Simple dual battery approach?

[tech_dog]

I've been looking for a dual battery solution with less complexity than most I've been seeing. I haven't seen anyone discuss this particular option, so I'd like to throw this out for public scorn. At first glance, it seems like it may be a very simple and effective solution.

Here's the schematic:





The Blue Sea L-series LCR is a relay that closes when either high current terminal is at 13.4 volts or greater, i.e when the vehicle is charging. Otherwise, it is open. It sells for about $150 and is rated at 450+ amps, depending on wiring gauge used.

Without the control switch, the batteries would both be charged whenever the alternater was working. The second battery would be isolated if the alternator were not generating, so you could run the winch on the isolated second battery by shutting down the engine.

Adding the control switch lets you manually open or close the relay, or leave it in the automatic mode described above.

The manually open mode allows you to isolate the second battery and winch with the engine running.

The manually closed mode allows you to use the second battery for emergency starting, or use both batteries to get home without a working alternator.


Advantages are:

o minimized length of fat, high current wiring
o no required cutting into the stock wiring
o no need to pull an "alternator good" signal
o only one small relay required (about 2" x 2.5")
o very high amperage capabilities
o supports most use/charge combinations, except those listed below
o fewer points of failure
o comparatively cheap

Disadvantages are:

o Can't run winch ONLY off of battery #1 (it's both or #2)
o Can't charge ONLY battery #2 (it's both or #1)

I think these are fairly small inconveniences.

You could also add another battery switch between battery 2 and the winch if you want to disable the winch when you're not using it, but I prefer the total simplicity of what I've got drawn above.

Blue Sea makes a control switch for this, but you could use any switch that provides +12 for closed, ground for open, or floating for automatic mode. I'm not sure if any stock Landcruiser switches can be modified to provide these three conditions but I think it's likely. Any ideas on that one?

Note that I didn't show the ground connections, but for each componant you'd have to hit the closest appropriate ground.

I also showed the control switch being powered off of the relay terminal, but you could pick up +12 from any convenient location. The switch wire current is very low, so you can use a thin wire and put the switch anywhere you like.

Comments?

[Mickldo]

Looks similar to the ARB Smart Solenloid setup and the Redarc Solenoid. They are a very good system that is fully automatic. Can't really go wrong with a system like that.

[Mike S]

I used the BluSea ACR (Mechanical) set up on my 60 with two Optima Yellow Tops. The manual switch was a marine grade unit and fit into the knock out to the right of the steering wheel. I am sure that Cole Hersey would have a switch that works on an 80.

I was very happy with the performance, and never had any issues - cycling or failure to switch on command. Good stuff. I'll probably do a similar set up on my new-to-me FZJ80.

M

[tech_dog]

Originally Posted by Mike S

I used the BluSea ACR (Mechanical) set up on my 60 with two Optima Yellow Tops. The manual switch was a marine grade unit and fit into the knock out to the right of the steering wheel. I am sure that Cole Hersey would have a switch that works on an 80.

I was very happy with the performance, and never had any issues - cycling or failure to switch on command. Good stuff. I'll probably do a similar set up on my new-to-me FZJ80.

Fantastic. Thanks for the validation.

This forum has got to be one of the most useful things on the entire internet.

Tom

[FloridaFJ80]

What kind of control switch are you talking about, anyone in particular? I am interested in doing this to my FJ80. Maybe you can do a write up on doing this particular setup and maybe get it added to the FAQ's....

[Newps]

tech_dog, I like it. I am currently investigating options for Project 80's duel battery set up. I may use this set up in my article and on Project 80. The only item I would change is a way to discount the winch via another switch.

Tare

[Hants]

I'm also in the planning stages of a dual battery system.

Running the winch while in "auto" mode on the ACR will likely cause cycling. Switching it to "on" should resolve it.

I second adding a switch to kill power to the winch (prevents knuckle-heads from *icking with you).

You should consider upgrading the grounds on the OEM/primary battery if you're installing a winch or other high-draw accessories.

I've heard opinions both ways about fusing the high-amp positive between the batteries. I will likely run mine in the galley behind the radiator. It will be in a risky position in case of a frontal collision, and will have a battery at both sides. I'll likely fuse mine at both sides -- I'm not a fan of car-b-q's!

