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Aux battery and plow electric

Discussion in 'Chevy Trucks' started by SteveVB, Nov 8, 2003.

  1. SteveVB

    SteveVB Member
    Messages: 66

    Im finishing up the install of my plow tomorrow. Hopefully :D

    I have an electrical question:
    My 1991 K2500 has an Aux Battery package. Build code TP1.
    It is an aux battery with a relay to prevent a drain on the aux battery from stealing from the starting battery.

    Is there any reason NOT to use the aux battery as the feed for my E-60 pump solenoid.

    This is the second plow Ive had on the truck, I removed and sold the last one- it was connected directly to the starting (main) battery. Im thinking the installers had a reason to do so? Or maybe just habit they installed to the main battery and didnt know about the aux battery?

    Anyone run off the aux (camper) battery terminals?

  2. Crash935

    Crash935 2000 Club Member
    Messages: 2,377

    go off the aux battery, if you run down the aux battery the truck will at least still start
  3. The Grassman

    The Grassman Member
    Messages: 55

    I was thinking of putting in a second battery into my 96 k2500 i have asked a few people on how to do it and they say just run pause and neg cables from the main battery to the aux battery and away you go. The problem i see with this is or have read about over or under charging one of the 2 battery's. There is something called a battery isolator and if i am not mistaken it prevents the over under thing from happening. If it was just a matter of running 2 cables to a spare battery hey i could do that no problems, but i want to be sure i am doing the right thing here and don't want to mess up my electrical system on my truck.

    any suggestions on how to do this properly ?
  4. The Boss

    The Boss 2000 Club Member
    Messages: 2,099

    :) Hi grassman:waving:
    I put another battery on my old truck the same way you are describing (pos. and neg. cables from the existing battery to the new aux. one) After that I put in a 140 amp alternator and never had a problem. It worked great!
    Good luck:)
  5. HerkFE

    HerkFE Member
    Messages: 92

    Battery Isolator

    If you are running dual batteries for items such as plows and winches, etc you should run a battery isolator in between them. It prevents the heavy accessory draw from depleting your main battery as well as ensuring both batteries are being charged correctly. Here's the url to a site with some good explainations and great tech help. www.hellroaring.com/

    Upgrading your alternator is also a great idea. It has been discussed on the boards here before.

    Good luck!

  6. The Grassman

    The Grassman Member
    Messages: 55

    Thanks Boss

    Hey Boss :waving:

    I was trying to make it look clean by going hunting for a old diesel GM truck where i can get a Battery Tray and the cable's if possible.

    GM put's in a storage box in the engine compartment if it isn't a diesel or don't come with 2 battery's. l want to get rid of it because i don't put anything in it and a extra battery would serve me better since i have 2 150watt spot lights on the front of my truck and prolly will add a plow soon and a salter and some reveres lights and strobes. Lean mean plowin machine :cool:

    Did you get 2 new battery's or did you keep the old one and add a new one in ? I have been told to get 2 new ones. How many cranking amps are your battery's ? The alternator in my truck is 105 amps. Does your volt meter move when you raise the plow or does it stay at the 14 volt line ? I never payed attention to that when i got in a plow truck last year, i know the lights dim a little when you move the blade.

    Thanks Boss man...

  7. The Boss

    The Boss 2000 Club Member
    Messages: 2,099

    HI grassman:waving:
    I no longer have the truck but here's what I did:
    I left the factory battery in the truck and went and bought a 750 cranking amp battery. I didn't have to put in a tray because there was room for it in top of the wheel well. I secured it with a battery hold down kit. I then took black gm tubing and wrapped the pos. and neg. cable with it so it looked real nice in the engine compartment.:)
  8. The Boss

    The Boss 2000 Club Member
    Messages: 2,099

    Sorry, I forgot,
    After I did all that, I gauge never moved when I raised or moved the plow. Keep in mind though I had to install a bigger alternator.
    Keep me posted!:waving:
  9. campi

    campi Member
    Messages: 53

    aux battery

    I agree with boss, always had trouble with power, I installed 2 new batts, dont just replace 1new and 1 old!! also put a 140 amp alt. in 2 yrs ago i have 1980 i ton run all my stuff no problem now!!! Campi !!!!
  10. The Grassman

    The Grassman Member
    Messages: 55

    I have been told i should add a isolator so in case one battery gets drained i can use the other to boost it ?
  11. campi

    campi Member
    Messages: 53

    aux battery

    grassman, i dont know about this islator your talking, like i said before, my mechanic hooked up the 2 new batteries same size, put in 140 amp alt. had no problems since! i also said my truck is 1980 1 ton, it does not have the electronics, that a newer truck has!! had the charging system checked last week, both batts were charging at the same rate, alt was putting out what it should!!! whin i redid my truck, put 84 front clip on it , ibought 2 batt boxes from dealer that are for a diesel truck bolted righted in hope you make out ok , you dont want to fry elec, system!! Campi !!!!
  12. Mac

    Mac Member
    Messages: 77

    An isolator is a very good idea for two reason. 1. It will not let current flow between your secondary battery and main battery unless the alternator is producing current, its like a big switch between the primary and secondary batteries. So in return you will always have a healthy battery. 2. If you leave an older run down battery in the truck, and add a new one you can cause the new battery to fail quicker then it would normally. This is were a isolator can protect you new battery because the batteries are only connected when the alternator is producing current. So in return you would only have to buy one battery.

