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Forum Index : Solar : 60 Amp MPPT Solar Charge Controllerfor 48v 500Ah

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Old Seagull Man
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Joined: 21/12/2019
Location: Australia
Posts: 26
Posted: 11:35am 17 Jul 2020
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Can anyone recommend a good charge controller suitable for a large 48 volt lead Acid bank. Its an old fork lift battery pack. so 48v at 500Ah when new.

I have about 3000 watts of 250watt 30 volt panels. So i can work with a fairly wide voltage range. But was thinking of putting 4 panels in parallel . Giving me 132 volts.
And putting 3 set of 4 panels in series. Giving me 132v at 24amps. in theory.
At my age, no with my eyesight building would be beyond me. So please suggest away Please.
 
Solar Mike
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Joined: 08/02/2015
Location: New Zealand
Posts: 680
Posted: 12:02pm 17 Jul 2020
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I have used these less expensive Tracer model 8415AN in the past, they have an 80amp output @ 48V, setup by a program that runs on your laptop to set charge points etc. Never had any issues with them. They also have a less expensive 60 amp version 6415AN.

Note max PV input voltage is 150v, your 30v x 4s maybe too high, eg unloaded they would be about 38v odd each giving > 150v.

I would only have 3 in series for reliability. More expensive controllers can run up to 180-200v input, but cost near twice the money.

4 x PV's in parallel (current) may have too high a voltage drop if you are using 4mm cable, I would split it out into 2 sets each with their own cables back to a common fused connection hub.

Cheers
Mike
 
Warpspeed
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Joined: 09/08/2007
Location: Australia
Posts: 3374
Posted: 11:14pm 17 Jul 2020
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The high voltage is the problem, it really limits what you can use.

For 48v lead acid battery, the battery should never see more than about 58 volts, and two series connected panels should be able to just achieve that.

The controller will have a very easy job and will run cooler too.
Edited 2020-07-18 09:21 by Warpspeed
Cheers,  Tony.
 
Old Seagull Man
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Joined: 21/12/2019
Location: Australia
Posts: 26
Posted: 01:52am 18 Jul 2020
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Ok Guys thanks for the info and ideas. I set three panels up in drive this morning.
Connected them i series and got 99.8 volts open circuit. and about 7.5 amps. 60 cell panels.

Two gave me 66.2v and 7.4 amps, open circuit, off cause. So on that basis, 6 panels would give me 66 volts at around, 22 amps. This would make the controller happier, and it should work ok with 4mm cable. And be easier on the pocket.

I just wonder if 22amps is enough, current to charge a 500Ah battery?

Thanks All for the input.
 
Warpspeed
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Joined: 09/08/2007
Location: Australia
Posts: 3374
Posted: 02:02am 18 Jul 2020
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  Old Seagull Man said  
I just wonder if 22amps is enough, current to charge a 500Ah battery?


As long as you are putting in as much (or more) than you take out, it should be fine.
Cheers,  Tony.
 
Davo99
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Joined: 03/06/2019
Location: Australia
Posts: 540
Posted: 08:46am 18 Jul 2020
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How can you measure amps open Circuit?
Do you mean as in the rating of the panels?

You will be lucky to get rated output, especially in winter and below the rated VMP.
You would probably gain a lot buy adding a second pair of panels in Parallel.
You mention you have 3 Kilo of panels so you could parallel several pairs to give significant amperage.

As long as you stay below the rated voltage you should be able to overclock the charger so it will still deliver max charge in winter and less than Ideal weather.

I bought some little Chinese boards again the other day and they handle 60V@ 15A and can be set to whatever end voltage required. They are also adjustable for amps.
Some other boards I got are designed to switch a  charger on and off.
This also monitors to 60V and could be used to Drive a Relay or Mosfet to whatever Voltage you wanted.

It may be  wise to set one board up to do bulk charging and give it a lower cut-off point and have a 2nd setup that does the end float charging as the charge rate is supposed to be backed off above 80% charge level.

You could look up what the bulk charge rate and voltage is and the float and set up accordingly.

I have been keeping some old battery's charged with the switching boards.  Connected a 30V panel and just let the battery bounce between the high and low cutoffs. Just connects the panel in for short durations during the day once it's up to voltage and stays connected if I have a load on it.  Basic but works well enough.
 
Jim Jr
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Joined: 04/05/2020
Location: United States
Posts: 2
Posted: 04:17pm 19 Jul 2020
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  Old Seagull Man said  Can anyone recommend a good charge controller suitable for a large 48 volt lead Acid bank. Its an old fork lift battery pack. so 48v at 500Ah when new.

I have about 3000 watts of 250watt 30 volt panels. So i can work with a fairly wide voltage range. But was thinking of putting 4 panels in parallel . Giving me 132 volts.
And putting 3 set of 4 panels in series. Giving me 132v at 24amps. in theory.
At my age, no with my eyesight building would be beyond me. So please suggest away Please.




Lead acid batteries are designed to be recharged in 8 hours . the forklift ones need
 1/8 capacity in amps to prevent acid stratification . ( making bubbles to mix the      
 acid ) If this happens you will lose capacity by the day. In your case you need a
 minimum of 62.5 min amps to help the battery life. Trickle charging is one of the
 worst ways of killing a lead acid because of you don't know till it's too late.

