It would be marginally faster (best case probably a percent or two) for a much more expensive charging circuit. The reason for this is that you can discharge ba

It would be marginally faster (best case probably a percent or two) for a much more expensive charging circuit. The reason for this is that you can discharge batteries much faster than you can charge them. Also, it seems like you're imagining that you can charge batteries with more power if you charge them in parallel instead of series. This isn't true since you're just trading a higher voltage/lower current for a lower voltage/higher current.