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Dual batteries in e350

  1. Please fill out the following to ask a question.

    MAKE: Ford
    MODEL: E350
    YEAR: 2006
    MILES: 168,500
    ENGINE: 5.4 liter
    DESCRIBE ISSUE.... Battery dies because of cargo lights. I kill a battery in about two years because I have seven LED cargo lights and a cab light that stay on for about 10 minutes after I open a door. I run a Handyman Business. I have to charge the battery about every 10 days. The charging system is in good order. I even installed a volt meter in the cab to monitor charging and voltage levels. Battery will be at 12.6 volts when fully charged, or driven a distance. Voltage output is 13.8 to 14.2 Yesterday the battery was at 11.0 volts... you guessed it... no start.....jump from a customer. My goal is to add a dual battery system with an isolator system that charges the main battery and then the secondary battery. My question is : For the time being can I install an auxiliary battery and run cables to it in parallel from the main battery. This way I still am running 12 volts, but two batteries. I have two brand new batteries here, a 850 CCA for the main and a 770 CCA for the auxiliary. This would be temporary until I get a dual battery install kit and all the extras I need, and the time to do it all. Now I need to hear Yay or Nay and why please. Thank you.
  2. I do not see any problem with two batteries, but why not install a switch that can turn off those pesky lights that are causing you the problem during the day when you do not need or want them.
  3. JackC van.png Thanks for the reply. My van is full of "stuff" that is hard to find with seven cargo lights even during the day. I would like to add more lighting, but not sure that would be a good idea.
  4. But with a switch you can turn it on when needed and off when you leave, thus eliminating the 10 minute automatic delay that seems to run down the battery.
    Just a thought.

    Or, how about a strong flashlight?
  5. If your seven lights are incandescent, maybe like backup light bulbs, you could re-lamp with LED's and get as much light from seven as you do now, with less amps draw than from one...
  6. He states they are already LED.
  7. All our chevy vans with diesel have dual batteries in parallel, not a problem
  8. Thanks guys. I know I can always rely on you to give me information I can trust.
  9. Sorry for missing LED in about the first line of the thread...

    You could set it up like an RV. Second battery is Deep Cycle (trolling motor battery etc.) connected to the road engine battery with an isolating relay. This relay energizes when the ignition is in RUN, charging the Deep Cycle. Engine off, the Deep Cycle gets discharged by your seven LED's, but Engine battery isn't because the Relay isn't energized. Crank up the Van, Relay energizes, Alternator charges BOTH batteries.
  10. jd, Great idea. I might just ask you more information down the road if I may. Size of Deep Cycle, rating of isolating relay, etc.
  11. [​IMG]

    Very simplified example.

    1. Many don't use the Fuses
    2. That Solenoid is Three Wire so it has to be Grounded
    3. The "ON" wire is any 12V source that's live only when the Engine is Running
    4. Motor homes add a push button switch from House Battery Positive (or that terminal on the Relay) to the "ON" terminal of the Relay. Then you can push the button to have the House Battery "Jump Start" the Starting Battery

    I can help you source a Relay or a "Smart Isolator." Just be sure the Relay is Continuous Duty. It may look like a Starter Relay for a Riding Mower, but Mower can get by with a Momentary (till it starts) Relay. You need Continuous for charging.

  12. I can't remember to turn off a flashlight. Always killing batteries (AA, AAA, D) I buy Heavy Duty batteries at the Dollar Store because I just burn up the Alkaline
    Thanks jd, looks not too complicated or expensive. How well will this work with two conventional batteries. 850 CCA and 770 CCA both new batteries
  13. It will work just fine. For your application you will not see any appreciable difference.
  14. This Relay [​IMG] at
    will do it. It's four wire, so one of the two small terminals needs to be grounded. From there, all you really need is wire and terminals. If your lighting battery is a regular "starting" battery rated in CCA, it won't tolerate deep discharge as well as a "trolling" battery rated in AH (amp hours) will. So take that into account when your replace.
  15. Hello, me being the cheap ass guy I am, why don't you check out the local auctions and you may find a old ambulance that has all the goodies you need for the conversion.
  16. Would probably be cheaper that way.

    too much time on your hands.


