Thread: Solar and truck charging of deep cycle batteries.

  1. #1
    Join Date
    Feb 2009
    Location
    Santa Maria, CA
    Posts
    35

    Default Solar and truck charging of deep cycle batteries.

    I've been banging this around in my head for so long I'm starting to hear rattling noises, but this time I mean it...I'm close to making the plunge and will call a few distributors next week, but thought I would present an idea here.

    My plan is to build a hybrid system, one that will allow me to charge golf cart batteries from either a 100W solar panel or the truck's alternator. Furthermore, I don't plan to mount the panel on the truck. Instead it will be a remote unit on a stand of some sort that I plug into the truck using heavy duty quick connects. That way I don't have to worry about it getting damaged by low hanging branches and I can park in the shade, but have the panel in the sun (provided I can find such a place). Also, I'll be able to turn it throughout the day to get maximum efficiency out of the panel. The draw back is that the batteries will be discharging when I don't have the solar panel plugged in.

    From my research on the internet, golf cart batteries can be drained as much as 50% with no harm done. However, when drained that much, they must be recharged slowly (no more that 20% of their Amp-Hour rating). The truck's alternator would probably charge them far to quickly.

    The MPPT charge controller I'm think of getting is a smart charger and should work well with the golf cart batteries.

    So, here is my idea. Connect the input circuit of the charge controller to the truck's electrical system. I would use a break-before-make switch to select either the solar panel, or the truck's system. Furthermore, I would incorporate a DC-DC converter to limit the current from the truck to something the charge controller can handle.

    Does this sound like a reasonable design? Or, am I likely to fry components? What might I be missing? I'm starting to hear rattling again!
    Ed,
    2000 FWC Hawk on 2006, Chevy K2500HD, Duramax.

  2. #2
    Join Date
    Sep 2006
    Location
    Canadian in Colorado
    Posts
    1,174
    Solar is a great thing when the sun is shining, my concern with remote panels is the potential for theft. Make sure you find a way to secure them thoroughly.
    Typically the alternator charges camper batteries very slowly , too slowly unless you rig up an alternate method of charging. I am currently looking at a better means of doing the same thing. One thought, though not real efficient is a 1000 watt inverter off the truck's electrical system to an Iota 30 amp smart charger, that I just purchased for charging batteries more efficiently off my 1000 watt generator.

    The other means is a regulator, but I know next to nothing about them or how they work.

    Sounds like you're on the right track and keep posting with updates.
    Last edited by Carlyle; 03-02-2009 at 03:06 PM. Reason: typo
    '12 Dodge 5500 6.7 diesel slightly modified. 14' 3" Alaskan camper (Alaskanabego)
    My camper build: http://www.expeditionportal.com/foru...ead.php?t=9502

    KD0ERY

  3. #3
    Join Date
    Feb 2009
    Location
    Santa Maria, CA
    Posts
    35
    Quote Originally Posted by Carlyle View Post
    Solar is a great thing when the sun is shining, my concern with remote panels is the potential for theft. Make sure you find a way to secure them thoroughly.
    Typically the alternator charges camper batteries very slowly , too slowly unless you rig up an alternate method of charging. I am currently looking at a better means of doing the same thing. One thought, no not real efficient is a 1000 watt inverter off the truck's electrical system to an Iota 30 amp smart charger, that I just purchased for charging batteries more efficiently off my 1000 watt generator.

    The other means is a regulator, but I know next to nothing about them or how they work.

    Sounds like you're on the right track and keep posting with updates.
    It's funny you of all people should reply. I read much of the thread on your Alaskan build last night.

    I hadn't thought about theft. I'll have to take that into consideration.

    I thought about the inverter to charger too, but I figure there must be a better way. I hope I'm smart enough to figure it out.
    Ed,
    2000 FWC Hawk on 2006, Chevy K2500HD, Duramax.

  4. #4
    Join Date
    Feb 2009
    Location
    Saint Augustine, FL
    Posts
    47
    This guy can answer all your questions and sell you what you would need. John is a great guy too: http://www.jolynenterprises.com/

    Terry
    2005 4X4 Jeep KJ Limited: 3" lift, 32" Dunlop Radial Mud Rovers, Smittybilt Winch, Custom front bumper, 25# CO2 Tank, 4.10 gears etc etc!

  5. #5
    Join Date
    Sep 2006
    Location
    Canadian in Colorado
    Posts
    1,174
    Ed,

    Feel free to email or call if you have any questions about what I've done and learned. The most important thing to start with is figure out your load in amp hours, double it and go from there.
    '12 Dodge 5500 6.7 diesel slightly modified. 14' 3" Alaskan camper (Alaskanabego)
    My camper build: http://www.expeditionportal.com/foru...ead.php?t=9502

    KD0ERY

  6. #6
    Join Date
    Feb 2009
    Location
    Santa Maria, CA
    Posts
    35

    Default Thanks Carlyle

    Thanks for your replies, and I will likely contact you before spending any money. Based on my daily usage to date, I figure a 65 Watt system, at 70% solar efficiency, with 4-6 hours of usable sunlight per day would suit me, which is why I thought a 100 Watt system would be a good starting point.
    Ed,
    2000 FWC Hawk on 2006, Chevy K2500HD, Duramax.

