alternater question

[campi]

To all you mechanics out there i own 80 chev k-30 with a 350 I am running 2 interstate 850 cca batts yes they are hooked up right! have 110 amp alt now but after runnining 12-14 hrs of plowing and all the sstuff running lifting the plow the amp guage drops then coes back to around 12 volts i saw add for an alt 175 amps and puts out 75 amps at idle states it has heavy duty regulator and what ever else the put in there! i can buy it for $139.00 is this good or BS? Thanks Campi !!!!

[wyldman]

If it's the same case size as the OEM alternator,then it's BS.Most small frame small block alternators can only handle 90 or so amps before overheating,and failing.Most large frame chevy alternators can handle 140 or so.

If your stepping up to a larger case size,then go for it.It will run cooler and put out more consistant amperage when it gets hot.

[Alan]

Yeah, I got suckered into one of those hotrodded alternators in the stock size case. Works good for a while but then it gets hot and output falls off and yer scrod! I'll be remodeling the bracket to take the 140 amp Camaro alternator I picked up after JohnD enlightened me on the alternator subject.

[campi]

Thanks chris trying to get in touch with the guy he stated before what i said before it has high amp stator,heavy duty rectifier, heavy duty voltage regulator i am waiting to here fron him if its an oem case or a bigger one i will let you know what he says Thanks as always Campi !!!!!

[wyldman]

Like Alan said,the larger frame Camaro,or Caddie alternator is a good choice.

Ford also has a large frame external regulator alternator used on some trucks that puts out a solid 100 amps.They also make a 200 amp model (used on ambulances),but it's pretty pricey.

[thesnoman]

Originally posted by campi
To all you mechanics out there i own 80 chev k-30 with a 350 I am running 2 interstate 850 cca batts yes they are hooked up right! have 110 amp alt now but after runnining 12-14 hrs of plowing and all the sstuff running lifting the plow the amp guage drops then coes back to around 12 volts i saw add for an alt 175 amps and puts out 75 amps at idle states it has heavy duty regulator and what ever else the put in there! i can buy it for $139.00 is this good or BS? Thanks Campi !!!!

I have never had a problem with a stock 110 amp unit keeping up with my two battery setup. Voltage will drop as altenator heats up and it will after 12 hour. You should use a DVM to get actual voltage. Also, I have disabled my day time running lights to save drain and use parking lights when possible in lite lots at night and I do run a double rotating beacon too. IF you choose to upgrade alt you must upgrade wiring too from alt to truck or you may have some serious problems from overheating wiring. In my setup, the second battery is somewhat isolated in that it powers the plow but it is kept charged with its own feed from alt but not hooked to main buss. I use a 10 gauge feed from alt to limit amount of current that can flow from main battery to aux when plow is in use (it acts a limited resitance link of sorts) and keeps the in truck voltages more stable and keeps heavy loads off of main battery. It works well and I have done this for years on more than one truck too.

[drofdar]

Speaking of dual battery hook-up. Is there a easily obtainable diagram w/info on dual batts? I run a rollbar mounted aft facing wench for my baja boat. It has seperate battery hooked into main bus for charging. Love to make sure I got it right.

[thesnoman]

Originally posted by drofdar
Speaking of dual battery hook-up. Is there a easily obtainable diagram w/info on dual batts? I run a rollbar mounted aft facing wench for my baja boat. It has seperate battery hooked into main bus for charging. Love to make sure I got it right.

It depends on whether it is just a aux battery or if it is used for starting too.

[wyldman]

Originally posted by drofdar
Speaking of dual battery hook-up. Is there a easily obtainable diagram w/info on dual batts? I run a rollbar mounted aft facing wench for my baja boat. It has seperate battery hooked into main bus for charging. Love to make sure I got it right.

If it's a separate battery,just for the winch,it should be connected to the winch only,and an isolator installed on the charge wire.If you don't install an isolator,current can backfeed through the charge wire to the starting battery,overheating the charge wire,causing a fire.The isolators are easy to hook up.Center terminal goes to the alternator,main goes to the starting battery,and the aux goes to the winch battery.Make sure you have an isolator that is rated for more than your alternator output.

