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View Full Version : Dual Battery Install W/ Voltage Sensing Relay


rover67
10-06-2009, 08:55 PM
After a bunch of reading and some stupid questions I decided to do the dual battery install using a marine voltage sensing relay, or VSR. I liked this option because the thing is rated at 300amps continuous and something like 1500 for less than 10 seconds. It also won't join both batteries untill the main battery voltage comes up, and has a manual connect/disconnet switch on it. I was able to find one on ebay from a marine supply company in florida for $150

I figured i'd write it up since I haven't seen a write up on one of these before.

http://www.jgtech.com/pdf/300A_Vsr_Instructions.pdf

I also am using a National Luna Dual Battery Monitor to monitor both batteries. I figured it'd be nice to know how low they were both getting and I liked the idea of being able to monitor charging voltages. I got the recessed one from Paul at Equipt since I figured i'd install it in the fuse box cover to keep it out of the way and to keep clutter down. $75 for this little gem.

http://www.equipt1.com/h/component/page,shop.product_details/flypage,shop.flypage/product_id,447/category_id,153/option,com_virtuemart/Itemid,31/

For the wiring, I kinda over did it by accident. I was going to buy 1ga cable from a marine store, get all the nice ends and shrink wrap and do them up myself, but when I looked at the total for that it was close to what I could buy them made for.

I had bumped into these folks online and thought that their cables looked nice, and I am always stoked to get something professionally done in the mail for about what I coulda done it for.

http://www.urbanlandcruisers.com/csfs/cables.php

They had a kit that came with a new fusible link (spare for the tool box) REEEAAALY beefy 1/0 main cables, Mil spec battery terminal clamps, and all cables to replace the grounds on the truck. I called them and told them what extras I needed and they put it together for me in no time.

Their standard FJ60 Cable kit with fusable link and battery clamps
Additional 84" 1/0 gauge cable with red shrink wrap and 3/8" lugs on both ends (Driver Batt to VSR)
Additional 16" 1/0 gauge cable with red shrink wrap and 3/8" lugs on both ends (Aux Batt to VSR)
Additional 36" 4 gauge cable with red shrink wrap and one 1/4" lug and one 3/8" lug (Alternator)
Additional 11" 1/0 gauge cable with black shring wrap and 3/8" lugs on both ends (Driver Batt Gnd)
Additional set of battery post clamps

They charged me about 150 bucks for these additional parts, and I got their FJ60 kit. When I got the cables I realized that 1/0 was almost retarded big. Part of me didn't really mind since I had a few kinda long runs that could be loaded while winching. If I were to do it again i'd really skip down on the main cable gauge. When I worked it all out, the $330 I paid for cables was probably 60 bucks more than what i would have paid to do it myself.

Battery Trays were from the stainless trays place.

Anyways..

The layout was kind of non standard i'd say. One of the things I did not want to change was all of the cable routing I had already previously set up. Basically everything went to the passender side before. All the Auxilliary stuff like the Winch, fridge, CB, HAM, Subwoofer Amp, and stereo was wired over there as well as the trucks main wiring. I really did not want to extend those cables and wires. Sooo I decided to put the Auxilliary battery over there and hook all of those Aux items up to it. This made it so none of those cables or wires had to change. The main battery had to move to the other side though. So What I did was run the main positive cable from it to the VSR and hook all of the "lifeline" stuff from the truck, and the starter cable up to it. I essentially used that main post on the VSR as the main post for the truck. It got crowded but it all fit, and even though all of this crap was hooked up really far from the main battery, it was through a 1/0 cable.. so i figured it was fine.

Tho other side of the VSR just hooked up to the aux battery with the big 1/0 cable again.

So here's a bunch of pictures. This first one is my schematic. I am at home, so I drew it up on a peice of paper and took a pic of it. pretty cheap, but all I could do.

1. Schematic
2. Old battery (it's 10 years old)
3. New cables
4. New cables
5. New tray, relocated overflow tank

rover67
10-06-2009, 09:03 PM
More pictures...

First few are my bracket for the VSR. My aluminum welding is not so great.. been toooo long.

