Dual Battery Advice (1 Viewer)

[askeyey]

I was finally ready to pull the trigger on all the parts for my dual battery set-up. Using a set up similar to NLXTCY, I had made up my mind I was going with a HR BIC and West Marine fuse panel and 80a breakers, and two Diehard Platinum 880 CCR deep cycle marine batteries.

So here's the monkey wrench...yesterday at the local West Marine I came across this.

West Marine: "Add-A-Battery" Dual Circuit System Product Display

It's a BIC but it doesn't operate with Diodes...instead it uses relays..therefor less voltage drop and less heat generation.

It claims to "Simplify switching and automate battery charging with this system that includes the 7610 Automatic Charging Relay (ACR) and 5511e Dual Circuit Plus battery switch. The ACR combines batteries for charging, automating battery charging."

Can someone with a little more experience provide some feedback?

 

[soggy60]

See

SI-Series Automatic Charging Relay - Blue Sea Systems

and

http://bluesea.com/files/resources/instructions/990170140.pdf

 

[ntsqd]

That is exactly the combo that I currently favor. The ACR (other brands call them "VSR"'s 'Voltage Sensing Relay') controls the charge to the second battery and the disconnection when the engine is turned off.
The manual battery switch allows for an over-ride should it be necessary (self jump-starts, etc.).

Link to the VSR: Voltage Sensing Relay - Single Sense ($76 each)

And to battery switches: Battery & Ignition Switches

EDIT: What I like about the ACR/VSR + marine combiner switch option is that it is automatic with little chance of accidentally changing the switch to a normally undesired setting. And if the ACR/VSR fails you have a back-up option in the separate switch.

 

[sl33py]

I'd vote for the BIC still. I just installed mine and really like it. One thing you might do is chat w/ the HellRoaring guys -very helpful and knowledgeable. I'd be curious what the differences are - any voltage drop or draw vs BIC? etc.

there is a pretty decent comparison chart (generic of brands of course) And not sure what category this kit would be, but check it out at bottom of the page here:
Hellroaring Battery Isolator/Combiner BIC-75300

Good luck! Dual batts are nice, and any configuration is better than one batt alone.

Also - check out delcity.net for fuse box - they have some nice ones. I looked at the 6 fuse/60A max, and 6 fuse/100A max. got the second and like it a lot.

GL!

rob

 

[slcfj62]

Just my two cents. Any solid state device will drop some voltage. Typically from .3 volts on the low end to nearly a volt on the high end. On a 120 volt system, this is insignificant. But on low voltage systems like a 12V vehicle, this can be a big deal. This voltage drop is what causes heat generation. A .5 voltage drop with 100 amps of current makes 50 Watts! Combine that with the heat under the hood, and you have hot semiconductors. The hotter they run, the sooner they fail. Additionally, just a few tenths of a volt of battery charge can equal a big difference in how fully charged the battery is. For instance, at 80 degrees F and with no load, a fully charge battery will be about 12.7 volts. A battery sitting next to it at 12.5 volts is only 80% charged.

Relays are old school, but they are still around for a very good reason. They work. As long as the contacts are not dirty, they have zero voltage drop and zero heat generation. With the metallurgical technology that exists today, relay contacts will last a long time. Look how long the solenoid in your starter lasts, and it switches some major current. I worked in a power plant for a while, and saw relays as big as a refrigerator that could switch enough juice to power a small town. So I wouldn't be afraid of relays. In a dual battery setup, I think it is the way to go. A relay and a switch. That is good and simple. Just what you want on a hot day in the middle of nowhere.

EDIT: And as ntsqd points out in post #3, you can get the whole setup cheap enough to get a spare relay to boot.

 

[askeyey]

Relays are old school, but they are still around for a very good reason. They work. As long as the contacts are not dirty, they have zero voltage drop and zero heat generation. With the metallurgical technology that exists today, relay contacts will last a long time. Look how long the solenoid in your starter lasts, and it switches some major current. I worked in a power plant for a while, and saw relays as big as a refrigerator that could switch enough juice to power a small town. So I wouldn't be afraid of relays. In a dual battery setup, I think it is the way to go. A relay and a switch. That is good and simple. Just what you want on a hot day in the middle of nowhere.

I like the relay concept for just this reason. It seems most on Mud have worked a system that has an HR BIC or some similar concept so that's what people are comfortable with.

I also like the price of the West Marine unit...at $157.00 with the ACR and master control switch I think it's a good deal. Plus I can pick it up local which will save on shipping and ease on possible returns. I am still impressed with what HR has to offer and I think I'll get my 80a fuses through them.

 

[askeyey]

Considering how I'm going to mount everything, I have decided to run the second battery from the back of the truck. I realize how pricey the cableing is going to be so I started shopping for alternatives. Has any one ever used 2 guage aluminum wire like is commonly found in residential construction. Just a thought.

 

[slcfj62]

Considering how I'm going to mount everything, I have decided to run the second battery from the back of the truck. I realize how pricey the cableing is going to be so I started shopping for alternatives. Has any one ever used 2 guage aluminum wire like is commonly found in residential construction. Just a thought.

It's too brittle for vehicle use. It would crack and break over time. Even using copper, you would need wires as big as your thumb to go that far. Be sure and use wire intended for vehicle use. Cheapest would be a whole sale battery place--the kind that puts batteries in forklifts and golf carts. They could help you figure the size wire you need for a run that far.

EDIT: Welding leads may also be an option. Find some cheap used welder for sale, just so you can get the big fat leads.

