T-Pain Is On A Boat: Re: [electricboats] Power in and out of battery bank

Friday, September 29, 2023

Re: [electricboats] Power in and out of battery bank

Hi Richard,

A fuse is a good idea. BTW, industrial motor controllers here in the States usually have a fuse (or breaker) _and_ an 'overload.' Overloads are specialized devices designed to sense the long term heating of the motor's windings and shut off the motor if it's getting too hot. It might seem redundant but, the fuses and breakers are typically rated well above the maximum current that would burn the motor. Really they're more to protect the wiring than the motor. You probably have a fuse and an overload _in_ the controller.

However, fuses and breakers are over_current_ protection. The overvoltage protection is a different mechanism. It might be that the overvoltage causes an overcurrent situation, but it's probably not good practice to count on that. The voltage rating is more related to the wire's insulation breakdown rating than the wire's size.

If you're asking these questions you're probably already well on your way to a good setup. Fair winds and following seas amigo!

On Thursday, September 28, 2023 at 07:00:32 PM CDT, Richard Holden <richard.holden@softmachine.co.nz> wrote:

Thanks for all the feedback folks - really appreciated it from down here in New Zealand, and now seems very obvious when explained correctly.

With the comment about driving the motor supply to too high voltage. I was concerned about that and set a 100amp fuse between the motor controller and the battery - and I did once pop that reset fuse in a panic. I figured that the motor could draw 208 amps (10K motor / 48-volt system ? ) - which may kill or maim the close-cell electric car batteries - so I set up the fuse. Not sure if this is a great idea or a fail.

Cheers again - really enjoy the information I get from the experienced minds in this group

Richard

On Fri, 29 Sept 2023 at 06:29, Dave Yamakuchi via groups.io <dyamakuchi=yahoo.com@groups.io> wrote:

Just make sure you're not driving the motor's supply to too high a voltage. Generally, you won't and often actually can't have this problem. The only way you might get into trouble is if there's not a proper charge controller with over-voltage protection between the charging system and the motor _and_ you're charging the batteries up to 'full.'

Note: it's really the same problem if you don't have a good controller charging the batteries even _without_ the motor. Charge applied to a 'full' battery can overcharge and damage the cells. The charge controller/balancer makes sure your cells don't get overcharged. That's one of it's jobs.

As an example: On MinnKota 12V trolling motors, the Max voltage allowed is 13.6V This is actually lower than the 14+ volts some chargers will apply to fast charge a 12V battery. This would be a problem. IDK the max allowable for _your_ motor, but if you're charging with potentially more power than the motor can draw, you can end up significantly higher than the nominal 48V. Just make sure your motor is cool with whatever might happen worst case...

On Thursday, September 28, 2023 at 01:24:47 AM CDT, Thierry <thierry.lequeu@gmail.com> wrote:

Just to clarify: you can!

There's no problem charging the battery and using the motor at the same time.

The only risk I see is that if the motor is regenerated (charged via the motor) and via a charger, the battery voltage may rise without "control", and even then... the charger will stop, and if the motor's speed controller is properly adjusted, regeneration will stop too!