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Unread 01-10-2008, 04:27 PM   #76
JeepHammer
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Quote:
Originally Posted by RVNCAVEMAN
The reason for fine wire is that the electrons (current) travel on the surface of the conductor (wire). So the finer the wire, the more surface area in a given size of cable.
True only with Alternating Current.
Direct Current, what we are dealing with, uses the entire conductor.

The reason for fine strand wire in this context is fine strand packs denser in the allotted cross sectional area, and conducts more total amperage simply because there is more conductor.

A solid conductor would be preferable in this application, but solid conductors don't play nicely with vibration and they are a pain to work with.
The next best thing is densely packed fine strand wire, so that's why I recommend welding cable instead of 'Automotive' wiring or 'Battery' conductor...


Quote:
The only problem I see with the dual battery "self jumping" feature is that if one battery is dead (or severly drained down) the charged battery will loose some of it's power "back feeding" into the low battery in the schematics shown.
Take a good look at the diagram again...

The dual starter solenoids allow for the batteries to be connected together only for the short time of cranking the engine...
The batteries are isolated from each other when the engine is not running, for what ever reason.

When the engine 'Starts' and is charging, the heavy amperage relay closes via the oil pressure switch, and BOTH batteries get charged.

IF one is bad, or needs special attention, you *MIGHT* have a problem, but if it's just discharged, it will charge from the alternator when the oil pressure comes up.

Quote:
The 2 circuits would need high amp diods which act as "check valves" to allow current flow towards the starter only and not back to the low battery.
*IF*
You isolate the second battery with a diode, then it will have two effects.
First off, you will need a diode that can handle about 50 amps.
A diode rated for 50 amps is going to drop the line voltage to that battery by AT LEAST 1 volt, and probably more more than one volt.
That means the second battery will never be fully charged.

That battery would also demand a constant charge, and that alone would ruin the first battery.

(Remember, the voltage regulator sense wire is sampling from the 'Batt' terminal on the back of the alternator or the starter solenoid battery cable terminal... NOT the battery or batteries them selves)

If you had a diode in the charging lines for BOTH batteries, then you would get NO signal for the sense or sample for the voltage regulator, and the alternator would shut down, since that is also the feed for the rotor (field) in the alternator...

The batteries are 'Battery Isolated' and 'System Isolated' they way they are,
And if you need separate Charging control, like for dissimilar batteries, the ONLY way to do that is with a charge controller that splits the alternator output and feeds each battery with an isolated regulator.

Try reading the text, it will become more clear to you.

Take my word for it,
My diagrams are correct and function correctly.....

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Unread 01-10-2008, 10:36 PM   #77
buddy
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Quote:
Originally Posted by JeepHammer
IF you have a winch, or some gigantic output alternator, you will probably need to run a Relay in the charging circuit, since deeply discharged batteries from winch use will draw more current than the oil pressure switch is intended to handle...

In this diagram, the oil pressure switch activates a 70 Amp automotive relay, and that should be plenty for even the largest of the 'Mega Output' alternators...



The oil pressure switch is a common one used on Chevy pickups for several years
(The oil pressure switch I use is for Chevy pickups, Car Quest p/n PS 127.)
The relay is easily available, and completely reliable, and will keep the contacts in the oil pressure switch from having to carry too much current.
One of the common uses for that particular relay is for the starter solenoid on Harley Davidson motorcycles, so it WILL carry some amperage.
----------------------------------------------------------------------------
I have a few questions about this diagram.

1) My TJ has a Durango 136 amp alternator on it, will the additional 50 or 70 amp relay tied into the oil pressure switch circuit be feeding the secondary battery by itself or would it supplement the secondary starter solenoid? Do you just use a 10 ga. jumper on it from pos 85 to 87

2) What are the functions of you're "factory harness 12, 13 & 14" leads? What would they correspond to in a universal-type application?

3) Application specific - Where on a 97 TJ 2.5L would you locate or tie in the oil pressure switch?

I must say that I'm quite impressed by how simple, cheap & robust these diagrams are & while I don't have any problems with using welding wire as a main condutor, I'd also like to recommend marine grade wire. They use a tin coating of some sort to limit the amount of corrosion that will occur in a harsh marine envronment, & they are typically a very fine strand as well. While not usually necessary, I think that marine grade electrical pieces are bulletproof for a hardcore offroad enthusiast.

