Solar Power Pack Proj.

I'm new to all this and I'm trying to build a small solar battery pack, in theory all sounds good but in an attempt not to fry myself or my equipment I figured it would be a good idea to get advise from the experts.

I am in the market for some stuff but let me start by saying I am trying to maintain portability so that I can watch movies, use laptop or allow kids to play ps3 while camping. On top of a few other misc. power uses.

I'm considering buying an amstron 12v 80ah or 100ah sla agm battery and dropping it into a pre-made wooden box, I have a Duracell Powerpack 600 now and this has been a source of inspiration for me, apparently it has a small 12v 28ah sla battery and also has the ability to be connected via included battery/jumper cable to an external battery to increase capacity. This being said, what I would like to do is to mount two battery terminal/posts to one side of my wooden box connected to the battery that are externally accessible, enabling me to do 3 things, (a) connect to duracell pack with jumper cable (b) connect to Sunforce 11240 1000-Watt Pure Sine Wave Inverter via ring connectors and (c) charge battery externally using an electrical outlet and jumper cable style connectors on a/c charger.

I would also like to use the Brunton 26w foldable solar array with the Brunton 12v solar charge controller/monitor and to connect them via power pole connectors which I intend to mount 2 pairs of on the opposite side of my box also externally accessible allowing me to connect charge controller to battery and I would use the 2nd power pole connector on the box for 12v dc out although both pp connectors can be used for either/or.

My question(s) are as follows....

Does this sound do-able? and what size cable(s) should I use for (a) battery to posts (b) posts to inverter? also viewing the inverter online, I see what appears to be a ground connection on the back, do I need to ground this unit to use it? and assuming I have all the connections right, would it be possible to charge this battery from vehicle via cigarette lighter connected to power pole? if so would I need some kind of charge controller for that as well or is it regulated by vehicle charging system?

One more thing, I assume it would be a good idea to use a fuse or fuses in this setup, what size should I use and where should I use?

If anyone can give advise, would be greatly appreciated.

Thanks in advance
Smoove

Comments

  • BB.BB. Just some guy Posts: 24,209Super Moderators admin
    Re: Solar Power Pack Proj.

    I am sorry, I thought I had already replied to your post... But I guess I did not.
    Smoove69 wrote: »
    I'm new to all this and I'm trying to build a small solar battery pack, in theory all sounds good but in an attempt not to fry myself or my equipment I figured it would be a good idea to get advise from the experts.

    I am in the market for some stuff but let me start by saying I am trying to maintain portability so that I can watch movies, use laptop or allow kids to play ps3 while camping. On top of a few other misc. power uses.

    It is really helpful if you have a good measurement of peak power (Watts) and the total power (Watt*Hours) you plan on using. For AC power, a Kill-a-Watt meter is a great too. Also very handy for conservation projects around the home. If you are going to work a lot with DC, a DC Watt*Hour/Amp*Hour meter like one of these is real useful too.

    Once you know how much power you will need, then you can plan out the major component requirements (size of solar panel, battery bank, and inverter).

    Solar PV power is not cheap, and the equipment is relatively large and heavy. So, you need accurate information to design the right size system for your needs.
    I'm considering buying an amstron 12v 80ah sla agm battery and dropping it into a pre-made wooden box, I have a Duracell Powerpack 600 now and this has been a source of inspiration for me, apparently it has a small 12v 28ah sla battery and also has the ability to be connected via included battery/jumper cable to an external battery to increase capacity. This being said, what I would like to do is to mount two battery terminal/posts to one side of my wooden box connected to battery that are externally accessible, enabling me to do 3 things, (a) connect to duracell pack with jumper cable (b) connect to Sunforce 11240 1000-Watt Pure Sine Wave Inverter via ring connectors and (c) charge battery externally using an electrical outlet and jumper cable style connectors on a/c charger.
    In general, people over estimate how much power a solar panel can supply and a under estimate their loads.

    Typically, that means that they have way too little solar power (and usually too small of battery) and way to large of inverter for their needs (large inverters tend to have more losses when running small loads).

