I've got one of these Noma units as shown, and I'm hoping someone else can find their manual for it. I surely can't find mine.
(https://www.ovas.ca/forum/proxy.php?request=http%3A%2F%2Fa116.g.akamai.net%2F7%2F116%2F8068%2Finfinite%2Fwww.canadiantire.ca%2Fmedia%2Fimages%2Fproducts%2Fimages%2FAssortments%2FPrimaryAssortments%2FAutomotive%2FPortablePower%2FPowerPacks%2F0111817_160_CC_v1_m56577569830822479.jpg&hash=087b3cbb0f228675103559546a3f83a4c4cc82d8)
If you've got one, can you tell me what -1 on the display means?