Later,
Buddy
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Unread 01-11-2008, 05:38 AM   #78
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Quote:
Originally Posted by buddy
1) My TJ has a Durango 136 amp alternator on it, will the additional 50 or 70 amp relay tied into the oil pressure switch circuit be feeding the secondary battery by itself or would it supplement the secondary starter solenoid?
It will FEED the second battery, and allow the second battery to join the electrical system....
Once the oil pressure comes up and the relay closes.

When you are using the starter solenoid, the oil pressure will still be non existent, so the pressure switch and relay will be open and non conducting.

Quote:
Do you just use a 10 ga. jumper on it from pos 85 to 87
The proper flow through a common automotive relay is terminal 30 to terminal 87 for the heavy current.

The proper flow for the activation current is terminal 85 to terminal 86.

10 Ga. wire is enough for roughly 35 amps continuous, and up to 70 amps for a short period of time.
I use 8 Ga. most of the time, but a 10 Ga. wire is usually enough to charge/discharge the second battery through the normal electrical system.

10 Ga. is all the larger the Fuse Block feed is,
10 Ga. is all the larger the alternator feed is.

Since the second battery should only see as much load the orignal system ever saw at any one time,
(as in self rescue when you are powering everything off the second battery, and it has 100% of the load)
You should be able to use the same size wire the orignal system did, and that was 10 Ga....

(BTW, your fuse block wire has a fusible link that will burn at about 35 amps, so if the vehicle draw is more than about 35 amps, the fusible link with burn and the relay wiring will remain intact.
Just a way I use the vehicle protection to my advantage.)

I'm always for 'A Little More' when I do things, so I use an 8 Gauge wire in my 70 amp relays sockets.
...............
Quote:
2) What are the functions of you're "factory harness 12, 13 & 14" leads? What would they correspond to in a universal-type application?
Factory harness #12 or #13, depending on what vehicle you have, are the 'Full Power' leads to the ignition coil and module during cranking.
They supply the ignition system with power when the starter is turning.
A requirement on some ignition systems that have breaker points or like on the Jeep/DuraSpark module, that has a separate 'Start' circuit to make things easier to start, then switches over to a 'Run' circuit when you let the key switch drop back to the 'Run' position.

Factory #14 is the activation wire for the starter relay/solenoid.
If it were on a home built system, it would be hooked to the 'starter' push button.
In this case, it's connected to the ignition switch 'Start' or 'Crank' position.
...............

3) Application specific - Where on a 97 TJ 2.5L would you locate or tie in the oil pressure switch?

Application specific answer....
I wouldn't.
I don't work on TJ's on a CJ forum

Seriously, same place as anywhere, you can 'T' into the oil pressure sending unit source.
.................
Quote:
I must say that I'm quite impressed by how simple, cheap & robust these diagrams are & while I don't have any problems with using welding wire as a main condutor, I'd also like to recommend marine grade wire.
Marine grade wire is tinned, and has a tendency to not carry as much amperage as virgin copper wire (no alloys).

When working on off shore power boats for races, I use silver bearing solder to seal my electrical joints and ensure a fool proof connection,
THEN,
A top quality Heat Shrink Tubing, WITH GLUE, for environmental seal, and I really don't have problems.
(And believe me, as snarky as those rich boy power boat racers are, If they failed, I'd hear about it!)

Quote:
They use a tin coating of some sort to limit the amount of corrosion that will occur in a harsh marine envronment, & they are typically a very fine strand as well. While not usually necessary, I think that marine grade electrical pieces are bulletproof for a hardcore offroad enthusiast.
I would agree with 'Marine' or 'Tinned' wire for low current devices, like gauges, lights, ect., battery cables really are in a different class...
Most off roaders will not subject their vehicles to constants doses of salt water...
AND,
For the Desert guys, you have to consider the 'Dry Corrosion' factor that Tin on copper will bring to the table.
Galvanic corrosion from dissimmilar metals will cause problems over time,
PLUS,
Tinned or 'Marine' wire might not be the easiest thing for 'Joe Average' to acquire in the middle of the desert or up in the mountains 1,500 miles from the nearest salt water!

I typically say,
'SOLID COPPER CONNECTORS, VIRGIN COPPER WIRE, SILVER BEARING ELECTRICAL SOLDER' and 'RUBBERIZED HEAT SHRINK WITH GLUE'...
That covers 99.95% of the people that will read this stuff with out problems!