    Also, starting out with a large and inexpensive MSW (Modified Square Wave) inverter to run small electronic loads can be a problem too. Small wall mount transformers and many small AC to DC power supplies for computers/DVD players, etc. tend to run hot on MSW inverters and will have a short live (sometimes they will "wear out" in in months/year or so, sometimes in minutes--It is really hard to guess--some will run just fine).
    I would also like to use the Brunton 26w foldable solar array with the Brunton 12v solar charge controller/monitor and to connect them via power pole connectors which I intend to mount 2 pairs of on the opposite side of my box also externally accessible allowing me to connect charge controller to battery and I would use the 2nd power pole connector on the box for 12v dc out.
    People really do like these solar panels--A neat idea... But you have to decide if they will work well for you. Using generic summer weather, most people will get a least 4 hours of "noontime sun" per day. And the system will be around 50% efficient (from solar panel power rating to 120 VAC power available for running your devices). For example:
    • 52 watts * 4 hours of sun per day * 0.50 eff/derating = 104 Watt*Hours per day...
    That will run a 30 watt laptop computer:
    • 104 WH / 30 Watt = 3.5 hours per day
    A 600 Watt inverter running at full power:
    • 104 WH per day * 1/600 watts * 60 minutes/hour = 10 minutes per day
    A smaller, true or pure sine wave (TSW/PSW) type inverter would be a better solution.

    To do that, you will have to leave the panels laid out on a slop facing the sun for at least 6-8 hours per day... That means somebody needs to watch the panels/charger/battery to make sure that the system does not "walk away". And you cannot hike travel from point to point while charging.

    If you have an RV or even a vehicle--it might be better (and less expensive) to bolt a fixed panel to the roof and keep the rest of the hardware locked inside during the day.

    Then you need to look at the size of the battery bank... At the very least, the battery should be 2x your daily load. Lead Acid is used for solar--but they are very heavy. Perhaps, the new Lithium Iron Phosphate batteries would be of interest:

    Lithium Iron Phosphate Batteries; LFP; LiFePO4
    Portable Solar Power
    My question(s) are as follows....

    Does this sound do-able? and what size cable(s) should I use for (a) battery to posts (b) posts to inverter? also viewing the inverter online, I see what appears to be a ground connection on the back, do I need to ground this unit to use it? and assuming I have all the connections right, would it be possible to charge this battery from vehicle via cigarette lighter connected to power pole? if so would I need some kind of charge controller for that as well or is it regulated by vehicle charging system?
    For a small battery bank, yes, you probably could charge it OK from the vehicle 12 volt outlet... It would be limited to ~10 amps (will blow the lighter fuse). And will only charge when the engine is running. Fine for driving portion of trips--but tends to be very wasteful of fuel if you idle the vehicle engine to charge the battery bank. Would be much better to use a small Honda eu1000i genset instead (things are getting more complicated and expensive).
    One more thing, I assume it would be a good idea to use a fuse or fuses in this setup, what size should I use and where should I use?
    Fusing protects the wiring... So, generally, you place the fuse(s) next to the main source of large amounts of current (battery bank in this case). So if you use 12 awg wire, then you need a ~20 amp fuse to protect that length of wiring.

    One thing that people don't realize is that 12 volt appliances use a lot of current. At least 10x that of the equivalent in 120 VAC circuits. For example, using your 600 watt inverter as an example:
    • 600 watts * 1/10.5 volt cutoff * 1/0.80 inverter eff * 1.25 fuse-wiring derating = 89 Amp Circuit/Fuse/Breaker minimum
    So, you would need somewhere around 6 to 2 awg gauge cable to run this inverter from 12 volts (depending on length of wire) and roughly a 175 AH 12 volt battery to run the inverter at full power for any length of time (about 2x the size of a standard car battery).

    There is a nice thread here that goes through the entire project from start to finish for another poster that wanted to build a portable emergency power supply. Pretty similar to what you asked about here:

    Emergency Power

    -Bill

    PS: I deleted the duplicate thread--Keep all the replies in one location.

