newbie with lots of questions

westcoastsliderwestcoastslider Registered Users Posts: 20
I have a school bus/ motor home that I am equipping with a small off grid solar electric system to meet my power needs when I'm not near a plug in.

I have a fair amount of knowledge of AC wiring from house wiring. I also have delt with a lot of DC from auto mechanics. However, my experience with RE systems is limited to non existent. I have been trying to pick up as much as I can from the FAQ links at the NAWS site. Those sections have been invaluable. Thanks very much for the FAQ's and this forum.

I started with a small simple system. 4 Trojan T-105's, 2 80w suneletric panels, cheap 12v 20amp charge controller(couldn't find a name), and a xantrex X-power 1000w inverter. 3500w Coleman generator. Small automotive type 6amp battery charger.

After realizing that the bus needed more power, or I was really interested in RE(not sure which had more of an influence) First I got a smaller inverter xantrex X-power 175w) to power small loads and avoid having the larger inverter on as much. I stated searching for some used panels. I found 4 40w arco panels. Two look very old and have some browning on the glass(possibly from the Carrizo solar plant?). This put me past the ability of the little 20a charge controller. I saw 26 amps running through it a couple of times and decided I need a larger controller. Got a xantrex c40 charge controller cheap. Started reading about it's functions and how to wire it and all kinds of questions start popping up.

?'s

1.Should I run all six panels through the c40 or should I keep the two 80w sunelectric panels on the c40 and run the four 40w arco panels through the small 20a controller?

2.Is it ok to wire the inverter(175W or the 1000W) ac output into the ac breaker box for the bus? So I can use the plug ins in the bus. It seems like I read that this was hard on the inverter. (I have disabled the 30amp converter that powers the DC loads when your plugged into grid power.)

3.I already figured out that my little 6amp battery charger is not going to be sufficient. I have been looking at the 55amp iota charger. Would I have any problems running that with my Coleman 3500w generator?

4.The batteries I got where already two years old. They had been maintained with the small generic charge controller which had no BTS or ability to equalize the batteries. What would you do to try to get the most life out of these batteries? Do I need a desulfater?

5.Where do you get a temp compensated hydrometer for checking batteries.

Sorry for the lengthy post. It's my intro as well as questions that have been building for a few months now.

Comments

  • mike95490mike95490 Solar Expert Posts: 9,359 ✭✭✭✭✭
    Re: newbie with lots of questions
    1.Should I run all six panels through the c40 or should I keep the two 80w sunelectric panels on the c40 and run the four 40w arco panels through the small 20a controller?

    Look for the voltage specs on the panels, if the labels are still on the back. pair the panels up, according to their " V max power ". If I counted right, you have 320W of PV, which could give you 24A max, if your batteries were really low.
    I'd put the most wattage thru the C-40, and if you had any odd panels (I suspect they are all about 18V output give or take) put them on the other controller. Voltage difference of 2-3V is ok, but if some are 19V panels, and some are 32V panels, those should be on different controllers.
    2.Is it ok to wire the inverter(175W or the 1000W) ac output into the ac breaker box for the bus? So I can use the plug ins in the bus. It seems like I read that this was hard on the inverter. (I have disabled the 30amp converter that powers the DC loads when your plugged into grid power.)
    Before connecting the wires up, use a tester, and make sure neither side of the outlet slot, is connected to the bus chassis. That's what makes inverters smoke, grounding one side of the AC, which is common procedure in a conventional house, but bad for inverters where the battery (-) cable is connected to ground too.
    3.I already figured out that my little 6amp battery charger is not going to be sufficient. I have been looking at the 55amp iota charger. Would I have any problems running that with my Coleman 3500w generator?
    55A @ 12V = 660watts, so that should be fine. The Iotas are very tolerant of generators
    4.The batteries I got where already two years old. They had been maintained with the small generic charge controller which had no BTS or ability to equalize the batteries. What would you do to try to get the most life out of these batteries? Do I need a desulfater?
    I would try each battery singly, on the c-40, in a EQ cycle, as you don't have enough PV to EQ the entire bank.

    Also look into getting some more PV, you are short on charging all the batteries, unless you plan on daily running the generator. Also, use only distilled water, filtered, tap, and bottled drinking water all have minerals which damage batteries.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • westcoastsliderwestcoastslider Registered Users Posts: 20
    Re: newbie with lots of questions

    Thanks for the help Mike!

    The older panels have no labels, but checking them with a multi meter revealed that they are all close to the same voltage(19.1v). Would there be anything wrong with running them all through the c40? The c40 also says that it can handle input voltage up to 125v dc. Does that mean that I could wire all six panels in series? What would be the pro's and con's of doing this. Would having one array on a tracker and the other fixed make it not a good idea to put them all in series together?