And yes, I still tin the copper terminals and exposed wire in marine or wet applications!
Nothing like that 2% or 4% silver bearing solder to seal things up and tin things out when you need it!
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Unread 01-12-2008, 06:23 PM   #79
buddy
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Thank you for the detailed & NOT condescending responses!! That is becoming few & far between on forums these days. It's nice to have somebody respond to my questions & suggestions with a well-informed, experienced recommendation regardless of what I may have brought into the discussion. Also, thanks for clearing me up on the circuit specific questions. I just did a general search for dual battery systems. I didn't even realize that this was in the CJ forum.

I applaud & thank you again.

Later,
Buddy
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Unread 01-20-2008, 12:29 PM   #80
CJ5Glenn
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This is what we do in the Netherlands....whit the dual bat...



Greetings Glenn..
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Unread 01-21-2008, 03:11 PM   #81
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Looks pretty good, Great battery tray and tie down, and good execution of of wiring and applications...



The only thing I can see I wouldn't have done...
In the upper right corner picture,
You can see the current from the back battery go under to a starter 'Combiner' type solenoid, then back up to the front battery,
THEN out to the actual starter solenoid and starter....



If you are using two starter type relay/solenoids, why not run them parallel instead of series and double the amperage to the starter?
This way (and this is the way most people do this particular thing) all the current is being run through one solenoid/relay, and the solenoid/relay is already the 'Choke Point' in the system...
The cables, connectors & batteries can handle more current than the solenoid, so feeding double current to the second 'Starter' Solenoid/relay doesn't make much sense...

No Redundancy in that either...
One Solenoid/Relay responsible for the entire load, and it's being fed TWICE as much as designed for!
--------------

Now, if BOTH solenoids/relays fed the starter like in my systems, one could fail and you may not even know it!

Charge isolators like the one in the picture have been covered here in detail...
I have a few problems with using one,

1. Not necessary when running the same kind/size/age of batteries. So if you buy your batteries as a set,... You simply don't need one.

Charge isolators are only necessary when running two different kinds/sizes or dramatically different ages of batteries...

2. Charge isolators drop the voltage to both batteries by at least a volt from what the alternator intended.
That means your batteries are NEVER fully charged or charge compensated.

Simply tying two like batteries together will allow both batteries to charge, discharge as one LARGE battery as far as the alternator is concerned, and I accomplish that very easily with a simple automotive relay.

3. Using the DUAL starter solenoids,
Instead of one constant use solenoid and one starting solenoid, you get FULL POWER from both batteries on start up. (instead of trying to choke both through one solenoid)

You also get full redundancy in the staring circuit for the same price, and you whittle down the wiring a little...

4. My system shuts off the second battery in the event of a roll over, and keeps it isolated in the even of someone leaving the key switch turned on or light, ect. turned on.
Since I can only assume which source this guy used for his continuous duty solenoid, I don't know exactly how his is wired...
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Unread 01-21-2008, 04:49 PM   #82
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If you are using two starter type relay/solenoids, why not run them parallel instead of series and double the amperage to the starter?
This way (and this is the way most people do this particular thing) all the current is being run through one solenoid/relay, and the solenoid/relay is already the 'Choke Point' in the system...
The cables, connectors & batteries can handle more current than the solenoid, so feeding double current to the second 'Starter' Solenoid/relay doesn't make much sense...

Hello,
I use only one statersolenoid/relay for the engine to start.
To connect the batteries im use the 1000amp mainswitch, only when one battery is to low to start when i have to use te winch.
Til now it works fine for my, after using the winch to get my out of the mud i can shut down the engine en start again


Charge isolators like the one in the picture have been covered here in detail...
I have a few problems with using one,

1. Not necessary when running the same kind/size/age of batteries. So if you buy your batteries as a set,... You simply don't need one.

Charge isolators are only necessary when running two different kinds/sizes or dramatically different ages of batteries...

2. Charge isolators drop the voltage to both batteries by at least a volt from what the alternator intended.
That means your batteries are NEVER fully charged or charge compensated.

Simply tying two like batteries together will allow both batteries to charge, discharge as one LARGE battery as far as the alternator is concerned, and I accomplish that very easily with a simple automotive relay.

When you use a goed one isolator, they have a connector to connect de sense wire from your altenator to it, then your voltage get higher to compensate the voltage drop on the isolator, and get the batteries full.
http://www.surepower.com/pdf/isolator1.pdf


3. Using the DUAL starter solenoids,
Instead of one constant use solenoid and one starting solenoid, you get FULL POWER from both batteries on start up. (instead of trying to choke both through one solenoid)

You also get full redundancy in the staring circuit for the same price, and you whittle down the wiring a little...

