Matt;

Gel cells are indeed lead-acid...it's just that the acid has been gelled as a result of some careful work by chemists...this results in the advantage of allowing the batteries to be mounted in any additude without having to worry about acid running out, but the dissadvantage that it does preclude hydrometer checks of the electrolyte...all the other rules still apply!...and this also puts further constraints on charging rate (too high and the hydrogen produced will expand and possibly damage the case...heat may also be an issue). I'm no battery expert, but you'd better become one...and if you're reading this, you on the best source for getting info!

...that's the problem with "sealed" batteries...they call them "maintenance free"...I call them UNMAINTAINABLE! Give me a normal battery with liquid acid and caps I can open to do a hydrometer check any day!

Cheers