dual batteries question

[96broncoman]

i searched alot and i was just wondering what is the best way to wire dual batteries? what are the advantages of the isolator. what about a relay? do you need a switch in the cab? what is the switch in the cab for? i found a diesel in the junkyard early this week and pulled the drivers side battery tray, so i plan on locating the batteries like plug ugly. i am just trying to get some knowledge. thank you.

[11jdsummerfield]

Hooking the batteries up directly to ecah other can lead to "Dual Battery Syndrome" basicly they don't last as long. Using as isolator with a switch in the cab allows one to be charged periodicly and then used for winching or any othe high power draw situation. However, this does cost some cash. It's up to you wheteher on not it's worth it.

[ToddACimer]

there's a dual battery thread going on right now. it's even in the newest posts

[carlos_83]

if ya are planning to run an isolator, keep in mind that isolators have current ratings, and they should match, or slighlty exceed your alternator output.

[96broncoman]

Originally Posted by carlos_83

if ya are planning to run an isolator, keep in mind that isolators have current ratings, and they should match, or slighlty exceed your alternator output.

i think i will go with an isolator, seems like the better way to go.
if i just get like the wrangler kit or the painless kit, will it have a schematic, including the starter and all that. i do a way better job with this type of stuff if i can follow a schematic

[hoefox]

if you searh petersens 4 wheel drive magazine they had a really got article about the correct way to run dual batteries. the way they had it used a switch inside the cab, it pretty much isolated the first battery to start your car and keep running, the second battery was for all your accessories (for lamps, system, winch, etc) good luck

[Gentle Giant]

im running dual batteries and isolator from painless wires ( bought it from jeg's - part # 076440102 ) works great. rated at 250 amps. batteries are running a 1000 watt sound system , 2 100 watts k.c. lights on my brush guard and soon will be running 4 k.c.s on the roof.

ps , with very easy to read schematic.

[jam0o0]

i got dual batteries. i put them side by side on the passengers side. made a tray to hold them both and i just finished the all new wires, 1/0 with soldered ends and dual wall shrink wrap. it's all like factory except the cables are twice as big. don't the factory dual battery systems in the diesels not use an isolator? if they don't use one i don't see the point of the extra expense. i did the think everyone tells you not to do and put one new battery in with the old battery. and it's been a year and they are both still fine. i still have crazzy reserve capacity. (left interior lights on for three days, started right up)

[Bronco4Life]

Originally Posted by 11jdsummerfield

Hooking the batteries up directly to ecah other can lead to "Dual Battery Syndrome" basicly they don't last as long.

I'd love to hear what "Dual Battery Syndrome" actually is...

If you parallel two batteries, they don't know or care what's going on with each other, they just give off electricity. The power is going to move from the battery with the higher charge. And whatever is using the power will continously draw from both batteries alternately as one becomes less charged then the other. With that said, you should still replace both batteries (no used/new) and replace them with the same type (eg. Two group 65 batteries)

As for charging, the power is going to flow from the alternator to the battery with the lesser charge, and will fill up the batteries in the same fashion that they were discharged - whether they are or aren't isolated. All putting an isolator in does is let you discharge a battery and not affect the other. When your alternator starts charging, it will fill the battery that is more discharged first until they become evenly charged, and then will charge 50/50.

Although I shouldn't say that is completely true. If you have one battery that is only absorbing 40 amps, and you have a 120a alternator, the rest of the output of that alternator will go to the other battery or however much that battery is able to take. Electricity follows the path of least resistance.

Whenever my buddies and I go tailgating, I have an 0g wire run to the back of my truck, and I clip it on to an 8D battery that I carry on my rear carrier. That way I can play tunes ALL day long. Never had a single problem with doing it that way. On the run home, I leave it hooked up and charging, and by the time we're done with the 2.5 hour ride, my battery reads fine with our load tester, as does the big one, and thats only with my stock 60a alternator... gotta do that 3g soon

[Weber]

Pretty close the only thing I'd correct in that statement is that if you have a bad battery paired up with a good battery, the good battery will be trying to compensate for the bad battery and fail prematurely. Batteries are like a chain, they're only as strong as the weakest link... That why if you've say got an RV or a Golf cart or a Semi or whatever, you don't just change out the bad battery, you change them all.

With that being said since you are adding a battery to a single battery system you probably won't suffer as badly as if the vehicle was originally designed with multiple batteries.

