Last night I had my inverter (24v Axpert with 2 x 12v 260aH Omnipower AGM's) running because our area was experiencing load shedding.

All was good and well, I boiled the little 900w "inverter friendly" kettle I have, and made a cup of coffee.

A little while later I decided to have another cup and put the kettle on to boil again.

The kettle stared heating up the water and then suddenly I was in darkness. The wife was less than impressed!

The inverter was showing a low DC cut off fault (04) - I have set this to be 21volts on the programming.

I reset the inverter and got the lights back on, tried boiling the kettle again and it was lights out again.

I had a look at the BMV with no load connected and it said that my bank was still at 90% capacity and the voltage differential between battery 1 and 2 was only 0,1% and that the bank (2 x 12V Omnipower 260aH AGM's) was at 23v.

So I did some more fiddling and I have concluded that the battery voltage drops below 21v when a large load is applied, I understand that the voltage will drop when a load is applied but this has never happened before.

What I wanted to know was:

How do I test these batteries to see if they are correctly charged up?

How to I test these batteries for a failed cell?

I am hoping that I have just set the charging parameters incorrectly and that these batteries were not fully charged?

If I remember correctly I have set the inverter to charge at 20amps at 27v (float service according to the attached spec sheet) 

My inverter acts as a UPS and only draws off of batteries when there is a power failure - could there be a build up on the cells of the batteries that's causing this poor performance and should I discharge them and recharge them every so often to get rid of this build up?

 

OmniPower Battery.pdf

2 hours ago, Noobie said:

How to I test these batteries for a failed cell?

Car battery shop, they have like Hawkins load testers, that is the best method I found.

1 minute ago, The Terrible Triplett said:

Car battery shop, they have like Hawkins load testers, that is the best method I found.

Or just boil the kettle again a few times while measuring individual batteries with a DMM. Turn the kettle on only a few seconds at a time to avoid a shutdown (so basically put the kettle where you can reach it during testing). You should find the problematic battery very quickly.

2 hours ago, plonkster said:

Or just boil the kettle again a few times while measuring individual batteries with a DMM. Turn the kettle on only a few seconds at a time to avoid a shutdown (so basically put the kettle where you can reach it during testing). You should find the problematic battery very quickly.

I will give that a go this evening and see what happens

Never mind the battery - Where did you get the kettle? I have only managed to find as low as 1200W, so would really like to find a 900W or lower (especially for my camping invertor that SH!T$ itself at 800W or more).😄

11 hours ago, KLEVA said:

Never mind the battery - Where did you get the kettle? I have only managed to find as low as 1200W, so would really like to find a 900W or lower (especially for my camping invertor that SH!T$ itself at 800W or more).😄

Takealot, I put a post on the forum about it but I can't seem to find it now

 

Found it - https://www.takealot.com/mellerware-piccolo-mini-cordless-kettle-white/PLID36957259

I stand corrected, its pulls 1160watts and not 900watts

 

So I tested both batteries in my bank under load today and found that one battery hits a minimum voltage of 10,36 when under load and the other hit a minimum voltage of 8,58 volts under load.

So I am assuming that the second battery (8,58volts) is what's causing my Axpert to shut down on a low DC voltage alarm.

Is there a way that I can have this battery repaired/reconditioned?

They are OmniPower 12v AGM 260aH batteries and are only 3 years old. I am not sure what could have caused this one battery to fail as I only use the inverter during load shedding, I do not cycle the batteries often.

 

1 minute ago, Noobie said:

So I am assuming that the second battery (8,58volts) is what's causing my Axpert to shut down on a low DC voltage alarm.

Is there a way that I can have this battery repaired/reconditioned?

I would say:
Jip.
Nope - replace both. It is time.

1 minute ago, Noobie said:

I am not sure what could have caused this one battery to fail as I only use the inverter during load shedding, I do not cycle the batteries often.

If they where in a UPS or a Victron kit, as they are good make, then I would have said hard use and / or incorrect charge settings. 

Just now, The Terrible Triplett said:

I would say:
Jip.
Nope - replace both. It is time.

If they where in a UPS or a Victron kit, as they are good make, then I would have said hard use and / or incorrect charge settings. 

Thanks TTT, much appreciated!

Any 24v battery recommendations? T105RE's?

 

18 minutes ago, Noobie said:

Thanks TTT, much appreciated!

Any 24v battery recommendations? T105RE's?

If I must buy today, I would look at:
1) Pylontech - but they don't have 24v yet - so we both are buggered there.
2) 12v Trojan AGM's if I don't want to be bothered with water. Like Trojan SAGM_12_205 12200 which are 12v 200ah at 1700 cycles to 50% DOD @ about +-R6500 each
3) 12v 200ah Trojan J200RE's if I had a watering kit - which I do. 🙂  They are about +-R5300 each

And then my latest thought, seeing as I can Keep Batteries Charged with batts only used if there are Eskom woes, I would actually consider lines like Koyo etc.

49 minutes ago, Noobie said:

So I tested both batteries in my bank under load today and found that one battery hits a minimum voltage of 10,36 when under load and the other hit a minimum voltage of 8,58 volts under load.

