To protect lenders from short-term volatility of BTC, we apply loan to value ratio of 70%. In other words, the amount of collateral BTC should be 30% higher than total amount of loan and interest due, based on BTC rate on the moment of placing loan application.
30% ratio is determined based on retrospective analysis of BTC rate fluctuations. 30% higher value of collateral is mutually beneficial for both lenders and borrowers. BTC rate is constantly appreciating, but the rate might be affected by sharp short-term fluctuations. Applying loan to value of 70% (30% higher value of the collateral over loan and due interest amount) guarantees stability of the transaction for both lenders and borrowers.