For a plow truck,dual batteries should be connected in parallel,so positive to positive and negative to negative.Running a larger gauge charge wire to ONE battery only will help too.Running dual charge wires can cause problems .

[thesnoman]

Originally posted by wyldman

For a plow truck,dual batteries should be connected in parallel,so positive to positive and negative to negative.Running a larger gauge charge wire to ONE battery only will help too.Running dual charge wires can cause problems .

Maybe if you do not know what you are doing. I have done it on several vehicals for over 15 year with ZERO problems and long battery life too. It is a science not guess work

[Alan]

Originally posted by thesnoman
Maybe if you do not know what you are doing. I have done it on several vehicals for over 15 year with ZERO problems and long battery life too. It is a science not guess work

Why not try to explain it to us from the scientific standpoint then? Maybe having some facts to back up your claims might make you seem like less of a blowhard.

[thesnoman]

Originally posted by Alan
Why not try to explain it to us from the scientific standpoint then? Maybe having some facts to back up your claims might make you seem like less of a blowhard.

Blow hard huh, vehicals is a hobby, I am a EE and a network and broadband guru by trade. You can calculate the wire size and length you wish to use to limit power transfer to second battery a few way. All wire has a fixed resistance value based on its size and length and will drop voltage under load accordingly. As load increases, the drop of feed will increase and limit current transfer. You figure out what limit you want and set circuit resistance accordingly this way it acts as a current limiting device and limits the amount of current you can pull off of main system. You can also use a low value 50 watt or 100watt power resistor in the circuit (about .1 of a ohm or so) too to limit current flow current. Example, a .1 ohm resitor will drop 1 volt at 10 amps and 2 volts at 20 amps and 3 volts at 30 and so on so if you have a heavy load on one battery and it is pulled down to 11 volts and truck is at a nominal 13 volts it will limit the draw to 20 amps from system. At nominal charging loads of 10 amps it will only drop a volt and a 5 amps or less it will drop less than a 1/2 volt and trickle charge nicely. It works pretty slick if you calculate the circuit correctly. Just need to define your values and build it accordingly. It is science (basic ohms law) not BS.

[wyldman]

For a plow truck,with lots of electrical load,you need reserve capacity,which is accomplished by running extra batteries in parallel.Running the batteries isolated doesn't help,as the plow battery will get run down,even though your truck battery doesn't.When that battery gets run down,voltage drops,and amperage increases.That kills solenoids,motors,etc.It also deep cycles the plow battery,which a regular automotive battery will not tolerate for long.The plow battery will get charged last with an isolator as well,which is not what you want.

The reason I recommend running a charge wire to the main battery only is simple.If for some reason,you get a loose\bad connection between the two batteries in parallel,it will pull current across the charge wire between batteries,far exceeding the current capacity of the charge wire,and possibly overheating it and catching fire.Been there,done that,and it ain't pretty.

While adding fancy resistance to the charge wire may work,it is silly to use it in an automotive application where alternator output is already limited.Limiting wire size,or adding resistance does limit current flow,which is exactly the opposite of what you need.We are charging a battery,not limiting it ! That resistance also uses up current,and disposes it as heat.Unless you used a huge resistor with a heat sink,you would have a hard time limiting 3-400 amps,as that's what can backflow if things go wrong.Thats near 5000 Watts ! That number will only go up as voltage decreases when the battery gets discharged.Same principle applies with limiting wire size,it will go up in smoke when it overheats.When it comes to high amperage DC current,the best way is to keep it simple.

The best setup for a plow truck is still two large batteries (in parallel),with a decent sized alternator to keep them charged up enough.

[Alan]

But what actual gain is there besides having a "trick" charging system? While you can limit current flow by your means you convert electrical energy to thermal energy. In our application, with a heavy current draw for lighting, accessories and the plow and (in some cases) spreader we're already running at very close to maximum capacity to produce electricity.

Granted, you can "protect" your primary battery from discharge but it would seem that your system would reduce an already marginal capacity. I don't see an advantage to your method over simply running high capacity batteries paralleled with heavy cable and charged through a heavy charge lead to one battery.

I am currently running a single battery but plan to go to duals this winter. I will run them in parallel with a high capacity, continuous duty relay to serve as an isolator when the truck is shut down. I figure that will keep one battery up if I leave something turned on overnight and kill the primary battery.

