Malcolm
10 kW
First off, apologies in advance if this is a dumb idea, but my understanding of electronics has never got much beyond the plumbing analogy of current as flow and voltage as pressure. This is a bit of a handicap for an EV tinkerer, but it does have the advantage of forcing me to try to find simple solutions.
So I’m looking for a simple charging system for a small electric car (my Mini). The LiFePO4 battery pack will be split into nominal 36V modules for safety and ease of handling.
I really like the idea of using DC/DC converters to charge cells individually, as covered by Doc and Jeremy here: http://endless-sphere.com/forums/viewtopic.php?f=14&t=2824
http://endless-sphere.com/forums/viewtopic.php?f=14&t=22881
I’ve bought a bunch of 48V to 3.3V converters, rated at 75W, and plan to trim them for 3.6V output by adding a resistor. All I need now is a power source to supply 36–72V for the DC/DC inputs. I already had a few second-hand Curtis 36V/30A lead acid chargers, which are easily trimmed for the desired cutoff voltage, so it would be great if I could use these. Unfortunately the charger is too smart to power the DC converters alone, as it doesn’t recognise them as a battery.
I was thinking I might be able to trick the charger into starting by briefly connecting it directly to the pack, when I started wondering what would happen if I connect the charger in parallel with the DC converters and battery pack and just let them run?
When the pack is at a low state of charge I guess the charger will do the bulk of charging directly, which is fine, but what’s likely to happen as the pack gets close to fully charged?
Could this work as a balancing charger or should I just forget it and buy a 48V Mean Well power supply?
So I’m looking for a simple charging system for a small electric car (my Mini). The LiFePO4 battery pack will be split into nominal 36V modules for safety and ease of handling.
I really like the idea of using DC/DC converters to charge cells individually, as covered by Doc and Jeremy here: http://endless-sphere.com/forums/viewtopic.php?f=14&t=2824
http://endless-sphere.com/forums/viewtopic.php?f=14&t=22881
I’ve bought a bunch of 48V to 3.3V converters, rated at 75W, and plan to trim them for 3.6V output by adding a resistor. All I need now is a power source to supply 36–72V for the DC/DC inputs. I already had a few second-hand Curtis 36V/30A lead acid chargers, which are easily trimmed for the desired cutoff voltage, so it would be great if I could use these. Unfortunately the charger is too smart to power the DC converters alone, as it doesn’t recognise them as a battery.
I was thinking I might be able to trick the charger into starting by briefly connecting it directly to the pack, when I started wondering what would happen if I connect the charger in parallel with the DC converters and battery pack and just let them run?
When the pack is at a low state of charge I guess the charger will do the bulk of charging directly, which is fine, but what’s likely to happen as the pack gets close to fully charged?
Could this work as a balancing charger or should I just forget it and buy a 48V Mean Well power supply?