Notices
Marine Electronics Forum

House Battery Depletion Warning

Old 11-15-2016, 11:50 AM
  #1  
Senior Member
Thread Starter
 
Join Date: Jun 2010
Posts: 4,458
Likes: 0
Received 27 Likes on 20 Posts
Default House Battery Depletion Warning

I'm looking for a device to give an audio/visual alert when the house bank has been depleted to
a low-enough voltage to cause shortened battery life (non-deep-cycle batteries).

I have seen these on Crown Vic police interceptors (R.I.P.), but one of our fleet managers told me he believed it was an integral feature of the heavy-duty alternator/regulator that comes with the police packages, mainly to insure the single battery would still be able to start the car after long periods of engine-off or idling with electronics (speed radar and mobile terminal, radio, etc.) running.

Anyone know of a stand-alone device that does this, preferably with an adjustable voltage threshold? I have heard that they are common with RVers, but my searches are not coming-up with anything suitable for a marine environment.

I don't want to have my eyes glued to a voltmeter, and would prefer an alert. I run AGMs for house bank, and don't want to over-discharge them, as that shortens lifespan.
Old 11-15-2016, 12:04 PM
  #2  
Senior Member
 
Join Date: Jul 2011
Posts: 8,554
Received 1,668 Likes on 1,265 Posts
Default

perhaps

http://so-bfd.com/

if you can find a waterproof location where you can still access it easily and hear the alarm
Old 11-15-2016, 12:46 PM
  #3  
Senior Member
Thread Starter
 
Join Date: Jun 2010
Posts: 4,458
Likes: 0
Received 27 Likes on 20 Posts
Default

Actually, their lower-priced one, "Low Battery Alarm XL" appears that it may actually be potted, and I really don't need an LCD voltmeter as several devices installed can do that.

The only thing I don't care for, is that voltage threshold has to be factory pre-set when ordering, and is not field adjustable.

What's a good minimum voltage for AGMs, without it becoming a nuisance alert?
Old 11-15-2016, 12:57 PM
  #4  
Senior Member
 
Join Date: Jul 2011
Posts: 8,554
Received 1,668 Likes on 1,265 Posts
Default

I'm no battery expert, but from what I've read,

regardless of the type of lead acid battery, going below 11.9 is going to cost you in longevity,

and below 11.6 really hurts

"A battery that is discharged to 10.8 volts regularly and then recharged can expect to get 354 charging cycles out of the battery. A battery that is discharged to 11.6 volts regularly and then recharged can expect to get 900 to 1000 charges out of the battery"
Old 11-15-2016, 04:59 PM
  #5  
Senior MemberCaptains Club Member
 
Join Date: Aug 2006
Location: marblehead
Posts: 2,398
Received 65 Likes on 52 Posts
Default

I just set the voltage alarm on my Garmins to alert me of low voltage.
Old 11-15-2016, 05:55 PM
  #6  
Senior Member
Thread Starter
 
Join Date: Jun 2010
Posts: 4,458
Likes: 0
Received 27 Likes on 20 Posts
Default

Helpful information.

In car starting batteries, which never really get discharged, I generally get 8 years out of a "no maintenance" battery, whatever they even are...not marked AGM, and have removable caps, and water may be needed every few years, but only if the color of the inspection "eye" changes.

All mine have been OEM Japanese batteries, mostly Panasonic, but I get nervous around the 8-year point, and replace proactively, if I still have the car that long. Being in a cool climate is a huge advantage toward battery life, compared to Florida, for example.

But, I also have an AGM starting battery on my portable Generac, which is 14 years old, but is maintained all year on a tiny 300ma smart maintainer (Yuasa brand).

