Spring Commissioning Surprises

[NorthernFocus]

Better to find surprises during spring commissioning than mid-season out on the water. It seems like every year I find something that I'm amazed by.

Yesterday I was installing one new battery and cleaning up/greasing connections while I was at it. I noticed the main cable that ties all the batteries to the ground buss had a kink it it right at the terminal lug. It was heavily taped so I couldn't tell if it was failing/corroded or what so decided to give it a tug to test the mechanical integrity. The cable came away in my hand leaving the lug attached to the terminal. The lug and the cable looked like new with virtually no corrosion on them. Apparently it was just never properly crimped on installation. It had been taped with the heavy, rubberized tape used for high voltage connections. Hard to believe this had not caused a problem last season. The tape was basically holding the cable in contact with the lug. Had it caused problems on the water it would have been a real bugger to troubleshoot taped up as it was.

Moral of the story, there's a reason for doing this stuff at start of season. Don't just go through the motions. This also prompted me to add a second connection to the ground buss at the other end of the battery ground daisy chain.

For the record the boat was six years old when we bought it so I have no idea whether the cable in question is original factory install.

 

[Paul Elliott]

This also prompted me to add a second connection to the ground buss at the other end of the battery ground daisy chain.

This second ground connection *may* cause uneven charging and discharging current-sharing among the paralleled batteries. Typically the positive and negative cables are connected at opposite ends of the battery bank daisy chain to ensure current balance. I couldn't guess the imbalance caused by the second ground -- perhaps it's not significant in a small, physically close bank?

 

[NorthernFocus]

... Typically the positive and negative cables are connected at opposite ends of the battery bank daisy chain to ensure current balance...

Wasn't aware of this. What does "opposite ends" mean? Does that mean if two Batts sitting side by side are in parallel with jumpers the load and ground should be landed on opposite batteries?

 

[BB marine]

Parallel batteries are wired with neg to neg, pos to pos the load cables Pos and neg come off the same battery and it works fine. The preferred way is to Have pos load cable come off one battery and Neg load cable come off the battery at the end of the chain. This is called Equalizing the battery bank it balances the voltages. Not really necessary in a parallel bank but some say it is preferred way.

 

[NorthernFocus]

...This is called Equalizing the battery bank it balances the voltages. Not really necessary in a parallel bank but some say it is preferred way.

Yeah I guess as in most things there's theory and there's practice. I'm betting eight inches of 1/0 cable between parallel batteries isn't enough resistance to cause a meaningful imbalance.