As I said before, depending on how the system works (I havn't seen a wiring breakdown) It could cause a short through the US2 and depth finder. At your request, this is how. The US2 is internally grounded to the trolling motor ground and the depthfinder ground, giving an electrical path from trolling motor negative to cranking negative. Say the trolling motor is fed by battery 1 negative. To get 24V, battery 1 positive is jumped to battery 2 negative. If a connection is made from the cranking battery negative to battery 2 negative (to jump batteries they are put in a parallel connection - pos to pos and neg to neg), this would be the same as connecting to battery 1 positive due to the jumper and would cause a direct short when the trolling motor is activated. Hope this helps, explain.
John

Z-8 from what I can tell by sketching it out, as explained by Jones Trolling Motor. A short exists if you choose the wrong battery from the (trolling motors two series connected batteries) to do the jump to the (cranking battery). If the other t.m.'s battery to do the jump is used there is no short condition.

You have to draw it out in order to see. At least I did. Your Push button system evidently is wired up right and uses the correct trolling motor battery for jumping to.

After reading your concerns I have connected the system to all 3 of my trolling motor batteries and gave it a go to test it out. I even had my 11 year old hold the button while I ran the trolling motor with both my depth finders on and nothing happened. All I can say is when NMMA tests something I am pretty sure they cover every base possible.

Hope this helps but you may just have to try it out for your selves.

Thanks

Thanks for writing about the test you've done that seals the deal for me. I'm completely satisfied with my built in America tournament saver pro. I'll have one on every boat I ever own.

So now you need to check and make sure you didn't blow the fuse protection located in the head of the trolling motor. It is there to protect in case someone wired to the wrong battery.
However, the fact that you were able to keep running the trollingmotor while the button was pressed tells me the system does not disconnect the trolling motor wiring while it's boosting. Thanks for the test

Does anyone know if the internal short is needed for the depthfinder to work? Maybe it is just for shielding purposes to help eliminate interference. If so it could fry when things are hooked up wrong and you wouldn't know it. Depthfinder would still work but you would not have the shielding and possibley get more interference afterwords.

Something just isn't right about this whole thing because on paper if you draw the circuit the short does exist and something would blow or fry.

Jones, is there a way with ohmeter someone can check for the short to see if it still exists in their system.

The internal grounding is a "shunt" that is made internally by MinnKota to reduce/eliminate interference. It is connected to the ground lead going to the light, so that wire is only "active" when the trollingmotor is activated. Later models are fused in the head so if someone does connect the starter battery to the trolling battery, the fuse will blow and not burn the transducer/depthfinder. The circuit is very real and does exist.
John

So then Fire227 may have unwanted interference on his depthfinder next time he goes fishing if he blew that fuse?

It is possible

Ha Jones give me a call i would like to talk to you about this.
Eric Wendeborn 254-216-9578

Eric, I can be reached at 870 773-3474, if I don't get a chance to call.
John

ok thanks i'll call you in the morning

Did you two get together and resolve anything on how it works?
Inquiring minds would like to know.

We discussed the wiring and the US2 issue. Eric wasn't aware of the issues with US2 and grounding, but that didn't surprise me as I've seen boat dealers that install the trolling motors not be aware of it. In talking to him, the unit is completely disconnected from the aux battery til the button is pushed, Since the ground doesn't connect through the trolling motor til the light comes on (remember the ground is shunted by connecting the ground from the lowerunit case to the ground side of the light), there should be no short if the motor is not activated. What all this means, is based on what we discussed, the short would exist if the jumper was wired to the wrong battery and was activated at the same time someone was using the trolling motor. This situation could exist if the cranking battery was low enough that a partner was using the trolling motor to stay of riprap while the operator was cranking the outboard and the unit was wired into the "wrong" cranking battery.
As I told Eric, I wasn't trying to run down or condone his setup, the idea is good and I've been building these as requested from individuals for several years. I just wanted those running the US2 to understand possible problems that could incur. I hope this post helps.
John