Lesson learned battery charger

[flounderpounder225]

Thought I would share this, I consider myself a pretty good electrician, but this shows how something can be overlooked when your just cruising along on an install and I guess I forgot to slow down and look.  So maybe this will help someone else down the line.  A few years back I installed my onboard DELTRAN battery charger, which only has one output, but plenty of capacity to trickle and float charge two batts.  Well this past Sunday I went to take the boat out and when I went to start the engine at the house it wouldn't crank, electronics were all beeping low voltage warnings etc.. So I switched batts on my perko switch... Same thing... Both batts dead!  Strange I thought.  So I pulled them out popped in my spare, and put one of them on charge for a while.  Then went to discover why both batts were down.  Well for one thing, the electrolyte was low in both batts I guess from the charger consistently on, and I was lax in checking them.  Then I saw it... When I installed the charger, I went to the Postive post on one batt, and ran a jumper lead to the other positive post... Duh....   I functionally eliminated the battery switch, because both + terminals were connected and drawing both batts down at the same time.  I realize the correct way would have been to connect the one output lead from the charger to the center output post on the perko switch, and put the switch in ALL if I wanted to float both batts at the house while on the trailer.  Will be fixing it this week...

[John Jones]

You aren't the first to do something like that and won't be the last either.  

I have found that onboard chargers seem to require more frequent water checks.

[seabob4]

Yes, Marc, you in effect eliminated the batt switch!  Let's see if I have a drawing of a single engine/dual battery set-up...

Well, close as I can get.  Note the only jumpers are between the battery grounds...

[wingtime]

What I want to know is what gauge wire was that jumper?    I had to be pretty heavy or it would have over loaded on ya.

[MarshMarlowe196]

Thanks for sharing that... seems like an easy mistake I could see myself making (again.. ) This reminds me, I need to check my troll motor battery fluid level.. It's been getting a little weak.

I realize the correct way would have been to connect the one output lead from the charger to the center output post on the perko switch, and put the switch in ALL if I wanted to float both batts at the house while on the trailer.  Will be fixing it this week...

That's a good idea.  I don't have an onboard charger, so I connect the leads from a battery charger to my house battery then set the switch to all.  Does this work too?  There's times when I wont use my troll motor battery for a few trips in a row, so I can't tell.

[seabob4]

Yes, Jess, if you have a single bank charger (one set of output leads), you can attach the leads to the start batt (or whatever), then turn the switch to "ALL".  Will take a while, but both batts will charge...

[flounderpounder225]

Well checked the batts tonight, both that were in the boat are toast, one dropped to 8vdc when loaded with my carbon pile tester, the other went to ZERO   .  And of course the batts are 35 months old in a 36 month warranty.". $9.00 ea back towards a new one, at least I had a new one in the shop as a spare, so only need one.  As I say, an education is never CHEAP, or easy, oh well :smurf:   As far as the size of the jumper that was on there, I think it was about 10 gauge, but it wasn't really carrying any load other than the charger output, the big #2 carried the system load.