circuit over view and help with extras - Page 1
Forum section: electronics / projects

author: shortcircuit2
author_rank: Newbie
timestamp: December 18, 2024, 12:04:17 am
content: hi all so i am wanting some comfermation that what i have done (as a rugh idea) will work fine and safly but also i would like to know how i would beable to tell if any of the contactors would be welded closedi soulw like the welded contact system to run off the controle 12v system (not shown) but if not possable i understand (just trying to isolate HV and LV best i can)so the long and short is my project will oparate ate aprox 110v dc but will charge are 220v dc (aprox)to do this i am useing a set of contactors to reconfiger how the 2 battery packs are arangedsee atached picbut the idea is as followsbefor any configeration a full welded contact test is performedif one of the 2 series contacters (eg contactor 1 and contactor 15) is welded closed it will throw/show a error of wich contactor if welded closedif both contactors in a series pair(eg contactor 1 and contactor 15) is welded closed performs an emergancy shutdown and prevents any contactor being activatedfor series oparationcantactors 1,2,15,17,9,13,14,12,3,4,18,19,5,6,22,23 are energised one at a time (indervidualy to minimise inrush current)for parallelcontactors 1,2,15,17,27,26,7,8,20,21,25,24,3,4,18,19 are energised one at a time (indervidualy to minimise inrush current)HVLC (high voltage low current (both battery packs in series))LVHC (low voltage high current (both battery packs in parallel))i know i shown contactors as switches it was just easyest and closest thing i could find for a quck mock upsorry nubering all over the placeTLDR: need to check if each contactor is welded closed for saftyorry for spelling and grammer issues due to suffering with dislexia

author: jwet
author_rank: Frequent Contributor
timestamp: December 19, 2024, 04:11:45 am
content: Putting a bunch of contactors in series won't prevent welded contacts. The last switch to close will take the same surge current.In high current apps like electrical vehicles, they use techniques like pre-charge resistors. You first turn on a relay with a series resistor in its path that keeps currents below your contact rating. This might 0.1 ohm. After some time period, you short this resistor with a relay that gives you the final current without any surges.Usually these things have a little bit of intelligence to measure voltages before closing switches.Be careful, batteries can produce huge currents and melt wires, etc.

author: shortcircuit2
author_rank: Newbie
timestamp: December 22, 2024, 04:45:47 pm
content: Quote from: jwet on December 19, 2024, 04:11:45 amho that is done for safty as i stated so just in case one dose weld closed the power can still be diconectedQuote from: jwet on December 19, 2024, 04:11:45 amthank you for the tip thereQuote from: jwet on December 19, 2024, 04:11:45 amthere will be constent voltage, temp and curretn measurements taken place and if anything falls out of line it will shut downQuote from: jwet on December 19, 2024, 04:11:45 amand i understand that i takeing all safty percotions needed even haveing special fire exstinglisher at hand that is made to deal with lithium based fiersand i was just mostly asking about how sound my idea is honestly