  17. Ok, I have everything I need to add a battery box to the frame. I am going to order the isolator from Amazon tomorrow. Thanks jd, and the next lighting battery will be a trolling battery. I have a good negative (went to the bone yard) cable and picked up two positive cables both long enough to reach from the frame battery box to the main battery. One measures .361 just under 3/8" and the other .276 just over 1/4" This is with the red plastic coating still on. I would guess 2 or 3 gauge on the bigger and 4 gauge on the smaller. Which cable should I use to run along the frame? Common sense tells the bigger the less resistance and less possible heat build up.
  18. I have the battery frame mount box, the above isolator, neg and pos cables, extra cable, lug ends. But as I look at the positive battery terminal on the e350 I see there are three red wires going to the positive post. One is heavier, so I would assume starter. Anyway I am confused as to how to wire the isolator because of the three red wires.

    I want the main battery disconnected when the ignition is off so the cargo lights draw off the auxiliary battery only.

    Thank you in advance!
  19. I haven't studied your situation completely, but will give a simple overview. Cargo lights and the switch for those lights should be connected directly to frame battery. Isolator between the batteries connects them to each other with key on, they will not be connected with key off.
    Hopefully, ignition switch will not energize the isolater while cranking, you don't want to ask your underhood battery to crank the engine AND throw a bunch of current towards a discharged frame battery at the same time.
  20. Mobile Dan, you have helped me in the past and I trust your advise, as I do other great mechanics on this site. My cargo lights are tapped into the dome light system. Sure there are six additional lights, but they are all LED and the factory rear cargo light has been changed to a LED bulb, only the cab bulb is original. So the draw is not huge but it slowly takes a toll on a battery. Using an isolator has brought up more question than answers isolator.jpg isolator 3.jpg
  21. Well, in the case of your last statement and you don't trust the isolator setup, why don't you just install a master kill switch for the auxiliary side?
  22. You will want a boost option and a master kill switch. That is how most ambulances are hooked up.

    Flick a switch for boosting, then kill switch if any auxiliary power may drain the rest of the system. In principle, this should be a self contained unit.

    Here is a good read that should help determine why you need a isolator.

    You probably know this already, but worth a read anyway to eliminate any questions you may have.

  23. The primary benefit of such an arrangement is the ability to simultaneously charge more than one battery from a single power source (e.g., an alternator) without connecting the battery terminals together in parallel.
  24. Why>>

    Mosfet rectifiers tend to have less voltage drop. Maybe you are using a relay type. Actually I know you are as your picture shows a relay type isolator. Maybe try to buy something more high end which will give you less grief in the future.

    I probably have not answered the magical question you are looking for. But education comes at a cost.

    Question, do you have a dual alternator setup on this E350?
  25. If it is difficult to separate cargo lamps from dome lamps, then your best option would be to wire the isolator as diagrammed. In that configuration, cargo lights would be powered by underhood battery, frame battery would come online during cranking to assist a depleted underhood battery.

  26. Well, Mobile Dan

    That is what I was thinking myself. My question is on the under hood battery there are three red wires going to the positive terminal. One would be for the starter, One to the power distribution box. And the third red wire???

    So the real Question is on the under hood battery will I add a fourth red wire and run that to the isolator and run a single red wire from the frame battery to the isolator
  27. "under hood battery.....will I add a fourth red wire and run that to the isolator and run a single red wire from the frame battery to the isolator?"


