DIY USB power bank?

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donnybrook
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DIY USB power bank?

Been thinking about buying a couple of those roll-your-own style power bank enclosures since I have some spare 18650s (specifically the cylindrical “lipstick” style ones). But most of them are made by companies I’ve never heard of and I don’t want to end up with something shoddy that could be a safety hazard. Does anyone have experience with these, or is there a brand you can recommend that seems well made? Thanks for any tips.

SIGShooter
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I have 4 of these and I haven’t seen any problems with them. They all cut-off at around 4.18v when charging the batteries (pulled immediately after charging is done). One thing to consider is that they don’t accept protected batteries (at least the Panasonic ones I have don’t fit).

Here is a HKJ’s review on them.

Jtm94
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I have a Tomo M4 and it’s been working good for me. I don’t use it religiously, but I find it being useful every other week or so. Takes a while to charge 4 batteries, and the screen gets flickery if you move it around, but it will fast charge my phone 2 to 3 times on one charge.

Lightbringer
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Yeah, was gonna suggest simplifying your life and just getting a Tomo. They take 1-4 cells, sport independent channels, and have decent-enough displays.

Think I got a T4 and M4, no idea which is which or what the diffs are other than one has an add’l Apple-type connector whereas the other doesn’t. Goggle ‘em for more details, but either one should be fine, and you get to burn off 4 cells at once.

09 F9 11 02 9D 74 E3 5B D8 41 56 C5 63 56 88 C0

agent80
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I am looking for a 1-2 battery DIY charger with an output of 2 amps. Most seem to have an ouput of 1 amp. Can anyone suggest. Thanks

ludolf
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http://www.xtar.cc/products_detail/productId=189.html
(not yet released, “coming soon”)

agent80
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Impressive. Thanks

leaftye
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I also have a Tomo. It’s slow, but it’s nice that each bay is operated independently.

If you’re just trying to use your 18650’s, a case is good, but I wouldn’t go this route to save money over a prebuilt powerbank. The only problem I’ve had with powerbanks is that they cut off earlier than I’d like, so if I try using it for charging my rc batteries, the powerbank will turn off as the rc battery is in the last 10% of the charging cycle because the current draw is low enough that the powerbank shuts itself off.

The low mode should be lower.

donnybrook
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Thanks everyone. I’ll check out the Tomo unit though I was really looking for something more compact that takes only a single 18650.

Don

cu42
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I have seen very portable small cables that can snap onto the end of any 18650 allowing it to be recharged from any USB port.
It would be nice if these could be used in reverse as well to charge another device.

GreenLights
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cu42 wrote:
I have seen very portable small cables that can snap onto the end of any 18650 allowing it to be recharged from any USB port. It would be nice if these could be used in reverse as well to charge another device.

agent80 wrote: I am looking for a 1-2 battery DIY charger with an output of 2 amps. Most seem to have an ouput of 1 amp. Can anyone suggest. Thanks

This satisfies both requests:
Mini Magnetic Emergency Charger Portable

Just discovered this wonderful addiction.

agent80
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GreenLights wrote:
This satisfies both requests: Mini Magnetic Emergency Charger Portable

The Xanes is very good. Unfortunately the battery is exposed. I wouldnt want to assemble the battery everytime I want to use it. Nor do I want to keep the battery connected and throw it in a pack. Without a case, the battery could be punctured.

jerm03
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If we consider that DIY Power banks cost $14 for a 2 cell bank, and $10 for the 2 cells the cost is $24. Now when one can get a Xiaomi 10,000 mAh power bank for $20.00 do the DIY banks make sense?

SIGShooter
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jerm03 wrote:
If we consider that DIY Power banks cost $14 for a 2 cell bank, and $10 for the 2 cells the cost is $24. Now when one can get a Xiaomi 10,000 mAh power bank for $20.00 do the DIY banks make sense?
For me it made sense because I already had many 18650 batteries so no cost for cells. Also it gives me the ability to swap in charged batteries and not have to wait to charge up the powerbank. One of my daughter also carries one when she goes backpacking and there’s no ability to charge a powerbank.
BlueSwordM
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Also, it is environmentally better to buy a DIY powerbank first, as you can easily replace the cells.

Also, they include nice features, like balanced parallel charging, meaning in you put in a 4V cell and a 3.5V one, one won’t dangerously charge with the other, higher efficiency, better looks, and easily swappable cells.

