Saving your Batteries

[Dockhead]

So, I'm in the midst of paying dearly for having ruined my batteries last year. It happened when I -- for the first time in my life -- started keeping my boat on a mid-river pontoon with no shore power.

I've just ordered a Rutland 914i wind generator with mounting kit and digital regulator (Ka-ching! Read: $$$).

Next, I need to order eight service batteries and one start battery (for the genset). (Ka-ka-ching!). Try to do that this evening, but I'm struggling a little over the choice of batteries (I'd like to buy some Trojans but they don't seem to fit in my battery boxes, which were designed for Varta 110ah "hobby" batteries).

After that, I'm finally going to wire the shunt for my battery monitor correctly so I can accurately measure current in and out.

And I'm going to finally program the low battery alarm on the monitor (Victron 601).

I suppose that ought to do it -- if I have some small leakage, the wind gennie ought to make it up besides keeping a trickle charge on the batts.


It occurred to me, however, that our expensive battery banks don't have one thing which every $50 cell phone and netbook has -- a circuit to take the battery off line after it reaches a certain level of discharge. And here is the real point of my post -- why not? It seems elementary to want to protect $1600 worth of batteries from being drained to destruction.

My Victron battery monitor has a programmable relay which is activated when the voltage falls below a set level. I suppose I could put big relay into my main ground connection to my battery bank and just blow the ground via the Victron's relay, if the batts fall below a certain level, protecting them from destruction. Why aren't all of our boats set up this way? Anyone do this?

I do have relays to isolate the battery bank when I leave the boat, but there is quite a bit of gear which is wired upstream of those relays -- bilge pumps, toilet, and I'm not sure what all else.

My batteries were ruined last year when a bilge pump went into a feedback loop pumping and repumping the same water.

[stevensuf]

Non return valve! or two linked bilge switches at different heights will stop the cycle.

As for the voltage cut off, youd need a more solenoid type of relay as it will need to switch 100a plus.

lastly, disconnect the battery ground when you go away if you really don't want any drain at all, other than the self drain of the batteries themselves!

[CarlF]

I bought a GSM alarm off of Ebay to address the battery worry. It sends a text message to my phone if the battery falls to a certain level. It also sends me a daily text message that shows voltage to 0.1 volts. I can watch for worrisome trends.

It also reports temperature in the boat. I added a bilge water alarm and a motion detector that has its own batteries.

In the US, the sim I use cost me $0.10 per text with no monthly contract or minimum. I rather enjoy receiving the daily "Hello" from my boat.

This is the one I bought although there seem to be many options. Battery drain is minimal.

GSM SMS Car Battery Voltmeter Voltage monitoring alarm Voltage Indicator Monitor | eBay


Carl

[Dockhead]

Originally Posted by stevensuf

Non return valve! or two linked bilge switches at different heights will stop the cycle.

As for the voltage cut off, youd need a more solenoid type of relay as it will need to switch 100a plus.

lastly, disconnect the battery ground when you go away if you really don't want any drain at all, other than the self drain of the batteries themselves!

Yes, I've solved the bilge pump problem in the mean time

And yes, I understand the need for a solenoid. I actually already have a solenoid, it's just that too much stuff is wired upstream of it. Now I'm thinking that maybe it would be better practice to rewire that stuff downstream of the solenoids and carefully analyze current leakage, instead of putting a new solenoid into the ground.

100 amps would be little on my boat! I have a 10hp bow thruster that will suck down 400 amps and more -- at 24 volts! -- just by itself! Any new relay will need to be 600 amps, which will be a pretty chunky piece of kit.


Anyway, anyone do this? Anyone able to articulate any reason why it is not commonly done?

[Hyprdrv]

A lot of questions for you dockhead,
First off typically how long are you away from the boat?
What are your loads when off the boat? Frig, all those monitors, parasitic loads?
Yes the WG should help or eliminate the losses.
The thing about completely shutting down the power is your sump pumps. These are connected directly to the batteries right? Loosing the frig contents is cheaper than the battery bank and probably the largest draw of things just left on on most anchored out boats. I just shut everything off in the winter. If this isn't your case then are the batteries getting fully charged before you leave?
You mentioned your start battery, is it separated from the house pack?
There's a good string on the Lithium batteries as a house bank her at the site. CACACACA CHING!!!