 

[askeyey]

It's too brittle for vehicle use. It would crack and break over time. Even using copper, you would need wires as big as your thumb to go that far. Be sure and use wire intended for vehicle use. Cheapest would be a whole sale battery place--the kind that puts batteries in forklifts and golf carts. They could help you figure the size wire you need for a run that far.

What do you think about this stuff from McMaster

McMaster-Carr

it's only 2.66/foot for more than 25'

 

[slcfj62]

It depends on how much current you plan on drawing. 2 guage wire is a little more than 1/4 inch in diameter and has a maximum current capability of 180 amps. (Unless of course the wire is made in China, and then it probably only has half that capacity. ) For normal charging (30-40 amps) and normal load (off road lights, etc) you should be fine. But if you have a killer alternator, or plan on powering a winch or a welder, you will want to go with something quite a bit bigger.

I like my old welder leads idea.

 

[dtrain]

EDIT: Welding leads may also be an option. Find some cheap used welder for sale, just so you can get the big fat leads.

Depedning on the guage - how about jumper cables?

 

[ntsqd]

FWIW my local PowerStride Battery store just quoted me under $1.50/foot for #4 when bought in a 20 foot plus length. This is for flexible welding cable rather than the stiffer battery cable. We need exactly that for work.......

Jumper cables can be big enough, but finding them in a long enough length can be difficult, and typically they are more expensive than just buying the cable and ends.

BTW, if you do plan on pulling a lot of current from that rear battery you should run the same size ground cable up to the main ground point for the front battery. If you plan on normal paralleled use this should be done even if you don't expect to pull a lot of current from the rear battery. IME just the small resistance between distant grounding points will draw down the batteries in a dramatically short time.

A vendor that I recently found, but have yet to use: quickcable.com

 

[NLXTACY]

hey guys, just happened upon this thread

Give me a few minutes to absorb what is here and I will give some feedback.

 

[NLXTACY]

Ok so, looking back would I use HellRoaring BIC again, yes. I am spec'ing out a dual battery set-up for myself, SPIKE STRIP and RANDY88FJ62 and the three of us are going to do our 60s at the same time.

We are all going the Sears Platinum, all using the 4+ battery trays instead of the stainless ones and so far I am still leaning towards using the HellRoaring units again although a different unit that what was used for my LX. My LX is setup as main, back up and aux. (3 total eventually) instead of main and back up for the 60. I looked at the West Marine set up but I didn't want to have to use a Perko switch for the battery system. I preferred using an automatic set up with a toggle to combine if needed.

Voltage drop is definitely something to consider BUT I do not think its something to worry about if it is your daily driver. Which both of my vehicles are daily drivers. So for me the voltage drop isn't much of an issue.

The Ford style automotive solenoids I see burn up way too often and I just don't trust it. A lot of people use them just fine but its not for me. I like solid state. Yes it creates heat due to the diode but the HR unit has built in fins to combat that and to this day I have never ever heard of an HR unit failing.

What really made my decision was when I called some of the companies and started asking questions about my particular project on the LX. HellRoaring was the ONLY one that spent plenty of time with me to talk through all the possibilities of set up and why one way works versus another. When I called West Marine about the same unit you are looking at, I got answers that were spoon fed to them. I really felt like they couldn't answer a question that was outside of their comfort zone.

I will say that although I don't like the solenoid usage, I do kinda like the National Luna. I would consider that but it has a high price point.

When it comes to cable length, remember that when calculating the draw and figuring out which gauge to go with, that the current path is for BOTH directions. So a 20ft run is 40ft both ways. This is what you want to use to figure out what gauge to use: http://www.btc-bci.com/~billben/maxwire.pdf

As for the cable itself, contact GenuineDealz.com. DO NOT use aluminum. Aluminum is NOT spec'd for automotive use because it doesn't have the same flexing specifications that copper does. Also the same gauge aluminum cannot carry the same current that the same size copper can. Also, the aluminum cables is not fine strand. Its thicker strips, kinda like spaghetti. DON'T use it!

What you want is tinned copper which you can find from good Marine supply shops.

 

[askeyey]

well...I guess I have some things to digest now

 

[askeyey]

well now I'm back at square one...I know the answer though...pick which ever one I want and go with it.

NLX...what guage wire did you ultimately go with. Even though I will start out with much less demand, my future plans have me ending up about where you are on total load.

 

[NLXTACY]

THE best advice you can take away from this discussion is "build it for all potential future uses". You do NOT want to be pulling out cable and doing it again to get larger gauge in there. I went with 1/0 to my distribution points. From there 8/10/12 depending on the load and distance.

I will be adding a jumper cable access point to the rear as well. This will more than likely be 1/0 as well. Still TBD. Just keep thinking about what you want.

 

[askeyey]

I went with 1/0 to my distribution points. From there 8/10/12 depending on the load and distance.

Did you use Genuinedealz as a source for your wire? Looks like there's no getting around the fact that wire is expensive.

I guess it's time to measure and order.

Thanks for all the help.

 

[NLXTACY]

Yes I got tandem wire for all the 8/10/12 gauge. I had already purchased my 1/0 from Wrangler Power products before I found GD. I would only use GD from here on out.

 

[NLXTACY]

BTW, there are many ways to skin the dual battery cat. I really don't think there is just one way. Just one way that works for you. Some people like using Perkos because they want the manualness of it. Some don't want to think about it. Also, the discussion was beaten to death in the 80s forum but personally I would not run a DC battery as my main even though the Platinums are spec'd to be both a DC AND and starting battery. I could be worrying about nothing but I just didn't. For me, main is main and deep cycle is for aux. YMMV