Off Roading Forums banner
1 - 18 of 18 Posts

·
Registered
Joined
·
4,767 Posts
Discussion Starter · #1 ·
I need to set my battery for my trailer winch to charge off of my truck while running down the road. I have seen this done with a small guage wire, but it always had some form of battery isolator in the system.

How can I Isolate my battery so it
1. Dosent overcharge.
2. stays charget through the vehicle charging system.
3. dosen't blow up un predictdly.

Thanks
 

·
Registered
Joined
·
6,870 Posts
Unless you are using the same size and type (storage, deep cycle, ect) you will have to use an 'Isolator' type splitter for the charging system.

An 'Isolator' or 'Splitter' has a voltage regulator for each battery in the system.
You hook the charging system up to the 'Isolator' and each battery up to the 'Isolator'.

DC doesn't travel distance very well through small wire, so you will probably have to use a 10 Ga. wire or better to the trailer battery.
That will include an independent 10 Ga. ground wire also.
The wire used for the lights isn't good enough for this application.

Small but heavy duty connectors are used for a number of things, including winch controls, that you can use for the circuit connecter. I'll try and find a picture/ part number for one.

A healthy fusible link will be required at the 'Isolator' for the rear battery positive circuit just in case the wire gets pinched or grounded.
These are available at NAPA and discount stores for $2 or $3 dollars.
 

·
Registered
Joined
·
391 Posts
You may even want to go with a thicker wire than that but it depends on the distance your running it? What kind of vehicle and trailer are we talking about here? If the stretch is going to be more than 15 feet you may want to use 8-4 guage and a heavy duty battery isolator.
A battery Isolator is nothing more than a large relay really. You could even use something like a ford starter solonoid if you want to. Your alternator has the regulator built into it.
You should also run a thicker wire from the alternator in you truck to the Isolator and maybe think about an alternator upgrade if your going to do that, Mind you I dont know your truck so your alternator might be strong enough. To push a charge more than 15 feet or so to a second battery may be hard on a stock alternator if you get caught at night in the rain or something.
good luck /ubbthreads/images/graemlins/wink.gif
 

·
Registered
Joined
·
4,893 Posts
I thought that the center pin on a 7 prong round connector was for exactly what he needs...
 

·
Registered
Joined
·
11,504 Posts
The coil in a starter solenoid is designed for intermittent use. If you leave it engaged for a long time it will overheat and fail.
 

·
Registered
Joined
·
6,870 Posts
Elusive,
If he had mentioned a 7 pin connector we may have discussed that very thing.
If he intends to do ANYTHING but charge the battery the trailer connector will be too small of contacts for the job.
-------------------------

I agree on wire size.
Mine did the best with about 6 Ga. on the Grand Wagoneer.
10 Ga wanted to heat up when I used the trailer appliances, and 8 Ga still got a little warm, so I used a 6 Ga. wire with no problems so far...

With a little larger wire (like 2 Ga. or 4 Ga.) the truck battery could help with winching, lights or running the electric compressor, stuff like that.
------------------------

Here is something else we didn't cover...

If you are using two or three of the same size and type of batteries on the trailer, then you only need one charging line set.
If the batteries are the same size, type and age, one charge line can charge all in the set.
That will save you having to buy a huge, costly (and inefficient) isolator.

Things may have changed in the 10 years since I did this for a living, but...

A 'Quirk' of battery isolators is they drop voltage about 1/2 to 1 full volt for each tap on the line.
Say input voltage is 14.5 volts, the first output tap will be around 13.5, and the next 12.5 and so on...
So keep your isolator to as few taps as possible.
 

·
Registered
Joined
·
4,767 Posts
Discussion Starter · #7 ·
I was wanting to run it through my 7 pin plug. The only thing it is for is to keep the battery fresh. as is I can winch on 7-10 cars without recharging dependin on what it takes. So the battery dosen't even need much of a charge, but at the same time I don't want it over charging and ruining the battery.

The system I have now preforms pretty good, but when I am busy I almost always have to pull one of the batteries out of the truck to finish winching something.

Truck is an 83 chev diesel with dual batteries under the hood. Trailer is just the run of the mill 16 foot utility. Although I will be upgrading trailers soon.
 

·
Registered
Joined
·
6,870 Posts
Use a battery isolator, one leg for the under hood battery set, one for the trailer.

Five pin won't do it, you still need a dedicated ground.
Trust me on this, I've been through it more times than I can count...

4 for lights, one for battery positive, one for battery negative... That's at least 6 prongs.