    PPS: I see you beat me to it. :D
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • SystemSystem Posts: 6,290 admin
    Re: Solar Power Pack Proj.

    BB

    Thanks for the reply, I do understand the importance of calculating the amount of watts I intend to use per hour/day, and I will take your advice with the "Kill-A-Watt Meter" to do so, as I have seen this referenced here and there during my research.

    In regards to the solar array (Brunton 26w foldable) my intention for this panel is not to use it to power any of my large devices, but just to provide (trickle) charge to them as well as the 12v battery pak, I also have a Tekkeon MP3450 rechargeable battery and the MP3450-10 add-on extended pak which are also solar chargeable through an add-on adapter, so again, the solar array will be just to add a little boost to the Druacell Pak, my new 12v batt-pak and my Tekkeon as well as my Nokia netbook. This is why I went with the foldable, because it would come in very handy with my smaller batteries, I also have an amstron 12v 12ah that I carry in a camera bag for 12v purposes (i.e cell phones, mp3 players, air mattress pumps etc.)

    I only intend to use this 80ah or 100ah 12v battery pack with the inverter connected to power my other (larger) devices (i.e TV, PS3 etc.) for short periods of time here and there while out and about, similar to the way that I currently use the Duracell PP, this is why I figured if I build this new batt-pak, increasing the battery size from 28ah to 80ah or 100ah and go with a PSW inverter of a larger load capacity vs the 600 MSW in the Duracell, I should be able to do much more than I can now.

    I have used the Duracell on several occasions but have noticed the effect of modified sine vs pure/true sine that's why I figured I would take the Duracell PP and go a step or two further with it.

    In my research it seems to me that a 2/0 awg wire would be good as an interconnect cable to go from the battery to the posts and perhaps even from the posts to the inverter, I did however find an inverter cable at amazon.com that is 6' long 0 AWG and was wondering if this would suffice from posts to inverter? There is also the same in a 3' version that may work as well, but to use the latter, I would have to place the inverter in close proximity to the Batt/Box or on top of it, would this be a problem with an SLA battery? or is it better to keep at a distance?

    Again thank you for your response, looking forward to hearing from you again.
    ~Smoove
  • BB.BB. Just some guy Posts: 24,209Super Moderators admin
    Re: Solar Power Pack Proj.

    I can't type a long reply right now (playing on my new android phone)... It sounds like you are looking at two different systems (larger vs smaller).

    In general you need to conserve power when running from solar and batteries. I would use as small as possible TSW inverter based on your loads. I don't think the 600 watt inverter will work well for what you are asking for--it seems way to large.

    Take a look at the morning star sure sine 300 watt TSW inverter for your larger system. It is a very nice 12 volt unit (low power search mode and 12 volt DC inhibit).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • SystemSystem Posts: 6,290 admin
    Re: Solar Power Pack Proj.

    Aaahhh, nice, I know you will enjoy your new phone, we guys love our toys....

    Once again, thank you for you time.

    I did look into the "Morningstar SI-300-115V-UL SureSine 300W Inverter" and I like what I saw, I thought since my Duracell Pak had a 600w inverter bigger would be better, in this case bigger would be wasteful, and now I realize that.

    I did happen to check on the wattage on the tv it reads 29w and from what I can tell the ps3 uses less than 120w, that would make this inverter ideal.

    I'm still curious about grounding the inverter, if I'm camping or what not, how am I supposed to ground this thing?

    In your opinion would you say that this inverter is a good one? there were no reviews to read....

    Also from what I could find in the specifications section it seems that any wire from 14 - 2 AWG would be satisfactory, which would you recommend?
  • BB.BB. Just some guy Posts: 24,209Super Moderators admin
    Re: Solar Power Pack Proj.

    If I recall from the Manual--6 awg is what MorningStar recommends for the inverter...

