HELP: Inverter is draining battery almost instantly! Why?

[inetdog]

Some charge controllers can communicate with each other. I don't see this discussed in the specs for the lower cost ones you are using, but I also don't think it is necessary. Best to call tech support. But if it works like I think it will, each charge controller will be monitoring the status of the battery and changing amps and voltage base on battery charge.

Should not matter if make and model are different.

Stacking compatibility is much more of an issue for off grid inverters than for chargers, since they have to synchronize their output voltage and frequency.
But there is one issue where coordination might be an issue for CCs:

Since, even with coordination, the two CCs will have to be connected to different panel arrays there can be both an offset and an overlap between the peak production periods of the two smaller arrays.
If you size the CCs so that one CC can deliver more than 1/2 the upper limit charging current for Bulk, to make best use of its array when it is producing and the other array is not, then when both are producing you might get more than the upper limit charging current total going into the batteries.
When two CCs coordinate they can limit the total current between the two CCs rather than just independently limit their own charging current.

Coordination is normally not an issue for Absorb or Float stages, as long as the two CCs can be set to roughly the same stage voltages.

[Raul]

I think your estimations are pretty close to be honest. Lets say the higher end to be safe at 300wh. My Isolation values are 4.68 in July and 1.13 in Dec. Now, those figues are for SW England and I am as far South West as you can get. So mine will actually be slightly higher than that but lets go with those. By your calculations then I should be looking to get 565wh (500w x 1.13) even in winter... Accounting for losses, I should still be getting my 300wh needs, yeh?

This is provided I change to the better CC, 2 panels and my batterys are good.

I think i'm going to go with the victron bluesolar 100/30 http://store.meadotech.com/#!/BlueSo...egory=13042968 So that I'm definately covered for 2x 250w panels.

Good choice, that CC can do both 12-24v . For any reason should you change to 24v this CC will do it . In Cornwall you get max 1.6 sun hrs , Dorset and summerset actually 2.5-2.6, ; when you get your charge Controler it will come pre set on no2 . Leave it like that don't change it . It has 5 presets. The 2 is spot on for sealed pb .

[lkruper]

Interesting, do the CC's ideally need to be the same model & spec?

Some charge controllers can communicate with each other. I don't see this discussed in the specs for the lower cost ones you are using, but I also don't think it is necessary. Best to call tech support. But if it works like I think it will, each charge controller will be monitoring the status of the battery and changing amps and voltage base on battery charge.

Should not matter if make and model are different.

[spoon]

The next least expensive path (I think. so run the numbers) would be to add another panel and another charge controller and run the outputs of those two charge controllers to the 12v battery at the same time. That is called stacking the controllers. Call the vendor and make sure that is ok, but many times it is fine to hook two up to a single battery. That would double your charging capability and you would not need to purchase a mains power charger or change out your inverter right away as your are still at 12v. It also gives your some redundancy if one CC dies, you still have one that works.

Interesting, do the CC's ideally need to be the same model & spec?

[spoon]

There are maps that give you solar isolation numbers for anywhere on earth (google search), that is a number you can multiply by your panel(s) watt rating to get the actual amount of wattage per day you can expect to produce, it will vary by time of year also, so you can check certain months if you only use solar seasonally.
In rough numbers if you will run (3) 5w led lights for 3 hours per day that = 3x5x3=45wh (watt hours), to charge a laptop once a day might be est. 70wh, car stereo for 2 hours = est. 30wh, plus charging phones apears to put you in the 200wh to 300wh range per day (if my numbers are close and laptop use is light), if you use 2 laptops every day for 4 hours each you could be as high as 500wh just on those (big difference), anyway once you calculate your loads as close as you can, then you find your solar isolation and multiply your panels total capability by that number, example phoenix in summer is around 6.0, and where I am at (pacific northwest) in winter is only 1.7 (once again, big difference) 500Wx1.7 =850wh, that is gross total and will still be losses to subtract from that, you may be fine starting with one panel and 12v system, just hard to tell until you figure your exact hours of usage of the various devices and what the solar isolation will be for your area at that time. Basically just calculating the amount of production you can expect to produce from a given panel(s) and making sure you do not need more power than they can produce. Hope that helps.

