Dual battery systems; making sense of the options

Joined
May 24, 2015
Messages
90
Got mine from Slee.........
Suddenly those arent desirable at all. $100 cad for some terminals and adaptors...will stick to bolting my eyelets directly to the terminal. 6 of 1 half dozen of the other..... either american wages are better or the canadian dollar is terrible :rofl:
 

RobW0

SILVER Star
Joined
May 22, 2019
Messages
171
Location
Central IL
Suddenly those arent desirable at all. $100 cad for some terminals and adaptors...will stick to bolting my eyelets directly to the terminal. 6 of 1 half dozen of the other..... either american wages are better or the canadian dollar is terrible :rofl:
As others have said, they are from Slee. They are not cheap at $49 us. The mil spec terminals are easy to find cheap other places. I have not been able to find the extensions anywhere else.
 
Joined
Oct 29, 2018
Messages
93
Location
Herndon VA
Ideally with electrical install locations, you want it as clean, dry and cool as possible. The BCDC also wants to be mounted as close as possible to the auxiliary battery in order to reduce or eliminate voltage drop. in my testing and experimenting, I have mounted the BCDC in an 80 in 4 different locations with no charging issues. My personal one is behind the PS headlight and it stays very cool there. Others near and around the aux battery or the starting battery. Taking temps throughout the engine bay, I’ve found the hottest place to mount would be high up, closer to the firewall. I’m sure a bracket can be made to mount it in front of the radiator, but I’d prefer, at least on an FZJ80, not to block airflow thru the radiator. I wouldn’t be afraid to mount the BCDC 10’ away from the aux battery either. With the 25amp unit, I run 8awg, but if you have longer runs, Redarc suggests a 6awg cable.
I have a 200 series and there looks like there is a lot of room to mount this thing... to minimize wiring I think i will put a blue sea fuse box in the rear of the truck and wiring everything up to it...
 
Joined
Feb 23, 2020
Messages
13
Location
Asia
hi everyone, can i just hard wire 2 lead acid batteries together as the cheapest option for extra led bar and a winch? if so, will 2004 LC100 alternator charge them in parallel? actually how many amps is lc100 2004 UZJ100 alternator ? thanks in advance
 
Joined
Sep 11, 2012
Messages
482
Location
Vancouver, B.C.
I installed a pretty basic dual battery system. I really wanted to isolate power used by accessories, like a fridge, when parked to a dedicated house battery. There are many possible routes to achieve a functional dual battery setup; this is how I did it.

Objective:
Install a simple and cost effective dual battery system

Goals:
System should operate automatically, manually or be switched off
Ability to self jump start
Keep it safe

I like to draw basic diagrams when doing electrical work, for home or vehicle. This helps keep me organized and greatly reduces the chance of me wiring in a short circuit or having and un-fused power source. Below is a basic diagram for this dual battery system.

Dual Bat Wire.png


This works as follows:

Voltmeters - I can view the battery voltage anytime. With the solenoid deactivated the voltmeters will show the resting voltage of each battery. With the solenoid active the voltmeters will display the voltage of the batteries combined. Obviously if the rig is running and the solenoid is active, the voltage displayed should be the charging voltage and the same.

Charge/Solenoid control
- AUTO, the solenoid is activated when it receives power from an ignition power source. This setting automatically ties the batteries together when the vehicle is running and isolates them when it is off.
- ON, the solenoid is activated when it receives power from the house battery. This allows a self jump start in case the starting battery has died.
- OFF, the solenoid will not activate and the batteries are isolated from each other.

The control center for the batteries is fitted to my overhead console. The primary switches replaced the useless sunroof controls in my 100 since the sunroof hasn't operated in years. The small digital voltmeters were cut into the console.

IMG_20190623_132519.jpg


The 2nd battery tray I am using is an old style Slee Offroad tray, which is designed for an Optima battery. Since I was trying to keep costs down, I found a Group47 AGM battery that fit the tray. As a bonus the terminals are recessed into the battery case.

IMG_20190420_162455.jpg


At both the starting battery and house battery, I installed Bussman fuse holders and 300A MEGA/AMG fuses to protect the vehicle and batteries from a massive short circuit in the event a cable breaks. I used 2AWG welding wire, tinned copper lugs, braided loom and adhesive backed heat shrink to build the battery cables.

00100dPORTRAIT_00100_BURST20190804124905909_COVER.jpg


I tucked the solenoid against the firewall directly in front of the driver's seat. The solenoid engages with a solid audible 'click'. I made sure to cover all positive terminals in the whole system.

00100dPORTRAIT_00100_BURST20190804124844090_COVER.jpg


I could easily add a solar charge controller + panel to the house battery if desired. With my current use of driving daily and only relying on the battery overnight, I have no problem maintaining a charge.
 

Irish Reiver

GOLD Star
Joined
Oct 24, 2015
Messages
1,276
Location
Orlando, Florida
Help me with this situation please,
Since I have been forced to work from home my '94 80 series has more or less been sat on my drive. I noticed over the weekend that the fridge had stopped. For the past 18 months it has more or less run 24x7 and never skipped a beat.
I have a 75Ah flooded lead acid deep cycle battery which is connected to my starting battery via a Blue Sea ACR. I also have 2 x 100watt solar panels on the roof which are connected to an EPEVER Tracer solar controller. The only thing that runs in the vehicle when it is parked up is the fridge. I always assumed that the 2 solar panels should provide sufficient power to run the fridge but clearly that is not the case.
Any suggestions on where to start making improvements?
 
Joined
Aug 28, 2014
Messages
530
Location
Santa Cruz
Is the fridge connected to the same battery that the solar is charging? Maybe just some small variables like fridge temp, outside temp, shade or battery condition made a difference? I run my half full 50qt ARB 24/7 with 100watt solar panel on my roof with no problems, but again environmental differences may be the factor.
 

Irish Reiver

GOLD Star
Joined
Oct 24, 2015
Messages
1,276
Location
Orlando, Florida
Is the fridge connected to the same battery that the solar is charging? Maybe just some small variables like fridge temp, outside temp, shade or battery condition made a difference? I run my half full 50qt ARB 24/7 with 100watt solar panel on my roof with no problems, but again environmental differences may be the factor.
Yeah, the fridge is actually connected to the load output on the solar controller. When the solar output is insufficient the power is taken from the second battery.
Over the next few weeks I will get to keep a close eye on this. Might make for an interesting science project (that's how bored I expect to be ). I had been toying with the idea of removing the ACR and solar controller and fitting the Redarc BCDC unit. Not sure if it worth it though...
 
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