Last few are the VSR. It has wiring to allow for remote control for emergency starts. Basically it manually closes the relay even if there's no charging voltage present. I didn't wire this up because I figured it'd not be too hard to hop out and flip the switch that it has on it. For winching the engine will be running and the solenoid will be engaged.

rover67
10-06-2009, 09:06 PM
More Pictures..


The VSR with the wires hooked up to it, and both batteries in and wired up. Tight squeeze in there now, but it all fits.

Uncle Ben
10-06-2009, 09:10 PM
Great setup! Essentially the same as the National Luna complete system. Thats the system I have and I like it for the most part. The only time it doesn't work flawlessly is when my big group 31 aux batt is heavily discharged it will drop out of combined charge too early. With the NL monitor it's easy to spot the shortfall at a glance and manually over ride the "brain" so both batts are again linked and charging. Good choice, obviously based on research! :thumb::thumb:

rover67
10-06-2009, 09:15 PM
Last pics..

Picture of the 4ga cable to the alternator, and the Dual Battery monitor.

I really like the way it turned out, but the cables again are kinda overboard I think. I also don't really want ot add it all up. Definitley more than the $375 for the NL kit from Paul, but it will handle winching, and has beefy cables. I feel like I never have to worry about it.

I did make a few compromises.. It has no fuses (god help me if there is a bad front end collision that severs cables), and the radiator overflow bottle and VSR are just mounted to the support braces for the battery trays. Not ideal, but it works, and they are pretty stout. We'll see if they crack.

So, the truck starts REALLY fast now, and the fuel pump runs faster and quieter. the fans also run a little faster. I'm thinking that the ground cables were in seriously bad shape.

Now I never have to worry about the battery going down at camp, or worry about my 10 year old optima giving up the ghost.

Anyways, hope ya'll enjoyed the tour.

-Marco

MDH33
10-07-2009, 10:01 AM
Great Job Marco! :thumb:

I still need to come up with a better solution for the relocated overflow bottle in my 60. want to weld me up a mount?? :beer:

rover67
10-07-2009, 10:05 AM
Sure, just let me know what you are thinking. I ditched my headlight washer bottle and there is ton of space over there. Either that or if your headlight washer bottle is in good shape convert it to an overflow bottle...

MDH33
10-07-2009, 10:12 AM
Sure, just let me know what you are thinking. I ditched my headlight washer bottle and there is ton of space over there. Either that or if your headlight washer bottle is in good shape convert it to an overflow bottle...

Yeah, I pulled out the headlight washer too, but I still have all the smog stuff in the way on that side. Right now I have it over on the PS fender via a booty fab bracket which isn't ideal.

rover67
10-07-2009, 10:17 AM
snap a pic of it, i'll make a little bracket if you want. Mine's pretty busy on the passenger side, but I might be able to mock it up

Jacket
10-07-2009, 10:43 AM
Sweet. Now you can hook up that electric blanket that Mead has always wanted....

rover67
10-07-2009, 10:57 AM
Sweet. Now you can hook up that electric blanket that Mead has always wanted....


exactly!

Red_Chili
10-07-2009, 11:39 AM
Super sano, Marco.

I did make a few compromises.. It has no fuses (god help me if there is a bad front end collision that severs cables), ...
I've been thinking about this as well. I used irrigation pipe to armor my 1/0, but with slight frame and body flex and not being able to see quite all the cable, the thought of the body coming into contact with the hot side is... :eek: I don't wanna think about it.

I have fuses in a box when I get the time to install. Probably after hunting.

... I'm thinking that the ground cables were in seriously bad shape.

OFTEN ignored. Excellent grounding solves lots of problems... from headgaskets to rust (in the case of a friend's truck at least - weird!), as well as strange electronic behavior. It's like voodoo or possession or something. We operate in some pretty galvanic environments I think. I have seen STRANGE things (and no, not just as a miscreant teenager...).

DaveInDenver
10-07-2009, 01:23 PM
the thought of the body coming into contact with the hot side is...
There is always some level of exposure. Winch cables aren't fused, right? You could crimp a 3 or so inch length of 6AWG/SXL between the post and end of the 1/0 cable as a fusible link.

Corbet
10-07-2009, 10:59 PM
Very nicely done.:clap::clap: Dual batteries is coming up on my to do list. You've given me some more ideas.