[drofdar]

Thanks for the info on the isolator. One of my concerns is using the winch battery to retreive my boat, and draining both batts. Here comes the tide. I assume the isolator allows the aux batt to charge at all times. Does the isolator prevent current loss from the main batt during winch use? Perhaps a simple toggle between alt and aux batt would prevent loss of current from main system during winch use. Also, I assume the hookup from isolator to aux batt possitive and simple batt neg to frame ground. One last question, with aux/winch batt in p/u bed, what qauge charge wire is best?

[wyldman]

The winch battery is connected directly to the winch,it is not connected to the truck at all.The charge wire from the alternator is what the isolator is connected to.It will charge the main battery first,then the aux battery.It also prevents the aux battery from drawing any current from the main battery.

A toggle switch wouldn't cut it for high current applications.

The battery charge wire should be at least 10 GA,unless you have a high output alternator.I would use an 8 GA for higher output.Stereo shops sell amp wiring kits which would be perfect for your application.Good quality flexible wire to wire the isolator.

[thesnoman]

Originally posted by wyldman
For a plow truck,with lots of electrical load,you need reserve capacity,which is accomplished by running extra batteries in parallel.Running the batteries isolated doesn't help,as the plow battery will get run down,even though your truck battery doesn't.When that battery gets run down,voltage drops,and amperage increases.That kills solenoids,motors,etc.It also deep cycles the plow battery,which a regular automotive battery will not tolerate for long.The plow battery will get charged last with an isolator as well,which is not what you want.

The reason I recommend running a charge wire to the main battery only is simple.If for some reason,you get a loose\bad connection between the two batteries in parallel,it will pull current across the charge wire between batteries,far exceeding the current capacity of the charge wire,and possibly overheating it and catching fire.Been there,done that,and it ain't pretty.

While adding fancy resistance to the charge wire may work,it is silly to use it in an automotive application where alternator output is already limited.Limiting wire size,or adding resistance does limit current flow,which is exactly the opposite of what you need.We are charging a battery,not limiting it ! That resistance also uses up current,and disposes it as heat.Unless you used a huge resistor with a heat sink,you would have a hard time limiting 3-400 amps,as that's what can backflow if things go wrong.Thats near 5000 Watts ! That number will only go up as voltage decreases when the battery gets discharged.Same principle applies with limiting wire size,it will go up in smoke when it overheats.When it comes to high amperage DC current,the best way is to keep it simple.

The best setup for a plow truck is still two large batteries (in parallel),with a decent sized alternator to keep them charged up enough.

Not really, I have had no problem at all with plow battery going dead, even in heavy use and I do not want to loss main battery to "limp" in. On the limiting the back flow, if you understand ohms laws you would know it is not possible if properly designed. Example, with a total circuit resistance of .2 ohm, a complete failure of one battery would transfer no more than 60 amps assumming a 12 volt drop. Even a .1 ohm circuit would max out a 120 amps. You simply set your values to meet your needs. Also if you a re really worried about it. Splice in a short piece of 14 or 16 gauge wire in a 10 gauge feed and it will "blow" like a fuse at around 60 to 80 amps (depending on size selected) or install a fuse block. 10ga automotive wire is good up to about 45-60 amps generally and 8ga up to about 65-85 amps continous (depending on length and routing) before wire heating gets to be too much of a issue. With a 160 to 180 amp altenator, I would use nothing less than a 6 gauge feed from it with a 4 ga feed being prefered. As a side note, you can use 2ea 14 ga wires to equal one 10 gauge wire (and actually it will do a tiny bit better because of increased surface area to disapate heat under heavy load) and two 10 ga wires equal one 6 ga and so on (you can see the pattern and it is not a fluke) which is nice to know if you are working in tight areas as smaller wire bends and routes nicer as a rule.

[wyldman]

You missed the point.While it can be done,you would need a huge resistor,to deal with the heat created as the current tries to flow between the batteries.That's 720 Watts ! ,if your using a .2 ohm resistor.Thats more than a block heater.I'm not saying it can't be done,it's just not practical,or reliable,in a severe duty plow application.

Battery isolators use the same principle.If you look closely at one,it's big,heavy,and finned,to deal with the heat.

