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11-03-2009, 07:33 PM #1Member
- Join Date
- Mar 2005
- Central IL
Dual Battery setups Pros and Cons
Trying to wrap my head around the dual battery setups used and the pros and cons.
1. BEP Supported Option: http://www.bepmarine.com/Single-Engi...-180-1460.html Includes Voltage Sensitive Relay and 4 Position Battery Switch(1, 2, Both, and Off) All load is wired to the COM terminal on the Switch which I think means all load and charging is passed to the sensed battery at all times. When the volts get high enough on the sense battery the relay is closed and charging is passed to both batteries.
The switch in this option appears to have 2 purposes:
A: Change the sensed battery which means the load and charging goes to that battery selected first and once volts are above the set limit then both batteries.
B: In the event that you run down the sensed battery while sitting(not charging the batteries due to engine running) you can turn the switch to the other battery or the both setting and start the engine(the new battery is the sensed battery the VSR will not charge the other battery until volts reach the level set on the relay)
2. Factory Option: Same device as the first but load is split between batteries (example: starter and engine on first battery and stereo and accessories placed on 2nd battery) and only the charging is connected to the COM terminal of the VSR. So in this option the Switch and VSR operate the same but the difference is the load does not move based upon the switch setting of 1 or 2. If you run down your second battery using the stereo and accessories while the engine is off then there is no need to turn the switch setting, just start the engine and Once running the VSR will run and once volts are high enough charge the stereo/accessories battery.
3. Another Option: http://bluesea.com/category/2/productline/overview/329 Includes Automatic Charging Relay and 3 Position Switch (Off, On, Combined) In this setup you would place starting load and charging on the Starting Battery and Stereo or Accessory load on the 2nd battery. ACR monitors the starting battery similar to the VSR and allows charging to the 2nd battery when the starting battery reaches a certain voltage threshold.
The switch in this case operates in the on position and send both respective loads only to the respective battery. When in the combined position both batteries are fully combined for emergency start or other purposes.
Considering these options that I have seen I would like some feedback as to the pros and cons of them.
Also, I wonder in option 1 and 3 what are the pros to using the switch in either set up(briefly is appears the ability to combine both batteries for emergency use without moving cables for both and for 1 it appears you could change the sense battery but I think the VSR would sense both batteries without the switch due to the Dual Sense feature (see more here: http://www.bepmarine.com/store/web/C...-125A_Inst.pdf).
Last edited by radryan; 11-05-2009 at 12:25 PM. Reason: made 2 factory option per Moomba Manual
11-03-2009, 07:58 PM #2
I have option 1.
set it to switch one and forget it.
Last edited by jmvotto; 11-04-2009 at 01:49 PM.A Day at the Lake...Priceless
A Day in Powder...Endless
2012 Möbius XLV~ Loaded & Exiled
2007 Outback V ~ sold
11-03-2009, 08:07 PM #3
I use the Blue Sea Systems 7650 ACR/switch and wouldn't have anything else, especially since i can combine in an instant if necessary. Imo any setup that requires manually switching between batts or moving cables is a con.2007 Mobius LSV
11-03-2009, 09:22 PM #4
Remember, you need to keep relays and switches away from confined areas where hydrogen gas or gas fumes can accumilate unless the relay or switch is designed for a hazardous environment due to the spark potential.1998 Mobius
310 HP PCM
11-04-2009, 11:47 AM #5
I have option 2, with it set to 1 as this is my starting battery, so it is the sensed battery and kept charged full. I have to look if i have the dual sense as i feel the house battery will need additional charging as it will most likely be at a constant higher discharged state due to stereo usage while sitting. this will then lead to a shorter life span of the house battery unless externally on a regular basis
As i understand it the vsr allows the sensed Motor battery to be charged first, then the 2 house battery will only be charged once the 1st sensed battery is fully charged......this is assuming your battery switch is at 1 setting, if it is at 2 setting the sensed battery is disconnected and all charging goes to 2. If in the 1+2 position then the batteries are placed in parallel and both batteries will be charged but both are connected and the stereo will now drain both batteries.
If you have the single sense vsr can you still additionally charge your house battery externally ...just there will be no charging of the motor battery thru the vsr? if you have the dual sense then when you add'ly charge your house battery the sensed battery will be charged as well , but will the vsr prevent over charging of the sensed battery if the house battery is very low and the charger is at a high charge rate?
I just went to the bep marine site and its faq answered all my questions,
Last edited by DOCDRS; 11-04-2009 at 11:55 AM.
11-04-2009, 01:22 PM #6Dan
08 LSV Mods
11-04-2009, 02:09 PM #7Member
- Join Date
- Mar 2005
- Central IL
Got it. Thanks for the replies!
I was wondering about the switches in all setups. Do they do more than combine both batteries in an emergency?
Also the stereo and accessory load being split to the second battery any cons to that? Must be some reason they don't do that as the factory supported option?
11-04-2009, 03:33 PM #8
The switches are for the batts only and only engage the batts. the proper way to do it is start load on batt 1 and stereo/acc on batt2, that way you don't drain your starting battery playing tunes.2007 Mobius LSV
11-04-2009, 07:35 PM #9
First, I don't think there are any cons to a dual battery setup. My boat didn't come with one from the factory, so I added one. I went with option 3 (the blue sea add-a-battery system). I think it is great. I have one marine starting battery powering all the engine stuff, and I have a second marine deep cycle "house" battery to run just the stereo. This system also does not need to be switched back and forth, you just turn it to on and go. The relay handles the load distribution and the charging. So i just turn it on and forget it too. I use turnthe switch off every time we get done using the boat just as a precaution I guess. I am also sure that the stereo is totally off and not drawing juice while the boat is sitting. The only bummer is the memory, but I just need to swap the memory power wire and run it straight to the battery.
11-04-2009, 07:41 PM #10
I actually looked in the manuals, where is this factory supported option 1. In all manuals back to 2006 the hook up is as in option 2.