These batteries are not getting fully charged, how best can I boost them, can I charge them directly using PV of 70Vdc, 

If there is a BMS that will protect the batteries, then I don't see a reason why you cannot connect them directly (without an MPPT that is to say). You'll lose a bit of efficiency. But I have to stress... at your own risk. I may well be wrong about this too... and definitely don't do it if there is no BMS to protect you from blowing stuff up.

Also consider whether the fast charger contactors can break say 8 A @ 350 V. Normally the CHAdeMO protocol will shut down the charge source before the contactors open. 8 A isn't much for a contactor capable of around 100 A, but DC arcs are hard to quench for something not designed for it (e.g. with magnetic blowouts). 

Edited January 9, 20197 yr by Coulomb
auto-correct error; CHAdeMO spelling

I wouldn´t do it, unless I was completely sure BVDS Mos is higher than PVo. In other case, BMS would result damaged.

How are you charging now? What voltages? 

Edited January 9, 20197 yr by Javi Martínez

hi please help me. are these batteries lithium and can they be used in house hold with a 5kw inverter ?

what settings must they be programmed into a mecer / expert 5kva ?

i can't seem to get the inverter to work properly with this battery. ESM-48100A!

 

A Google search for that part number (in quotes) returned (excluding ads) just one result:

https://www.google.com/url?sa=t&source=web&rct=j&url=https://powerforum.co.za/topic/2314-new-offgrider-with-questions-pls/page/2/&ved=2ahUKEwikzYeWirrhAhXZQ30KHXhoBi4QFjAAegQIARAB&usg=AOvVaw0Nmsaz2wnLHQzSbeR9qVgH&cshid=1554506360794

But now I realise that the exclamation mark after your part number is a typo, meant to be a "1". So yes, these are lithium batteries, in fact LFP.  (LFP, lithium ferrous (iron) phosphate) is a type of lithium battery, rather different to most other lithium chemistries, but popular with home energy storage).

When you say that you can't get them working properly, do they simply not last long, or they don't even light up the inverter display?

There are some suggested Axpert settings in the above link.

It's possible that these are "second life" cells, and possibly not well matched or with little life left. But we need more information before making that call. 

HI, thanks for reply.

They light up inverter. if i switch off eskom, i get around 4 hours 2 mins on a average of 1100 watt load. so they definitely hold charge... the strange this is just when i try and use a air fryer or something the inverter then dies... 

i have changed various voltage settings... I'm not sure what i should be using. and i don't really understand the difference on voltage etc. when using y 4 x 100AH AGM, i can use air fryers etc.

 

really appreciate the help.

2 hours ago, Doron said:

They light up inverter. if i switch off eskom, i get around 4 hours 2 mins on a average of 1100 watt load. so they definitely hold charge... the strange this is just when i try and use a air fryer or something the inverter then dies... 

Ah. They seem to be current limited to 50 A, or 0.5 C. I'd say there are a bunch of MOSFETs in there that let go at just over 50 A, or about 50 x 50 = 2 500 W. That's half your inverter's rating.

I can't see any way around that, other than buying another one to put in parallel.

Even paralleling to the limit (8 batteries), you only get 15 kW, but I'd guess that the cables would be limiting by that point. Otherwise, 8 in parallel should get you to 2.5 x 8 = 20 kW.

My guess is that most other lithium batteries let you get away with a fair bit more than 0.5 C at least for short periods of time, but I wouldn't know.

Good Day

I am new here and registered today.

After my recent installation I've been consumed by reading and gathering as much info as possible.  Funny how one thinks you've done enough research only to find out you know very little after an installation takes place. 

I got two of these batteries with my system. And have not managed to get the battery % above 83%. This was after even using Eskom power to do the charge.

The batteries are connected in parallel.  I'm Using a Mecer / Expert 5kva.

I do model aircraft flying and has been using Lipo batteries for the last 10 years.

My main concern here is battery monitoring and management. WatchPower gives me battery % , Volts, Amps charge and discharge. I however assume this is a average between the two batteries. How would one know the state of each individual battery pack?

I really look forward to some suggestions as I've seen there are members here which are extremely knowledgeable.

 

Finally some sun in Pretoria. Here is a screen capture of the current readings.

Greetings

Albert van de Vyver

 

1 hour ago, SnoopySniper said:

And have not managed to get the battery % above 83%.

According to who? The Axpert / Watchpower, or the battery?

