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After getting into drone racing (where you need to take good manual care of your batteries because they're basically a bunch of cells soldered together), I real

After getting into drone racing (where you need to take good manual care of your batteries because they're basically a bunch of cells soldered together), I realized that every battery we have everywhere is just some standard cells in some standard configuration. With that knowledge, you can replace the battery in any gadget (small ones are usually 3.7V, or 1S), if you know how to care for it. Replacing the battery in a MiniDisk like this, I would maybe not trust the internal MiniDisk charger and charge by hand, but it should otherwise work identically to the factory battery.

mrfusion 6y ago
Do you just reuse the battery management system (bms) that’s already in the cell?
- tgtweak 6y ago
  It is a single-cell battery so no onboard bms would typically be present - a look at the terminals confirms this. The charge and protection logic is built into the device which charges the battery itself. edit: http://forums.sonyinsider.com/topic/29187-lip-4wm-battery-rebuild/ http://forums.sonyinsider.com/topic/29187-lip-4wm-battery-re... A review of the original pack teardown reveals it has a small pcb with what looks like some voltage cutoff or thermal fuse.
- joshmlewis 6y ago
  No the batteries he's referring to (4-6 cell LiPo's) don't have any electronics in them. They are as bare bones as you can get for the racing factor (lightweight and more capacity).
OJFord 6y ago
Even off the shelf 9v batteries are typically 6x1.5v AAAA cells in series. (i.e. they actually are batteries) They can also be stacks of plates though, so buy a sample of a particular brand before you decide bulk-buying them is a great/cheap source of cells!
PragmaticPulp 6y ago
This might work if you're the kind of person to continue manually checking and caring for the battery pack, but it's not good advice for the average hobbyist. The crucial missing detail is that battery packs are assembled from identically matched cells, which age together as a unit. As soon as you replace a single cell with a new cell of the exact same model, or a new cell of a different capacity and charge characteristics, that cell will charge differently than the rest of the battery pack. This results in an unbalanced charge situation. If the battery pack has a battery management system with leads in between each cell to balance the pack, this might work. The BMS can drain off excess charge from the unbalanced cells and convert it to heat. If the battery pack does not have a BMS, the unbalanced charge situation can lead to pack failure, with varying degrees of smoke and flame depending on the battery chemistry. When in doubt, play it safe and just get a new battery pack.
- DenisM 6y ago
  On a tangent, but... do you think it's possible to build a battery that discharges as a pack (in series), but charges each cell individually? I imagine it will require some creative wiring, but charging efficiency should then go through the roof, right? I image I went e-biking and returned to my car to recharge - having individually chargeable cell should reduce the overall charge time a lot.
  - PragmaticPulp 6y ago
    A battery management system handles this. You still charge the pack in series, but the BMS will discharge cells that have a higher voltage than others. This results in all cells having similar charge levels. It doesn't change the charge time, though. You're putting the same amount of energy into the pack either way. 14.8V @ 100mA applied to 4 cells in series is the same energy as 3.7V @ 100mA applied to 4 cells individually. Can't escape the laws of physics. If power efficiency is critical (solar applications, for example), the BMS might have fancy switching circuitry to re-route energy from overcharged cells to undercharged cells. This is expensive, though, so most BMSs just use resistors to burn off extra charge from overcharged cells.
kenward 6y ago
For many people integrating batteries into their projects, this is true and you can simply take most off-the-shelf cells with the right voltage profile and put them into some series/parallel config. At least with lithium-ion technologies, for larger applications, this ignores a lot of the degradation phenomena and electrochemistry of the battery.
vicnov 6y ago
How does one can get into drone racing? Where should I start?
- StavrosK 6y ago
  You buy a cheap controller (RadioMaster TX16S is the best value for money right now, at $120ish, but you can do quite well with a $30 FlySky), some goggles ($40 for some Eachine EV800D, I forget the exact model number), $150ish for a low-end starting 5" quad, and $30 for a 4S battery. I might also recommend getting a tiny whoop instead, those are very small drones for inside the house, they are super fun and you can fly them whenever you want, vs having to make a trip to a suitable location. That should get you started. Nowadays I much prefer acrobatic wings, though, I made a Flitetest Versa from Depron foam for like $30 and it's amazing fun.
  - bittercynic 6y ago
    I'm not having any luck finding the TX16S for that price, any suggestions?
    - StavrosK 6y ago
      Here is one, though it's a bit more expensive, I think maybe I used points to get the price lower: https://m.banggood.com/RadioMaster-TX16S-Hall-Sensor-Gimbals-2_4G-16CH-Multi-protocol-RF-System-OpenTX-Mode2-Transmitter-for-RC-Drone-p-1652191.html?rmmds=search&act_poa=POA6384750&cur_warehouse=CN https://m.banggood.com/RadioMaster-TX16S-Hall-Sensor-Gimbals...
    - joshmlewis 6y ago
      Don't order from Banggood. It takes weeks to arrive and is likely to be a knockoff. There are several US retailers like RaceDayQuads.com, GetFPV.com, etc.
  - StillBored 6y ago
    very small drones for inside the house, they are super fun and you can fly them whenever you want House yes, anywhere with a fire suppression system _NO_. The little glass bulbs used in most of them don't react well to having a drone bump into them. Buddy of mine had this happen where he worked not long ago, you really don't want to be that person...
kregasaurusrex 6y ago
Even though cells may exist with the same specs, it's hjighly recommended to create a battery pack from a single supplier and standardize on that. For example when I used to do professional laptop repair, I discovered the '18650' is only a size rather than a catch-all for all 12V cells, and isn't recommended to daisy-chain the various good ones together if they only share the same voltage. There's over a dozen different colors that indicate these batteries were built by various suppliers with use cases such as fast discharge rate, higher peak voltage, greater capacity, or a cost-effective battery that survives fewer discharge cycles. Creating a pack with mismatched batteries could cause the load balancer or device to operate outside of spec- don't cheap out on your power source!
- StavrosK 6y ago
  Agreed (except you probably mean 3.7 V cells and not 12 V). Your cells should be as similar as possible to prevent uneven wear.
dzhiurgis 6y ago
> I would maybe not trust the internal MiniDisk charger Why wouldn't you? It has same voltage and even same capacity (weird considering evolution, but maybe choice was deliberate). I dunno, but maybe MiniDisk charger even has temperature sensor.
ChuckMcM 6y ago
I don't disagree, and building battery packs for battlebots was a fun experiential way to learn this, but it is important to match chemistries. Chargers for nickel-metal-hydride batteries won't correctly charge lithium-ion batteries, or worse nickel-cadmium batteries. Not to mention that some battery packs (the ones in the Thinkpad come to mind) have a "battery monitor IC" actually built into the battery pack so it helps to start with an existing pack and then "re-manufacture" it with cells rather than just wire together the same number of cells. Perhaps to most critical element in these "smart" batteries is the temperature sensor which dials back the current when they start getting hot to avoid thermal runaway. (source of MANY battery fires in laptops from counterfeit battery packs). As for matching the cells, in our battlebot we would take each "unit" (which in our case was 20 NiMH batteries) and condition it by draining it and charging it in cycles while monitoring voltages to level out the batteries and "sync" their charge levels. We still ended up with a couple of fires but that was because we were charging them right at the limit of what is reasonable to do because the time between bouts could be pretty short.

