Humminbird SI also DI?

Newbie here...... I've been looking for a FF and the humminbird SI (500 or 300 series) is where I'm heading, but I can get away from the DI. During my research I read somewhere that you can download DI capabilities for free online? Has anyone heard about this?

Comments on Lowrance instead?

While I'm asking, any reccomedations for a battery if I pick up a 500 series?

Thanks!

If they are anything like the lowrance models the transducers are different, so I don't see how you could download Di capabilities.  As far as hummingbird vs. lowrance everyone has brand loyalties based on experience.  I am a lowrance guy and just recently went with the elite 4 combo.  I got standard as opposed to dsi as it has certain limitations.  Get a sealed lead acid battery, and they will run for days on a single charge. 

Ok, I've emailed humminbird. I'll update this when I get a reply. Thanks for the help, I appreciate it.

I had a early SI Humminbird FF, I could have downloaded and upgraded the SI to DI but never did.  You cannot upgrade a non SI or DI to make it SI or DI if that is what you are asking, for one thing the transducers are very different between the non SI/DI and Si/DI units.
If you have the room get a 10 amp 12 volt battery because the DI/GPS/FF color units will draw more from the battery than a basic FF unit.