Thinking (POSSIBLY) of adding a small battery box to my 16HP LT. That way the battery system will be on the motor and I wont have to have the wires hanging down into my boat, and have my marine battery in the back of my boat. The box will be all aluminum angle and covered in aluminum sheeting and welded, with a cover to keep it dry. kind of like saddle bags on a motorcycle. Gonna either use a lawn mower battery, or a motorcycle battery (to save weight/space).

Question is would the extra 5-15 lbs greatly affect how the motor works given the location I want to mount them in?

Here's a few pictures so you can kinda get the location I am thinking of placing them.

Am I crazy?

Yes your nuts leave it alone!

It would definetly throw out the balance and make it uncomfortable to drive.

reach down on the floor, pick up your brain, and put it back in your head.

leave the battery in the boat.

Don't let these guys discourage you. Every mudmotor owner is sure he has ideas and modifications that will make them run better. (I'll let you decide what better means) Some of these ideas actually make it into production....most don't. I've tried dozens of wonderful ideas and actually have implemented a few, but I've never failed to learn from each one.... even the failures.

i would think after hitting a couple stumps that the weight and this shit being beat out of it would break the welds imo.. then youd have no batterie at all.. if you do go throuh wth this... leave an extra in your boat

I would bet with the added weight on the tail it would make it more difficult to do turns as I think the balance would be off and the prop will want to run deeper. Only one way to find out though... go for it. You can always take it back off if it dont do what you want or expect...

Balance will be the biggest issue. The handle/motor is made to "float" as the motor is running. I would assume the extra weight will negate any free floating the motor does while being operated. If you have ever gotten any trash on top of the cavitation plate while operating the performance changes... I would assume the same will apply if there extra weight added from a battery box, even though it is a little further up the drive shaft. The extra weight will also create more torque on you when turning. Not saying don't do it, just think about all the possibilities revolving around the potential change.

Personally, I agree with the others that think putting the extra weight back there will throw off the balance and make it much harder to maneuver and drive. I guess the real issue for me would be where do you run your motor. If you are in shallow lakes and ponds and using the motor just to get through veggies it probably would be fine. If you use your motor in areas where you would be regularly striking stuff and having the back end kick out- I can't imagine it would stay on there long no matter how well it is welded. I have several feet of fuel line looped below my motor so there should be no problem with rotating the motor around for trailering and hit a stump last weekend so hard the motor kicked out and sheared the fuel line where it got momentarily caught on something. There are multiple stories on here of guys getting thrown right out of their boats when the motor kicks up from hitting something. You put a battery in a box back there with that kind of force being thown around and just don't think it will stay put for long- just my opionion though.