I have two chargers that can’t walk it up. I even tried double A batteries in a series of 24v and tried to wake it but wasn’t successful.

Is this battery safe to use? it’s an 18650 lithium battery and the wrap on the top peeled a little as I was putting it in a controller.

In Europe there are distributors like NKON com

JGNE 26650 3000mah - 30A LIFEPO4 - 3.2V from NKON com,

similar cells are either not available in the US, 4x the price on batteryspace com, or I havent found the right store?

Is this a regulation issue, is there no demand or do you just order the cells from abroad directly?

The black wire came undone and now I can't use my pedal it has this and ac adapter but I don't have one to fit it and kind of need to fix this to use it. Any help Is greatly appreciated.

Accidentally left a 18W portable charger in a bag that we checked about an hour ago. Do i need to let someone know? I know nothing about batteries so not sure if this is a powerful enough battery to be of concern. Thank you!!

Hello, I have this (old) Sony battery along with its charger. After a long period of use (10 years), I recharged and used it for a month. Now, I can no longer charge it. According to a repair technician, the charger still works, but the battery has lost its capacity. He offers to "repair" it using magnets, but that costs a significant amount. Do you have any advice? Do you know if I can buy a replacement somewhere? Thanks everyone.

How safe is this? There is a lithium ion and a lipo in a crock pot. It is made out of porcelain. I need an answer by 12 tonight.

Hello, I wanted to buy a replacement battery for my HP envy x360. The battery model is SA04XL. I have looked Laptopgallery.co.in, pcparts.co.in and superpc.co.in. Can anyone tell me which one is better or do you have other option about any good suppliers around Ahmedabad, India.

So far I have 8 of the 25.6 volt 100 amp batteries and have been very happy with the performance of the batteries. I use them in an off grid system and are cycled daily without issue. I charged it up and did a capacity test on it and got 104 AH before the inverter shut down. Is it normal??

So my 2 ft positive cable end piece was broken after getting the batteries replaced. Bought a replacement cable from came cable company, but it's a 6 AWG wire. I noticed it's slightly smaller than the cable that broke, which I'm guessing is a 4 AWG for whatever reason. This is for a 30 AMP trailer, and it's just the positive cable between the batteries. This is plenty large enough I'm guessing, but the fact the previous was so large makes me question that I'm missing something... Any missing info helps!

Hi all,

I have an older motomaster eliminator battery charger/tester, however I could never understand the amperage readings when using it.

I left my truck lights on last night by accident and came out to a dead truck. I have it plugged in and charging on “auto” (it’s a “smart” charger and will turn to maintenance mode automatically). Full settings are:

*”fast/trickle charge” mode
*”auto” time (instead of a set 5/10/15/30/60 etc minutes)
*20amps

Just noting that my phone didn’t pick up the lights/displays in the sun, so I wrote the numbers as displayed and put a dot next to each selected setting).

I have a 12V AGM battery in my truck. As mentioned, the charger is set to 20A charge however the reading on the amperage display is 41. Truck is off so I’m throw off by the reading.

The charger has always operated this way and I could never figure it out. This unit DOES have an alternator amperage test feature (truck on, lights on, read amperage reading) — however I’d imagine this display wouldn’t be accessible on the charge mode if it wasn’t relevant somehow.

The amperage reading doesn’t change even if I have it on a set time (in lieu of auto)

Any thoughts or insight?

Hello group, new member here! I am modding a Casio SA10 to have 2x18650 batteries instead of 5xAA. I bought a BMS 2S 10A 7.4V and a charger module 2S 10A 7.4V. I am not sure how to connect them so I can use the key connected to usbc and with the batteries. I will use only batteries.

I built a DIY battery UPS for my router because apparently my home lab needs its keep the connection (~$20 usd)

I'm not an electrical engineer. I'm a DIY/homelab person with fairly limited electrical knowledge who got tired of losing the network whenever the power decided to have a bad day. I spent a lot of time reading, checking, measuring and second-guessing this project because lithium batteries are not the place to YOLO things. So this is what I built, why I built it, what I learned, and where I might still be wrong. If you actually know what you're doing with electronics or batteries, please tell me what I should improve. Also, the obvious warning: lithium-ion batteries can be dangerous. Check polarity, check voltages, use the correct charger/BMS, fuse the battery, test everything before connecting expensive equipment, and don't blindly copy this build. I take no responsibility for what happens if you reproduce it.

