your lifetime, try and enjoy, until it cr*ps out on you (i.e. the USB sockets wear out), and then never look back. And never buy again.
Overall i still like it, gets my Thumbs Up, and i could recommend it as First Purchase, if you never owned a powerbank before and you are looking for a budget-friendly solution with display/screen.
Oh and tinkerers could turn this soso product into a great product, simply by substituting higher quality (tighter fits!) USB sockets. Heck yeah, maybe i'll do that in future, i'll keep that idea in mind. Problem is, i never need or use a powerbank! Hence why would i go through the trouble and improve the TOMO? Doesn't make any sense.
No. It's time to move on. My TOMO and other powerbanks stay unused in my drawer, and right now i can trash the piece of paper. Finally. Bye.
Merry Christma