hey everyone,
my last project went rather successful, converting my dynamo driven bike lights to lithium powered. Because of the rather small current draw, I was able to get away with using a DC-DC converter to get a stable voltage for the lights.
my next project is a bit more powerful. I intend to build a big mobile battery for my sailing kayak.
The battery has to support the following items: 2Blue Robotics thrusters (25A each 6-20V I would like around 14-15 V max), lights, 5 cigarette lighter outlets(10 A each, 12V) and a bilge pump.
I calculated that I almost need 2kwh for the range I want to get eventually. so far so good.
The problem occurs in the pack voltage. I need at least 12 V for the cigarette outlets to work properly. so if I drain my cells to 2.8 volts I need at least 4-5s. but then charged the voltage is too high for the 12 v equipment I believe the maximum voltage is around 14-15 v but at 4.1 v per cell, the pack has 20+ volts
the thrusters are ok with up to 20 v so if I only charge to 4 v per cell everything should be ok. the other instruments cannot handle the voltage so I thought of dc-dc converters but I need rather many of them to supply all my other devices and they all have to provide at least 10 A (max amperage from cigarette lighter outlet I will never use 10 A but I do not want to ).
As an encasing, I want to use a big plastic Ammunition Box or something equal but it has to be watertight because my kayak ist open an often waves get into the boat so there sometimes are 4-10 cm of water in the boat if there is no time to bale. Maybe I will add a bilge pump. Because of the plastic box, I don't think I can get all my dc-dc converters in there because of the generated heat.
is there a better solution instead of the DC-DC converters
the other equipment BMS and charger I still have to research a bit.
thanks,
Albach
my last project went rather successful, converting my dynamo driven bike lights to lithium powered. Because of the rather small current draw, I was able to get away with using a DC-DC converter to get a stable voltage for the lights.
my next project is a bit more powerful. I intend to build a big mobile battery for my sailing kayak.
The battery has to support the following items: 2Blue Robotics thrusters (25A each 6-20V I would like around 14-15 V max), lights, 5 cigarette lighter outlets(10 A each, 12V) and a bilge pump.
I calculated that I almost need 2kwh for the range I want to get eventually. so far so good.
The problem occurs in the pack voltage. I need at least 12 V for the cigarette outlets to work properly. so if I drain my cells to 2.8 volts I need at least 4-5s. but then charged the voltage is too high for the 12 v equipment I believe the maximum voltage is around 14-15 v but at 4.1 v per cell, the pack has 20+ volts
the thrusters are ok with up to 20 v so if I only charge to 4 v per cell everything should be ok. the other instruments cannot handle the voltage so I thought of dc-dc converters but I need rather many of them to supply all my other devices and they all have to provide at least 10 A (max amperage from cigarette lighter outlet I will never use 10 A but I do not want to ).
As an encasing, I want to use a big plastic Ammunition Box or something equal but it has to be watertight because my kayak ist open an often waves get into the boat so there sometimes are 4-10 cm of water in the boat if there is no time to bale. Maybe I will add a bilge pump. Because of the plastic box, I don't think I can get all my dc-dc converters in there because of the generated heat.
is there a better solution instead of the DC-DC converters
the other equipment BMS and charger I still have to research a bit.
thanks,
Albach