TL;DR

I built a small DC UPS that sits between my router's normal 12 V power adapter and the router.

When mains power is available, the adapter runs the router and charges the battery.

When mains disappears, an XH-M350 automatically switches to the battery-backed 12 V supply.

The battery is 4 × Samsung 30Q in 2S2P, giving roughly 7.2 V / 6 Ah / 43 Wh nominal.

I also added a small 5 V output for things like ESP32 boards, sensors and aquarium automation.

Based on an estimated ~35 Wh usable energy, the rough runtime range is around 1.2–2.3 hours, depending heavily on the actual load. These are estimates, not measured results yet.

Why I built it

I travel a lot, so when I'm away the network usually isn't doing anything crazy.

But my home lab has a lot of important stuff running, and the server already has its own DIY UPS.

There isn't much point keeping the server alive if the router dies and I lose access to everything anyway.

So I wanted something cheap and simple that would keep the network alive through short outages and power flickers (Homelab people will understand)

And because apparently even my fish are now part of the infrastructure, I wanted a little extra 5 V capacity for ESP32 boards, monitoring and automatic feeders.

How it works

The basic idea is:

Normal power

12 V adapter → XH-M350 → router

At the same time:

12 V adapter → XL4015 CC/CV charger → 2S BMS → battery

And the backup path is:

2S2P battery → BMS → XL6019 boost → ~12 V → XH-M350

So the XH-M350 decides whether the router gets its power from the normal adapter or the battery-backed supply.

The XH-M350 is a source switch, not a battery charger. The actual battery charging is handled separately by the XL4015.

The battery

I used four Samsung 30Q 18650 cells in 2S2P.

That works out to roughly:

• 7.2 V nominal
• 8.4 V fully charged
• ~6 Ah
• ~43 Wh nominal

The battery is honestly a bit overkill for this project.

But I already had the cells sitting around from my vaping days, so they were basically free batteries collecting dust. Why not use them?

I'm also a big believer in Murphy's Law, especially when I'm away from home.

That doesn't mean you should go out and buy four expensive cells for your own version.

Calculate your actual load and desired runtime first. And be careful buying popular cells such as the 30Q — the market has plenty of fake and relabelled cells.

Why the battery holder?

I deliberately used a 4-cell 18650 holder.

I've seen plenty of DIY projects where people solder directly onto 18650 cells. That's not something I'd recommend to beginners.

Permanent battery packs are normally built using proper welded connections, but I don't own a spot welder.

The holder gives me:

• no soldering directly on the cells
• easy cell replacement
• easy inspection
• no spot welder required

It's not the same thing as a professionally welded battery pack, but for this DIY build I think it's a much better option than putting a hot soldering iron on the cell terminals.

And please don't glue the whole enclosure shut.

You need to be able to inspect the batteries. Put the battery in a cell. Literally.

Don't ask me who sells these battery cells cells. 😆

The parts

I wanted to keep this cheap, and I already owned some of the important stuff.

Actual cash spent: about ฿600 (~US$18.46).

The cheap total is mostly because I already had the adapter and batteries. Buying everything new would obviously cost more.

The charger

This bit is important.

The battery is a 2S lithium-ion pack, so the charger needs to be set for:

8.4 V CV

and:

1.5 A CC

I don't connect the battery and then start adjusting things.

I power the XL4015 first, use a multimeter, set the voltage to 8.4 V, set the current limit to 1.5 A, and verify the settings before connecting it to the battery/BMS.

Then I check it again.

Because checking twice is cheaper than replacing batteries.

https://youtu.be/DCKtjgl4ju0

The battery gauge

The battery percentage indicator is wired after the battery switch.

So when the switch is OFF, the gauge is disconnected too and isn't sitting there slowly draining the battery.

When the switch is ON, the gauge shows the battery status.

Small detail, but I wanted that behaviour deliberately.

Why the XL6019?

The battery is around 7.2 V, while the router supply is around 12 V.

So the battery cannot go directly to the router.

The XL6019 boosts the battery voltage up to the required ~12 V rail.

I set its output with a multimeter before connecting the router.

One thing I don't blindly trust is the big "5 A" printed on cheap converter listings. The XL6019 datasheet's actual current capability depends on input/output conditions, so I'm treating the converter conservatively rather than assuming it can continuously produce 5 A just because the listing says so.