How is your system different than the NL kit other than your "brain" can handle 300A where it looks like the NL can only take 85A. Correct me if I'm wrong there on current loads. Also did you hook up any in the cab controls for switching and/or the LED light described in the pdf for your relay?

I like the idea of building my own kit too as I'm heading in the direction of placing my 2nd battery under my truck using the Metal Tech battery tray that bolts up to my sliders. Keeping my center of gravity lower and less crap in the engine bay.

rover67
10-07-2009, 11:57 PM
Thanks guys! :beer:

The only big differences are the 300 amp continuous rating (1500 intemittent), and the fact that the second battery is not switched into the system untill the first one's voltage comes up. The NL kit keeps them separate after starting for a fixed amount of time, then joins them.

I didnt hook up the cab controls since I didn't care about being able to join them manually from inside the cab. The VSR has a manual switch on the box itself that switches it from off, to auto, to on. the switch forces it to be in any of those conditions no matter what the charge voltage is. I figured that the only time i'll need to mess with it is if the main battery goes flat, then its easy enough to pop the hood and flip the switch.

I didn't do the NL kit because I knew i'd want to upgrade cables, I liked the way the VSR worked a little bit more, and the VSR can handle general winching loads (didn't have to worry about it being on while winching). If you take the cables out of the equation the price of the VSR (I found it for $150) versus the NL solenoid ($140 from equipt) is not too far off, and the battery monitor would be used in either setup.

The cables are what really cost money...

rover67
10-08-2009, 12:00 AM
There is always some level of exposure. Winch cables aren't fused, right? You could crimp a 3 or so inch length of 6AWG/SXL between the post and end of the 1/0 cable as a fusible link.

yeah.. I'm not toooo worried about it. I mean the cable to the starter is not fused in really anything i've seen before either.

Maybe we should grab a group 31 battery, charge it up, and short it out with some beefy cable. I wonder what would happen :eek:?

Rock Dog
02-24-2011, 02:36 PM
I am resurrecting this thread because
1) i found it incredibly useful
2) i have been sourcing the same VSR that Marco used and want to share my finding's on where these little Gem's can be procured...

Unfortunately i have not found any of the 300A ones on Ebay or Craigslist.... The 70A and 125A versions can be found at:
Amazon's , Defenders, and Delcity's websites..
The only place from the list of US distributors for BEP Marine products that had the 300A version were

Fisheries supply for $194.00
West Marine for $214.00

http://www.fisheriessupply.com/productgroupdetail.aspx?cid=109829&keywords=VOLTAGE+SENSITIVE+RELAY

http://www.westmarine.com/webapp/wcs/stores/servlet/ProductDisplay?productId=93176&catalogId=10001&langId=-1&storeId=11151&storeNum=10109&subdeptNum=10544&classNum=10337

I went ahead and picked up one of the 2 that Fisheries supply had in stock....
West Marine's website indicates it is a "hot item" and they are currently out of stock...

Thanks again Marco! :thumb::thumb:

sleeoffroad
02-24-2011, 02:48 PM
Now you need this. Here is what it does

rover67
02-24-2011, 02:55 PM
No problem, glad you found the thread useful!

My setup has been working really well and I have basically not touched it at all. I have winched a lot (combined), and run the spare battery down a bunch and it always performs well.

I never really touch it.

The only annoying thing is that the National Luna Charge display almost always shows an overcharge condition and beeps at me. I have to cancel the beeping a lot. I understand this is a common problem from looking around a bit online. Seems like their set point for the alarm is a bit low.

I have noticed that the 300A VSR's are hard to find. I guess I lucked out that I found that one on ebay...

rover67
02-24-2011, 03:03 PM
Also, I found out that I overpaid for the cables.....

Make them yourself or go to Hensley Battery and have some made up. It will save you some cash.

That monitor looks cool Christo

Rock Dog
02-24-2011, 03:07 PM
Now you need this. Here is what it does

Got any pictures of the front ?
you attachment only has a picture of the rear...

I really like the idea of the color changing LED's... I will PM you...

Rock Dog
02-24-2011, 03:13 PM
Also, I found out that I overpaid for the cables.....

Make them yourself or go to Hensley Battery and have some made up. It will save you some cash.

