Ever since the Switch was released my friend and i were very disappointed about battery life we ordered extended battery cases that made the switch twice as heavy but it was just not a good solution overall.

So I ordered 2 NEW OEM Switch batteries from ebay,charged both to 100% and soldered the positive-negative together to run them in parallel then cut the metal shield with scissors and cut the back cover with a plexy glass cutter to glue one battery on top of the other and covered the exposed battery with vinyl

The switch weights 476 grams vs the original 398 grams the battery last 5:30 to 6:00 gaming and it takes about 6 hours to charge thats the only downside.

 

[FAST6191]

Straight parallel charge gets tricky. It can be done but I would want a management chip. If one battery is already slightly used (thus lower capacity, or otherwise lower capacity because manufacturing reasons) you start charging them at different rates or overcharging or something equally not so good for lithium cells.

 

[Migoma]

Yeah both batteries are brand new that i used.

 

[Reploid]

cool, but deformed

 

[FAST6191]

Even so if there is a slight difference in input impedance (there will be, impedance matching is terribly difficult), different ageing in the batteries (if one has more heat dispersal than the other then it almost inevitably will) or something along those lines you start getting them charge and discharge each other.
Absolutely do parallel things up if it comes at a weight cost you can deal with (Nintendo has to design it for the skinniest Japanese 5 year old after all) but make sure they are still managed. I imagine you have seen or even replaced a laptop with a single 18650 that tanked and took the whole thing down with it, almost same deal here). Alternatively a simple switch, possibly with a capacitor to handle switching overlap, will also do what you want if you can handle the multiple charge cycles or otherwise provide an external option.

 

[Migoma]

true its very hard to match-balance batteries in parallel and there will always be differences i am working in a plug and play solution where I can externally charge the batteries and quickly attach them to the switch without adding much weight but in the meantime this will have to suffice.

 

[quazimojo]

Very cool. Battery life is so bad on the switch and all the external batteries are tanks. This is a nice happy medium and because you can buy a replacement OEM cover for $10 on fleabay if you ever want to get it back to stock then the cost is absolutely nothing.

 

[RedBlueGreen]

Straight parallel charge gets tricky. It can be done but I would want a management chip. If one battery is already slightly used (thus lower capacity, or otherwise lower capacity because manufacturing reasons) you start charging them at different rates or overcharging or something equally not so good for lithium cells.

Aren't Nintendo's batteries supposed to protect against overcharging?

 

[sarkwalvein]

Aren't Nintendo's batteries supposed to protect against overcharging?

The charging circuit does that, but it expects one battery, not two in parallel.
If you connect both in parallel to the on IC output, it has no way to control how much current goes into each one.

 

[nukeboy95]

I'd be extremely careful with an exposed battery cell like that. A single scratch could result in a fiery explosion

 

[Deleted member 191657]

Cool idea, but this is looking for trouble:
- Exposed cell, you need a solid shell to cover that battery
- Parallel charging without a dedicated IC? They won't last very long.

 

[Hayato213]

Not a good idea, higher chance of a fire due to chance of battery being exposed and heating on top of each other. It would just be disaster as compared to using an larger capacity battery.

 

[Taffy]

...How do you dock it?

Doesn't that stick out too much? Or did you slice the dock up?

 

[Migoma]

Not a good idea, higher chance of a fire due to chance of battery being exposed and heating on top of each other. It would just be disaster as compared to using an larger capacity battery.

Yeah I built a shell out of an external HDD caddy to cover the battery I'll let you guys know if it catches on fire while playing or charging

...How do you dock it?

Doesn't that stick out too much? Or did you slice the dock up?

I use a USB c extension all the time even before adding the battery.

 

[Migoma]

The charging circuit does that, but it expects one battery, not two in parallel.
If you connect both in parallel to the on IC output, it has no way to control how much current goes into each one.

Parallel batteries balance themselves the charger just gonna take twice as long to charge the same pack parallel batteries without a controller are a common practice and they last years the problem is matching the batteries with the same capacity

 

[smf]

Parallel batteries balance themselves the charger just gonna take twice as long to charge the same pack parallel batteries without a controller are a common practice and they last years the problem is matching the batteries with the same capacity

Your main problem will be that you can now discharge one of them further than is safe.

 

[Migoma]

Your main problem will be that you can now discharge one of them further than is safe.

How could I discharge one further if they are always balancing themselves that's only if one of them fails before the other

 

[FAST6191]

If you are doing simple charging then maybe.

If you are doing http://batteryuniversity.com/learn/article/charging_lithium_ion_batteries and all the temperature managed charging (the nice external one flapping in the breeze, the original internal one blocked by both the case and the extra battery) and again if you have a different discharge rate (being wired and soldered it is less likely than simple spring contact but if even welded cells in laptops and tools hose this up...) then not so much. Said low resistance will also cut the other way though and if one cell does end up different for whatever reason (some kind of charge recovery or temperature masked voltage perhaps) then you all of a sudden end up whacking in a few more amps than you might care to. All of this is then negated by having a charge management chip for each of the cells, or a toggle switch to swap them out.

 

[The Real Jdbye]

Parallel batteries balance themselves the charger just gonna take twice as long to charge the same pack parallel batteries without a controller are a common practice and they last years the problem is matching the batteries with the same capacity

That's only true if the batteries have integrated protection circuits. Many do, but whether the Switch ones do I couldn't tell you.
When you measure the voltage to calculate battery charge level, you get the average of the two voltages.
As an example, if one battery is charged to 4.15 and the other to 4.2, the 4.2 battery is fully charged but the voltage will be measured as 4.17-4.18, causing the 4.2 battery to be slightly overcharged until the average reaches 4.2, at which point the other cell will still not be fully charged, and charging will stop. Overcharging can damage or kill the cells. And the cell with slightly less voltage on it will never be fully charged. Also when discharging, the cell with slightly higher voltage will never be discharged fully, since it will cut off once the average reaches 3.1 or whatever the Switch has set as the cutoff point, and the cell with slightly lower voltage might be discharged below that level (but the safe minimum voltage is 2.5v so we should still be good there and it shouldn't harm the battery, unless the voltage difference is huge)

This will cause the batteries to be worn unevenly, so the problem will get worse and worse.

If the battery has a built in protection circuit, it will protect it from overcharging or over discharging. However, if the batteries are of slightly uneven capacity to begin with or aren't charged to the exact same level, then you'll still not get the full capacity of each battery as you'll still have problems with charging cutting off before every cell is charged, and similarly the Switch shutting off while one battery still has some juice left in it, and that problem will still get worse over time, at least you won't be damaging the batteries though, merely lowering the apparent capacity of them because they're not being utilized fully.

 

[smf]

How could I discharge one further if they are always balancing themselves that's only if one of them fails before the other

How are you balancing them?

http://batteryuniversity.com/learn/article/bu_803a_cell_mismatch_balancing
A battery expert once said: “I have not seen a cell balancing circuit that works.”