  28. Thank you Mobile Dan and one more question if I may before Hurricane Irma blows me away, I live outside Orlando, FL and the 80 mph winds will be here soon. The positive cable that I was going to run from the frame battery up to the hood battery (I don't know gauges on large wires very well) measures about 0.25" without the red insulation and 0.375" with the insulation on. Seeing as how the frame battery was going to be the auxiliary battery I was not overly concerned with the size of the cable. But now if I hook the isolator to have the frame battery assist the under hood battery in starting do I need to use a larger gauge wire from the frame battery? cable.png
  29. Jumper cable wires sould be OK. What you have appears to be that size??
  30. I would say yes, the wire I have is the size of a good jumper cable. Thank you for the reply!
  31. What is your plan for the ground circuit? Some vehicles only run a smaller wire between batt and frame. If you plan to ground frame battery with a short cable to a spot on nearby frame. you may want to add equal wire to front frame area for underhood battery.
  32. Yes, the ground wire I have will connect to the frame maybe 18" from the battery box. I imagine the idea of running a similar ground wire from the underhood battery is be sure both batteries are equally well grounded. I found out once what it's like to have a poor ground in our mini-stock, shot sparks from gauges to dash, dash to body, roll bars to me.

    Anyway, please take a look at my rough schematic and see if I have all this straight in my head. I may add a couple 80 amp fuses at the battery positives and a cut off switch on the frame battery under the hood. Daul battery schematic 3.png
  33. Ok....I would think wire labeled "factory ground" would connect to underhood battery.

    A possible upcoming challenge would be the "true ignition power source" thing. Hopefully your can find a fuse that has power when key is "on" and while "cranking", but not when key is "off". Piggyback connection at that fuse might be the way to go.
  34. [​IMG]
  35. Mobil Dan...Thanks for catching my Daul battery schematic 4.png mistake on the schematic, Factory ground should be on under hood battery. Posting modified schematic

    Question to everyone at BAT: What the heck is Hot while cranking, but not with the key in off position? aka: "true ignition power source"
  36. Hmm...what needs to be working during both cranking and running? Well, you've got to have spark and gas, so maybe fuel pump, ignition coil, injectors.
  37. See any problem with tapping into " hot when key on" side of fuel pump fuse?
  38. I would think it should work. But it might be helpful to add a relay to reduce power loss to fuel pump. Are you the same guy I helped to wire up some relays to get fog/driving lights added to some kind of small SUV?
  39. Yes sir! A 2005 Ford Escape. Still have it, 108,000 miles. Don't drive it much, but we bought a 2011 Escape, sold that, and now a 2014 Escape, but I still like the '05 and the fog/driving lights work great

    What about the idea of mounting a switch in the cab that controls the isolator. The switch would be powered by the Frame battery and have an indicator light on the dah that comes on when the isolator is energized .

    Well, Mobile Dan, when you have time, which direction would you go? I've had some experience with relays (as you know). So I'm open to ideas.
  40. Trying to contact Mobile Dan. Are you out there friend?
  41. I think a switch/light connected to frame battery would work. The only downside would be that if you switched on isolator to charge frame battery, but shut off the engine later at the end of your day, and did not switch off the isolater, in the morning BOTH batteries would be discharged because to isolator would stay energized and keep the batteries connected until they were both so low that there was not enough power to keep the isolator energized.
  42. What was your relay idea Mobile Dan?
  43. [​IMG] Wire it like this diagram, but change info on diagram to read "+12V (from fuel pump fuse, a true ignition power source)" for pin 86.
    Also change to read "+12V (to right hand small terminal on isolater shown on your homemade schematic) for pin 87.
    Info for pins 85 and 30 would remain the same.

    Wiring in a relay in this way would greatly reduce the amount of power to be "stolen" from the important fuel pump circuit to keep that large isolater relay energized.
  44. Let me gently and humbly poke back into this... I'm reluctant since I'm not a pro mechanic, and much of my experience is dated. But it IS experience, and what I drew on recommending an Isolation Relay is based on owning Ford-based Class C motorhomes. We've had two over the last over 20 years, and both used isolation relays. I'm very active on an RV forum, and the popular setup that works and is relatively trouble free is isolation relay. Electronic solutions that are diode based are not recommended. The gold standard is Intellitec's "BIRD" which allows Either Coach (sometimes called House, which would be Bill's lighting battery in this case) OR Chassis (the starting battery) to be charged when the Other is being charged. So when driving, the Chassis would charge the House. When parked on a powered RV site or running an onboard generator, House would charge Chassis. I don't have one and the Chassis battery hasn't required charging, even when camped for 60 days. I didn't recommend it to Bill because he doesn't plug his van into a 120 VAC shore tie. If he did, and used a Battery Charger on his Lighting Battery, BIRD would charge Chassis as well. Bill's problem statement doesn't seem to require that.

