dwh
Tail-End Charlie
If it draws 2a per hour then a 100ah battery is good for 50 hours and then dead. If 3a per hour, 33 hours.
How to make a cheap isolated dual-battery setup for $50
- Thread starter evldave
- Start date
If it draws 2a per hour then a 100ah battery is good for 50 hours and then dead. If 3a per hour, 33 hours.
105 A/hr should get you a couple of days of running a 40L Engel no problem unless the weather is really warm.
I have a just slightly smaller Engel MT35 running off a 60 A/hr AGM, sized for mainly ~24hr use but it will go 48hr+ no problem at all. I haven't had it trip the low voltage cutout on the fridge yet which is set at a fairly conservative level IIRC. I read about 1 A per hour total for an average 12V fridge, haven't used mine in the height of summer yet but at medium temps I think it's using well under that.
If you are wiring an aux batt off a trailer connector I'd be worried about the size of that feed to the trailer when you start the rig with a discharged aux batt. As per the discussion a page or so back you can expect maybe 25A of charging current & minimising voltage drop is also important. I guess if it blows the fuse you'll know you need to run a heavier feed back from the main batt
Cheers
Clint
I have a just slightly smaller Engel MT35 running off a 60 A/hr AGM, sized for mainly ~24hr use but it will go 48hr+ no problem at all. I haven't had it trip the low voltage cutout on the fridge yet which is set at a fairly conservative level IIRC. I read about 1 A per hour total for an average 12V fridge, haven't used mine in the height of summer yet but at medium temps I think it's using well under that.
If you are wiring an aux batt off a trailer connector I'd be worried about the size of that feed to the trailer when you start the rig with a discharged aux batt. As per the discussion a page or so back you can expect maybe 25A of charging current & minimising voltage drop is also important. I guess if it blows the fuse you'll know you need to run a heavier feed back from the main batt
Cheers
Clint
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With the setup described in this thread, should the batteries match?
I have a brand new Tundra with a group 27F battery. This is my daily driver and sometimes don't drive on the weekend so it can sit ~60 hours, but that is rare. I will be running an Engel 60qt fridge full time (still trying to figure out if it has a low voltage cutoff and if not, if I should install an external one???).
Considering this is a brand new battery, I'm considering some different options. I might install a second battery in the bed if it doesn't have to match the starting battery. If it does have to match, I will probably put off dual batteries for a while due to cost.
So if I stay with the single battery, should I already replace it with something bigger? I would carry a jump pack either way. Solar is not really something I want since I always park in the shade or garage.
I will install a battery monitor as well.
I have a brand new Tundra with a group 27F battery. This is my daily driver and sometimes don't drive on the weekend so it can sit ~60 hours, but that is rare. I will be running an Engel 60qt fridge full time (still trying to figure out if it has a low voltage cutoff and if not, if I should install an external one???).
Considering this is a brand new battery, I'm considering some different options. I might install a second battery in the bed if it doesn't have to match the starting battery. If it does have to match, I will probably put off dual batteries for a while due to cost.
So if I stay with the single battery, should I already replace it with something bigger? I would carry a jump pack either way. Solar is not really something I want since I always park in the shade or garage.
I will install a battery monitor as well.
As long as only connected while charging, no need to be same model, but should be spec'd for similar charge voltage range.
The House bank should be of true deep cycling type, not the falsely labeled 12V units sold in big box.
Best value is 2x Duracell flooded golf car 6v, from Sam's Club or Batteries+.
The House bank should be of true deep cycling type, not the falsely labeled 12V units sold in big box.
Best value is 2x Duracell flooded golf car 6v, from Sam's Club or Batteries+.
v_man
Explorer
vman's dual battery setup
What's up guys, this thread was a big inspiration/help with my dual battery setup in my 07' LX. Much appreciation to the OP and all the contributors...
With the addition of a Dometic fridge, and other accessories down the road, I wanted more aH's, plus starting redundancy, plus I love a good project.
Job #1 was to identify a space for the second battery. The PO had removed the AHC reservoir so that area was an obvious choice. I relocated the power steering reservoir and a couple other electronic do-dads and I had my spot behind the air filter.
Job #2 was to create a battery tray to secure my yellow top Optima. The tray was easy and I added two side trays to mount a BluSea auxiliary fuse box and my circuit breakers...
Now that the second battery had a cozy home in the engine bay, it was time to hook up the big cables and the solenoid...
I went with the solenoid recommended by the OP...
https://www.amazon.com/gp/product/B001YIPXR2/ref=oh_aui_detailpage_o01_s02?ie=UTF8&psc=1
The next task was to find a spot to mount the solenoid and the switch that controlled it. Here's where it landed. I like that I can hear it engage and disengage with a very satisfying click...
Next I mounted an in-cab switch to control the solenoid.
The last step was to wire every thing up. I went with 2/0 gauge welding wire for my main cables. I added the yellow wire sheathing just for looks....