Lights,
1 Right turn/ Brake
2 Left turn /Brake
3 Tail Lights
4 Trailer Ground (not to be confused with battery negative)

Battery,
5 Trailer Battery positive
6 Trailer battery negative

NOW...
If you use a big truck type plug, you will have one large terminal, and it is enough to charge the battery if trickle charging is all you have in mind.
This will also give you an extra or two so you can turn on lights or have an extra electrical accessory in the back controlled by switches in the cab.

Use the big truck 'Bullet & Socket' type connector,
not the next to useless 'Mobile Home' type of connector.
----------------------

If you don't use a dedicated ground for the battery, you will find your lights doing stupid things (like glowing after the trailer is unhooked) and the battery will never get fully charged.
Depending on were the ground wire for the trailer lights is anchored, you may not get any battery charging.

If you don't run a battery isolator, one of two things will happen...
1. The battery will slowly run down because it's not being charged up completely each time...
2. The battery will overcharge and dry out or warp plates until they touch internally and ruin the battery.

A battery isolator and large gauge feed wire is the ONLY way to ensure the battery is fully charged and not overcharged.
 

·
Registered
Joined
·
391 Posts
"If you don't run a battery isolator, one of two things will happen...
1. The battery will slowly run down because it's not being charged up completely each time...
2. The battery will overcharge and dry out or warp plates until they touch internally and ruin the battery.

A battery isolator and large gauge feed wire is the ONLY way to ensure the battery is fully charged and not overcharged. "

Plus one on that JYG He could use 8 guage with a quick disconnect. I do it all the time when I run big stereo systems with quick change amp racks and such. Any car stereo store or "good" auto parts store should have these things.
 

·
Registered
Joined
·
6,870 Posts
[ QUOTE ]
"Plus one on that JYG He could use 8 guage with a quick disconnect."

[/ QUOTE ]

Could you elaborate more on this?
I'm not quite sure what you are talking about, so I'd like to know more!
I'm always up for learning something, and if you have come up with a quick and dirty way to charge a remote battery, I'd sure like to know how it's done!
 

·
Registered
Joined
·
391 Posts
I have run second batteries in many of my larger stereo systems. Companies like stinger and tsunami make dual battery isolators that are like giant solonoids. I have run everything from 8 guage to o guage wire through a car to a second battery. It goes like this: Run a larger guage cable from your alternator directly to your primary battery, then from the primary battery to the dual battery Isolator input post. From the output post you run whatever guage wire to the second battery, the longer the stretch the thicker the cable the better. Now there is the activation posts on the isolator, one goes to ground and the other would normally go to some ignition source that is live when the key is in the on position however in a trailer I would hook it up to a toggle switch so that it can be turned off at the solonoid when your not using the trailer. And somewhere in the back between the trailer and the truck you can use standard male and female crimp on connectors. I use them at work all the time, I use a hammer crimper to put them on. Oh I also usually use a resetable circuit breaker between the isolator and the second battery also ( just in case)
http://cgi.ebay.com/STINGER-SR80-HIGH-CU...2QQcmdZViewItem
 

·
Registered
Joined
·
6,870 Posts
OK, I kind of though that might be what you were talking about...

I'm not trying to be insulting, so please don't take it that way...

Your 'Stinger' is nothing more than a starter solenoid for a lawn mower.
If you don't need the 'Stinger' label, you can probably buy them a lot cheaper at the local small engine shop.

When the solenoid is activated, it directly links your secondary battery to the primary system, and cuts the secondary battery off from charge, or discharge, when the solenoid is inactive.
--------

A battery 'Isolator' we were talking about is a charge controller.

The output of the alternator is directed into the charge controller, an there is a built in voltage regulator for every battery in the system.

That way no battery is undercharged or overcharged.

Different batteries in the systems will charge at different rates. (different sizes, or types, like Deep cycle, storage, or fast discharge)
Also, batteries are made in different ways from different materials, ('Dry' cells, gell cells, flooded, ect.)
so they charge at different rates.

The 'Isolator' or 'Charge Controller' we are talking about keeps the batteries from cooking themselves or from not getting charged as the charging system cycles.
 

·
Registered
Joined
·
10,815 Posts
On my car hauler trailer - although I don't winch on 6 or 7 vehicles a day - I just ran a 12 gauge wire from a solenoid on the truck's battery through the 7 pin connector to the trailer battery.

Most of the time the trailer is not in use or connected, so occasionally I toss on a battery charger. But on the road it keeps the battery up fine.

