Sept 27 (Reuters) - Electric truck maker Nikola Corp (NKLA.O) said on Monday it had entered into another deal with Tumim Stone Capital to sell $300 million of its stock, taking the total to up to $600 million. Phoenix, Arizona-based Nikola entered into a share deal with Tumim, according to a filing earlier in June. Under the agreement, Tumim had committed to purchase up to $300 million of Nikola"s common stock. Since entering into the first agreement, Nikola has issued nearly $47 million of common stock to Tumim. New York-based investor 3i is the manager and general partner of Tumim Stone Capital."The equity lines with Tumim, together with estimated cash and cash equivalents, will provide Nikola with access to approximately $800 million of liquidity at the end of 2021," Nikola Chief Executive Officer Mark Russell said in a statement. Shares of Nikola were down nearly 1.5% in premarket trading on Monday.