    Most RV's with Isolation Relay have "Aux Start" and all it does is apply 12 VDC to close the Relay, so House (Lighting) helps Chassis. I didn't suggest including that because I wasn't sure of Bill's wire size. He could be running wire that's plenty for powering the lights, and charging from the Alternator that was NOT adequate as a "Jumper Cable." Intellitec BIRD, in the GAS version, allows Aux Start also.

    Since both of our RV's already had Isolation Relays, and I never had to work on them, I don't know which exact Fuse/Circuit/Terminal the "True Ignition" came from.
    The Ford Van Owner's Manual should be a good start. If Bill can confirm the Year Model, I'll see if I can find a Manual on line and look. Simply stated,
    START: Fuel, Ignition, Cranking
    RUN: Fuel, Ignition, Accessories (Radio, A/C, etc.)
    ACC: Accessories only
    So, what you want to find is Fuel or Ignition. I'll help if needed. Seems you could pull the respective Fuse and tap in with an adapter like pictured above. That would only power the Isolation Relay's Coil. NOT the load to charge or use the Lighting Battery

    The "Bosch" relay pictured above might not be adequate for Isolation. They're rated around 30A. If I'm reading right, using a Bosch type relay as a Slave to the Isolation Relay's control coil. Ford Vans are that way. A fender liner mounted Relay powers a Solenoid on the Starter. Chrysler used to use a small Relay (like a Bosch) between Ignition Key Start and the Starter Solenoid. It's in no way a bad idea to insert a small relay to supply power to the Coil (small terminals) of the Isolator. Again, the RV's I've known do not, but it wouldn't hurt anything unless the "Bosch" is a super cheap one and becomes a point of failure.

    Bill should either:
    Break Interior Lights OFF of Chassis and ONTO Lighting along with the LED's or
    Leave Interior ("Dome") as is, and wire the LED's separately

    Lots of words, but I hope I've helped.
  45. Yes, "using a Bosch type relay as a Slave to the Isolation Relay's control coil" is a good description of the proposed setup.

    I think Bill's goal is to keep rewiring to a minimum and just add a "frame battery" that will boost power when cranking and be recharged when engine is running. Also...isolated from electrical use (depletion) when key is off.
  46. [​IMG] With a maxi fuse, may be able to remove some plastic and attach a wire with solder or small screw.
  47. I wonder if the contacts on a maxi fuse are the same as 1/4" solderless crimp terminals. Then we could use a maxi holder and tap an ATO off of it to power the Bosch relay. I haven't been able to find an add-a-fuse tap for maxi. ATO is easy. We need to be careful with this - Our tap connection fails and the van stops. I'd want the Bosch fused, close to the Maxi, so anything wrong with the Isolator circuit wouldn't blow the maxi and disable the van.
  48. Yes, a short and safe distance to an in-line fuse holder for the wire headed to Pin 86 on the Bosch relay would be a good idea. I imagine a 5 or 10 amp fuse would suffice for the small amount of amperage required to energize the Bosch relay coil.
  49. Wow jd, a lot for an old fart like me to absorb all at one time, but I sure do thank you and I will keep re-reading it.
    The van is an 2006 e350, 5.4 liter, cargo van
    the isolator I plan on using is rated at 80 AMP with a 150 AMP Surge
    Mobile Dan is right on the money as to my goals in his last post. I could not have put it into better words
  50. Here is my latest schematic . Note: Batteries final wo fuses.png and isolator to be safely fused before activating
  51. I noticed that in my owners manual it shows a "15A Back -up lamps, Auxiliary battery relay"

    Located in the Passenger compartment fuse panel, position 12

    Would this be of any use?