My very own high current Beryllium Copper springs Gen 3:
http://budgetlightforum.com/node/67401
Liitokala Aliexpress Stores Battery Fraud: http://budgetlightforum.com/node/60547

jerm03
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BlueSwordM wrote:
Also, it is environmentally better to buy a DIY powerbank first, as you can easily replace the cells.

Also, they include nice features, like balanced parallel charging, meaning in you put in a 4V cell and a 3.5V one, one won’t dangerously charge with the other, higher efficiency, better looks, and easily swappable cells.

Which ones do “ balanced parallel charging” ?
I have to admit I never use any of mine, as I am at home or in the car. I’m curious to know if you or anyone uses the power bank often and for what?
Thanks, Jerry

BlueSwordM
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There are the Tomo power banks, and the XTAR PB2 which I am using currently.

My very own high current Beryllium Copper springs Gen 3:
http://budgetlightforum.com/node/67401
Liitokala Aliexpress Stores Battery Fraud: http://budgetlightforum.com/node/60547

jerm03
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Thanks, I have the PB2 on order.
Regards, Jerry

Zulumoose
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jerm03 wrote:
If we consider that DIY Power banks cost $14 for a 2 cell bank, and $10 for the 2 cells the cost is $24. Now when one can get a Xiaomi 10,000 mAh power bank for $20.00 do the DIY banks make sense?

Yes they do, for a number of reasons.

We already have the batteries, and don’t generally pay $14 for a 2 cell, I bought a 4 cell for under 10 a few months ago.

A DIY can do everyting a fixed cell can, PLUS you can charge your other batteries with it, reload it instantly, use it to reload any other 18650 device instantly, use an empty slot to store the cable and adaptors or something else, use your flashlight battery to charge your phone in an emergency.

Also, if the circuitry blows, the cells are unaffected, and immediately available, if one of the cells goes bad, the bank is unaffected and immediately available.

Beam me up!

nquinn
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The reason I plan to use something like this is for travel. I carry an 18650 headlamp (skilhunt h03), so I can hot swap batteries directly between the powerbank and headlamp as needed.

Speed4goal
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agent80 wrote:
I am looking for a 1-2 battery DIY charger with an output of 2 amps. Most seem to have an ouput of 1 amp. Can anyone suggest. Thanks

https://m.banggood.com/TOMO-T2-Dual-USB-Ports-DIY-18650-Battery-Charger-Power-Bank-Case-for-Mobile-Phone-p-1261029.html?rmmds=detail-bottom-alsolike

1 to 2 cell and 2 amp charging

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jerm03
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good reasons, thanks for the info.
Jerry

BlueSwordM
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I would not recommend the Tomo power banks.

They have problems with self discharging the cells too quickly.

My very own high current Beryllium Copper springs Gen 3:
http://budgetlightforum.com/node/67401
Liitokala Aliexpress Stores Battery Fraud: http://budgetlightforum.com/node/60547

jerm03
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What are the best at a reasonable price?

BlueSwordM
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For a 2 cells powerbank, I would recommend the XTAR PB2. Best one yet.

For a much bigger powerbank, I would recommend:
https://www.ebay.ca/itm/DIY-USB-Mobile-Power-Bank-Charger-Case-Kit-Pack-7×18650-Battery-Holder-For-Phone/272466114930?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

I’ve tested it, and it is the only one which cuts off charging at always 4.19-4.21V. Never goes higher, and never goes lower. It can also charge at up to 1.95A(confirmed by my USB tester), and can output up to 4A before shutting down. Out of many other DIY chinese powerbanks that I bought and tested, it is the only one I actually trust my life with it, and sold it to many of my friends with tested cells.

It also has a reasonable efficiency of 88% at 5V 1A, and 86% at 5V2A, as per advertised specs and per port. You can’t easily remove cells though, but if something dies, you can actually remove it without any tools, unlike sealed powerbanks

For the ultimate DIY powerbank, I would recommend this monster, if you can easily buy it though, and can stomach the price:
http://budgetlightforum.com/node/48561

My very own high current Beryllium Copper springs Gen 3:
http://budgetlightforum.com/node/67401
Liitokala Aliexpress Stores Battery Fraud: http://budgetlightforum.com/node/60547

SIGShooter
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BlueSwordM wrote:
I would not recommend the Tomo power banks.

They have problems with self discharging the cells too quickly.


I have a couple of the Tomo’s and I just put a piece of cardboard on the positive ends of the batteries until I need to use it.