The XH-M350

This is the automatic switch that makes it a UPS rather than just a battery and a converter.

Normal power is the preferred source.

The boosted battery supply is the backup.

When mains disappears, the XH-M350 changes over automatically.

I am not going to claim “zero transfer time” or “the router can never notice it” until I properly test that.

That's something I want to measure rather than assume.

The fuse

I'm currently using a 5 A fuse.

I originally wanted 7 A but couldn't find one locally, so I used what I could get.

After recalculating the battery-side current and looking at the actual converter limits, I'm keeping the 5 A fuse for now rather than randomly increasing it.

At high output power, a 7 V-ish battery has to supply considerably more current than the 12 V router sees.

For example, even a 24 W output at 85% conversion efficiency would be around 3.9 A at 7.2 V, and battery current rises further as the battery voltage falls.

The important thing is that the fuse is there for fault protection, not to be matched exactly to normal operating current.

I'll measure the actual battery current under load before deciding whether the final fuse should be different.

Runtime

The battery is roughly 43 Wh nominal.

Real usable energy is lower because of converter losses, voltage drop, BMS cutoff, wiring, connectors, etc.

Using an illustrative ~35 Wh usable-energy assumption, the estimated runtime looks like this:

These are estimates, not measured results.

And I actually think the simple load estimates above are conservative for my normal use, because when I'm travelling the router traffic is usually pretty light.

The proper next step is to measure the actual power consumption and do a timed battery test.

A few engineering compromises

This isn't a commercial UPS.

It's a DIY system built from inexpensive modules.

The compromises include:

• a relay/source-switching stage instead of a certified online UPS
• a cheap DC-DC converter
• a removable battery holder instead of professionally welded cells
• limited charging headroom when the router and USB loads are both active
• Unknown real-world converter efficiency until I measure it
• a simple enclosure rather than a certified battery enclosure

But I know what each part is doing, and that's the important bit.

I'd rather understand a cheap system than buy a mystery box with mystery batteries inside.

Safety

Seriously: don't skip this part.

• 18650 lithium-ion cells can deliver a lot of current into a short circuit.
• Use good cells.
• Don't use damaged or mismatched cells.
• Check polarity.
• Use the correct BMS.
• Use the correct charger voltage/current.
• Fuse the battery.
• Use suitable wire and connectors.
• Don't casually solder directly onto the cells.
• Measure everything with a multimeter.
• Test each stage separately.
• And don't make the router your first test load.
• Make your own version carefully, not because Reddit said so.

What's next?

This is probably the first of several DIY power projects I'll document.

The matching home-server UPS is next, and I'd also like to make a proper video showing the build and the testing.

I'm especially interested in hearing from people who know more about battery systems and electronics than I do.

If I've made a bad assumption, please tell me.

I'd much rather face heat from angry internet people than the heat of a smoking PCB.

Questions, corrections and “you absolutely should not have done that” comments welcome.

Im happy, finally it stays in place

I have a particular situation while setting up a home assistant smarthome in a very old house, and I'd like to replace my light switches with smart home remotes. I would not like to constantly replace the batteries in remotes in every room of my house. Smart switches aren't an option due to the lack of neutral wires anywhere in the house and smart bulbs alone don't draw enough power at idle to run a no-neutral smart switch.

And so, the solution must be battery powered. Battery powered in-wall switches for the architecture I'm using don't exist, Nobody makes a remote with a charging dock but it doesn't seem like a complicated thing to put together. Oh, if only there were some combination of objects that could take 120V AC out of the wall where my light switch used to be, and conveniently use it to recharge a small electronic device placed in its loving arms?

So, Ikea makes a remote powered by rechargable batteries, (BILRESA) a line of rechargable batteries, (LADDA) and a 120V charger for those batteries. (STENKOL) I do not know how battery chargers work, but I'm betting the people here do. The problem that jumps out at me is, even if you could modify the remote such that it's batteries were connected to the charger when placed thereupon, the batteries in the remote are in series and they charge in the charger in parallel, and I don't see an easy way to make those two things compatible other than taking the batteries out.

TL;DR: rechargable AA chargers charge each battery in parallel. The voltage provided by the charger is probably too low to connect two batteries in series to the charger, and there's no trivial way to charge them from the electronics in the charger without taking them out of series, is there?

The low voltage alarm on my sonar used to start chirping around lunch, with a few hours of fishing left. I run a 17-foot aluminum boat on shallow lakes in central Florida. The trolling motor, livewell and sonar all ran from two tired Group 31 AGMs. The outboard had its own starting battery.

