Welcome to the Solar Collector
Brainstorming and Development Page!



Hot Air Collector

Hot Water Project 1

Hot Water & Space Heating

Solar Electric

Solar Construction 101


Best Collectors

Simply Solar
Register Calendar Latest Topics

  Author   Comment  

Posts: 3
Reply with quote  #1 

14 years ago I installed an off grid solar system that has worked well for me , I had 600amp/hrs of Trojan batteries and my consumption has always been between 2000 and 2500 watt/hours every 24 hours split fairly evenly between the day time charging and night with no charge coming in . My batteries are fully charged by midday when the suns out and both my Solener ( good quality Spanish make ) and Morning Star controllers ( both good quality and lasted 14 years so far without issue as I double check everything regularly with a multi meter ) float at 28.8 volts , I am assuming I am only taking about 25% at most from my battery bank ( 2500watts / 25v = 100amp/hrs , 600 / 100 = 15% + a generous allowance for anything not accounted for , equipment self use etc ) ( please correct me if I have that wrong as 2000-02500 watts is the cumulative total shown each day on my Solener 1.5kw watt inverter ) . The batteries have lasted 8 years showing no sign of failing however now winters here they are dropping to low late at night if they haven't had a full charge in the daytime so I have replaced them with 600 amp/hr Rolls 4 x 6v ( S605 ) I raised the SG to 1.280 after standing 24 hours as required when I first received and replaced my Trojans batteries with them but now after 10 days that has dropped to 1.21 , have not been able to get the SG of these batteries back up to the required figure , they remain around 1.20 -1.21 ( 10c ) Rolls have told me I need a Bulk/Absorption charge of 29.8 and a float volt of 27.6 which is greater than my present charge controllers can supply so I have looked to replace the 2 x 30amp ones with a single 65amp one and have found two reasonably priced ones that allow adjustment only of the Float voltage up to 26-30 volts , neither give the Bulk/Absorption figures which don't have any adjustment and the sellers have no idea either and the manufacturers can only supply the manuals which don't give it either which to me seems silly as I would have expected them to be an important factor , they have adjustable load parameters but are of no interest to me as I never take anything direct of them . I wish now I had looked an the charging voltages required for the Rolls batteries as seeing they are higher than I would have expected I would not have bought them , I expected considering they are not cheap to be compatible with other deep cycle batteries .My panel array is 1020 watts at 24 volts and when the sun is out which here in Spain is a good deal of the time the charge controllers show an input between them of 30 – 50 amps . Any advice which doesn't involve a large outlay for expensive controllers would be very much appreciated .


Avatar / Picture

Posts: 2,545
Reply with quote  #2 
Before I spent any money I'd find out if your existing controllers are adjustable, and if so adjust them to the required voltages.

Also disconnect say, half of your batteries, let them sit for a day and then check them individually. Then do the other half. A bad cell or two can pull the whole bank down, but can be hard to isolate when they're connected.

Willie, Tampa Bay

Posts: 3
Reply with quote  #3 
Thank you but the controllers have no adjustments at all so thats not an option however your suggestion to remove half the batteries would be useful were it not for the fact that i have 4 x 6 volts on a 24 volt system so all of them have to be in use all the time , The batteries are 2 weeks old . I did charge them fully when they arrived and allowed them to stand for 2 days to check everything and every cell was the same to .001v so its not that either , the SG of each was also as near as makes no difference 1.280 at that time . The problem i have is that my controllers are strangling the system as the set points on them are as most controllers which is to low for Rolls Batteries .

Posts: 3
Reply with quote  #4 
Decided to bite the bullet and buy one of two 60amp charge controllers that have user set points , either the Morningstar TS-60 or the Xantrex C60A , was leaning towards the Xantrex because of costs and sturdy metal construction however it lacks the option to monitor the parameters and cumulative historical data on a PC which would be invaluable as well as extremely interesting to know so looks like the Morningstar will the the one i end up with . 

Posts: 6
Reply with quote  #5 
The Midnight Classic is a great choice and very programmable.           The model would probably depend on your panel string voltage but the 150 works for most people.

Having built a few systems I've learned that the ability to occasionally adjust the voltages is important to maximize battery life.       In the winter with shorter days the batteries generally like a little higher voltage.        Try to get your SGs over 1.265 at least a few times a week to maximize battery life.

I run a Conext system so I'm using a Conext controller on the house system but many serious solar people prefer the flexibility of the Midnight Classic.     I run a TriStar on a smaller system and it is ok for AutoZone deep cycle batteries but for Rolls you really need the higher voltage a programmable controller allows.
Previous Topic | Next Topic

Quick Navigation:

Easily create a Forum Website with Website Toolbox.


web statistics