    I wired the AC box and I didn't connect the ac neutral to the chassis. I have had the inverter running the bus plug ins before but read that if the inverter wasn't designed to be hard wired to the breaker box then it could burn up the inverter. I had no problems before so I will try it again.

    I will try equalizing one battery at a time until I have a better way of doing it.

    I would love to have a few more panels, but this project is on a very tight budget and unless I find them used at a VERY good price it really isn't a option for me.

    Is a hydrometer the most accurate way to measure batteries SOC? I have a hydrometer for beer making. Can I use that for testing my batteries?

    What should I do for a ground? Most of what I have seen involves a grounding rod which isn't easy to do with a motor home. I currently only have a ground on the ac side when I'm plugged in to an ac service that has it.

    Seems like the more I learn the more questions I have:blush:
  • mike95490mike95490 Solar Expert Posts: 9,359 ✭✭✭✭✭
    Re: newbie with lots of questions
    ... they are all close to the same voltage(19.1v). Would there be anything wrong with running them all through the c40? The c40 also says that it can handle input voltage up to 125v dc. Does that mean that I could wire all six panels in series? What would be the pro's and con's of doing this. ...

    I'm assuming you are running a 12V battery system. While you *could* feed the c-40 90Volts, it is a PWM charger, and you would waste 70% of your power.

    So wire them all in parallel. Tracker panels, and fixed. That will get the most power from your existing system.

    An MPPT controller could downconvert high array voltage to your battery voltage, but the expense of one, is not practical for your system size

    Mike
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: newbie with lots of questions

    there may be a concern with the efficiency of paralleling the pvs as 19.1v (assuming open circuit) is a bit on the low side and would possibly indicate a low vmp as well, especially when the pvs are hot as it's possible it may drop too low to charge properly. it may be more money, but getting an mppt controller that can down-convert from higher voltages would take away those worries. this would involve series/paralleling of the pvs and possibly less wire involved, but at a higher cost. no matter what controller used, try to get a battery temperature sensor to compensate for the battery's changing needs.
  • westcoastsliderwestcoastslider Registered Users Posts: 20
    Re: newbie with lots of questions

    I am running a 12v battery bank.

    OK so my 80w panels are solarex not sunelectric. The Voc on the panel state 21.1v. I checked the voltage again and it was just over 20v for all panels. Should I wire all the panels parallel and check voltage of the entire array? Assuming I have at least 20v would the c40 be able the charge my batteries fully?

    To answer my own question of can you use a beer making hydrometer to test battery voltage. No.

    I'm still unsure how to get an earth ground for a mobile system like an RV. Or if I need one. Any thoughts?

    How many people use desulfaters? Most RE stores sell them, but I don't hear you guys talking about using them here. Would it be a good idea for 2 year old batteries that have never been equalized and where recharged by a small array all their life(160w of pv charging a 2700w hr battery bank)?
  • mike95490mike95490 Solar Expert Posts: 9,359 ✭✭✭✭✭
    Re: newbie with lots of questions
    I am running a 12v battery bank.

    OK so my 80w panels are solarex not sunelectric. The Voc on the panel state 21.1v. I checked the voltage again and it was just over 20v for all panels. Should I wire all the panels parallel and check voltage of the entire array? Assuming I have at least 20v would the c40 be able the charge my batteries fully?
    20V, should make the c-40 and the batteries happy.
    How many people use desulfaters? Most RE stores sell them, but I don't hear you guys talking about using them here. Would it be a good idea for 2 year old batteries that have never been equalized and where recharged by a small array all their life(160w of pv charging a 2700w hr battery bank)?
    Well, if the batteries are given a chance to be fully recharged, and some are still not happy, you are likely better off replacing them, instead of mucking around with desulfaters. No real clear results that they work. They also don't seem to hurt, except your wallet.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • KamalaKamala Solar Expert Posts: 452 ✭✭
    Re: newbie with lots of questions
    ... I'm still unsure how to get an earth ground for a mobile system like an RV. Or if I need one. Any thoughts? ...

    I can't answer this question. Some of the threads here discussing earth ground make my head spin.

    I can tell you that I'm going without one.

    Craig
  • PhilSPhilS Solar Expert Posts: 370 ✭✭✭
    Re: newbie with lots of questions

    No motorhomes or RV trailers I've ever seen have an earth ground. That'd be like putting an earth ground on your car.

    *******

    Electrically, wiring an inverter to a string of outlets is no different than plugging a long extension cord into it. The inverter in my RV (Prosine 1000W) is wired directly to two circuits of the trailer (not microwave, not A/C).