Assuming you used the same +-1kw kettle to test, you were drawing around 50A from the batteries at the time (roughly 1000W/20V). The batteries you have their are 260h at C/100 but probably closer to 200Ah at C/10 (marketing strikes again). So at 50A you are drawing them down hard, but even then 10.4V seems very low, especially if the battery had a good state of charge, so I am inclined to agree with TTT:

48 minutes ago, The Terrible Triplett said:

Nope - replace both. It is time.

The one at 8V... well that one is obviously shot.

48 minutes ago, Noobie said:

Any 24v battery recommendations? T105RE's?

FreedomWon Mini. It comes in a 24V variant. It's around 30k so for the capacity it rivals Pylontech cost. On this battery there's no precharge, and no canbus comms (you don't need the latter).

19 minutes ago, plonkster said:

The one at 8V... well that one is obviously shot.

You can only replace one yes but 3 years difference, the other batt having worked harder the last few months ... how much time, that is the question.

So I'm thinking, an option is to buy one new batt, the 3 year older batt affecting it so after say i.e. 1-2 years the older one goes.
Buy another new one, now the two batts are 1-2 years difference.
Keep buying one at a time till the two batts are as close as can be.

Must say 30k is not small change. Even 10k for new batts irks me. Eskom is cheaper and if they do get their increase, just drop more loads. 

Or if we had regular unreliable Eskom and need to power more at night, then 30k makes a teeny bit more sense. But we don't and I don't need to.

Sometimes I wonder if we don't get caught up in it all and just want to want bigger batt banks, latest tech and all that. Eskom still works. Our parents and their parents where not like that, yet here we all are. 🙂 

Edited February 16, 20197 yr by Guest

7 minutes ago, The Terrible Triplett said:

30k is not small change

So when LFP batteries started to become mainstream, it was 10k ZAR for 1KWh storage. It's been at around 7.5k/KWh for a while now (Pylontech and most of the local ones are around that bracket). Second life batteries obviously cuts that about in half... but is still a bit of an unknown. But I heard rumours of a potential 5.5k/KWh option... only rumours though.

9 minutes ago, plonkster said:

... was 10k ZAR for 1KWh storage. It's been at around 7.5k/KWh for a while now ...

That is a good way to look at it - Rand per KWh - and it is 100% right.
Comparing that against Eskom is always the core debate - with Eskom you can drop your costs easily, same as you would do on batts, take more loads off.
So if we do it with batteries, why not do it with Eskom?
Because we are at or below the monthly 600 usage number, the less we pay.

We in cities are not there where batts are cheaper than Eskom. Having only an option of off-grid or being on a farm - this is NOT about that. 🙂 

So another way to look at it is say over a 5 year period you need 250 times backup for when Eskom is off, driving batts to 50% DOD. Work them hard.

For that you can use cheap leisure batts - 100ah at wot, R1850 each.

Because the thing is, when the banks say "hey, I'm outa here", 10 to 1 that happens at a time when one can least afford it. My experiences over the last decade is that is also the time you sit there and ask yourself: Is it worth the cost?

Ps. It "feels" like more and more here are asking that question lately - perfectly normal and anticipated - is my bank shot?
With even more of us to face that question one of these days / months / year ... myself included.

 

I have exactly the same batteries and in the 3 years that they were installed I doubt they were ever cycled even once due to zero load shedding or power failures in that time. However I suspect one of the batteries may be faulty as the inverter cannot go into ups mode when the grid goes down. It cost close to R19K for 4 when purchased and it galls me that they did not last as long as advertised. I am looking at getting a single Pylontech US2000B for now.

1 hour ago, The Terrible Triplett said:

take more loads off

There are limits to that. Hard limits, such as the 4KWh/day limit I cannot avoid even if I turn off just about everything. I go away on holiday... that's what the house uses... though fully covered by solar in my case. Then there is that point of diminishing returns... the "less cost vs unhappy spouse" limit. For me that limit is around 15kwh/day.

1 hour ago, The Terrible Triplett said:

So if we do it with batteries, why not do it with Eskom?

Cause they have you over a barrel. You can say to the family: Guys, you can have x amount of backup, but then we have to stick to limit y. And generally the family agrees because some power is better than nothing. So getting them to agree on switching off some appliances is way easier with battery power than with grid power.

Also... I kinda like my luxuries.

12 minutes ago, plonkster said:

Cause they have you over a barrel.

No they don't. Any time I chose I can go off-grid if I so desire. Our bank managers on the other hand, they are the ones having us over a barrel.

 

4 minutes ago, plonkster said:

I kinda like my luxuries.

And nothing wrong with that.

All boils down to priorities ... we all differ. I just think there are as many of the ones who like their luxuries versus the ones who just don't give a damn about luxuries. 

Don't have to chase the Jones'es ... their priorities could be different.

 

14 minutes ago, plonkster said:

So getting them to agree on switching off some appliances is way easier with battery power than with grid power.

