Battery keeps going flat

[HMC]

Hi my names Dave, im from the U.K and im only running a very simple system, well to you guys anyway

I tried to read on here as much as possible before posting but my heads going around in circles




ok the basics


2 x 12v dc 1050 ma (hopefully im correct with my electronics conversions 1050 ma = 1.05 amps ?)

100 watt 5.7amp soloar panel plus 2 x 20 watt 2 amp solar panels plus 1 x 15 watt 1 amp panel ( reason why different sizes, i expanded the system once i started having issues with charge of battery

giving me = 8.7 amps ( i halfed this to give me a good charge rate, or so i thought)

30a charge controller

450ah lead acid battery

everything apart from the 100 watt panel is wired using 12v 11amp twin cable


sun for approx 12 hours a day on full sun min, i live on one side of the chilterns which is in the middle of the uk, the sun rises at 5am at the latest in spring and sets around 9 pm up untill autumn

the panels are actually mounted to catch the sun horizontally for mid day sun, i tried facing south but then the panels dont get sun after 3pm i even tried facing west for 3 pm till 8pm


ok heres the system and an explanation


in full sun i get around 17 volts but around 19 amps ( checked with a multi meter, i did have a 10 amp cc untill i saw the amps being produced)

checked the draw @ 2 amps



the pumps run 24/7 but after 36 hours running the battery drops down to 7 volts


so my question is, what am i doing wrong ? yes weve had a few cloudy days


i will take new running readings as i havent rechecked them using a multi meter but my 30 cc now says no volts and no amps going into it from the panels and yet if i run the pumps direct from the panels they run fine


is is a case my CC is stealing all the power ?

do i need more panels ?

is it the cabling im using ?

what am i missing ?

sorry to ask silly questions, i havent done electonics since i left school some 30 years ago


Thank you in advance for you time in answering,
Kind regards

Dave from the UK

[Sunking]

2 x 12v dc 1050 ma (hopefully im correct with my electronics conversions 1050 ma = 1.05 amps ?)

Well yes that is correct, but what does that have to do with anything?

100 watt 5.7amp soloar panel plus 2 x 20 watt 2 amp solar panels plus 1 x 15 watt 1 amp panel ( reason why different sizes, i expanded the system once i started having issues with charge of battery

giving me = 8.7 amps ( i halfed this to give me a good charge rate, or so i thought)

30a charge controller

450ah lead acid battery

everything apart from the 100 watt panel is wired using 12v 11amp twin cable

Well no wonder you are having problems silly. It is never going to work. you pump runs 24 hours per day using 25 to 30 watts. That means you use 30 watts x 24 hours = 720 watt hours per day. OK to start with if using 12 volt battery means the battery needs to be a minimum size of 300 AH. Yours was 405 AH which was fine, but since dragging it will below 100% DOD you have likely destroyed it in the process.

But the core of your problem is your panels and charge controller with your location. You do not get up teen hours of sun like you think. If you are in the UK during winter at best you only get 2 Sun Hours, and summer no more than 4 Sun Hours. Based on worse case 2 Sun Hours in winter would require you to use 500 watts solar panels with 40 amp MPPT controller, or 750 watts using a 40 amp PWM controller. You are not even remotely close to that, nor can you use anything you have to get there.

So throw everything away you have except the pump and start over. Get yourself:

2-250 watt Grid Tied Panels
40 amp MPPT charge Controller
2-6 volt 300 AH AGM batteries wired in series for 12 volts.
All new properly sized cable

Do that and your system will work. Otherwise give up.

[jimindenver]

What is your controller? Recently I have seen cheaper PWM controllers that have a temperature probe and if it isn't plugged in, the controller will not function.

Are you saying you run two pumps at 1 amp/12v each for roughly 50 ah a day? Those are some tiny pumps considering the pump in our trailer pulls 8 amps.

Now 50 ah a day isn't much with a 450 ah battery and you should be good to go for four days before the bank hits 50% unless the battery isn't fully charged when you start.

155w should support 50 ah a day in good weather. Mounted flat means you will only see peak production mid day but it and the shoulder hours should be enough. 155w on a 450 ah battery is fine if you never need to bring it up from 50% or more discharge. It is way to small however to try to recharge the bank down a few hundred ah's down. It will take days without load to bring it back up.

