This page is not yet finalized, and more discussions are still to happen.
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Internal resistance for eneloops, is around 100mOhm (www.stefanv.com/electronics/sanyo_eneloop.html), but can be as low as 18mOhm for the Maha Powerex Precharged D cells (https://mahaenergy.com/powerex-precharged-d-10-000mah-2-pack/). The Turnigy NiMH pack has around 18mOhm/cell (NiMH IR Testing)
To achieve the required voltage, a battery pack with 10 cells in series would be constructed. This does not add any additional complications as NiMH cells tend to self-balance, and thus charging can be done as if it is one high voltage cell. See Charging Algorithms for NiMH Batteries for more details on the charging procedures.
NiCD
This is now an older chemistry and is no longer relevant. From my research, NiMH has surpassed it in every category.
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No Lithium based secondary batteries are allowed per regs.
LiFEPO4
No Lithium based secondary batteries are allowed per regs. I'm really hoping that ASC changes their minds on this, as the main issue with Lithium batteries is thermal runaway, and LiFEPO4 batteries are not susceptible to thermal runaway. For now, this may be out of the question.
Other Strategies to eliminate AUX issues
There are several other approaches we are also analyzing to avoid all the AUX issues we have been having as well.
- Properly analyze the minimum voltage for switchover on the DC-DC power path IC. Choose the resistor divider accordingly.
- Add a time delay filter on the voltage measurement circuit if it does not impact any other switchover time characteristics significantly.
- Use thicker wires and nickel strips in the construction of the AUX battery (not the cause of the issue, but it can certainly help).
- Shorter wires for the AUX current path (don't go from battery to driver AUX Switch then back to battery - too much resistance and voltage drop).
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