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View Full Version : Dual Battery setups Pros and Cons



radryan
11-03-2009, 07:33 PM
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-Engine%2C-Two-Battery-Banks-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/Catalog/Category/Battery%20Management/Battery%20Charging/VSRs/Docs/710-125A_Inst.pdf).

jmvotto
11-03-2009, 07:58 PM
I have option 1.

set it to switch one and forget it.

my .02

Razzman
11-03-2009, 08:07 PM
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.

zabooda
11-03-2009, 09:22 PM
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.

DOCDRS
11-04-2009, 11:47 AM
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,
http://www.bepmarine.com/710-125A---Voltage-Sensitive-Relay-314.html

brain_rinse
11-04-2009, 01:22 PM
I have option 1.

set it to switch one and forget it.

my .02

Yep, same here

radryan
11-04-2009, 02:09 PM
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?

Razzman
11-04-2009, 03:33 PM
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.

NCSUmoomba
11-04-2009, 07:35 PM
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.

DOCDRS
11-04-2009, 07:41 PM
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.

radryan
11-05-2009, 12:24 PM
Your right! The Moomba manual shows option 2. I was got option one straight from BEP's documentation of the cluster VSR/Switch. So Moomba factory supports option 2(I updated the original post).

So I am getting that if you are cheap you could cut out the switch in any setup and you would be losing the ability to combine the batteries with the switch(you would have to move a wire form the positive of one battery and connect it to the other manually).

DOCDRS
11-05-2009, 01:08 PM
Your right! The Moomba manual shows option 2. I was got option one straight from BEP's documentation of the cluster VSR/Switch. So Moomba factory supports option 2(I updated the original post).

So I am getting that if you are cheap you could cut out the switch in any setup and you would be losing the ability to combine the batteries with the switch(you would have to move a wire form the positive of one battery and connect it to the other manually).

It would seem you could do that, and spend that money in a battery float charger to put on your second battery when your not using the boat. they are only about $30 but then it looks like the switch is only about $35. the bep is dual sensing now so i would get this one as it will also charge both batteries with an external charger. not sure if the blue sea is dual sensing

Razzman
11-05-2009, 01:45 PM
So while option two may be the factory "approved" method mine came with dual batts and no sensing relay, just a Perko switch. Hence the reason i yanked it all and added the Blue Seas setup.

Having a switch wether one is cheap or not is a must have as it allows the batteries to be disconnected from the electrical system while the boat is sitting and eliminating the possibility of an electrical fire. Many a fire a marine fire has happened due to this very reason.

cab13367
11-05-2009, 02:57 PM
The Blue Sea ACR is dual sensing. See FAQs link below:

http://bluesea.com/viewresource/1366

I am going thru this right now also. I have decided to go with the Blue Sea ACR and Dual Circuit Plus switch. Was able to buy each separately on EBay brand new for a total of $67 shipped!

Here is a link to the Blue Sea 5511E switch (the same one that comes with the add a battery package) for $16.99 (plus $10.55 shipping). I bought one plus found the ACR for $40 shipped (they only had one of the ACRs).

http://cgi.ebay.com/ebaymotors/New-Blue-Sea-Dual-Circuit-Plus-Battery-Switch-E-Series_W0QQcmdZViewItemQQhashZitem35a2647f9bQQitem Z230357761947QQptZBoatQ5fPartsQ5fAccessoriesQ5fGea r

Razzman
11-05-2009, 05:08 PM
Way to go Al! Those are killer deals!

DOCDRS
11-05-2009, 05:12 PM
Your right! The Moomba manual shows option 2. I was got option one straight from BEP's documentation of the cluster VSR/Switch. So Moomba factory supports option 2(I updated the original post).

So I am getting that if you are cheap you could cut out the switch in any setup and you would be losing the ability to combine the batteries with the switch(you would have to move a wire form the positive of one battery and connect it to the other manually).


The Blue Sea ACR is dual sensing. See FAQs link below:

http://bluesea.com/viewresource/1366

I am going thru this right now also. I have decided to go with the Blue Sea ACR and Dual Circuit Plus switch. Was able to buy each separately on EBay brand new for a total of $67 shipped!

Here is a link to the Blue Sea 5511E switch (the same one that comes with the add a battery package) for $16.99 (plus $10.55 shipping). I bought one plus found the ACR for $40 shipped (they only had one of the ACRs).

http://cgi.ebay.com/ebaymotors/New-Blue-Sea-Dual-Circuit-Plus-Battery-Switch-E-Series_W0QQcmdZViewItemQQhashZitem35a2647f9bQQitem Z230357761947QQptZBoatQ5fPartsQ5fAccessoriesQ5fGea r


ya have to love Al , he always knows where to get a deal, best i could find was 106 here for the Bep dual and switch
http://www.boatersland.com/basw.html
and i agree with razz for 30 or 35 more get the switch ...it gives you ease of complete control.


Now to add one more thing what do you guys think of desulfators?

radryan
11-05-2009, 06:01 PM
Yeah I am going with the ACR too. It has some extra circuitry to account for the cycling that could happen when batteries are combined. http://bluesea.com/viewresource/527

I heard this happening on my old 05 battery setup in certain cases. Also has starter isolation if you want to hook it up. Hopefully all those extra features won't cause it to have problems easier.

Razzman
11-05-2009, 06:06 PM
Now to add one more thing what do you guys think of desulfators?

I'd never even heard of one until i looked up what it meant. It's an interesting concept.

DOCDRS
11-05-2009, 06:21 PM
i've been checking my battery voltages and there is a def difference between the motor 12.93 and the house 12.77 battery

DOCDRS
11-09-2009, 09:31 PM
this is my set up
http://www.flickr.com/photos/44449644@N07/4087962437/

cab13367
11-20-2009, 01:48 PM
Hey doc,

How did you connect the 2/0 battery cables to the battery switch? Did you use crimp on ring terminals and if so, what do you use to crimp them so you are assured a good, solid connection? I will be doing this also and don't know what is the best way to go.

Thanks,

Al

Razzman
11-20-2009, 02:36 PM
Al, Ring terminals are definitely the best way. i'll explain here how to make your own cable on the cheap. I've made them this way for years and it works real good.

Materials & tools needed:
Cable
Cable ends for proper cable gauge
Xacto knife or razor blade
Vise, anvil or facsimile
1/8" or so blunt end punch
Hammer
Solder
Small butane torch
Heat shrink tubing

Strip the cable housing back enough so that about an 1/8" of cable is exposed when insert into the cable ends. Place your heat shrink on the cable and slide it back far enough so it won't shrink prematurely. Insert cable into cable end and hold it on the vise anvil and using the blunt end punch give a real good whack, this acts like a set screw to hold it on. Using the butane torch heat up the cable end just enough to float some solder into the cable end. Slide up your heat shrink when cooled and shrink it down. Done.

DOCDRS
11-20-2009, 06:44 PM
razz pretty much summed it up, really can't add anything other than sanding or scoring inside connector and wire if you can and slight amount of flux will increase the flow and adhesion , great post razz

cab13367
11-20-2009, 06:52 PM
Thanks guys, appreciate the info.