Then a few circuit breakers later, a relay here and there, and a generous helping of zip ties and it was all over...
A few other details: Total cost was anywhere between $600 and $800, that includes a new Yellow Top and a new group 27f Bosch starting battery, also included in that cost was the solenoid, 3 circuit breakers and the Blu-Sea aux box. Voltage drop between the two batteries with the car running is less than .02 volts. Total time to setup was several hours a day for about a week. Total beers consumed during install: quite a few. Number of times I accidentally sparked both battery posts with an errant wrench: 3.
What's up guys, this thread was a big inspiration/help with my dual battery setup in my 07' LX. Much appreciation to the OP and all the contributors...
With the addition of a Dometic fridge, and other accessories down the road, I wanted more aH's, plus starting redundancy, plus I love a good project.
Job #1 was to identify a space for the second battery. The PO had removed the AHC reservoir so that area was an obvious choice. I relocated the power steering reservoir and a couple other electronic do-dads and I had my spot behind the air filter.
Job #2 was to create a battery tray to secure my yellow top Optima. The tray was easy and I added two side trays to mount a BluSea auxiliary fuse box and my circuit breakers...
Now that the second battery had a cozy home in the engine bay, it was time to hook up the big cables and the solenoid...
I went with the solenoid recommended by the OP...
https://www.amazon.com/gp/product/B001YIPXR2/ref=oh_aui_detailpage_o01_s02?ie=UTF8&psc=1
The next task was to find a spot to mount the solenoid and the switch that controlled it. Here's where it landed. I like that I can hear it engage and disengage with a very satisfying click...
Next I mounted an in-cab switch to control the solenoid.
The last step was to wire every thing up. I went with 2/0 gauge welding wire for my main cables. I added the yellow wire sheathing just for looks....
Then a few circuit breakers later, a relay here and there, and a generous helping of zip ties and it was all over...
A few other details: Total cost was anywhere between $600 and $800, that includes a new Yellow Top and a new group 27f Bosch starting battery, also included in that cost was the solenoid, 3 circuit breakers and the Blu-Sea aux box. Voltage drop between the two batteries with the car running is less than .02 volts. Total time to setup was several hours a day for about a week. Total beers consumed during install: quite a few. Number of times I accidentally sparked both battery posts with an errant wrench: 3.
AdventureWelder
New member
Does the amperage of the alternator effect the size/amperage of the solenoid, fuses and wire size? I have a 2014 F350 with stock alternator that I believe is 200 amp. What should I have to complete this type of set up?
AdventureWelder
New member
I'm planning to use a Group 31, 105 ah, AGM deep cycle auxiliary battery.
dwh
Tail-End Charlie
You might see 100a peaks for a couple minutes here and there. Most of the time, a lot less. Plus however many amps might be pulled by loads like inverters or microwaves.
If 200a is the max your source can supply, then size for the max and no worries.
AdventureWelder
New member
Thanks for the information. Ill do that.
V_Man, that looks like a great setup! What circuit breaker are you using? Is there an advantage or disadvantage of a circuit breaker versus a fuse other than not having to carry spare fuses? Also, is the switch in the cab in lieu of a wire tired to a starting circuit? You manually set connect/disconnect the batteries when you want versus just when the car is running?
Thanks for the help.
Thanks for the help.
v_man
Explorer
Here is the CB I used x3 :
https://www.amazon.com/gp/product/B001PT7XBE/ref=oh_aui_detailpage_o00_s02?ie=UTF8&psc=1
I like to use CB's because that's what I've used in other vehicles, and you can quickly disconnect/isolate different components with the flick of the breaker. In my rock crawler, I have my starter going through my aux. fusebox which is protected by a CB. Quickly tripping the breaker renders the truck unable to start; a poor man's kill switch.
As for the in-cab switch, yes I wanted full manual control of the solenoid. The operation of the solenoid is completely independent of when the car is started, running, sitting etc...
Ok so I came here looking for info on making a similar setup to the national luna its system. I've started hearing people having issues with the controllers and the solenoids on those systems and wanted to see if I can replicate the setup using off the shelf parts. I come here to find 97 pages of info. Any of you guys know if you've talked about doing something like this already or is this something new.
What I'm wanting is an automated dual battery monitor and charger. Also the ability to link(jump) the two batteries together using a switch from inside the cabin. I was already prepared to spend the $400 on the NL setup so anything costing the same or less is good with me. Also if its a bit more but adds functionality thats useful is fine too. I will go through this whole thread but can't at the moment.
What I'm wanting is an automated dual battery monitor and charger. Also the ability to link(jump) the two batteries together using a switch from inside the cabin. I was already prepared to spend the $400 on the NL setup so anything costing the same or less is good with me. Also if its a bit more but adds functionality thats useful is fine too. I will go through this whole thread but can't at the moment.