And I ran an isolator in my set up so I can run my accessories without affecting my starting battery, and this way also allows you to run 2 different types of batteries.

[Optika1 illushun]

if my original battery is in good condition and realitivly new (purchased nov 2004) should i worry bout adding a new battery?

[bronco boy]

Originally Posted by 96broncoman

i searched alot and i was just wondering what is the best way to wire dual batteries?

This is mine, with the in-cab switch.

Originally Posted by 96broncoman

what are the advantages of the isolator.

I prefer a continuous duty solenoind. Not as fancy as an isolator, but works just as good. I'm on my second solenoid in 12 years.

Originally Posted by 96broncoman

what about a relay?

Would work, but to find a hi-amp relay would probably be expensive. Cheaper to go solenoid or isolator.

Originally Posted by 96broncoman

do you need a switch in the cab?

That is optional.

Originally Posted by 96broncoman

what is the switch in the cab for?

In my case, the switch opens the solenoid allowing the auxillary battery to be used to start the truck when/if the main battery goes dead. There are kits (see Painless Wiring) where they have a two or three way switch to contol the isolator, ie Batt 1, Batt2 no Batt etc.

[Steve83]

Originally Posted by bronco boy

I prefer a continuous duty solenoind. ... I'm on my second solenoid in 12 years. ...to find a hi-amp relay would probably be expensive. Cheaper to go solenoid...

You're using a RELAY.

[bronco boy]

Originally Posted by Steve83

You're using a RELAY.

No, it is a solenoid; same as what starts your truck, just continuous duty.

[Steve83]

My truck has NO solenoid on the starter - neither does yours. We both have RELAYs on the inner fender. Here's the difference:

[bronco boy]

Originally Posted by Steve83

My truck has NO solenoid on the starter - neither does yours. We both have RELAYs on the inner fender. Here's the difference:

Never said nothing about a solenoid "on the starter".

Steve, I've been in the automotive parts business for 13+ years now, and the industry refers to them as "starter solenoid". I was going to say that it may be Canadian vs. American terminology, but 90% of the catalogue's in this business are from American Company's. Not saying you're wrong, as a quick 'net search found results for both solenoid and relay, but if you were to ask me for a starter relay, this is what you would get. :)

Anyways, I have a Niehoff #FF134A starter solenoid starting my truck and a Cole Hersee #24059 65 amp continuous duty solenoid controlling my dual battery's.

[Bronco4Life]

Originally Posted by Optika1 illushun

if my original battery is in good condition and realitivly new (purchased nov 2004) should i worry bout adding a new battery?

Depends on the condition of that battery. Load test it, and see how close it comes to its rating.

[Steve83]

Well, this is a Ford forum, so I use Ford terminology. It's not a parts forum, and the "parts industry" didn't invent or design them, so what they call it isn't really important. Yeah, there are a lot more GM parts sold, and all GM starters use a solenoid, and so most people incorrectly label a Ford relay as a solenoid. The typical car owner would call every part under the hood a "thing", but I'm not going to. It is a relay, regardless of how many parts books call it something else, or how long they've been doing it. A relay is distinct from a solenoid, so the terms aren't interchangeable. Participating in that kind of slang only causes more confusion.

Originally Posted by bronco boy

...a solenoid "on the starter".

The ONLY place there's a solenoid in the starting system is ON the starter; that's on Ford, GM, DC, or any other vehicle, so yourself.

And your example is of a Bosch/ISO relay - it can and IS used for many applications other than starters. I'd say less than 5% of them are used in starting circuits, but that's just a guess.

[bronco boy]

Originally Posted by Steve83

It is a relay, regardless of how many parts books call it something else, or how long they've been doing it. A relay is distinct from a solenoid, so the terms aren't interchangeable.

So you're saying that every parts mfg and every parts store is wrong?

[Steve83]

Was that quote unclear??? I'm saying they're using the wrong name for that part: yes. Look it up - a solenoid is a mechanical device (usually electro-mechanical) for performing a mechanical operation; a relay is an electrical or electronic device that allows a small current to control a large one. Starter solenoids DO have an internal relay, but the fact that they consume a high current for their mechanical function is an easy way to distinguish their primary function, which is why they're still solenoids. The one on the fender does NOTHING mechanical, so it's not a solenoid - it's just a heavy duty relay.

But "wrong" is a very subjective term. They're making money, which is what they're in business for, so if they can sell it as a "solenoid", then it must not be absolutely "wrong".