    *******

    I have three desulfators, two on my main bank and another that is "portable" (it used to be in my RV but it didn't play well with the C-30 controller so I put some battery clips on the wires and can attach it to any battery easily).

    I have two 1 1/2 year old batteries that sat for much of their early life undercharged. For a few months, I had them connected to my main bank during some days. On one, I put on the desulfator at night. Then off during the days when they were charging (usually a couple of days per week). The other one never got the desulfator.

    Net result = nothing measurably different between the two.

    It was a VERY unscientific test. Maybe the desulfators on my main bank were "helping" those two batteries. Those two DSs are attached at each end of the main bank and I was tapping off of the middle of the bank with some "mini" jumper cables to the batteries in question.

    Maybe those batteries weren't old enough to sulfate.

    I normally get 8 - 9 years from a set of T-105s. That doesn't seem different than what others have posted here about battery life.

    I wouldn't purchase desulfators again but I'll continue using the ones I have since they seem to "cause no harm".

    Phil
  • westcoastsliderwestcoastslider Registered Users Posts: 20
    Re: newbie with lots of questions

    I wired all the panels through the c-40.

    Plugged AC breaker box into inverter.

    I ordered a 55 amp iota charger.

    I ordered a battery hydrometer. NAWS has them. I'll wait to take some readings before try to equalize.

    Not going to get a desulfater.

    I'm not going to worry about a earth ground.

    Everything's up and running nicely. Thanks for all your help.
  • icarusicarus Solar Expert Posts: 5,433 ✭✭✭✭
    Re: newbie with lots of questions

    I would watch the IOTA charger on the Coleman generator. Many battery charges don't like cheap gennies.(Colemans!)

    "GENERATOR REQUIRED: Battery chargers need a full sine wave 120 volts AC to give their rated amount of charge. Most under $2500 also have low peak voltage causing many chargers to give only a fraction of their claimed charge rate. This may be cured with our 10% voltage boost transformer. Some generators can be adjusted for slightly higher speed to maintain 120 volts to compensate. Allow minimum generator size of 1 KW (1 kilowatt) per 30-amp 12-volt charger. Beware low cost 120/240 volt generators with only half rated wattage on each 120 volt circuit."

    The above is a quote from competitor of NAWS site.

    I know that the Xantrex TC series of chargers run quite well on cheap gennies. (Both the old series and he new ones). I don't know about the IOTA. (This is not an indictment of IOTA, quite the contrary as I think they have a good rep, but rather an indictment of cheap gennies)

    The reality is that you are likely to use way more than you really need to running the Coleman. They are cheap however.

    Tony
  • mike95490mike95490 Solar Expert Posts: 9,359 ✭✭✭✭✭
    Re: newbie with lots of questions

    I've understood Iota chargers, are switch mode, they convert to DC, and use a high-Fq switching transformer to convert to the needed voltage. I've heard they run on DC even.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • dagr51dagr51 Solar Expert Posts: 72 ✭✭✭✭
    Re: newbie with lots of questions

    My Iota75 never puts out more than 65 amps into my 660ah battery bank from my Honda EN2500 - Honda's economy genny.
  • mike95490mike95490 Solar Expert Posts: 9,359 ✭✭✭✭✭
    Re: newbie with lots of questions
    dagr51 wrote: »
    My Iota75 never puts out more than 65 amps into my 660ah battery bank from my Honda EN2500 - Honda's economy genny.

    Without knowing the voltage of your battery bank, we've got no idea what sort of wattage you are pushing.
    14V @ 65A = 910W.
    48V @ 65A = 3120W which I know can't be right.

    The EN2500 offers 2500 watts max and rated at 2300 watts
    So, call it an even 2000W into 24V = 83A Still need to know your battery voltage.

    A partially full battery will not draw full amps - but it would if discharged deeper.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • icarusicarus Solar Expert Posts: 5,433 ✭✭✭✭
    Re: newbie with lots of questions

    Remember Power factor as well. I know that the Xantrex TC series run with a PF of ~60% so that even though I should be able to run the TC 40 on the EU 1000, I couldn't as it exceeded the continuous rating of the genny. Somewhere I had the formula from Xantrex but it escapes me now.

    Tony
  • westcoastsliderwestcoastslider Registered Users Posts: 20
    Re: newbie with lots of questions

    Well, the charger is already ordered so I guess we'll see how it does.
  • dagr51dagr51 Solar Expert Posts: 72 ✭✭✭✭
    Re: newbie with lots of questions

    Sorry. My 660 ah bank is 12v.
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