  7. #7

    Default Golf cart batteries

    Like to be charged hard, it is called an equalize charge. You raise the charge voltage much higher than the normal battery voltage ...etc.

    Your alternator connected to a charge controller with a setting for wet cell batteries at the appropriate voltage would be required.

    A 100 watt solar panel is not going to cut it. That is it will never charge the wet cells back to full charge.

    If you are going to play with Lead acid batteries invest in a Hydrometer.

    Quote Originally Posted by EdoHart View Post
    I've been banging this around in my head for so long I'm starting to hear rattling noises, but this time I mean it...I'm close to making the plunge and will call a few distributors next week, but thought I would present an idea here.

    My plan is to build a hybrid system, one that will allow me to charge golf cart batteries from either a 100W solar panel or the truck's alternator. Furthermore, I don't plan to mount the panel on the truck. Instead it will be a remote unit on a stand of some sort that I plug into the truck using heavy duty quick connects. That way I don't have to worry about it getting damaged by low hanging branches and I can park in the shade, but have the panel in the sun (provided I can find such a place). Also, I'll be able to turn it throughout the day to get maximum efficiency out of the panel. The draw back is that the batteries will be discharging when I don't have the solar panel plugged in.

    From my research on the internet, golf cart batteries can be drained as much as 50% with no harm done. However, when drained that much, they must be recharged slowly (no more that 20% of their Amp-Hour rating). The truck's alternator would probably charge them far to quickly.

    The MPPT charge controller I'm think of getting is a smart charger and should work well with the golf cart batteries.

    So, here is my idea. Connect the input circuit of the charge controller to the truck's electrical system. I would use a break-before-make switch to select either the solar panel, or the truck's system. Furthermore, I would incorporate a DC-DC converter to limit the current from the truck to something the charge controller can handle.

    Does this sound like a reasonable design? Or, am I likely to fry components? What might I be missing? I'm starting to hear rattling again!

  8. #8
    Join Date
    Feb 2009
    Location
    Santa Maria, CA
    Posts
    35
    Quote Originally Posted by BigJim View Post
    Like to be charged hard, it is called an equalize charge. You raise the charge voltage much higher than the normal battery voltage ...etc.

    Your alternator connected to a charge controller with a setting for wet cell batteries at the appropriate voltage would be required.

    A 100 watt solar panel is not going to cut it. That is it will never charge the wet cells back to full charge.

    If you are going to play with Lead acid batteries invest in a Hydrometer.
    Why won't a 100 watt panel suffice? From my reading, at maximum efficiency it would make around 25 volts at 4 amps. I know "maximum" means direct sunlight and cool temperatures and I can expect to see maybe 70% of maximum on a cloudless day for a few hours. I figure my maximum amps per day requirement is between 17 in the summer to 32 in the winter (unfortunately inversely proportional to the amount of power a solar system can provide).


    Because of the location I'm thinking for the batteries, I'll use AGM batteries, so I want to be careful about cooking them off.

    I talking to a couple of suppliers today, and if I understand things correctly, the solar charge controller expects to see voltage and amperage increase as the solar panel efficiency goes up (that is, it gets more direct sunlight, combined with cool temperatures). If the input is say 13.8 volts and 5 amps (69 watts) that is not the same to the controller as 15 volts at 4.6 amps (69 watts). So my idea was nixed by 2 different companies, but I got points for thinking.

    An internet search for "DC input battery chargers" found a few companies that make 3 stage (bulk, equalization and float) chargers that take an input of 8-14 Volts. I'm rethinking my design to accommodate these chargers.

    Thanks for everyone's input. It really helps!
    Ed,
    2000 FWC Hawk on 2006, Chevy K2500HD, Duramax.

  9. #9

    Default Charge Controllers

    Morningstar makes several nice charge controllers.

  10. #10
    Join Date
    Apr 2008
    Location
    Apache Junction, Az
    Posts
    766
    I am finishing up my own solar panel system, check out my build thread for some details.
    I am using a 55 watt mono panel, 7amp charge controller hooked up to 2 yellow top Optima batteries and a 1000 wat inverter. I am also building my own dual battery altanator set up, basicly the isolator is a 200 amp selanoid made for a RV, I am putting a toggle switch in line to select main battery or coach batteries. The way I understand it is the charge controller will maintain the batteries if they drop below 13 volts, so in therory, when the engine is running the altanator will produce 13.5 ish volts so the altenator matains the batteries.
    I am still undecided if I will keep the optima batteries, I only have them because they were free, I am considering a 8D Trojan battery it has 205 amp hours and weighs 165 lbs....and cost about $550


    I have been trying to get everything dialed in and had some issues with the electrical but so far everything is good to go.

    This is the output of the solar panel, sunny afternoon


    this is the output of the charge controller




    and here is the battery voltage with the fridge on.




    I tested the system last week and so far it works very well. I started by disconnecting the solar panel and fully charged the batteries over a couple days, I pluged the fridge into 110volt power and filled it and got everything cold. I then hooked up the solar again and monitored it for 3 days with the fridge on med-hi and opening and closing several times to get drinks, I used the power inverter , plugged in a radio ,used a drill, turned lights on at dark for several hours. After 3 days everything was charged and in great condition. I will do another test for a week or so to get a better idea of what works and what doesn't.
    --------------------------------
    Jess
    ---------------------------------------------------------

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •