Understanding LAVA’s True Dead Battery Mode
By: Adam Swimmer
3 Min Read
October 11, 2022
How LAVA’s True Dead Battery Mode Can Charge a Truly Dead Device
LAVA SimulCharge adapters provide simultaneous charging and access to data to compatible mobile devices. For SimulCharge to work, the USB-C based mobile device must be able to negotiate a power contract with the adapter. This can be a problem if its battery is truly dead as it needs some power to negotiate that contract. Read on to understand True Dead Battery Mode and how LAVA has solved the problem.
Normally, a dead mobile device’s battery isn’t completely drained. It conserves a bit of power so that it can try to negotiate a power contract when it is next plugged in. However, if you leave your device uncharged for an extended period, the battery will eventually be completely used up. Let’s take a look at a case study for an example.
LAVA Case Study
The Problem
LAVA had a customer that operates mobile POS stations specifically for outdoor festivals and other events. The inventory was kept in storage off-season. When they’d take the tablets back out after a few months, the tablets’ batteries would be completely drained.
LAVA’s engineers discovered that when one of these tablets was plugged into our COTS SimulCharge adapters, it either wouldn’t charge at all or it would start charging very slowly (5V at 0.4A). After gaining a tiny bit of power, Android would boot up and the device would try to negotiate a power contract. This would drain what little charge it had just built up and the tablet would die again. Again, this would cause it to go back to charging very slowly. The tablet would get caught in a loop, never gaining enough charge to finish negotiating the power contract.
The Solution
To solve this, LAVA built a custom adapter, which is the first in what will likely be a new line of products, the oSynC-3U OTG.
The oSynC-3U OTG is a USB-C mobile adapter with three Micro USB ports for peripherals. It provides SimulCharge when connected to an external power source and OTG when powered by the mobile device. (As a reminder, SimulCharge is a LAVA technology that provides access to power and data, simultaneously.)
The adapter also features a new LAVA technology, True Dead Battery Mode, which allows you to charge a mobile device when its battery is completely drained.
True Dead Battery Mode
True Dead Battery Mode turns the adapter into a dedicated charging port (DCP), which is equivalent to a wall charger. This mode will automatically initiate if the tablet is unable to negotiate a power contract when plugged in.
How It Works
In True Dead Battery Mode, the mobile device is able to charge without negotiating a power contract with the adapter. MUX USB data lines are shorted, so it does not enumerate the adapter’s Micro USB ports. This means the mobile device can’t access any peripherals attached to those ports in this mode. Crossing out data lines is part of the specification for being a DCP.
True Dead Battery Mode will charge the mobile device for five minutes, as a DCP charger. After this, the adapter and mobile device will try to initiate a power contract. Five minutes is long enough of a charge for many mobile devices to start a power contract. If it is successful, the adapter will switch to SimulCharge mode. If it’s unsuccessful, it will charge for another five minutes in True Dead Battery Mode before attempting another negotiation.
Most mobile devices we’ve tested negotiate a power contract after a single cycle of charging in True Dead Battery Mode. However, it will run as many five-minute charging cycles as needed until a successful power contract is negotiated. Then, it will switch to SimulCharge mode.
Our Adapter
The adapter doesn’t use Fast Charging. It charges the mobile device at 5 volts, 1.4 amps. This is because the customer was already using the voltage converter that inputs a higher voltage and temperature was a concern. Moreover, the tablets would often be used outdoors in direct sunlight. Therefore, the extra head produced by Fast Charging raised real concern about damaging the tablet.
The oSynC-3U OTG adapter’s True Dead Battery Mode is a straightforward solution to charging tablets when they are truly dead. It turns the adapter into a DCP charger, which allows it charge the mobile device without any digital communication. Once the mobile device has received enough charge to negotiate a power contract, it will switch to SimulCharge mode and provide data access to the peripherals.