Duel NP-1 cups

[teamrawfish]

Curious if I could have one Cup with a battery in it and another running off AC so if I lost power it would switch over to the battery seamlessly. Or would it constantly be drawing off the battery and the AC at the same time and eventually kill the battery? 

[The Documentary Sound Guy]

You need to spell out more details about how you are converting AC into something that plugs into an NP-1 cup.

There are ways to do AC failover, but a dual battery cup is not one of them.

[teamrawfish]

I would use one of those ac cup adapters that slot into one of the cups. Run to a remote audio v4 bds system 

[The Documentary Sound Guy]

I haven't seen one of those, but it's a start.  How it interacts will depend on the relative voltage between the battery and whatever the DC adapter puts out.  It will always pull to some extent from both, but it will favour the higher voltage source, which will often be the battery (meaning, the battery will not stay charged as an emergency source).  I don't think it does what you want it to do, which is draw from AC and only pull from the battery if the AC is removed.  You need a proper fail-over circuit to do that.

[teamrawfish]

The AC plug on outputs 15V/5amp.

[The Documentary Sound Guy]

In that case, it would probably draw most of the power from the AC, but you'd still get residual draw on the battery that would slowly deplete it.  It wouldn't stay at full charge.  I'm also not sure what the long term effect of having a voltage difference in parallel would be on the battery.  It should tolerate it to some degree, but there's a reason for the standard recommendation to use similar brands & age when pairing multiple batteries.  You'd be violating that recommendation.  I would think most NP batteries should have circuitry to prevent damage, but it's not a scenario I'd be happy with long term.

If you feel like trying it, I would think it should be safe enough to 'work' in the short term and you can see if you can live with the oddity around running the battery down, but it's not something I'd recommend.

[teamrawfish]

Thank you , yea I’m ok with it drawing on the battery a little bit.  I have access to AC power 90% of the time but it would be nice for kick outs and quick moves to stay powered up. Thank you 

[Derek H]

My biggest concern would be how is the lithium np battery going to handle being in parallel with a constant DC source of fairly high amperage? You should contact your battery manufacturer and tell them your proposed setup with the voltage and wattage of your ac adapter and let them advise you. I think it will depend on what the battery circuitry does. Products like the PSC triple play which have multiple power inputs are designed to isolate the sources so you don’t have one trying to charge the other. 
 

You could just try it, best case scenario it works fine, worst case your battery overheats, shuts down or worse. 

[JesseF]

On 6/28/2026 at 2:49 PM, teamrawfish said:

The AC plug on outputs 15V/5amp.

 

 

I've not experienced an AC to DC converter for NP-1 cups that outputs 15v.  If yours does, then you should be fine.  All of mine did 12-13v which was way lower than my NP-1 output and so I never got this particular setup to work properly.  I did use the dual NP-1 cup for two NP-1 batteries and that worked great.  However, take care if you decide to hotswap NP1 batteries with dual cups, if the battery voltage is too disparate you can snap drain a fully charged battery and run into problems.

[Conor]

The better solution would be something like the PSC triple play with multiple power inputs. Then you have proper load balancing, regulation etc.

[Tyler Faison]

I don’t like this as the best solution tbh. Looks like you have decided on an NP battery, in which case you might consider an NP-9X which can be charged via D-tap connector while in use/outputting DC power. We keep one in every kit as a more portable charger/emergency backup. that keeps the energy flowing all day. It will deactivate after 6-ish hours, so just a quick unplug/plug back in and you’re good to go.

 

The SL-2 is such a nice addition to keep everything powered with internals that we eliminated all of our dual-cups. 

[rich]

what will happen when you are using a fully charged Li-ion battery and a 15v power supply is that the battery will discharge until the voltages are equal, then the power supply will take over.

i faced this years ago when i bought a Hawk-Woods APD. to get around this, i ended up getting an 18v power supply so that there would be no draw on the batteries until i lost mains.

if you want to keep using your 15v supply, look at the Audioroot eSmart Trio as it has an override input, meaning that if there is voltage at that input, the distro will use that rather than anything plugged into its other two inputs, even if they have a greater voltage.

[IDX]

NP-9X users regarding the comment " Consider an NP-9X which can be charged via D-tap connector while in use/outputting DC power". 

Just to clarify this comment. 

The IDX NP-9X can be charged using the IDX JL-2Plus charger or the IDX VL-DT1 Advanced D-Tap charger via the IDX NP-9X advanced D-tap port which is a blue d-tap that is designed to provide the bi-directional power I/O. So, you can charger the battery via this blue advanced d-tap port with the VL-DT1 when the battery is not in use to power your product.

It is not recommended to have the VL-DT1 attached to the Advanced D-Tap port when the battery is powering your unit using the standard NP-9X battery interface. You can use the Advanced D-tap port as a standard D-tap power output port to power other products. 

For more information, please visit the IDX website at www.idxtek.com