Battery charging question

larrybc1 · May 2015

Hi all....i was discussing with Sunking about how long the absorb time should be. He is saying that bulk=absorb=float...for a 48 volt system all should be set to 57.6.. Apparently there are a lot of warranty claims cuz with 3 stage CC batteries are not getting fully charged and causing early failure rate...i value Sunking's opinions as he is very knowledgeable... The question I have is has anyone gone to this basically 2 stage CC method and what are your opinions/results..it seems to be a radical method but does make sense..thks

BB. · May 2015

That is a relatively mild charging voltage (14.4 volts @ 12 volt equivalent) for a flooded cell battery bank. And if you are running this for your solar charging voltage, then for 12-14 hours per day, there is no charging due to position of sun (aka night). So less chances of over charging. I probably would not run this as a float voltage if the battery bank is not being cycled (away on vacation).

For some place with longer hours of sun (towards equator and towards the poles for local summer), it probably can work OK. If you don't have a lot of hours during the winter, having a more aggressive charging voltage would probably do better at keeping the bank charged during the shorter hours of sun.

As long as the specific gravity of the battery bank is OK, and if the water usage is OK (i.e., you have to fill the cells every month or so)--Seems like it could work.

If your SG is not working out, use too little water or too much--Then you will have to play with the charging voltages/set points.

-Bill

larrybc1 · May 2015

Ok BB thks...i guess just keep any eye on it so no overcharge

Photowhit · May 2015

larrybc1 wrote: »

i value Sunking's opinions as he is very knowledgeable...

He may have some knowledge, but he has a bigger opinion of himself and refuses to learn. I wouldn't trust anything he says.

It's getting close to 10 years ago now that I spent may hours every day correcting his posts on a long forgotten forum. Among other things he has claimed solar systems are only 90% reliable. That no electric company would pay you the same for electric that they were charging, even after links were posted directing him to Net Metering executive order. He's said that solar panels would never produce as much electric as it takes to create them...

He also has taken direct shots at a limited life style working with in an energy budget, Told me I couldn't run an AC off 4 golf cart batteries after I had been for years and was replying to him from the cabin, and said something derogatory about my lifestyle. You can have him... He has some letters after his name and thinks that makes him right and above learning. Unfortunately he has some admirers who just haven't had other make helpful discussions because they don't want to spend time defending their opinions.

That said there is something to be said for systems that are in use to have a somewhat higher float, but we have seen this voltage as being very low for a few of the larger flooded batteries, Rolls-Surrette appear to have a bit different alloy and want a higher charging voltage. I personally would stick with the manufacturers recommendations. Then again Trojan says not to equalize unless the SG vary a good bit when fully charged but they also put out a video suggesting a monthly equalizing.

softdown · May 2015

Last I checked Outback was pretty well thought of. Their recommendations for 48 volt non-sealed lead acid (neither GEL or AGM):
59.2 Absorb
55.2 Float
from p. 86 of the FLEXmax 80 and 60 User's Manual

If some bloke thinks they know better than Outback, then they should enjoy a comparable reputation.

Photowhit · May 2015

softdown wrote: »

If some bloke thinks they know better than Outback, then they should enjoy a comparable reputation.

I've got no problem with Outback, but suggest they offer these as a general starting point and that the battery manufacturers would be the correct source of information about individual battery types.

softdown · May 2015

Yes....that would make perfect sense to reasonable people.

Photowhit wrote: »

I've got no problem with Outback, but suggest they offer these as a general starting point and that the battery manufacturers would be the correct source of information about individual battery types.

westbranch · May 2015

Photowhit wrote: »

but suggest they offer these as a general starting point

Yup, every battery is a slight bit different, even those from the same production run, same day, NOT necessarily same service.

There are several threads here from people with brand new system that have had issue with their batteries getting recharged properly, and within that group one or 2 have had cells that failed after 1 - 2 years of normal use with little warning.. others dwindled slowly .
IMHO ''one rule'' is the starting point, then fine tuning from there for as optimal life as you can manage to extract from your batteries.

softdown · May 2015

For me....getting my 48 volt system operational was like "giving birth to a baby". I experienced significant stress, worry, concerns, issues etc. If others are like me, I would encourage them to keep it simple and start with manufacturer recommendations. More sophisticated solar is so initially challenging that ones mental health could be at risk.

I don't think I would have survived as "easily" without this board. Even with four books at my disposal, many questions remained unanswered. So much so that I don't think a large percentage should even attempt a solo install of a somewhat sophisticated system,

Last week I lost power for a couple hours after replacing aluminum 4/0 with copper 4/0. Inadvertently hit the wrong switch.

I think I am still healing from it all.

Keep it simple at first.

westbranch wrote: »

Yup, every battery is a slight bit different, even those from the same production run, same day, NOT necessarily same service.

There are several threads here from people with brand new system that have had issue with their batteries getting recharged properly, and within that group one or 2 have had cells that failed after 1 - 2 years of normal use with little warning.. others dwindled slowly .
IMHO ''one rule'' is the starting point, then fine tuning from there for as optimal life as you can manage to extract from your batteries.

Shooter Magaven · May 2015

softdown wrote: »

For me....getting my 48 volt system operational was like "giving birth to a baby". I experienced significant stress, worry, concerns, issues etc. If others are like me, I would encourage them to keep it simple and start with manufacturer recommendations. More sophisticated solar is so initially challenging that ones mental health could be at risk.

I don't think I would have survived as "easily" without this board. Even with four books at my disposal, many questions remained unanswered. So much so that I don't think a large percentage should even attempt a solo install of a somewhat sophisticated system,

Last week I lost power for a couple hours after replacing aluminum 4/0 with copper 4/0. Inadvertently hit the wrong switch.

I think I am still healing from it all.

Keep it simple at first.

LOL!
That was well said and so true. I am still trying to get my 48v bank to work right...Man...I had no idea what I was getting into.

BB. · May 2015

What, specifically, were/are the 48 volt system issues you are having (words to the wise)?

-Bill

softdown · May 2015

Seems to be running smoothly these days. I had a lot of questions about:
1) Properly mounting the array. One could write a book about this subject alone.
2) Wiring the combiner boxes. I'd say wiring worried me the most. I'm pretty good with mechanical things. Not so much with electrical.
3) Placement of inverter/CC and batteries considering wiring and temperatures etc.
4) Wiring the batteries was even a bit of a challenge. I discovered that I could turn a small bolt head into fire if I played my cards right(wrong).

It all seems pretty straightforward....after one has done it. But the obstacles seemed quite large at the time.

I thought running a small 12 volt system for a few years would pave the road for me. Helped a little but not a lot.

Note: I elected to have a pro spend three hours hooking up the final connections. Didn't want to risk blowing up my MATE. He said I did a "perfect job". Reckon I did OK for a newbie then.

BB. wrote: »

What, specifically, were/are the 48 volt system issues you are having (words to the wise)?

-Bill

Battery charging question

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