mrfusion 6y ago

Do you just reuse the battery management system (bms) that’s already in the cell?

tgtweak 6y ago
It is a single-cell battery so no onboard bms would typically be present - a look at the terminals confirms this. The charge and protection logic is built into the device which charges the battery itself. edit: http://forums.sonyinsider.com/topic/29187-lip-4wm-battery-rebuild/ http://forums.sonyinsider.com/topic/29187-lip-4wm-battery-re... A review of the original pack teardown reveals it has a small pcb with what looks like some voltage cutoff or thermal fuse.
joshmlewis 6y ago
No the batteries he's referring to (4-6 cell LiPo's) don't have any electronics in them. They are as bare bones as you can get for the racing factor (lightweight and more capacity).

OJFord 6y ago

Even off the shelf 9v batteries are typically 6x1.5v AAAA cells in series. (i.e. they actually are batteries) They can also be stacks of plates though, so buy a sample of a particular brand before you decide bulk-buying them is a great/cheap source of cells!

PragmaticPulp 6y ago

This might work if you're the kind of person to continue manually checking and caring for the battery pack, but it's not good advice for the average hobbyist. The crucial missing detail is that battery packs are assembled from identically matched cells, which age together as a unit. As soon as you replace a single cell with a new cell of the exact same model, or a new cell of a different capacity and charge characteristics, that cell will charge differently than the rest of the battery pack. This results in an unbalanced charge situation. If the battery pack has a battery management system with leads in between each cell to balance the pack, this might work. The BMS can drain off excess charge from the unbalanced cells and convert it to heat. If the battery pack does not have a BMS, the unbalanced charge situation can lead to pack failure, with varying degrees of smoke and flame depending on the battery chemistry. When in doubt, play it safe and just get a new battery pack.