The Axpert is estimating the SOC based on battery voltage, treating it as a lead acid battery. In other words, it doesn't have a clue.

Quote

WatchPower gives me battery % , Volts, Amps charge and discharge.

As noted above, Watchpower doesn't know the battery %.

Quote

I however assume this is a average between the two batteries. How would one know the state of each individual battery pack?

The two batteries are in parallel. So their states of charge should be quite close. If one was discharged more than the other, its voltage would go down, causing the other one to charge it back up until they were nearly the same again.

But hopefully you get at least an indication from the batteries themselves.

Thank for the reply

The value is read from watchpower. As shown in the picture the value was 68%.  I understand your explanation.

What is the best way to get actual battery values?

 secondly if the values on watchpower is used to determine when system falls back to grid and when to stop charging . If those values are not accurate this decision is taken on wrong info. How does one rectify that?

Greetings

11 hours ago, SnoopySniper said:

What is the best way to get actual battery values?

That depends on the battery. Nearly all of them have a crude "LED bar graph" giving the state of charge to the nearest 20-25%. I would hope for an LCD display with a percentage, but that may be too much to expect. Perhaps you can plug in a PC and read it from a web page?

Failing all that, you can use a good monitoring program that runs on a PC, e.g. ICC (SA made). It supports Pylontech and now Blue Nova batteries directly, but obviously can't support every possible brand. I believe that you can add a BMV battery monitor, which will count coulombs and give you a state of charge withing a few percent. You can use that figure to switch the inverter between line and battery mode at true SOC levels.

11 hours ago, SnoopySniper said:

 secondly if the values on watchpower is used to determine when system falls back to grid and when to stop charging . If those values are not accurate this decision is taken on wrong info.

Yes, it will switch at inappropriate levels. It's based on battery voltage, not even considering load level, and switching to and from battery and line mode is at whole volt settings, so it's pretty crude.

Quote

How does one rectify that?

As above, with ICC and a BMV. If you don't want to shell out for these, and if your Axpert is eligible for 73.00e or 72.20e patched firmware, these have KettleKomp™, which at least compensates the battery voltage for load. That will cause the inverter to not switch to line mode just because a largish load like a kettle came on, or at least much less often. You might find this good enough, after you carefully choose settings 12 and 13 (back to grid and back to battery voltage settings) to suit your situation. See the AEVA PIP-4048MS and PIP-5048MS index page for more. Read Can I Update my Firmware, and if so to What? first.

Hi

Some feedback and thanks for the detail answer. 

Sadly the battery has no led % or capacity indication. It only indicates on, charge, discharge and fault. 

I did however take a multi meter and measured the voltage at the battery poles. These values were exactly the same as those on the inverter. 

My priority now is to see if i can get the batteries charged past 83%. I’ve also engaged with the installer and await their feedback. 

Greetings

It seems very likely that when the inverter and/or Watchpower say 83%, it actually is at 100%. If so it won't go any higher.

This ESM 48100A1 was certified with an upper charging limit of 55 V.  The recommended float voltage is 53.5 V.  If 70 V work, good for you, but it's not something I'd do if I could avoid it. 

The 8 unit parallel limit is if you connect their BMSes with the RS485 interface.  If you use the CAN interface you can connect up to 32 in parallel.

The BMS limits the output current to 50 A.  That means that a single battery can't give you more than about 2.5 kW output.  You can get more by parallelling them, but be careful.  At the very edge of capacity you'll reach a point where one of them disconnects because it is empty, throwing the whole of the load to the remaining one, which would then disconnect due to a overload condition.  All should be fine, but I'd prefer to disconnect at e.g. 44.5 V when parallelling.

As for the inverter and the battery's SoC - I wouldn't worry too much if the battery reads about 49.8 V on load.

@Tacet Makes allot of sense. no matter what i did anything over 2.5KW and the inverter would trip. clearly your above explains why. i opted to move over to 1 Loech 48v 100AH i had also which on its on (non parallel) works perfectly under the larger load. The 2 x ESM48100A1's ill parallel and use on another site of mine.

any feedback from others that have used the Leoch 48v 100AH batteries. they have a very nice built in BMS etc.

On 2019/04/08 at 1:22 PM, SnoopySniper said:

 have not managed to get the battery % above 83%.
 

What is your Axperts "Battery cut-off voltage" set at?

Can you post a picture of your Parameters settings?

