End amps and absorb time

Discussion about the FM100, FM80, and FM60 Charge Controllers

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wingnutter
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End amps and absorb time

Post by wingnutter » Fri Mar 15, 2013 2:23 am

Hi Folks,

Can someone tell me if absorb time and end amps are an either or thing? I have been told that setting the end amps with more than the zero default value on a FM controller will mean that the absorb time setting will be ignored? Please can anyone shine a light on this issue as I have been setting Outback controllers with both absorb time and end amps thinking that both functions will work together?

Thanks in advance

David

SandyP
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Re: End amps and absorb time

Post by SandyP » Fri Mar 15, 2013 3:19 pm

wingnutter wrote:Hi Folks,
Can someone tell me if absorb time and end amps are an either or thing? I have been told that setting the end amps with more than the zero default value on a FM controller will mean that the absorb time setting will be ignored?
David
My understanding is that if either of the settings are reached then absorb will end' So, if end amps are reached before the set absorb time then absorb will end ignoring the time setting. However if absorb reaches the max time set before end amps is reached then the end amps is ignored and absorb ends.

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Re: End amps and absorb time

Post by Gordon-Loomberah » Fri Mar 15, 2013 4:37 pm

SandyP is correct. You do need to be careful using end amps with the FMs, as they can't sense net charge going into the battery. If you have fairly constant loads, just add however many amps that is onto your desired end amp value. If they loads are highly variable, it is better to set end amps to zero, and use time only.
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petertearai
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Re: End amps and absorb time

Post by petertearai » Mon Mar 18, 2013 2:50 am

My off grid holiday home often has 1 to 2 weeks with no one there . The end amps is great for the time when no one in residence as the absorb time is normally cut down to 15 to 20 minutes. But while in residence the absorb will usually go to the 3 hour time I have it set to.
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wingnutter
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Re: End amps and absorb time

Post by wingnutter » Tue Mar 19, 2013 3:02 pm

Thanks for your replies. I have set quite a few systems up without giving too much thought to just what exactly I was trying to achieve. I will have to reprogram them on my next visits. Next install I do will be zero end amps to stop me guessing at the clients use. They never tell me the truth about power use, like it is a dirty secret and that I will scold them for using too much. Personally I blame either the over calming music and voice on the OB information video, it lulls me into a false sense of knowing what I am doing :grin:

WNY DAVE
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Re: End amps and absorb time

Post by WNY DAVE » Sun Sep 01, 2013 3:07 pm

on my FM60. I've had the ABSORB set to 1 hour (default I believe), it's been ABS for 1 hour for the past 3 weeks according to the data (just put it online and brand new batteries Exide GC135). however, the past week, The ABS has been lowering itself to 45 mins?
Is that because the bulk charge time is so short to full charge and the batteries are fully charged? Does it automatically reduce the ABS time?

There is no load during the week or weeks when we are not there.

I am going to try the END amps around 8 or 10 (690aHr bank of batteries) and see if that reduces it more, since the batteries are typically above the 25.2 voltage most of the time. I don't want to do more absorbing than necessary.

Thanks.

SandyP
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My RE system: 8 x 190W 24V Suntech panels (4 strings of 2)
4 x 325W 24V Suntech panels (2 strings of 2) added Sept2018
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12 x 2V Hoppecke GEL 660 Ah C100 - 24V System
Outback VFX3024 Inverter/Charger
Victron BMV-602s
Honda 5.5kW Genset
Location: Victoria, Australia

Re: End amps and absorb time

Post by SandyP » Mon Sep 02, 2013 4:34 am

WNY DAVE wrote:The ABS has been lowering itself to 45 mins?
Is that because the bulk charge time is so short to full charge and the batteries are fully charged? Does it automatically reduce the ABS time?

There is no load during the week or weeks when we are not there.

I am going to try the END amps around 8 or 10 (690aHr bank of batteries) and see if that reduces it more, since the batteries are typically above the 25.2 voltage most of the time. I don't want to do more absorbing than necessary.

Thanks.
WNY Dave, what was the weather like when the ABS time was less than 1 hour? I expect that if there was insufficient sun to maintain the ABS voltage then the timer would have stopped.

Remember the END Amps will include any amps going to loads hence it may not be reached if you are drawing power.

WNY DAVE
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Re: End amps and absorb time

Post by WNY DAVE » Mon Sep 02, 2013 6:56 am

Possibly, I think most of the time it reaches abs and float quite early in the day. There are NO loads typically, the inverters and breakers to the house are off when no one is there. It's a summer home.

I wasn't sure if the CC counts down if it reaches the high limit on the MPPT Bulk stage early, it says it adds time to the ABS stage if it can't reach the high limit on the bulk charge. Maybe that's why I did see 1:10 on the ABS right after going online, since the batteries were a bit low, otherwise, it was exactly 1:00 (Hour) default the rest of the time until the past week, then it looked like it was lower, but I will check the data and output and see if it was cloudy and if it did go into float and for how long.

I'l check it next week and see if the end amps or if it still goes the full 1 hr ABS.

I did check the SG, most were 1.275-1.285, the hydrometer was a bit hard to read at times. Each battery was 6.78-6.81 volts.

Everything seems to be charged good from what I can tell so far.
I did find a good deal on some more panels (4 x 255 Watt) and will probably order them, so we have at least 4 of them for charging.

THanks.

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