  52. Is the fuse a "true ignition source"? Do you know the location of the AuxBattRelay? If you find that AuxBattRelay and associated circuits work as needed, you could attach to your isolator solenoid and get your new system to work that-a-way.
  53. The location of the AuxBattRelay is location 20 of the PDBox, PDB fuses 8 and 24.

    I already have everything installed, except frame battery is not in the box yet, and I have not hooked up to a "true ignition source"
  54. Does "everything installed" include the "Bosch relay"?
  55. Yes sir, and I will be adding a 10Amp inline fuse on the 86 card  back.png
  56. Question, When hooking up the 10 Amp in-line mini-fuse for the "Bosch Relay" should it be attached to the fused side or the hot side of the 20 Amp Maxi-Fuse for the Fuel Pump when in "true ignition source" mode.
  57. Probably doesn't much matter, but the "fused side" seems like a better choice.
  58. OK, Tell me what you think (photos) 20 Amp Maxi for fuel pump with 10 Amp piggy back for "Bosch Relay". I also was thinking of putting a little JB Weld Quick Set epoxy over the top of the exposed jumper wire solder connection
  59. If you are doing that for insulation, then I would say NO. I believe JB weld is slightly conductive.

    If you are doing it for a better connection then it would be OK, although the solder joint should be fine without it.
  60. Thanks JackC. The JB Weld is to improve the integrity of the connection, not as an insulator (see photo)
  61. That should do what you want. Just be cautious as that could be "hot" 12 volts.
  62. JackC, I've been knocked on my butt by 12 volt spark, arc, and just not too smart.

    Anyway, I have learned (ok, so I had sparks flying off the wire cutter on a 110 volt job a few weeks ago)

    So, my point. I checked this circuit with the key out of the ignition, and in the lock position, every way possible for a hot reading.

    Cold and safe....but good point!
  63. And now eat humble pie. The fuel pump circuit is HOT all the time. I did one more good test today and 12.6 volts pops up on the screen.
    So looks like the injector 20 Amp circuit (position 16) is the only cold circuit engine off
  64. I was using a poor body ground under the hood for my initial testing. As my last post states the fuse circuit I am going to use is the 20 Amp injector, piggy backed with the 10 Amp fuse for the "Bosch Relay". I also installed a 100 Amp inline fuse between the isolator and the frame battery cable connector to the isolator ( Tried to find a 80 Amp but connections were too small)
  65. I did a test run of the under hood circuits this morning. I hooked up the line running from the 20 Amp Fuel injector fuse, to the 10 Amp in line fuse, to the "Bosch Relay".
    I then used the under hood battery as a power source to the Bosch Relay. (The frame battery has been removed while putting this all together).
    I then hooked up a 1.5 volt circuit test light to the isolator .
    All ground circuits are connected
    When key is off, test light is off
    Key is in the on position, start position, and run position, light is on.
  66. New system ready to go! (just add battery)
  67. Good catch on that one Dan. Your memory is flawless.
  68. You can always count on Mobile Dan, as with many of the great BAT people like nickb2, JackC, jd, and many more.
    I will check in as soon as I get the frame battery installed. Frame box is installed and wires are all run. I'd call in sick today, but I'm the boss, crap!
  69. System up and running! I don't have a dash indicator light installed, but I did run a test light. Van pulls off under hood battery only when key off/lock. Pulls off both batteries during on, start, run
  70. Great! Now you can work late into the evening/night and not worry that your truck won't start when you want to "head for the house".
  71. Yes, It is great, and once again Thank You and everyone who helped. You guys Rock!
  72. A question did arise in manually charging the two batteries. I assume the under hood battery can be charged the normal way, just hook up the charger, small 6 amp. Can the frame battery be charged by using the connection at the 100 amp fuse before the Isolator and a good frame ground. And just an idea: could the negative connection on the under hood battery be used to ground the frame battery while charging . I have added a second ground cable to the under hood battery
  73. Yes. You can connect the (+) cable of your charger to the large terminal of the Isolator Relay that does NOT go hot till the engine's running. For the (-) cable, connect to the best ground closest to the (-) of the frame battery.

