[JRP3]

I don't know the actual efficiency losses of the hydrostatic setup but it certainly would be a lot easier and cheaper to use it than multiple motors and controllers. Efficiency losses could possibly be made up by just using an extra battery. Lithium would be neat but probably not cost effective.
Regarding creating another forum for unusual vehicles, I don't think there is enough demand, even though I own one myself. The occasional oddball can hang out here in All Conversions and not feel like an outcast

 

[JRP3]

Tried following your link but it appears to be broken .

Wasn't actually my link, just some automated feature of the forum that creates links for certain terms. Annoying.

I am also interested in the maintenance issue. With brushless electric motors, there would be few issues in that department. The system would also be more straightforward (battery->controller->motor->wheels) instead of (battery->controller->motor->transmission->wheels).

Actually you'll need two controllers since you'll be sending different signals to each motor when turning if you don't use a transmission. Maintenance on brushed motors would not be a real issue in normal service.

Plus transmissions take up space-> space I could use to add more batteries to the mower perhaps?

True. You really need to figure out how much run time you need and how much battery it's going to take.

 

[JRP3]

Here are some wig wag pots, they also have hall effect versions:
http://www.tecknowledgey.com/catalog/default.php?cPath=54_55&osCsid=f9dc9165cb26880b4ce3de251a48d6b0

 

[JRP3]

That might be a good application for a swappable pack so you don't carry around excessive amount of batteries. How many gallons of gas does a mower use in three hours? That should give you an idea of the kwhs you need in a pack.

 

[JRP3]

Also: BMS...ERRRRG!

Or not.....

 

[JRP3]

I've never seen a large format LiFePO4 cell exploding without a BMS. I'm running my CALB 100's with no BMS.

 

[JRP3]

First step is to get a closely matched set of cells. Then balance them, either top or bottom balance the pack, benefits to each method, the more closely matched your cells are the less it matters which you use. Finally, don't charge or discharge them to the max, which you should avoid with or without a BMS to maximize life. If you want a simple monitor you split monitor both halves of the pack, any differences between halves denotes a problem.