Trying to avoid unintended abuse of the boat house bank, since I'll often sit on the hook for hours, with some electronics on.
Old 11-15-2016, 06:48 PM
  #7  
Senior Member
 
Join Date: May 2014
Posts: 2,078
Received 23 Likes on 16 Posts
Default

Your MFD should be able to do that for you without needing a separate device. You should be able to select to the nearest .1 volts.
Old 11-15-2016, 09:00 PM
  #8  
Admirals Club Admiral's Club Member
 
Join Date: Mar 2011
Location: Canada
Posts: 3,975
Likes: 0
Received 337 Likes on 282 Posts
Default

the MFD voltage will be lower then the battery voltage.

get a battery monitor like a victon 700. there should be no need to to wait for a waming. you should know hours or days ahead where you batteries are, what your loads are, and how long they will last. and prepare. not react.

some of the battery monitors have a buzzer output as well. not sure if the victron does. the xantrax does I think
Old 11-15-2016, 09:09 PM
  #9  
Senior MemberCaptains Club Member
 
Join Date: Feb 2003
Location: M.Vineyard, MA
Posts: 16,420
Received 983 Likes on 761 Posts
Default

There are some more active auto-disconnects here:

https://www.waytekwire.com/products/...e-Disconnects/

But some electronics may not appreciate a sudden cut-off.
Old 11-16-2016, 08:43 AM
  #10  
Senior Member
 
Join Date: May 2014
Posts: 2,078
Received 23 Likes on 16 Posts
Default

Originally Posted by smac999 View Post
the MFD voltage will be lower then the battery voltage.

get a battery monitor like a victon 700. there should be no need to to wait for a waming. you should know hours or days ahead where you batteries are, what your loads are, and how long they will last. and prepare. not react.

some of the battery monitors have a buzzer output as well. not sure if the victron does. the xantrax does I think
It should be very close, but even if its off, it doesnt matter. You just adjust the MFD voltage alarm setting to what ever voltage you want. Measure the battery voltage with a DVM, then compare that to the MFD readout and adjust accordingly.
Old 11-16-2016, 09:29 AM
  #11  
Senior Member
Thread Starter
 
Join Date: Jun 2010
Posts: 4,458
Likes: 0
Received 27 Likes on 20 Posts
Default

Originally Posted by Fwpratt View Post
perhaps

http://so-bfd.com/

if you can find a waterproof location where you can still access it easily and hear the alarm
The company responded to my inquiry, and said the devices are not splash-proof and not designed for high humidity locations either.

If I can find a suitable schematic, I will build one. I can fab printed circuit boards and cover the completed board with conformal coating. I've been out of the business for decades, but this is something I could have designed in 5 minutes with discrete components...there may even be a dedicated IC for the purpose now. Google time.

I don't want to rely on an MFD alert as I'm likely not to be staring at it, and since I seldom wear my hearing aids on the water, the wimpy audio alert is likely to go unnoticed...a strobed LED is what I'm thinking, perhaps in several locations.

Edit: Numerous circuits found, using either a 741 op-amp or a 555 timer chip as a voltage threshold detector...both ICs are under a dollar, and Radio Shack has an approx 1.5" square circuit board with properly spaced solder pads for either chip...$2.49, for two. This will have to wait for a month or two, as I have several projects that take priority

Last edited by Karl in NY; 11-16-2016 at 10:03 AM.
Old 11-16-2016, 02:29 PM
  #12  
Senior Member
 
Join Date: Jul 2011
Posts: 8,554
Received 1,668 Likes on 1,265 Posts
Default

Originally Posted by Karl in NY View Post

I don't want to rely on an MFD alert as I'm likely not to be staring at it, and since I seldom wear my hearing aids on the water, the wimpy audio alert is likely to go unnoticed...a strobed LED is what I'm thinking, perhaps in several locations.
I don't know about the other brands,

but if you have a Garmin MFD you likely have an "alarm output" wire in the main harness

(actually provides a ground)

use that to energize a relay, and you can have all the bells, whistles, strobes you want.
Old 11-16-2016, 09:21 PM
  #13  
Senior Member
 
Join Date: May 2014
Posts: 2,078
Received 23 Likes on 16 Posts
Default

Originally Posted by Fwpratt View Post
I don't know about the other brands,

but if you have a Garmin MFD you likely have an "alarm output" wire in the main harness

(actually provides a ground)

use that to energize a relay, and you can have all the bells, whistles, strobes you want.
From my 7610 installation guide.
Attached Images   
Old 11-17-2016, 02:07 AM
  #14  
Senior Member
 