    A big issue is how long the cables will be--You have only about 1 volt of drop allowed (~11.5 volt loaded battery to 10.5 inverter cutoff). Keeping the inverter close to the battery bank will be a big help (it also will run ~600 watts for 10 minutes--so if you plan on running heavier loads, you will have to do the voltage drop calculations for those "surges").

    The Sure Sine 300 watt inverter has had lots of "love" here from posters (I don't have one--so it is just specifications and other posters' experiences here). One warning--the Sure Sine does not come with any cables or AC receptacles. You have to know enough, or have a friend, to hardware the inverter to your system. Also, note that the inverter is larger/heavier than it appears in the photographs--Check the size/weight if that will be an issue for you.

    The Sure Sine has a floating/isolated 120 VAC output (think transformer). There is no neutral / hot orientation.

    Generally, floating output is very safe--you can touch one or the other AC output wires and not get a shock (obviously, touching both will give you a surprise).

    There are a few appliances that may run better if you ground the neutral to an RV's frame (some tube type florescent lamps, some spark ignitors in stoves/heaters, and possibly some radio/audio gear). I would not ground the AC output unless you are having "issues" with an AC appliance.

    Note, many TSW inverters can have a grounded neutral (along with a grounded battery bank). Many MSW inverters will smoke if the battery bank and one leg of the AC line is grounded (aka grounded neutral). Always read the instruction manual for your model of inverter before installing and grounding any inverter.

    As for wiring... Use the formula I posted earlier (and recommendations from the manual). For a 600 watt rating:
    • 600 watts * 1/10.5 volt cutoff * 1/0.80 inverter eff * 1.25 fuse-wiring derating = 89 Amp Circuit/Fuse/Breaker minimum
    That would be 100 amp fuse/breaker/wiring circuit.

    Using any old Voltage Drop calculator (this one uses "one way" wire run--AKA 10' run is 20' of round trip wiring). 71 amps peak worst case current and 6 awg wire would give ~1 volt drop:
    • 15' of 6 awg wire is ~1 volt drop...
    That would be the absolute maximum wire run... Add a fuse or breaker, I would probably keep the wire run to less than 7.5 feet--And only a couple feet if you can swing it. The less wire run / voltage drop, the better your inverter will run (and less power loss due to wire heating):
    • 71 amps * 1 volt drop = 71 watts wasted as heat in wire run (for 600 watt load).
    So, you can see why everyone uses large gauge, short cables when ever practicable. That run of wire would cost you about 10% extra losses (the inverter is around 80-85% efficient--over all efficiency of 70-75% with long wire run). These losses add up quickly.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • bmetbmet Solar Newbie Posts: 630Solar Expert
    Re: Solar Power Pack Proj.

    WWhere does a person buy these short, thick cables which have the properly-attached connections at both ends? For example, I read about a true sine-wave inverter which doesn't come with cablesd. It's like purchasing a home appliance that you can't immediately use. Has the solar industry expanded to have standardized interconnects, or does each manufacturer build custom cables, sold separately, of couse?
  • BB.BB. Just some guy Posts: 24,209Super Moderators admin
    Re: Solar Power Pack Proj.

    The SureSine 300 watt inverter has binding screws (simply strip the 6 awg / 14 awg wires and use a straight slot screw driver to tighten them down).

    For larger cables, you can purchase pre-made from our host (NAWS):

    Battery Interconnect & Inverter Cables

    Or from probably from a local battery distributor.

    You can purchase manual crimping tools:

    Hammer Crimp Tool for Large Terminal Lugs
    wind-sun_2125_32012383

    The middle of this thread has some links/information about crimping:

    Battery Cables

    You can search for more information on Crimping by using Google and adding "site:wind-sun.com" for easier searching:
    • hydraulic crimp tool site:wind-sun.com
    The problem is that many of the inexpensive inverters (typically kWatt rated 12 volt inverters) do come with their own cables... But the cables are way to light weight and frequently use two cables in parallel to carry the current--That is usually a no-no in electrical wiring (one cable fails then the other overheats).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
Sign In or Register to comment.