Jump to content


Photo

Boiling Batteries


  • Please log in to reply
52 replies to this topic

#31 harrytom

harrytom

    Advanced Member

  • Advanced Members
  • PipPipPip
  • 1,021 posts
  • LocationAuckland

Posted 02 January 2018 - 11:12 AM

OK, so a (very) rough calculation then, fridge 25 amp hour, lights say 3 hours, 3 amps total draw say 10 amp hours. That's 35 amp hours per day. So that's a min 70 amp hour battery - I'd go for a 100, provided it will fit in your battery box.
Also, consider your charging - the last 20 percent of charging takes hours. Many cruisers only ever charge to 80% for this reason, unless on shore power. The 100amp hour battery gives you that ability.

got a new 120ah battery today ,so will be taking care of it,no cranking,have a good crank onboard.


  • 0
The boss said "see you in the morning"didnt know he liked sailing

#32 carpenter29

carpenter29

    Member

  • Members
  • PipPip
  • 45 posts
  • LocationGulf Harbour

Posted 04 January 2018 - 09:14 AM

I'd like to add that the battery computer needs to be correctly installed -, the shunt being the first connection on the negative lead - NO other wires direct to battery negative. Then it needs to be correctly programmed - battery type and capacity, reset current (circa 1% of capacity), proper purkets factor for that battery etc.
The purkets factor for that battery and the correct charging voltages will be given on the product data sheet, and sometimes on the side of the battery.
Not to do all this means the battery computer will not be accurate, possibly by so much its useless. In my experience 90 odd percent of them are not set up correctly.
Personally I use VRSLA batts (sealed) so I don't have to worry about electolye levels.
Remember, never discharge below 50%,recharge asap to full, use float charge systems, and you'll get 10years or more from your batts. .
Don't do this and you'll kill them early.


Hi IT,
I have a BEP Matrix on mine and it appears to be wired up as you describe (negative lead to the shunt first), with the exception that the wires from the solar panel regulator go direct to the battery terminals (so it still charges when the batteries are isolated). should the negative from the solar panel battery go to the shunt instead of the terminal? And if so which side of the shunt?
Cheers
Paul
  • 0
Boat is in Gulf Harbour. Working in Wellington

#33 island time

island time

    Advanced Member

  • Administrators
  • 5,283 posts
  • LocationHome from Cruising, Now Gulf Harbour

Posted 04 January 2018 - 09:41 AM

Hi Paul, absolutely yes.
But isn’t the matrix a tank monitor? Did you mean a dcm 600?
In your setup as is, the computer does not know about the solar panel. They should be wired to the load side of the shunt ( not battery side), and they should be fused. The power for the meter should also be on full time.
The new draft electrical standards for nz boats (not -yet- law) require batteries to be fused with ignition protected fuses, so a fuse is also ok as first thing from + terminal, and the solar + to the load side of that.
That’s what I have + terminal to fuse to always on bus distribution ( solar, wind gen, bilge pumps, battery computer ) then to mains switch ... all the things on the always on bus also have their own fuses of course, that battery fuse is way to big and slow to blow for them!
  • 0

There is nothing, absolutely nothing, half so much worth doing, as simply messing about in boats


#34 carpenter29

carpenter29

    Member

  • Members
  • PipPip
  • 45 posts
  • LocationGulf Harbour

Posted 04 January 2018 - 10:14 AM

Hi,
The monitor is a BEP Matrix DC monitor - so not a computer - monitors voltage for house and engine batteries, shows amps charge or discharge, and shows a percentage of remaining capacity. The solar panel has a MPPT Controller then to the battery. Seems to work okay, but I’ll move the negative to the shunt.
The shunt seems to have a negative from the house battery on one side and a negative from the engine on the other side of it, with a smaller wire heading up to the monitor - does that sound right?
  • 0
Boat is in Gulf Harbour. Working in Wellington

#35 island time

island time

    Advanced Member

  • Administrators
  • 5,283 posts
  • LocationHome from Cruising, Now Gulf Harbour

Posted 04 January 2018 - 10:34 AM

OK, that is a dcm600, and it is a battery monitor computer. What I said above stands.
Move the engine neg to the load side of the shunt, There should be NO other connections on the battery side of the shunt, except the main cable to the battery, and, on the small screw terminal, the neg sense wire for the meter. Nothing else to the terminal either. Loads must pass thru the shunt to be seen by the monitor.
So your battery monitor, like most, wasn't installed correctly, and was telling you lies!
Once the wiring is fixed, check the programming!
  • 0

There is nothing, absolutely nothing, half so much worth doing, as simply messing about in boats


#36 carpenter29

carpenter29

    Member

  • Members
  • PipPip
  • 45 posts
  • LocationGulf Harbour

Posted 04 January 2018 - 10:43 AM

Thanks, just checked - engine battery is on load side, house negative is on the battery side. So I just need to put the solar neg on the load side to have it seen by the monitor, is that correct?
  • 0
Boat is in Gulf Harbour. Working in Wellington

#37 island time

island time

    Advanced Member

  • Administrators
  • 5,283 posts
  • LocationHome from Cruising, Now Gulf Harbour

Posted 04 January 2018 - 12:15 PM

That and move house neg to load side too.
Again, battery neg to shunt. NOTHING ELSE ON THE BATTERY TERMINAL, OR BATTERY SIDE OF SHUNT. The only exception is the neg sense wire on the little screw terminal for that purpose on the battery side of shunt.
  • 0

There is nothing, absolutely nothing, half so much worth doing, as simply messing about in boats


#38 carpenter29

carpenter29

    Member

  • Members
  • PipPip
  • 45 posts
  • LocationGulf Harbour

Posted 04 January 2018 - 12:30 PM

Thanks- one more question if you don’t mind. I’ve been looking at the VSR and noticed that the wires going from the VSR to the battery isolator switches are quite small in diameter - about 6mm, certainly not battery cable size. Could this affect charging efficiency when the motor is running?
  • 0
Boat is in Gulf Harbour. Working in Wellington

#39 island time

island time

    Advanced Member

  • Administrators
  • 5,283 posts
  • LocationHome from Cruising, Now Gulf Harbour

Posted 04 January 2018 - 12:44 PM

Yes. Vsrs should have cable appropriately sized for their rated throughput and length. What amp rating is the VSR, and how long are the cables (battery isolator to VSR to the other battery isolator)?
Sometimes, if one battery is full and the other low, a lot of current can flow via the VSR.
  • 0

There is nothing, absolutely nothing, half so much worth doing, as simply messing about in boats


#40 carpenter29

carpenter29

    Member

  • Members
  • PipPip
  • 45 posts
  • LocationGulf Harbour

Posted 04 January 2018 - 12:53 PM

Only about 600mm. It’s a 140 amp model
  • 0
Boat is in Gulf Harbour. Working in Wellington




0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users