Join Date: Oct 2013
Posts: 2,486
Received 539 Likes on 314 Posts
Default

Hello. I can recommend the Maservolt Batmann lite battery monitor, displays voltage and capacity, easy install, comes with everything in the box, including the shunt. You just have to tell it what battery capacity you have and a few other bits, really easy, then charge the batteries right up to calibrate the unit. We have installed a few now. You have to supply the positive and negative cables, so you can make then as long as you need. The one thing we did was to tin the ends of the cables with solder to stop them splaying out as you have to screw them down in the back of the unit in a cable strip, the unit even came with a screwdriver of the right size. The good thing about a monitor is it takes voltage and capacity at the batteries. Hope this helps.
Old 11-17-2016, 02:27 AM
  #15  
Senior Member
Thread Starter
 
Join Date: Jun 2010
Posts: 4,458
Likes: 0
Received 27 Likes on 20 Posts
Default

Originally Posted by buxa View Post
Hello. I can recommend the Maservolt Batmann lite battery monitor, displays voltage and capacity, easy install, comes with everything in the box, including the shunt. You just have to tell it what battery capacity you have and a few other bits, really easy, then charge the batteries right up to calibrate the unit. We have installed a few now. You have to supply the positive and negative cables, so you can make then as long as you need. The one thing we did was to tin the ends of the cables with solder to stop them splaying out as you have to screw them down in the back of the unit in a cable strip, the unit even came with a screwdriver of the right size. The good thing about a monitor is it takes voltage and capacity at the batteries. Hope this helps.
For a mere $140.95...

I can home-brew an alert for under $10....just to warn me when house battery drops below a pre-set minimum voltage. That is basically all I need.
Old 11-17-2016, 06:32 PM
  #16  
Admirals Club Admiral's Club Member
 
Join Date: Mar 2011
Location: Canada
Posts: 3,975
Likes: 0
Received 337 Likes on 282 Posts
Default

Originally Posted by Karl in NY View Post
For a mere $140.95...

I can home-brew an alert for under $10....just to warn me when house battery drops below a pre-set minimum voltage. That is basically all I need.

reacting is for emergency situations and people with poor planning.

a battery monitor allows you to plan ahead.
Old 11-18-2016, 05:38 PM
  #17  
Admirals Club Admiral's Club Member
 
Join Date: Dec 2007
Location: Lakeville Ma
Posts: 6,037
Received 597 Likes on 327 Posts
Default

Originally Posted by buxa View Post
Hello. I can recommend the Maservolt Batmann lite battery monitor, displays voltage and capacity, easy install, comes with everything in the box, including the shunt. You just have to tell it what battery capacity you have and a few other bits, really easy, then charge the batteries right up to calibrate the unit. We have installed a few now. You have to supply the positive and negative cables, so you can make then as long as you need. The one thing we did was to tin the ends of the cables with solder to stop them splaying out as you have to screw them down in the back of the unit in a cable strip, the unit even came with a screwdriver of the right size. The good thing about a monitor is it takes voltage and capacity at the batteries. Hope this helps.
Can you monitor more then one battery?
Old 11-19-2016, 01:16 AM
  #18  
Senior Member
 
Join Date: Sep 2015
Location: South Australia
Posts: 2,055
Likes: 0
Received 7 Likes on 7 Posts
Default

Originally Posted by Karl in NY View Post

Edit: Numerous circuits found, using either a 741 op-amp or a 555 timer chip as a voltage threshold detector...both ICs are under a dollar, and Radio Shack has an approx 1.5" square circuit board with properly spaced solder pads for either chip...$2.49, for two. This will have to wait for a month or two, as I have several projects that take priority
That would work with a 555 with its output feeding a latching relay requiring an 'accept' or 'cancel' button to reset the alarm (which should be a piezo). The lach function will ensure any recovery of voltage is detected. The trigger may need an RC time delay of a few seconds in order to ignore spurious low voltage excursions caused by turning on loads. Once done pot the whole thing with a flexible compound.
Old 11-19-2016, 07:13 AM
  #19  
Admirals Club Admiral's Club Member
 
Join Date: Nov 2009
Location: Tarpon Springs, FL
Posts: 8,770
Received 4,103 Likes on 2,337 Posts
Default

You should be able to monitor your house battery on your MFD with nothing else added. Verify that before you waste money on something you don't need.
Old 11-19-2016, 09:33 AM
  #20  
Senior Member
 
Join Date: May 2014
Posts: 2,078
Received 23 Likes on 16 Posts
Default

Pay attention Mike - thats already been covered and he explained why that wont work for him without some custom circuitry added.

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information -

Copyright © 2021 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.