    I personally do not have a isolator I just brought two new batteries the same type, size, and manufacture.
  13. SteveVB

    SteveVB Member
    Messages: 66

    Thanks for the responses- hooked the plow motor solenoid to the Aux battery.

    Everything works well.

    I checked my batteries - starting batt has 12.7 volts in it. The aux battery has 11.5 volts in it both sitting with engine off. With the engine running the voltage at the terminals of both batteries is 14 +. Tells me the isolator is doing its job- keeping the main battery from discharging into the other battery to equalize the voltage.

    The stock chevy "camper package" with the aux battery uses the isolator- I bet you could find one in a yard someplace- and the wire harness for the control voltage. Though I doubt the part is much more than 30 bucks new. I have the FSM with a schematic if someone wants to see the set up-
  14. tileman

    tileman Member
    Messages: 55

    Aux batt

    Steve I WOULD NOT hook up to the aux batt. The primary batt (start batt) is in the charging system first. You will run down the aux batt with the plow on it, It can not be charged up fast enough.

    I have a 2000 gmc with factory dual batts. The truck has snow plow prep on it. The plow was installed by the upfitter the plow is on the primary batt.

    The aux batt is just a back up not the main.

  15. SteveVB

    SteveVB Member
    Messages: 66

    Re: Aux batt


    Why do you say one charges up first? Im weak when it comes to electrical systems. I thought that the charge would go to both- the voltage readings Ive taken lead me to believe they will both charge. The isolater allows the batteries to charge, but not discharge- like a one way valve. The isolater on mine prevents one from charging, or discharging the other, but the alt can charge both. Maybe Im mistaken. This system is different than the dual starting batteries such as the diesels have.

    Anyone else have a view on the aux batt hook up?
  16. porkhead1

    porkhead1 Member
    Messages: 70


    Now's the time to see if your set-up works (hooking up your plow to the Aux. battery).......with your plow hooked up, raise/lower/turn your plow a number of times just like you were actually plowing....if possible, actually drive the truck up/down your driveway. My theory is that after a while your plow will slow down because your aux. battery is not being re-charged fast enough to keep up with the demands of a plow. The factory "camper special" aux battery was intended to supply electricity a slide-in camper. Even if you were to only plow one driveway a couple of times a week, your aux. battery would probably slowly go dead.

    Try this site for some information.....


    Try this site for a High Output Alternator....


    Good luck.........

  17. SteveVB

    SteveVB Member
    Messages: 66

    It seems to work fine, Ive been driving around lifting, lowering, left right for the last couple of days. I checked the batt yesterday and I will again today. I have no reduction in volts available at the battery- either main, or aux.

    Everyone keeps saying the battery will wear down faster since its second in line to be charged, but I don't think thats the case- the alternator output doesn't know its going into one battery or another - it just puts out. With the engine running, if I check voltage at the main battery and the aux battery it is the same. The batteries will accept the charge if they need it up to the volt limit on the alt.

    Any electrical gurus out there back up either view expressed here?

    Porkhead- if the alternator cant keep up with the demands of the plow then it wont matter which battery I hook to- either one will go dead. As I understand it the battery acts as a reserve. If the alt cant keep up then the plow takes what it needs from the aux battery (doesn't effect the main in my set up) if the alt cant keep the battery refilled then the battery dies , but in my case the aux battery is dead, but I can start the truck and drive to the shop since the plow has only taken the capacity from the Aux batt not the starting batt.

    Ill see how it goes if we get some snow this season. I just need to coat the connections and Ill be finished.
  18. Mac

    Mac Member
    Messages: 77


    It does not matter which battery you hook it up too. They will both charge at the same rate as long as the internal resistance of the two batteries are comparable. Another factor would be the gauge of the wire between the two batteries. An inadequate gauged wire will cause a resistive load, which will herder the alternators ability to charge that battery.
  19. SteveVB

    SteveVB Member
    Messages: 66

    Good point, Ill look into upgrading the alt to aux battery connections. Currently they look to be 8 gauge, so Ill look into upping them to 4 or 6 gauge.
  20. porkhead1

    porkhead1 Member
    Messages: 70


    That's why I gave you the link for a High-Output Alternators. Most plowing is done at low speeds, which means your std. alt. is not putting out max amps. Continous low speeds along with alot of plow maneuvering ( aka. plowing driveways) + lights/heater/wipers/radio all on & a lot of snow will takes its toll on the batteries. You may want to ask what some of the other people on this site think of installing a High Output Alt.

    Good luck....:waving: