Joey
100 W
I perceive that there is a dichotomy in LiFePO combined balancer and charger design where a potentially useful middle ground may exist. At one extreme is the Voltphreak single-cell charger approach for which, for example, a dozen individual units are required to charge and effectively balance a 12s battery pack. At the other extreme is a pack charger and balancers tailored to a predefined number of cells in series. I lump the single-large-power-supply-with-multiple-DC-to-DC-converter designs that I've seen here in the forum into the latter category because they appear to be sized for charging large numbers of series cells. I know they could be made smaller if designed for fewer cells in series, but I haven't seen anybody do it.
What I think is missing is a self-contained, physically small module, resembling a Voltphreak single-cell charger that is capable of charging and individually balancing 4s pack modules. These charging modules should be packaged so that multiple units can be plugged side-by-side in a power strip. They could be larger in size in either or both of the remaining dimensions if necessary to house the additional components. An important goal would be to keep the module's use as simple as that of the single-cell Voltphreak charger.
I think people like the Volphreak single-cell chargers because they are simple to use. It is just inconvenient to deal with 12 or more individual units to charge a pack of typical voltage. Higher current output would be desirable, but lets consider that as a separate issue. One could design a range of models with different max current output. The single transformer and multiple DC-to-DC converter approach is a potential solution but nobody is offering it as a product.
I also think this approach would be a very good match for Goodrum's 4s4p cell-stacking scheme. His stacks are modular at 4s, and can be connected in series to obtain a number of common pack voltages. The 4s charger configuration could do the same trivially.
-- Joey
What I think is missing is a self-contained, physically small module, resembling a Voltphreak single-cell charger that is capable of charging and individually balancing 4s pack modules. These charging modules should be packaged so that multiple units can be plugged side-by-side in a power strip. They could be larger in size in either or both of the remaining dimensions if necessary to house the additional components. An important goal would be to keep the module's use as simple as that of the single-cell Voltphreak charger.
I think people like the Volphreak single-cell chargers because they are simple to use. It is just inconvenient to deal with 12 or more individual units to charge a pack of typical voltage. Higher current output would be desirable, but lets consider that as a separate issue. One could design a range of models with different max current output. The single transformer and multiple DC-to-DC converter approach is a potential solution but nobody is offering it as a product.
I also think this approach would be a very good match for Goodrum's 4s4p cell-stacking scheme. His stacks are modular at 4s, and can be connected in series to obtain a number of common pack voltages. The 4s charger configuration could do the same trivially.
-- Joey