I think your estimations are pretty close to be honest. Lets say the higher end to be safe at 300wh. My Isolation values are 4.68 in July and 1.13 in Dec. Now, those figues are for SW England and I am as far South West as you can get. So mine will actually be slightly higher than that but lets go with those. By your calculations then I should be looking to get 565wh (500w x 1.13) even in winter... Accounting for losses, I should still be getting my 300wh needs, yeh?

This is provided I change to the better CC, 2 panels and my batterys are good.

I think i'm going to go with the victron bluesolar 100/30 http://store.meadotech.com/#!/BlueSo...egory=13042968 So that I'm definately covered for 2x 250w panels.

[lkruper]

So I think 2x 250w panels will be more than sufficient. What you all seem to be saying is that they will be much more efficient going into a 24v battery bank though... To maximise solar input.

Don't forget that your current charge controller cannot access the power from 2 X 250 panels unless you go to 24v. Your current charge controller cannot even handle all the power from your one existing panel. 250w / 12v = 20.8 amps. If you get 80% of that from the panel, that is 17 amps. Your controller can only handle 15 amps, so you are throwing some away even with your one panel. If you add one more panel you will need to move to 24v to access it, and even then it would be about 17 amps at 24 volts. You are still not using all the power from your panel, BUT it might be enough for two 100AH 12v batteries in a 24v bank. I say "might" because it really depends on your insolation values, or how much quality sun you consistently get, even in the wintertime.

If I remember correctly, your battery would have sufficient capacity if it were healthy. The least expensive path for you to fix this would be to upgrade your charge controller, so long as you have sufficient sun to charge your battery in one day. That is because you would not need to change all your electronics to 24v.

The next least expensive path (I think. so run the numbers) would be to add another panel and another charge controller and run the outputs of those two charge controllers to the 12v battery at the same time. That is called stacking the controllers. Call the vendor and make sure that is ok, but many times it is fine to hook two up to a single battery. That would double your charging capability and you would not need to purchase a mains power charger or change out your inverter right away as your are still at 12v. It also gives your some redundancy if one CC dies, you still have one that works.

If you go the 24v route, you will need two batteries in series and perhaps you can get by with your existing controller depending on how much sun you have because 250w / 24v = 10 amps. However you would probably get 8 amps or less @24v which is at the low side of sufficient charging for 100AH battery bank @ 24v. You would still need to purchase a 24v inverter and also find a way to charge a 24v bank with mains power.

In any event, I would plan on routinely taking your batteries to 100% with shore power as it is very difficult to do this day in and day out with solar and if you don't get your batteries to 100% they will sulfate and you will lose capacity permanently.

[LETitROLL]

P.s. What does that bit mean ^^?

There are maps that give you solar isolation numbers for anywhere on earth (google search), that is a number you can multiply by your panel(s) watt rating to get the actual amount of wattage per day you can expect to produce, it will vary by time of year also, so you can check certain months if you only use solar seasonally.
In rough numbers if you will run (3) 5w led lights for 3 hours per day that = 3x5x3=45wh (watt hours), to charge a laptop once a day might be est. 70wh, car stereo for 2 hours = est. 30wh, plus charging phones apears to put you in the 200wh to 300wh range per day (if my numbers are close and laptop use is light), if you use 2 laptops every day for 4 hours each you could be as high as 500wh just on those (big difference), anyway once you calculate your loads as close as you can, then you find your solar isolation and multiply your panels total capability by that number, example phoenix in summer is around 6.0, and where I am at (pacific northwest) in winter is only 1.7 (once again, big difference) 500Wx1.7 =850wh, that is gross total and will still be losses to subtract from that, you may be fine starting with one panel and 12v system, just hard to tell until you figure your exact hours of usage of the various devices and what the solar isolation will be for your area at that time. Basically just calculating the amount of production you can expect to produce from a given panel(s) and making sure you do not need more power than they can produce. Hope that helps.

[spoon]

+1, That is why it is so important to really come up with precise concrete numbers on expected loads, if you have that and your solar isolation for the area of use, it takes most of the guess work out and allows you to buy the correct stuff the first time.

