Battery Chargers, Safety, and a FlyBack Burnup

[Stu Jackson]

Jeff, that idea that he used wire that was available sounds reasonable - horrible choice of colors though.  Many chargers have multiple outputs (like the one I linked to yesterday) for just what you described - multiple banks being charged from one charger without a combiner or echo charger or relay of some kind.  The "turn it on with the outlets" is actually not a bad idea, since it puts a switch in the power to the charger.

I suggest confirming how the charger output actually does go to the batteries.  Please explain your battery setup: two single batteries 1 & 2, or a multiple battery house bank with a single start battery; and any other things you can share as to how you manage your battery banks with the 1-2-B switch.

Good feedback, we're on the right track...

[Sundance]

I have a very simple set up, only have two single batteries.  I took a quick stab at a diagram showing what I remember.  I will verify this weekend.

[Stu Jackson]

Jeff

That looks like a "normal" installation.  Since the PO used A.C. wiring for the wires from the charger to the batteries, you can either replace them or carefully label them to avoid confusion in the future.

If you're going to replace your charger anyway, that would be the time to replace the wiring from the charger to the banks.

[John Langford]

Some questions re the TrueCharge 20+ which I just installed to replace the smoking PorMariner Flyback 20 (possibly named because if Kate and I hadn't been there to turn it off when it began to catch fire, we would have had to FLY BACK home from Friday Harbor).

First, the Xantrex manual recommends that the chassis of the charger be grounded to the boat's negative buss bar. The ProMariner was not grounded and there is no indication in our schematic diagram for the boat that this is required or recommended. Is grounding necessary or even advisable?

Second, the Xantrex manual recommends that 30 amp breakers and disconnect switches be located in the positive cables between the charger and the batteries. Again, I have never seen anyone do this and can't sort out why it would be necessary. Gave the ABYC guidelines changed recently to make these additions recommended or even mandatory?

[jmnpe]

John,

As I noted in a recent post on this subject, all of the Truecharge+ chargers have internal fuses on the output lines that I can attest work quite well, so I wouldn't worry too much about additional inline fuses.

The case of the charger should actually be grounded to the "green" buss of the AC wiring. In fact, on many/most boats in the US, the "green" AC ground gets connected to the DC ground at some point, so I guess it is essentially the same. I personally  "feel" better grounding the case to the AC "green" ground, even if it eventually gets connected to the DC ground as well...... Call me silly.

John

[Robert Mann]

I will say that after setting this one in motion I have learned a great deal.  New Truecharge 40+ is working nicely.  John Nixon is correct overheating batteries are a sign of problems.  But a pair of new, nicely charged 4Ds will get WARM on the sides so don't panic, check the water regularly.  The obsessive part of my character took over last week, and I have a nice set of terminal voltages readings plotted against time with various lights, fan and fridge combinations.  Check it out with a digital meter some rainy afternoon and you will learn a lot about 3 stage chargers algorithms an the points bulk, absorption and float rates switch over.

[Ron Hill]

John : I don't have my Truecharge 20 manual handy, but I have a 25amp fuse on each of the 3 positive leads to the 3 batteries.
I didn't ground the case of the charger to the negative buss, but did run the 1 negative wire from the charger to the furtherest negative battery pole.   

[jmnpe]

Ron,

That's actually better than the recommended 30 amp fuses because the internal fuse on the 20+ is a 30 amp fuse on each output line. If you are going to have external fuses, you would rather have them blow before the internal fuses blow. The external fuse is probably easier to get to for changing.

The internal fuses are actually pretty easy to change once you know the "secret handshake"..... The trick is in knowing which screws to take out so that you can slide the whole assembly out of the case to get to the fuses. If I can find the data that the factory sent me several years ago, I'll post it on here.

John

[Ted Pounds]

Ron,
If you hooked up the green AC wire and your boat is wired properly (which I'm sure it is) then the case is grounded to the neg battery bus via the AC ground.