The solenoid is a continous duty from a camper supply dealer.
Simple, cheap, effective.

KISS

Remember, most batteries can't take much over a 30 amps charging for any length of time anyway. More than that the plates warp - then it's history.

The small wire limits the current by it's resistance. The side benefit is the truck's battery gets charged fully before much current goes to the trailer battery.

Not fun to have to jump start yourself from your trailer.
 

·
Registered
Joined
·
391 Posts
Thats why in my first post I said that it was kind of like a ford starter solonoid. And you are correct this will only work if both batteries are the same. You dont have to worry about an internally regulated isolator if you have a truck newer than the 1970's because most alternators have one built in so it wont overcharge the battery you already have. It will charge two batteries just the same as it will charge one assuming your alternator is in good working condition and has enough amperage to do the job. The isolators you are talking about are alot more expensive and you really only need them if your going to run different types of batteries. but you can also use a simple resistor inline to accomplish the same result /ubbthreads/images/graemlins/wink.gif
 

·
Registered
Joined
·
6,870 Posts
A charging 'Isolator' keeps the demand battery (the one not completely charged) from demanding current from the alternator and overcharging the already charged battery...

There are several charging levels to properly charge a battery.
If you rotate your trailer battery frequantly with your truck batteries you should keep them about working at about the same duty rating...

If you are trying to fast charge a deep cycle, or use a starting battery as a deep cycle, you are going to need DEEP pockets!

Good luck!
 

·
Registered
Joined
·
10,815 Posts
An interesting phenomenon occurs when you connect 2 batteries in parallel. Even if they are the same type, same make, and the same batch - no matter how closely they are matched.

They tend to drain each other - not fast, it's a trickle, small current - but measurable with a simple ammeter between them. For lack of better term, I'll call it "backfeed" here. (I'm sure there's a word for it already.)

It will drain them about as fast as leaving your radio on. Depending on their capacity and charge, that might be a few days.

That's why an isolater "Isolates" them, not from the charging source, but from each other.

Most of the isolators around - even the complicated big expensive ones, are just diodes splitting the current and preventing "backfeed." Some use a solenoid to disconnect to the charging source, some don't.
 

·
Registered
Joined
·
13,432 Posts
[ QUOTE ]
An interesting phenomenon occurs when you connect 2 batteries in parallel. Even if they are the same type, same make, and the same batch - no matter how closely they are matched.

They tend to drain each other - not fast, it's a trickle, small current - but measurable with a simple ammeter between them. For lack of better term, I'll call it "backfeed" here. (I'm sure there's a word for it already.)

It will drain them about as fast as leaving your radio on. Depending on their capacity and charge, that might be a few days.

That's why an isolater "Isolates" them, not from the charging source, but from each other.

Most of the isolators around - even the complicated big expensive ones, are just diodes splitting the current and preventing "backfeed." Some use a solenoid to disconnect to the charging source, some don't.

[/ QUOTE ]

Let's keep things simple, as I've said before, [ QUOTE ]
by isolation you can use two batteries as without stressing/killing the batteries due to improper use or charging.

Think of batteries as buckets of water that you need to fill up with water. If you put a hole in the bottom of the buckets and put a pipe between the two, they are now in parallel. If you fill one bucket, you fill the other. As long as the buckets are identical, the buckets will fill to capacity.

Now what happens if you put a hole 5" down from the top of one of the buckets? Can you still fill both buckets? Let's try. You start filling one bucket with water. Being in parallel, you're filling both buckets. So, the water approaches the hole in one damaged bucket. Then it starts to pour out the hole. You pour more water into the bucket to fill them both to the top and walk away. You were able to fill them because the fill capacity was larger than the hole.

But the hole was still there, and it's working. Soon, the hole in the bucket will drain the water level with the bottom of the hole... and stop. Ah, but then look at the other bucket. It's water is drained too that same level! Drats, it's as if you've got two holes in the buckets, even though only one is damaged. The undamaged bucket has taken on the characteristics of the damaged bucket.

So now how about separating the buckets from one another?

Now, you can fill both buckets up with water and when you walk away, only one will drain while the other will remain full of water.

Do you see the analogy? It's exactly the same with batteries, and why you should use an isolator.

[/ QUOTE ]
 

·
Registered
Joined
·
4,767 Posts
Discussion Starter · #18 ·
I took RRitch's aproach with the addition of a self reseting breaker. I copied it from his Ideas and looking at dad's dump trailer. Now I just need to decide to let it charge or figure out a better method.
 
1 - 18 of 18 Posts
Top