DenisM 6y ago
On a tangent, but... do you think it's possible to build a battery that discharges as a pack (in series), but charges each cell individually? I imagine it will require some creative wiring, but charging efficiency should then go through the roof, right? I image I went e-biking and returned to my car to recharge - having individually chargeable cell should reduce the overall charge time a lot.
- PragmaticPulp 6y ago
  A battery management system handles this. You still charge the pack in series, but the BMS will discharge cells that have a higher voltage than others. This results in all cells having similar charge levels. It doesn't change the charge time, though. You're putting the same amount of energy into the pack either way. 14.8V @ 100mA applied to 4 cells in series is the same energy as 3.7V @ 100mA applied to 4 cells individually. Can't escape the laws of physics. If power efficiency is critical (solar applications, for example), the BMS might have fancy switching circuitry to re-route energy from overcharged cells to undercharged cells. This is expensive, though, so most BMSs just use resistors to burn off extra charge from overcharged cells.

kenward 6y ago

For many people integrating batteries into their projects, this is true and you can simply take most off-the-shelf cells with the right voltage profile and put them into some series/parallel config. At least with lithium-ion technologies, for larger applications, this ignores a lot of the degradation phenomena and electrochemistry of the battery.

vicnov 6y ago

How does one can get into drone racing? Where should I start?

StavrosK 6y ago
You buy a cheap controller (RadioMaster TX16S is the best value for money right now, at $120ish, but you can do quite well with a $30 FlySky), some goggles ($40 for some Eachine EV800D, I forget the exact model number), $150ish for a low-end starting 5" quad, and $30 for a 4S battery. I might also recommend getting a tiny whoop instead, those are very small drones for inside the house, they are super fun and you can fly them whenever you want, vs having to make a trip to a suitable location. That should get you started. Nowadays I much prefer acrobatic wings, though, I made a Flitetest Versa from Depron foam for like $30 and it's amazing fun.
- bittercynic 6y ago
  I'm not having any luck finding the TX16S for that price, any suggestions?
  - StavrosK 6y ago
    Here is one, though it's a bit more expensive, I think maybe I used points to get the price lower: https://m.banggood.com/RadioMaster-TX16S-Hall-Sensor-Gimbals-2_4G-16CH-Multi-protocol-RF-System-OpenTX-Mode2-Transmitter-for-RC-Drone-p-1652191.html?rmmds=search&act_poa=POA6384750&cur_warehouse=CN https://m.banggood.com/RadioMaster-TX16S-Hall-Sensor-Gimbals...
  - joshmlewis 6y ago
    Don't order from Banggood. It takes weeks to arrive and is likely to be a knockoff. There are several US retailers like RaceDayQuads.com, GetFPV.com, etc.
- StillBored 6y ago
  very small drones for inside the house, they are super fun and you can fly them whenever you want House yes, anywhere with a fire suppression system _NO_. The little glass bulbs used in most of them don't react well to having a drone bump into them. Buddy of mine had this happen where he worked not long ago, you really don't want to be that person...

kregasaurusrex 6y ago

Even though cells may exist with the same specs, it's hjighly recommended to create a battery pack from a single supplier and standardize on that. For example when I used to do professional laptop repair, I discovered the '18650' is only a size rather than a catch-all for all 12V cells, and isn't recommended to daisy-chain the various good ones together if they only share the same voltage. There's over a dozen different colors that indicate these batteries were built by various suppliers with use cases such as fast discharge rate, higher peak voltage, greater capacity, or a cost-effective battery that survives fewer discharge cycles. Creating a pack with mismatched batteries could cause the load balancer or device to operate outside of spec- don't cheap out on your power source!

StavrosK 6y ago
Agreed (except you probably mean 3.7 V cells and not 12 V). Your cells should be as similar as possible to prevent uneven wear.

dzhiurgis 6y ago

> I would maybe not trust the internal MiniDisk charger Why wouldn't you? It has same voltage and even same capacity (weird considering evolution, but maybe choice was deliberate). I dunno, but maybe MiniDisk charger even has temperature sensor.

ChuckMcM 6y ago

I don't disagree, and building battery packs for battlebots was a fun experiential way to learn this, but it is important to match chemistries. Chargers for nickel-metal-hydride batteries won't correctly charge lithium-ion batteries, or worse nickel-cadmium batteries. Not to mention that some battery packs (the ones in the Thinkpad come to mind) have a "battery monitor IC" actually built into the battery pack so it helps to start with an existing pack and then "re-manufacture" it with cells rather than just wire together the same number of cells. Perhaps to most critical element in these "smart" batteries is the temperature sensor which dials back the current when they start getting hot to avoid thermal runaway. (source of MANY battery fires in laptops from counterfeit battery packs). As for matching the cells, in our battlebot we would take each "unit" (which in our case was 20 NiMH batteries) and condition it by draining it and charging it in cycles while monitoring voltages to level out the batteries and "sync" their charge levels. We still ended up with a couple of fires but that was because we were charging them right at the limit of what is reasonable to do because the time between bouts could be pretty short.