4. My system shuts off the second battery in the event of a roll over, and keeps it isolated in the even of someone leaving the key switch turned on or light, ect. turned on.
Since I can only assume which source this guy used for his continuous duty solenoid, I don't know exactly how his is wired...

I have use one battery for the engine en factory electric in te car, the winch, headlights (with solenoid), radio with amp en all the other things on the second battery.

I have make this system after I was stuck in the mud, i'm pull myself out the mud, try to get to switch to 2wd.... let the cluts go en the engine stops .
It never starts again....battery to low....and yes...i was alone...start walking

Thanx voor your reaction..
Greeting Glenn.
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Unread 01-22-2008, 01:27 PM   #83
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Guess it didn't translate too well...
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Unread 01-28-2008, 11:28 AM   #84
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I started building my dual battery tray over the weekend and have one concern. It seems like my heater hoses are going to be in the way of the engine side battery. Is it really that close or will there be room once I actually set the tray in?
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Unread 01-29-2008, 04:59 PM   #85
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Quote:
Originally Posted by azarchery
I started building my dual battery tray over the weekend and have one concern. It seems like my heater hoses are going to be in the way of the engine side battery. Is it really that close or will there be room once I actually set the tray in?
Yup it's pretty close. Mine does touch the hose. I think if I had taken alittle time with measurments I could have made mine so it did not touch. My dual tray was my second fab project so I learned somethings. I might make mods this summer. Anyway if you notice on the green jeep above the owner notched out the fender lip for one of the battery hold down all threads. That's how I plan on correcting mine. Just 1/4" more to the fender side and the hose won't be and issue. Measure twice (more like 10 times) cut once.
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Unread 02-08-2008, 04:36 PM   #86
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putting 2 batterys in would be a waste of time and mony a good deep cycle group 31 would last longer and be easyer to install
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Unread 02-09-2008, 05:51 PM   #87
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Quote:
Originally Posted by cj5-9inchlift View Post
putting 2 batterys in would be a waste of time and mony a good deep cycle group 31 would last longer and be easyer to install
He does not mean it Jeephammer.
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Unread 02-13-2008, 04:31 PM   #88
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Quote:
Originally Posted by kappa505 View Post
He does not mean it Jeephammer.
Sure he does, but he's not keeping up with the thread,
AND,
He wasted his very first post on this forum...

Since he missed the point of trail-redundancy entirely, there isn't much we can do for him...

AND,
Two batteries of normal BCI group 24 size will produce more total amp hours than a 31 series...
And two BCI 24 size batteries will release more energy faster than a single 31 series battery (more initial surface charge, more chemical conversion to electrical) because two group 24 batteries will have more plate surface area...

Sounds like he has a little experience with batteries since he knows what a BCI group 31 battery is, but doesn't have his basics down yet...

The easy way to tell what battery (single for single) is going to be the strongest and longest lived is to weigh them... (without electrolyte, or weigh the same case size batteries)

The heavier the battery is (minus the liquid), the more lead there is, and the longer it's going to live...
Two Group 24's are heavier than one group 31, so he's wrong on both counts, but I understand what he was trying to say...

Since a simple BCI group 24 battery is plenty to start and run our Jeeps, the single battery size isn't an issue...

We were discussing redundancy, so we could self rescue in the event of a battery or alternator failure.
I've never been so far out that two group 24's won't get me back to a parts store if I conserve on lights and radios when I notice the charging system problem.

A second battery is enough to raise voltage so you can weld off the batteries in an emergency.

Personally, I run a pair of 31's in my tow vehicle (FSJ) and they are enough to jump start semi diesels with the right kind of jumper cables...
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Unread 03-06-2008, 07:13 PM   #89
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ok maybe i missed something, my oil pressure swith is a single wire, there for it connects (controlls) the ground. Whats the best way to wire a solenoid stlye relay with this in mind.

or can i buy a solenoid that requires 2 wires, a positive and a ground????


thanks
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Unread 03-07-2008, 12:24 AM   #90
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i use two solenoids-- one keyed by ignition, as it normally starts and charges the main battery. the second is isolated by a continuous duty solenoid, that is manually switched from the dash whether to charge or not. all aux circuits are powered by aux battery and each has a dedicated blade fuse. there is a master kill switch between the aux panel and aux battery. also added a kill switch for the warn winch.



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