Steve in Solomons MD
Lagoon 410 SE

[stevensuf]

I'd be more inclined to use a 40w or so solar panel for battery maintenance, lot less likely to fail than a wind gen, now a 600amp solenoid ,that would be one hell of a beast and a very large wiring job as well.

[btrayfors]

The normal approach is to use a good regulator on a charging source which will maintain the batteries at float level (13.4-13.6VDC for a 12V bank). This is true of alternator regulators, solar regulators, battery chargers and, of course, wind generators.

You must find a way to take that puppy off-line, otherwise you'll burn up your new batteries. There are several ways to regulate the output from a wind generator. You can't just disconnect them...that can destroy them. You have either to physically stop them from turning (e.g., with a brake) and/or have a means of diverting their output (e.g., to a 12V coil in a water heater).

Absent such a regulator for your new wind generator, the best option would probably be to physically stop it and then disconnect it whenever you leave the boat.

BTW, the Victron is an excellent little battery monitor. But, don't believe what it tells you implicitly until it has been properly calibrated and recalibrated as your new batteries are exercised a few times and gain their rated capacity and until you've got some experience with it. After that, it's a wonderful tool.

Bill

[stevensuf]

I think the rutland 914i is a trickle charger ,a couple of amps max. mind you into 8 batteries youd hardly need a regulator!

[btrayfors]

Originally Posted by stevensuf

I think the rutland 914i is a trickle charger ,a couple of amps max. mind you into 8 batteries youd hardly need a regulator!

No, sorry, it's no trickle charger. It can put out 18A @ 16 knots windspeed, and it costs about $1,000 new. Plus a $300 controller. Not something you'd pay for a trickle charge :-)

Bill

[CarlF]

With a little cleverness, you could wire one of these relays to a voltage monitor. These are great because they let you minimize wire length by putting the battery switch so as to minimize wire length but the control switch where it's easy to reach. I have one of these wired for my both thruster because the batteries are in the bow. I turn it off whenever I am not expecting to use the thruster.

ML-Series Remote Battery Switches (Magnetic Latch) - PN - Blue Sea Systems

Carl

[stevensuf]

my mistake its the 504 thats the trickle one

[stevensuf]

Nb if i remember right you can get voltage sensitive relays, possibly one of these wired to a solenoid

[stevensuf]

Google low voltage sensitive relay

[Dockhead]

Originally Posted by btrayfors

The normal approach is to use a good regulator on a charging source which will maintain the batteries at float level (13.4-13.6VDC for a 12V bank). This is true of alternator regulators, solar regulators, battery chargers and, of course, wind generators.

You must find a way to take that puppy off-line, otherwise you'll burn up your new batteries. There are several ways to regulate the output from a wind generator. You can't just disconnect them...that can destroy them. You have either to physically stop them from turning (e.g., with a brake) and/or have a means of diverting their output (e.g., to a 12V coil in a water heater).

Absent such a regulator for your new wind generator, the best option would probably be to physically stop it and then disconnect it whenever you leave the boat.

BTW, the Victron is an excellent little battery monitor. But, don't believe what it tells you implicitly until it has been properly calibrated and recalibrated as your new batteries are exercised a few times and gain their rated capacity and until you've got some experience with it. After that, it's a wonderful tool.

Bill

Thanks, yes, I bought the expensive digital Rutland MPPT regulator to control the wind turbine - it will shut the turbine down when its services are no longer required.

[Dockhead]

Originally Posted by Hyprdrv

A lot of questions for you dockhead,
First off typically how long are you away from the boat?
What are your loads when off the boat? Frig, all those monitors, parasitic loads?
Yes the WG should help or eliminate the losses.
The thing about completely shutting down the power is your sump pumps. These are connected directly to the batteries right? Loosing the frig contents is cheaper than the battery bank and probably the largest draw of things just left on on most anchored out boats. I just shut everything off in the winter. If this isn't your case then are the batteries getting fully charged before you leave?
You mentioned your start battery, is it separated from the house pack?
There's a good string on the Lithium batteries as a house bank her at the site. CACACACA CHING!!!

Steve in Solomons MD
Lagoon 410 SE

A month max (I live four time zones away from the boat ), fridge always off. Bilge pumps (four of them) plus any leakage.

Start batts (two of them - prime mover pus genset) are totally separated from the 24v house bank consisting of 8 110ah 12v batts. The start batts even have their own alternators and separate chargers.