Yes and No.
Yes we are much much more aware of the costs.
And No, on Eskom we are just not that phased to push the same rules as being on batteries.
Double standards if you ask me. 🙂 

If my cell phone is charged and I can read Kindle books in the dark, wife pretty much asleep by then, I pretty much don't give a ___ that the one young adult cannot use her big TV or that the other young adult cannot stream the game he was playing. See, they are more than welcome to sort their own WANTS.

And if the wife is not asleep, I give her a table with earphones to watch her series on, for she still looks gorgeous if she could not use the hairdryer. 

So I'm just passing my thoughts on that others can read that it is ok to go cheap on batts. 😋
 

56 minutes ago, The Terrible Triplett said:

if the wife is not asleep

I can think of way better things to do...

(Come on.., you must have seen that coming! 😛 )

Thanks @The Terrible Triplett, for the time being I am goig to avoid using the kettle or micro when we have load shedding, this way at least I can keep the lights and TV running.

There is no budget to buy a new bank, hopefully by the time I can afford to get a new bank there will be a reasonably priced 24v lithium option on the market.

What I don't understand is how battery manufacturers claim an 8-10 year design life but the warranty is 12 months in most cases.

Has anyone on the forum got decent warranties on their battery banks and has the supplier assisted with warranty claims?

1 hour ago, Noobie said:

There is no budget to buy a new bank, hopefully by the time I can afford to get a new bank there will be a reasonably priced 24v lithium option on the market.

FreedomWon Mini. They make a 5kwh 24V option. It compares in price to 2 * Pylontech, because two of those would cost around the same price, and gives the same capacity (but it is 48V). Of course... if you don't have 30k... then it is moot.

1 hour ago, Noobie said:

What I don't understand is how battery manufacturers claim an 8-10 year design life but the warranty is 12 months in most cases.

Design life usually means "when used for backup purposes, aka left floating most of the time". The moment you cycle them, that number goes out the door. 12 Months is to cover "manufacturing defects"... but mostly it is just a marketing tool. Much like 5-year/90 000km service plans on cars... what precisely do you have to do on  car for the first 5 years or 100 000km? Oil and filters boys... oil and filters. First big thing that happens (timing belt) is for your own pocket.

20 hours ago, Noobie said:

What I don't understand is how battery manufacturers claim an 8-10 year design life but the warranty is 12 months in most cases.

Easy, if you follow the specs to the letter, you SHOULD get 8-10 years on say Trojan's.
12-36 months warranties, sit a moment and think of how many people abuse batteries, incorrect charging / overuse.

Manufactures know that as the "evidence" is in there if anyone wants to argue. Like my pal tried the warranty route after royally messing his 105ah batts up. He had a 800va 24v Axpert and 1 x 200w panel powering ALL his lights at night thinking that is saving. No matter what I told him, he refused. He paid good money for the batts, he said.

So I got fed up and asked the supplier to please visit. They literally laughed when they said to him:
"You overused the batteries as 1 x 200w panel is not enough to re-charged the 4 x 100ah batteries.
Then you forgot to add water, so the plates where exposed.
Then you tried to refill them and over filled them resulting in the mess on your floor when you tried to re-charge them using Eskom.
Tell us that is not what happened?" ... they said.

 

Now we don't buy form Sustainable, but this is interesting: Sustainable and Freedom Won

Personally I'm still not 100% convinced on the  >2000 cycles versus Trojan's where you can bet on 1600 / 1700 cycles if you follow all the rules.

So I'm waiting on - as I still have a few years on the clock:
1) Trojan lithiums. Trojan has a track record of standing behind their warranties.
2) To see other users saying after +-5 years that their Pylontech's / Freedom Won / ___ are still going as advertised ... that "timing belt" analogy of Plonkster not the case.

33 minutes ago, The Terrible Triplett said:

Now we don't buy form Sustainable, but this is interesting: Sustainable and Freedom Won

Those are not FreedomWon batteries. They are just Freedom.

I have changed my mind a little bit on sustainable. Someone pointed out to me that they deliver for free in Greater Cape Town area (ie as far as Gordon's Bay). Most others don't. Now perhaps that doesn't quite make up for the 20% extra you pay... but it accounts for at least some of it.

37 minutes ago, The Terrible Triplett said:

timing belt" analogy

Most recent acquisition has a timing chain... 😛

 

3 minutes ago, plonkster said:

Those are not FreedomWon batteries.

My bad? Freedom Won offers the long overdue next-generation energy storage with a quantum increase in service life ...

5 minutes ago, plonkster said:

Most recent acquisition has a timing chain...

As has mine, and they still get worn out, can snap. 😋

11 minutes ago, The Terrible Triplett said:

My bad? Freedom Won offers the long overdue next-generation energy storage with a quantum increase in service life ...

Oh bloddy hell, the URL is on the battery bottom right corner. No, not your bad. Mine! Didn't know they branched out into this market.

11 minutes ago, The Terrible Triplett said:

As has mine, and they still get worn out, can snap. 😋

Yeah but yours has three times the mileage on it, and is frankly a more robust motor anyway. These new-fangled "open deck disposable" diesels are nice and all, but you can't bore out the block or resleeve or any of those things... when it is done, it is done.