Help with small setup

System
System Posts: 2,511 admin
in Off Grid Solar & Battery Systems #1
For about four years I have been using a 3000w Coleman (pmp3000) in my car for power when working in areas where there is no power or access is limited. Tools such as a jackhammer, grinder, MiG welder, along with other power tools like drills, skillsaw, grey water pump. It works great I'm happy with the run times under load. Right now I either carry a battery with me or pop the hood on my car.
I have a gas powered generator and it works great but it's heavy and loud...fumes so I only like bringing it along when I really have to. Yes, louder then the jackhammer. ;)
I also have a Vector 3000w inverter (veco51d) that I seldom get to use.
The plan... Ok I want to run the Vector inverter and charge the batteries with panels on the roof of my car. :D Is this doable?
I'm looking for a simpler way to charge and maintain the batteries that does not involve running off my car engine.
Since I typically only use the inverter 2-3 times a week for about an hour or so at a rip I was wondering about putting a couple solar panels on the car roof to maintain the car batteries as I drive/park.
The Vector is a semi-modified sine inverter.... better then the Coleman modified sign inverter? The Coleman is a workhorse, she has taken some beatings. :roll: But I figured the vector is half the size which would give me more room for a second battery and more capacity. Right or wrong? The Vector needs a dual battery hookup to function properly. That is mainly why I seldom get to use it. With the Coleman I just connect alligator clips to the battery terminals and I'm good to go.
As for solar panels. I have a 1998 Chevy Blazer and was considering mounting a monocrystalline panel on the roof. Will I need two panels and two separate controllers for each battery? Or can I charge both batteries as one bank without screwing up the inverter/controller? What size panels would I need and how many? Using 2-105AH deep cycle marine batteries.
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Comments

  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #2
    Re: Help with small setup

    Welcome to the forum.

    It's a nice idea but ...

    Solar panels aren't going to be the best solution, or I miss my guess.
    For one thing, you'd probably need like three Kyocera 135 Watt panels. They're not going to fit easily on the roof of a small vehicle (as opposed to an RV). They aren't going to mount easily either. Although you could make a portable system, bring it with you, and set it up on site.

    For the money, you'd probably be better off investing in a good generator like a Honda EU2000i. Very quiet, very fuel efficient, and could run some power tools while recharging batteries (with a separate charger).

    I'm surprised you're managing with a MSW inverter. "Semi-modified" is just marketing gunk; you either have a sine wave or you have some variation of stepped square waves. Were it me, I'd look to investing in the gen, a true sine wave inverter capable of handling the loads, a decent battery charger, and a couple of T105 batteries.

    Others may have different angles on this.
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  • System2
    System2 Posts: 6,290 admin
    #3
    Re: Help with small setup
    Megaputz wrote: »
    I have a gas powered generator and it works great but it's heavy and loud...fumes so I only like bringing it along when I really have to.

    To keep 2 batteries charged I'm going to need 400w panels? Even when I'm only drawing 2-3 hours a week? So the little 171v/5.7a/8.5w (his specs) panel my cousin was giving me is way under what is needed.
    Ok, lets put my energy usage into perspective... I have been using old car batteries. Batteries that have dead cells and will not start a car to power the inverter. The dead batteries I have used are only 30-40 AH. I was only going to buy one or two 105 AH batteries so there would be plenty of reserve so they would not stress the batteries as much, increasing battery life. If I typically use only 30AH and a have a 210AH bank. See what I'm saying?
    Am I on the wrong forum? Is this a gas generator forum or a solar forum. :D
    I have gas generators and have built gas generators. It would be simple just to install a second alternator under the hood. Been there, done that... want to play with solar now. :)
    Heck, I have even considered putting a small wind turbine on my roof. 3 hours a day with 70mph plus 'passive' wind while parked. :D

    How long does it take to make a field repair? You use the grinder for a minute or two and MiG welder for another 5-10 minutes. I'm not asking for hours of sustained use. It takes like 20 minutes to break up a section of sidewalk/slab to get to a water/sewer line with a jackhammer. I'm using power for 2 hours a week in this fashion. I need 400w of solar for that? I'm way better off using old/dead batteries as I have been?
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #4
    Re: Help with small setup

    Nope. You're on the right forum. Possibly the only solar forum in the world that will tell you to buy a generator when that's the right answer.

    Here's a bit of preliminary reading for you: http://www.windsun.com/Batteries/Battery_FAQ.htm

    See, the problem is you've been running things on the edge with batteries that don't matter. If you switch to some new batteries, that's an investment you'll want to maintain (as they're bloody expensive these days). It's not just a matter of "putting back the used Amp hours"; you also have to be able to supply enough charge current to remix the electrolyte.

    So if you were going to start using, say, a pair of 225 Amp hour 6 Volt "golf cart" batteries (typical and good starting point) you'd be dealing with math like this:

    Recharge rate of 5% to 13% of Amp hour rating;
    11.25 Amps (5%) @ 14.2 Volts = 160 Watts, less typical 77% derating = 207 Watt array. (Double it for 10% target.) That's why three of the Kyocera 135's works out. Two would be minimum.

    Could you do it with less? Yes; at the eventual expense of battery life.
    But there's good news too! If you have an actual use target of 30 to 40 Amp hours you don't have to buy a huge battery to supply it. Normally the maximum DOD is 50%, so you could get away with a 100 Amp hour deep cycle battery (don't buy the RV/Marine type - they're really not suitable). One of those panels will supply about 7 Amps peak current in good sun, which would be within the 5%-13% range.

    See how critical it is to be able to size the system to the loads? It makes worlds of difference! :D
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  • System2
    System2 Posts: 6,290 admin
    #5
    Re: Help with small setup

    Thank you for the info. :) I'm going to stick with the used car batteries for now. At least until I can get my hands on that panel and see it's actual output. I'll mount the panels on a shed at first and go from there. I'll check the charge rates at home, add panels/batteries from there. Max is going to be 2 batteries and 400w of solar panel should be my goal right? Hope that is the higher end. :) I'm located in upstate New York.
    I know the old batteries will not be as efficient but I'll get my act together fist than invest in good cells. No sense in ruining good batteries. They have some pretty reasonable priced deep cycle batteries. Not going to get forklift batteries. They're pretty well priced but they're way too heavy.
    I have a small pure sine inverter charging cordless tools and laptop.
    Not much difference between the modified sign and 'semi-modified' sign inverter. The Vortek does seem more efficient but still hear cogging in fans and such. They're too old to sell with a good conscience so I'll use them until they burn out then sell them for parts.

    After reading other posts I am considering a grid tie system for home but that's a year or two down the road. Got to look into tax credits. :) I'm sticking to my gas powered generator for power outages which rarely occur here.
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