    Remember, the Frame Battery is Isolated from the Chassis Battery unless the Engine is running. If you remember to turn the LED lights off, the Frame Battery won't run down till you use the lights again. BUT!!! If you connect something "parasitic" (meaning it uses power even when OFF), it will drain the Frame Battery. RV's are like this. They have LP Gas Leak Detectors that are ON full time and they'll drain the "House" battery, the one you call "Frame" so there's a Battery Disconnect to remove all loads when the RV will be parked awhile without a power source. You shouldn't need that as long as you have only lights. Say you want a second Car Stereo running off the Frame Battery. If it's Display doesn't turn off when the Sound is turned off, say to display Time, it'll run the battery down. The Time and Station Memory doesn't draw enough to worry about.
  74. jd, The LED lights are on a automatic timed shut off after about 10 minutes. This is a good thing,
  75. Well, system up and running. I went over to Radio Shack and picked up a project box (remember them?). I did some major surgery on the box to cover the isolator terminals and most of the relay. I installed a dash indicator light when isolator is activated. I also have a pillar installed volt meter that reads everything off the ignition switch (ignore the warning, there is a red light that comes on below 11.5 volts) 105.png 106.png 107.png
  76. Having this two battery system is great. Starting voltage has not been below 12.3 volts, normally 12.6 - 12.8 starting volts now, and I have been doing short trips last couple of weeks. Before I would drop to as low as 11.5 volts (no start) with short trips.
  77. It's a beautiful thing! You finished it off nicely!
  78. sheild1.jpg sheild2.jpg I made a modification to make it easier to test and charge the frame battery from under the hood by adding a metal strip at the isolator connection. Then I added a removable cover to the end of project box
  79. I cleaned up the look. Put in a relay wiring socket, some blue wiring conduit on all the wiring for this project and the fog light project I did on this site. blue.jpg
  80. Very Professional looking. Nice job.
  81. Thank you JackC. A compliment from a BAT wrench means a lot to me. I try to do a job I can take pride in. Thanks again!
  82. I am going over the entire two battery system I installed, just to be sure everything is ok. It is working great except I may have been experiencing a power surge on the LED dash indicator light that shows that the Isolator is activated. Two new lights burned out about three weeks apart. I must admit it was not fused at the time. It is fused now, and I would like to list the fuses that I am using and get an opinion as to if I am in range of where I should be.

    20 AMP MINI FUSE - BETWEEN LARGE ISOLATOR TERMINAL (same isolator terminal as above) AND #30 PIN ON RELAY

    With my general knowledge of automotive wiring I think I am safe with the above, but if I am wrong please share with me.

    Happy Thanksgiving to all !!
  83. Just to me, the fuse sizes seem OK.

    About the LED surge part, I looked at this post right away, and have pondered it since. Haven't had the first suggestion till now, and it's only a stray thought. So here goes...

    The old Points and Coil Ignition works off of a COLLAPSING Magnetic Field in the Primary (12-Volt) side of the Coil. To put it another way, a Field is created when the Points first Close. When the Points OPEN, the Primary Field collapses with a BANG. Faster than it had Charged. Works good for Ignition but anywhere else, it's a Voltage Spike. So, I wonder if there's a Spike when the Isolator (even the Bosch Relay) shuts OFF. LED's are electronics and electronics often don't tolerate spikes. That's why we find Diodes in strange little places. For example, the connector to your A/C compressor clutch probably has a Diode in or close to it. How and Why it works, I Dunno. I just know it's there to control the spike caused by the clutch disengaging.
  84. Thanks jd for the input. I was wondering about a possible power surge. I did a couple things. First I went over all my connections especially splice connectors. I replaced some of the splice connectors and put shrink tubing over them. I also bought a red indicator light for the dash. The last two that burnt out were green indicator lights (just on the chance the red lights are not as sensitive...I know they may both have the same lamp)
    Anyway it has been a few weeks and it has not blown a lamp or fuse.