If your going to isolate the batteries,then fine,isolate them,but use something capable of doing it.It still IS NOT the best setup for a plow truck with high electrical demands.

Alan had a great idea with a high current relay,or solenoid between the batteries,so you can isolate as needed,but combine the batteries for the best performance.I choose not to go this route,as it adds another component for possible failure.

If you use a fuse,or a smaller gauge wire,you'll blow it,and then not be able to charge your plow battery.

You will also see better battery life if wired in parallel.The batteries will not see as much cyclic discharge as in an isolated setup,and will last much longer.

[John DiMartino]

I agree 100% with Wyldman, ive tried isolators,while they do work,the parrallel setup works much better.Running a resistor is counterproductive,adding resistance to the charge wire of a battery that needs all the amperage you can possible get back into it to recover it from the plow pump.Keep it simple and reliable.

[thesnoman]

Originally posted by John DiMartino
I agree 100% with Wyldman, ive tried isolators,while they do work,the parrallel setup works much better.Running a resistor is counterproductive,adding resistance to the charge wire of a battery that needs all the amperage you can possible get back into it to recover it from the plow pump.Keep it simple and reliable.

Not always true, a steady 20 to 40 amps going into it will keep it alive for a long time (and minimize voltage drops in cab too) and it will actually extend battery life because you will not be going for 150 amp discharges to 100 amps charges several times a minute which will keep battery heating down and increase its usable capacity as well. Just because you have never tried it or do not understand its theory and design, do not assume that it will not work.

[thesnoman]

One further note, I seen a guys truck where he had two batterys in parallel with no isolater and one of the batteries shorted out in internally and he had on heck of a mess. It killed the truck, toasted the other battery and burnt the cables before he could get it disconected and figure out what happened.

[wyldman]

Originally posted by thesnoman
Not always true, a steady 20 to 40 amps going into it will keep it alive for a long time (and minimize voltage drops in cab too) and it will actually extend battery life because you will not be going for 150 amp discharges to 100 amps charges several times a minute which will keep battery heating down and increase its usable capacity as well. Just because you have never tried it or do not understand its theory and design, do not assume that it will not work.

With only 20-40 amps going into it,it would be dead in no time flat.If you could keep a plow battery charged with that,everyone would be running tiny alternators.A plow motor can draw 250 amps.You still have the big discharge,but little charge rate.

Running in parallel reduces voltage drop over time,so the batteries don't need to charge at higher short term rates to recover.This is actually easier on batteries,and battery life is equal (or pretty close).Isolated setups usually have one battery that fails more often,due to the heavy use (that's why it was isolated),and continious deep cycling.

I will agree if one battery shorts out,you may loose the other one too,but those failures are few and far between.They can happen in any setup.

Just because you have never tried it or do not understand its theory and design, do not assume that it will not work.

I have tried it,many different ways.Big alternators,different battery setups,isolators,and have always come to the same conclusion.Big alternator,and multiple batteries in parallel.

I understand how it works in theory,and in reality.

Just take a look at most OEM dual battery setups........nuff said. :rolleyes:

[Alan]

Originally posted by Alan
But what actual gain is there besides having a "trick" charging system? While you can limit current flow by your means you convert electrical energy to thermal energy. In our application, with a heavy current draw for lighting, accessories and the plow and (in some cases) spreader we're already running at very close to maximum capacity to produce electricity.

You STILL haven't answered my question! WHAT DO YOU GAIN?

There's a whole bunch of OTR trucks running two batteries in parallel, not to mention all the heavy equipment that goes that way. Reliability in both those situations is paramount so I tend to think they would go with what offers the best service, as opposed to the cheapest.

[thesnoman]

Originally posted by Alan
You STILL haven't answered my question! WHAT DO YOU GAIN?

There's a whole bunch of OTR trucks running two batteries in parallel, not to mention all the heavy equipment that goes that way. Reliability in both those situations is paramount so I tend to think they would go with what offers the best service, as opposed to the cheapest.


A OTR truck is not a plow truck and they need a few thousand amps to crank over too and offer no comparision here.

What do you gain? You gain not having your lights on truck pull down every time you hit the plow switch and longer battery life and longer altenator life as well because you limit th e amout of current it can pull from truck system at all times..