 So the answer would be no to the 24 amps

Jimjr
 
Warpspeed
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Joined: 09/08/2007
Location: Australia
Posts: 3374
Posted: 09:49pm 19 Jul 2020
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Welcome to the Forum Jim.

I was aware of the dangers of slow trickle and constant float charging, but never really understood the mechanism of steady long term capacity reduction.
Cheers,  Tony.
 
Jim Jr
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Joined: 04/05/2020
Location: United States
Posts: 2
Posted: 12:00am 20 Jul 2020
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Great     I had killed my battery that way. Live and learn

Jimjr
 
Warpspeed
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Joined: 09/08/2007
Location: Australia
Posts: 3374
Posted: 12:21am 20 Jul 2020
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I have been responsible for quite a few very prolonged battery murders myself.
Cheers,  Tony.
 
Old Seagull Man
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Joined: 21/12/2019
Location: Australia
Posts: 26
Posted: 01:20am 20 Jul 2020
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Jim

Thank you, for the information..
Lots of panels and multiple charge controllers.

Davo

I have a Nieaf Smitt EazyPV Tester.  measures.

Insulation resistance measurement (Riso)
Earth continuity measurement (Rpe)
PV String Short circuit current (Isc)
PV String Open Circuit Voltage (Uoc)
Solar Irradiance
Roof ornamentation and pitch

Seams to work ok, got it from Grays Auctions.
 
nickskethisniks
Senior Member

Joined: 17/10/2017
Location: Belgium
Posts: 197
Posted: 08:57pm 26 Jul 2020
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  Warpspeed said  Welcome to the Forum Jim.

I was aware of the dangers of slow trickle and constant float charging, but never really understood the mechanism of steady long term capacity reduction.


Is that also true for deep cycle AGM batteries? I have some 12xfc58 and some enersys telecom batteries and that makes me think about how I treat those. 9-10 months they are on float. During 2 months they barely get a few full charge cycles. Datasheets recommend to fully charge them as soon as possible after you fully deplete them but nothing mentioned how you need to charge them after a partial discharge.
 
Warpspeed
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Joined: 09/08/2007
Location: Australia
Posts: 3374
Posted: 10:16pm 26 Jul 2020
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Probably.

If you have batteries for something like a security alarm, or starting up a generator, the batteries just possibly sit there for months or years and may never see high current usage, either charging, or discharging.

The worst thing you can do is just connect it across a 13.8v float charger and assume its going to be o/k and fully charged and ready to go when needed.

Its rather like spending six months in bed, and then trying to sprint around the block. Heart attack for sure.

A more successful strategy seems to be to charge the battery up to a decent voltage, say 14.2 volts at a "reasonable" current, say C/50 for example. Then switch off the charging altogether.

The battery voltage will fall rapidly at first, then at an ever slower rate. A good healthy battery should be able to hold up to perhaps 12.4v over 24 hours.

Allow the battery voltage to continue to fall over time, through leakage and self discharge, and at some low voltage threshold such as 12.3v, switch the charger back on.

Let the charger cycle on and off automatically between two voltage thresholds. The charging time will be quite short, because not much battery energy has actually been lost.  But frequent charging does create some cell activity and electrolyte movement which seems to be sufficient to greatly reduce the long term capacity degradation effect.

I have built several of these over the years, and have worked very well on vehicles that are very infrequently driven.
Cheers,  Tony.
 
Davo99
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Joined: 03/06/2019
Location: Australia
Posts: 540
Posted: 10:58pm 26 Jul 2020
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  Warpspeed said  

The worst thing you can do is just connect it across a 13.8v float charger and assume its going to be o/k and fully charged and ready to go when needed.

Let the charger cycle on and off automatically between two voltage thresholds. The charging time will be quite short, because not much battery energy has actually been lost.  But frequent charging does create some cell activity and electrolyte movement which seems to be sufficient to greatly reduce the long term capacity degradation effect.



Well that is something I wasn't aware of and am guilty of doing the wrong thing. :0(
Makes sense with the cell activity.

I got some little Charging Boards recently  ( finally) and they have an upper and lower threshold.  I'll adjust the parameters somewhat and should rectify the problem.

Thanks for the heads up!
 
noneyabussiness
Senior Member

Joined: 31/07/2017
Location: Australia
Posts: 279
Posted: 02:39am 27 Jul 2020
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Just to add to the above,  I have a traction battery ( among others ) that was chewing through water and not great for voltage over night... but cycling them over about 2 - 3 weeks ( 30% each night ish )  their capacity has enormously increased, significantly less watering and fast forward 2 years still going very strong... floating  a lead acid is good to a point, but as said above they need the workout..
I think it works !!
 
lizby
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Joined: 17/05/2016
Location: United States
Posts: 896
Posted: 01:55pm 27 Jul 2020
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  Davo99 said  I got some little Charging Boards recently ( finally) and they have an upper and lower threshold.

Can you provide a link to these charging boards?
 
Old Seagull Man
Newbie

Joined: 21/12/2019
Location: Australia
Posts: 26
Posted: 03:33pm 05 Aug 2020
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Ended up with an outback Flexmax. Real one not the chinese clone.

Though if you have a clone, i'd like to know what there like.

Thanks All For the advice.

OSM.
 
ryanm
Senior Member

Joined: 25/09/2015
Location: Australia
Posts: 153
Posted: 02:33am 06 Aug 2020
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If anyone else looks at this thread later they might want to check this one  as well. Australian designed and a bit cheaper than the outback.
 
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