There are batteries that can take being heavily discharged but you can damage them taking them down too far. You may need to have yours charged and tested.

[SunEagle]

Your 450Ah battery is certainly large enough to run those two pumps. My guess is that somehow your panels didn't fully charge the battery (not enough sun or wiring issues) and now you have drawn it down to 7 volts which means it is not going to work well for you and probably needs to be replaced

What I am curious is that you measured 19 amps. Was that from your panels or the output of the charge controller to your battery? I am not sure how your 155 watts of panels even using a MPPT type charger would generate that many amps.

While you listed some of you equipment you did not state how you built a 12volt 450Ah battery system or what type 30amp CC you are using. I presume your panels have been wired paralleled to the CC but again that is a presumption and I could be wrong.

Maybe start from the beginning and provide manufacturer and model numbers of your equipment and how it is wired.

[HMC]

Hi, again,

Thankyou for the replys,

sorry you are correct i didnt write a full explaination


ok all the solar panels are joined positive / negative into the contoller via 11 amp cables on the 20w panels and on the the 100w has a 5mm thick cable which it came with

so yes in parrallel

i measrured the postive and Minus going in to the controller from the solar panels side, it was at mid day in the 80's so the hottest and highest i would ever see, which is why i changed the 10 amp contoller as i had only calculated for 8amps and bought a 10 amp controller, i cant see the controller back feeding from the battery but possibly so i thought it best to cover myself, with a 30 amp controller

it was only after the hot days when i saw the 19amps ( within 5 days) i started having issues

becasue i started with only a 10 amp controller i thought maybe the high amps had damaged the 10 amp controller

so i replaced both the controller and the battery - thinking the same as you that i had damaged the battery


the pumps are very small as i was trying to keep the load to a min as i wanted at least 5 days running for winter as i really didnt know if i would get much light,

the only way i can explain my garden it a little bit like a desert, im one of 4 houses in 8 miles of corn fields so i seem to have a lot of sun light


this is the controller

http://www.ebay.co.uk/itm/400721718208?_trksid=p2059210.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

this is the cable

http://www.ebay.co.uk/itm/350745487260?_trksid=p2059210.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

theses are the pumps

http://www.ebay.co.uk/itm/350966930817?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

my plan is to recharge the battery, i now have 3 and eventually run them in parrallel to give me more days running

ive also now put one of the pumps running from the solar panel side of the controller so it will only run when the sun creates enough power and run just one pump for the time being untill i make sure the system is balanced again,


i just cant make my mind up to buy another 100w panel to boost the charge rate of the battery

im also going to upgrade the cabling to the battery from the controller to 30 amp cable incase the cable is slowing down charge rate,

i may if this doesnt work run 2 or 3 systems, with individual controllers as i just cant work out what ive done wrong


and yes you are correct i didnt put the temp sensor in, i have now !


please advise

if you think its better to run the system with 1 pump and battery to a 10 amp with the 100 watt panel and the smaller panels seperate i will

the system basically runs all panels in to the controller the battery out the controller and the 2 pumps running out the controller i just dont understand what ive done wrong


Dave

[SunEagle]

Dave

Ok. We now know more about your 30 amp PWM charge controller, wire and pumps. You did not mention what type of battery you have but they do make 12volt 450Ah ones that are very expensive and heavy.

You also have stated your panels (100w, 20w, 20w and 15w) are all wired in parallel. Although I still don't know how you got 19 amps from those 4 panels.

I can tell you that you will need 400 to 500watts of panels to properly charge a 450Ah battery. So with only 155 watts you have definately not charged the battery and it has now been drained.

Also you should not use different wattage panels in the same paralleled wired system unless they have very similar Voltage output rating.

Replacing the battery is probably the right thing to do but you should not wire multiple batteries in parallel. If you do then you will probably hurt your batteries again.

Connecting both pumps to the battery is fine. Your problem has been too little panel wattage to properly charge that 450Ah battery.

[Sunking]

Simple answer all your panels and charge controller need replaced with 2-250 Grid Tied solar panels and a 40 amp MPPT charge controller.