[RavenTai]

that is pretty much the same sutup I did, except I did not use the auto sensing relay I used a regular blue sea solenoid and I used the altenator good signal.

I was worried about cycling with the ACR.

[Beowulf]

Originally Posted by tech_dog

Advantages are:
o no need to pull an "alternator good" signal

Getting "Alt good" on your FZJ80 is trivial and well documented.

-B-

[Beowulf]

Originally Posted by Hants

I'll likely fuse mine at both sides -- I'm not a fan of car-b-q's!

What fuse rating and style?

-B-

[sjcruiser]

My plan is the same as yours plus the addition of a 4-way switch just in case the main battery needs a jump.

Frank

[FirstToy]

My electric skills are limited but when the time comes, I will be installing the Hellroaring or Granger for dual batts.
I have heard so many good things of Hellroaring (performance and customer service) so you can't go wrong.

[Brentbba]

Originally Posted by FirstToy

My electric skills are limited but when the time comes, I will be installing the Hellroaring or Granger for dual batts.
I have heard so many good things of Hellroaring (performance and customer service) so you can't go wrong.

How far in the future are you thinking?

[FirstToy]

dunno Sputnik, when I get around to it... it's not a priority right now tho.

[tech_dog]

I'll throw in fuses where appropriate. I didn't show every detail, as it makes it harder to understand.

One of my primary goals was to avoid putting anything between the existing vehicle electric and the primary battery. I saw that as a negative return on investment, as it could actually increase the chances of becoming stranded. I like the fact that everything new is hanging off of the positive terminal of the battery, and doesn't require any hits on existing wiring.

[Brentbba]

Originally Posted by FirstToy

dunno Sputnik, when I get around to it... it's not a priority right now tho.

Just thinking if I had the $$ we could have an install party and invite someone that knows what they are doing.

[Mike S]

Originally Posted by sjcruiser

My plan is the same as yours plus the addition of a 4-way switch just in case the main battery needs a jump.

Frank

The ACR manual switch can be set to isolate or combine the two batteries. No problem to jump start from the second battery - or a third battery.

But with this set-up, the likelyhood of having to jump start is pretty remote.

I ran the batt 2 cable between the rad and the fan enclosure, and did no add in-line fuses. I used 1/0 welding cable and covered it with split loom cover, and zip tied it to the radiator ears.

M

BTW, you can toast your alternator by allowing even momemtary disconnect from a battery. That is why most marine switches are 'make, then break'. devices. They connect batt 2 before disconnecting batt 1. Just something to keep in mind.

[Hants]

Originally Posted by Beowulf

What fuse rating and style?

I'm looking at the BlueSea ANL fuses:

http://www.bluesea.com/product.asp?P...63&l1=7463&l2=

or Class T fuses:

http://www.bluesea.com/product.asp?P...63&l1=7463&l2=

Either one in 400A. With dual batteries in parallel plus 80A alternator, I figure that the only way I'd exceed 400A would be a completely discharged secondary battery AND winching at near-stall AND a winch that could/would draw > 400A. In a more typical situation, I would expect a maximum of 240A across the solenoid/combiner.

A short with AGM batteries, though, could yield > 1000A across that line (at least for a short time)!

On another note, a nice feature of mobi-arc's Isolater/Combiner is built-in current limiting. In theory at least, that should prevent the fuses from blowing even if the winch tried to draw >400A across the line.

[Hants]

Originally Posted by Mike S

BTW, you can toast your alternator by allowing even momemtary disconnect from a battery. That is why most marine switches are 'make, then break'. devices. They connect batt 2 before disconnecting batt 1. Just something to keep in mind.

BlueSea offers several models of manual switches with AFD (Alternator Field Disconnect). I don't know the details, but I assume it is to keep from cooking your alternator if someone accidentally sets the switch to OFF (and thereby disconnects all loads from the alternator) while the engine is running.

http://www.bluesea.com/product.asp?P...58&l1=7458&l2=

[Boston Mangler]

Here is mine



Fuses sitting in my garage waiting to be installed!

More details here: http://www.yankeetoys.org/mangler/dualbats.htm

[mobi-arc]

Dare I mention???? Oh god, let me get my helmet.

[Rich]

Originally Posted by mobi-arc

Dare I mention???? Oh god, let me get my helmet.

What, that all solenoids are guaranteed to fail?