Take on board what all are saying. I will definitely not be expanding beyond 2 panels, certainly for a few years. Mainly because my needs will not increase, I have access to mains power & work for charging or running larger items. This is not at the caravan though.. All we will ever need to run at the van is laptops, phones, car stereo+speakers and LED lighting.

The only high consumption item that would be nice to run at home is a hand blender, which would simply need a larger inverter, no? This we can do without anyway so not a problem.

So I think 2x 250w panels will be more than sufficient. What you all seem to be saying is that they will be much more efficient going into a 24v battery bank though... To maximise solar input.

your solar isolation for the area of use

P.s. What does that bit mean ^^?

[LETitROLL]

Solar/Battery systems are difficult to expand unless planned carefully, and even then there are limitations. If you think you will eventually add more items to be powered and/or want much longer run times for your devices then biting the bullet now and moving to 24v can save you money in the long run.

+1, That is why it is so important to really come up with precise concrete numbers on expected loads, if you have that and your solar isolation for the area of use, it takes most of the guess work out and allows you to buy the correct stuff the first time.

[lkruper]

Oh. That sounds alot more expensive...

Solar/Battery systems are difficult to expand unless planned carefully, and even then there are limitations. If you think you will eventually add more items to be powered and/or want much longer run times for your devices then biting the bullet now and moving to 24v can save you money in the long run.

[LETitROLL]

It wouldnt hurt to check the Voc of your panel (not sure if that has been posted here yet), as long as it is less than 37V you would have the option of hooking up 2 panels in series, or parallel, if Voc is over 37V parallel only. Your selected battery bank voltage (12 or 24) is independent from the Panel voltage or wiring method (series/parallel), the CC will work fine either way, however in most cases it would not make good sense to hook up 2 panels of that size to a 12v battery bank, the CC will limit the input to 200W, in times of poor solar conditions (cloudy, sun low, etc.) it would make use of the extra panel, but during most of normal sunny days it would be a waste. Only with a 24V battery system can that CC Make use of 400W solar input.

[spoon]

Your cc cannot use the power from 2 panels unless you have a 24v battery bank. That also means a new 24v inverter and also prob a charger for mains power.

Oh. That sounds alot more expensive...

[lkruper]

Your cc cannot use the power from 2 panels unless you have a 24v battery bank. That also means a new 24v inverter and also prob a charger for mains power.

[spoon]

Ok, lots to take in. I'm going to try and simplify what people are saying just so I make sure I get this right, as someone mentioned I don't want to rush into anything.

The linked CC will be fine with 1 more panel, same as I have now... But no more. I don't plan to go any higher than this anyway. That would need the panels to be linked in parallel though, so as to maintain 12v.

If I link 2 panels in series, I will need 24v worth of battery, yes? So the 2 numax's I have (provided they are fine). Giving a total of 220ah, 24v. Aaaand, the next step up in CC to cope with that. (30a).

I probably have a budget of around £250-£300 ($350 - $450)

[LETitROLL]

One more question, will this CC still be fine if I add another 250w panel of the same type to the system?

The thing you want to make 100% sure of with that CC (I have one and love it) is that your solar input does not exceed 75V, it will use 200W @ 12v and 400W of input @ 24v (dictated by the battery), but you can hook up more with no problem, and actually some advantages in certain situations. If you are going to expand greatly I think you would want to look at other controllers, but at around the 400-500 watt gross panel total that CC is fine, considering you would probably be at 24v battery bank at that time anyway since 12v is kind of limited, and the nice thing about being overpaneled a little bit is more stable production throughout the day, you only get max production from solar for an hour or 2 per day around solar noon, the rest of the time it can be much lower, not to mention clouds, this way you can stay near max charging to battery bank (15A) for a large portion of the day. You can also buy a 2nd CC later and use 2 of these (30A total) if it ends up being cheaper than 1 large CC, and not have all your eggs in one basket (in case a failure, only half system down vs all with single CC), it mostly comes down to budget, there are many fine CC on the market in the $300+ price range, but this is the only one I have found for much, much less that has a pretty great reputation and performance Outback also has 2 new small ones, the 10A is slightly more $ than the Victron, and a 20A for quite a bit more, and I don't think they are customizable/adjustable? (the Victron is with optional usb cable).