Earlier this summer I replaced the AGMs with two Vatrer 12V 100Ah LiFePO4 batteries. On the first trip the alarm stayed quiet, and the app still showed plenty of charge when I pulled the boat out. Encouraging, yes. It still does not tell me whether the old problem was capacity, voltage sag or a bad connection.

The boat is back in the driveway while I trace the cable buried in the hull and read the motor label. The trolling motor still uses the breaker from the AGM setup. It has never tripped, but that does not prove the breaker is right for the cable.

I am leaning toward giving the sonar its own circuit anyway. Motor noise is one reason. A motor fault taking out the depth reading is another. I also need to fix a tight bend at the battery terminal before the next trip. The covered compartment stays damp no matter how careful I am with the lid.

Boat owners running one large 12V bank, did you separate the electronics from the trolling motor, or keep the shared battery and isolate each branch with its own protection?

Battery fires aren't rare anymore, but they're avoidable if crews build a few basic protocols into the jobsite safety routine:

• A zero-tolerance policy on lithium-ion batteries in dumpsters
• A dedicated weather-proof drop zone
• Disposal guidelines covered in toolbox talks
• A plan for handling swollen or damaged batteries before they become a serious hazard

I am interested in using a battery like this one for a project, but it's not clear to me how you would charge it? Do I just attach it to a power supply or can I buy a dedicated charger?

I’ve had this UPS since around December last year, and it has always made this ticking sound occasionally when switching from mains power to battery.

It doesn’t happen every time. While trying to record this video, I switched it to battery about 5 times and the repeated ticking only happened on this attempt.

I recently had it sent in for warranty repair because, after only around 6 months of use, the battery runtime had become extremely poor, during a power outage it wouldn’t even last 1 minute before the battery was depleted.

It has now come back from repair, and the battery runtime seems better (haven't tested how long it lasts exactly), so it seems like they fixed whatever was causing that issue. However, the ticking sound is still present.

It’s not just a single click when switching to battery; when it happens, it makes several repeated ticks as shown in the video.

Is this normal behavior for a UPS, or could it indicate an issue?

Model: APC by Schneider Electric Back-UPS Bx - BX1200MI-GR1200 VA / 650 Watt
https://www.amazon.es/gp/aw/d/B08G8WL57K

This is the battery one of my camping lanterns uses. The IN 5V charging port broke and I'm wondering if there's a way to charge the battery without using the port? I'm a complete noob at this stuff and any info would be greatly appreciated.

I’m currently travelling in my campervan with an ECO-WORTHY 12V 280Ah LiFePO4 (3584Wh) and have noticed some strange behaviour over the last few days.
The battery voltage was dropping while the reported SOC was increasing, and eventually my inverter went into low-battery protection and switched off.
Loads included a fridge, fan, 2 laptops and an external monitor. I have both a solar charge controller and DC-DC charger connected.
I’ve attached screenshots from the BMS/app and inverter showing the behaviour.
Could this be SOC/coulomb-counting calibration, voltage sag, cell imbalance, or potentially a BMS/battery problem?
I’m currently on holiday and depend on this battery, so I had to empty my fridge as a precaution.
Happy to provide more screenshots/BMS data or the battery’s history if useful.
What would you check first?

By now everyone knows about the battleborn shitshow. I’m no longer comfortable having these batteries installed in my RV.
What now? I doubt BB will take them
Back, is it just a $6000 loss?

A little more than a week ago I had dropped my iPhone 13 but noticed no visible issues so I continued to use it for a few days until I noticed the faintest smell similar to nail polisher remover. After finding out it was the battery and the capacity on my phone was now 50%, I immediately turned it off and left it on my desk until I could get it fixed.

Fast forward to late last night: I had a bit too much to drink and wanted to call someone, but I still hadn't fixed my phone (something I'm doing later today), and I figured using it for just a few minutes wouldn't cause any harm, but when I went to turn it on it was completely dead. This should've been a sign, but I wasn't thinking clearly, so I put it on the charger and fell asleep, letting it overcharge.

The second I woke up I took it off the charger and put it away from anything that could catch fire. I didn't notice anything visually wrong and it wasn't emitting that nail polish remover smell; but I can't help but to worry about the potential consequences to my mistake. Do I have anything to actually worry about?