10 hours ago, GVC said:

What is your Axperts "Battery cut-off voltage" set at?

Indeed. I believe that if you set it to 43.7 V, then the SOC will read 100% at an instantaneous battery voltage of 53.5%. That's because it gives you 2% at the cutoff point, and 1% for every 0.1 V of battery voltage above that. So 53.5 - 43.7 = 9.8 = 98 tenths, plus the 2% = 100%.

Of course, as soon as the bulk charge stops or a load comes on, the voltage will sag, and so will the SOC, but at least it will be somewhat realistic at high states of charge. And the OP can get past this 83% mindset.

Edit: it also illustrates how arbitrary the inverter's SOC "reading" is.

Edited April 10, 20197 yr by Coulomb

37 minutes ago, Coulomb said:

...43.7 V...

Does the Axpert then assume that all lithiums will have a range of ~10 V between float and cutoff?  Taking a few 100 Ah blocks:

The voltage range to the recommended cutoff can vary quite a bit.  A pity the Axpert doesn't allow you to enter seperate values to use for SoC calculations.

On 2019/04/10 at 2:52 PM, Tacet said:

Does the Axpert then assume that all lithiums will have a range of ~10 V between float and cutoff? 

Oops! I had the wrong formula; I've edited my previous post. But it makes little difference. I believe it assumes a range of 10 V for all batteries, lead acid, LFP, Cobalt, etc. Again: it's supposed to be a rough guide.

I've seen other firmwares where they take the load into consideration a bit, but still make lead acid assumptions. Maybe that's in another part of the firmware I can't find quickly now.

The latest patched firmware attempts to do slightly better; 0% SOC is the battery cutoff voltage, as before, but 100% is the float [ edit: was absorb ] voltage, and the battery voltage used is compensated for load and charge current (with 5 possible compensation strengths).

Quote

The voltage range to the recommended cutoff can vary quite a bit.  A pity the Axpert doesn't allow you to enter seperate values to use for SoC calculations.

Yes, indeed.

[ Edit: SOC is based on a battery voltage that is charge as well as load compensated. ]

Edited April 17, 20197 yr by Coulomb
As noted

Huawei ESM-48100A1 in parallel Max power is 2.2kw

On 2019/04/10 at 5:52 AM, Coulomb said:

Indeed. I believe that if you set it to 43.7 V, then the SOC will read 100% at an instantaneous battery voltage of 53.5%. That's because it gives you 2% at the cutoff point, and 1% for every 0.1 V of battery voltage above that. So 53.5 - 43.7 = 9.8 = 98 tenths, plus the 2% = 100%.

Of course, as soon as the bulk charge stops or a load comes on, the voltage will sag, and so will the SOC, but at least it will be somewhat realistic at high states of charge. And the OP can get past this 83% mindset.

Edit: it also illustrates how arbitrary the inverter's SOC "reading" is.

Hi @Coulomb. I have 2 of these 48100a1 batteries with a 5k Axpert, victron BMV712 and 9 x 330W panels. I am still trying to get the settings right, currently the inverter switches a lot between grid and batteries as can be seen below.

Settings are:

Bulk charge - 53.4

Float - 51

Back to grid - 48

Back to discharge - 51 

Cutoff - 46

SBU setting

 

Assistance would be appreciated a lot by anyone.

32 minutes ago, Ernie said:

Hi @Coulomb. I have 2 of these 48100a1 batteries with a 5k Axpert, victron BMV712 and 9 x 330W panels. I am still trying to get the settings right, currently the inverter switches a lot between grid and batteries as can be seen below.

Settings are:

Bulk charge - 53.4

Float - 51

Back to grid - 48

Back to discharge - 51 

Cutoff - 46

SBU setting

 

Assistance would be appreciated a lot by anyone.

I also lowered back to grid V to 48 but I kept getting low Voltage alarms from the inverter

The low voltage alarms stems from the fact that your Cutoff voltage setting is too close to your back to grid settings. i.e. 46 - 48

I have set my cutoff = 44 and back to grid = 50....It is running with no alarms on these settings.

21 minutes ago, GVC said:

The low voltage alarms stems from the fact that your Cutoff voltage setting is too close to your back to grid settings. i.e. 46 - 48

I have set my cutoff = 44 and back to grid = 50....It is running with no alarms on these settings.

Thanks GVC, which batteries do you have? Whats your float and back to batteries V?