That monitor looks cool Christo

Thanks Marco, i had planned on having Hensley make them up.. The cable runs should be really short, as the batteries will sit side by side in my FJ40. I have been waiting for the 9A34M batteries to come in for 3 weeks :rolleyes:... hopefully they will arrive about the time the VSR does.

sleeoffroad
02-24-2011, 03:18 PM
Got any pictures of the front ?
you attachment only has a picture of the rear...

I really like the idea of the color changing LED's... I will PM you...

Two LED's. Drill 1/4" holes into a switch blank or any other area you choose and install the LED's. What you are looking at is the "black box".

nakman
02-24-2011, 04:42 PM
Two LED's. Drill 1/4" holes into a switch blank or any other area you choose and install the LED's..

Drill holes??!! :eek: What are you, some kind of caveman? Why don't you just tighten your hub nuts with channel locks, while you're at it, geez...


After all, this the direct manufacturing era. :D

Inukshuk
02-24-2011, 05:39 PM
Drill holesWhy don't you just tighten your hub nuts with channel locks, while you're at it, geez...

JB weld it

Rock Dog
02-24-2011, 10:37 PM
Drill holes??!! :eek: What are you, some kind of caveman? Why don't you just tighten your hub nuts with channel locks, while you're at it, geez...


After all, this the direct manufacturing era. :D

pretty cool Nakman :thumb::thumb:
The multi colored LED is a GREAT space saving idea for a dual battery monitor.... and being able to snap in something like that into an existing blank is awsome...

This particular setup is for the fj40, so i have to give some thought to LED placement...

Corbet
02-24-2011, 11:52 PM
How about using a rear heater switch from an 80.

Re-label it for batteries. Then put the two LEDs on the right and left sides of the switch windows. So now you have the LEDs for the monitor and a switch to control the dual batteries all in one?

sleeoffroad
02-25-2011, 06:44 AM
Drill holes??!! :eek: What are you, some kind of caveman? Why don't you just tighten your hub nuts with channel locks, while you're at it, geez...

Nah, I use a screwdriver and hammer :)


After all, this the direct manufacturing era. :D

True dat. :D

nakman
02-25-2011, 11:32 AM
True dat. :D

speaking of which... that 100 series mic holder looks awesome!! :bowdown:

http://www.sleeoffroad.com/products/products_interior_main.htm

Creap
03-11-2011, 09:49 AM
Hi

I own a conversion van and thinking a dual battery system may be nice. I think I understand what I need but wanted to clarify something.

I want to install a second battery that will power a inverter that will power a lcd tv, dvd player, charge a netbook or ipod, cell phone and such. The question I have is not really related to using the items when the van is off but when it is running.

Is there a issue to have these items running from the inverter connected to the 2nd battery as the van is driving down the highway. I am unclear on if there is a separation of where the power is coming from if the car is not turned off. And if that load will just get transferred to the alt and burn it up.

Uncle Ben
03-11-2011, 10:27 AM
On your setup a "smart" system is probably overkill. A simple single continuous duty relay linking both batteries together when the key is in the hot position is most likely all you need. "Smart" systems take it a step further and monitor the primary battery. They will do what the simple "dumb" relay will do and charge the second battery but they do it by voltage spike sensing. When there is a spike of 13.5+volts (engine running and charging) they will activate the relay. Where they shine is when you are over drawing and voltage drops below 11volts they will drop out, thus isolating the batteries so both are not discharged. "Smart" and "dumb" relay setups can both be set up to self jumpstart if the main (starting) battery is dead. The generic battery isolators that are basically a large finned aluminum heat sink and a healthy diode work fine for RV use also because of the long engine run times associated with RV's. They are not nearly as efficient as a relay set up because they generate massive heat. Heat takes energy to produce thus robbing energy from your charging system.

Hi

I own a conversion van and thinking a dual battery system may be nice. I think I understand what I need but wanted to clarify something.

I want to install a second battery that will power a inverter that will power a lcd tv, dvd player, charge a netbook or ipod, cell phone and such. The question I have is not really related to using the items when the van is off but when it is running.

Is there a issue to have these items running from the inverter connected to the 2nd battery as the van is driving down the highway. I am unclear on if there is a separation of where the power is coming from if the car is not turned off. And if that load will just get transferred to the alt and burn it up.

Caribou Sandstorm
10-01-2012, 10:52 AM
Great write up Marco...