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Imeon 9.12


Chris-R

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Hi Neb,

Have you installed any batteries yet??

I bought 8 x 180ah agm batteries " Monbat ", but reading through the forum wonders whether I should not add another 4 batteries from the start.

Can anybody explain to me why the same type of batteries cannot be added a few months later than the first?

Neb, would you post a photo or two of your DB Room and your installation layout?

I am a newbie in this field and have purchased these products after many hours of research and lots of discussions with solar installers.

I need to start the installation, but again are very open for ideas, the what-nots and the definitely has to be's.

Cheers

Solar room.jpg

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5 hours ago, Chris Rossouw said:

Can anybody explain to me why the same type of batteries cannot be added a few months later than the first?

As batteries age so their internal resistance begins to change. This leads to a change in their charge characteristics. One would like to have uniformity over one's battery bank so that they accept charge at the same rate. Thus the recommendation of using batteries that are the same age so that the age at the same rate and therefore change at the same rate. It is not perfect but one is trying to reduce variation.

My own batteries are a year and a half old and I am now starting to see some variation of the acceptance of charge between the batteries which I manage through the use of battery balancers.

 

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7 hours ago, Chris Rossouw said:

I bought 8 x 180ah agm batteries " Monbat ", but reading through the forum wonders whether I should not add another 4 batteries from the start.

Can anybody explain to me why the same type of batteries cannot be added a few months later than the first?

If it is not too late yet, try to arrange with your supplier to exchange the 8 batteries for single batteries of higher capacity (Ah values) or even 2V cells of higher capacity.

It is not advisable to have multiple parallel battery strings for various reasons and discussed many times before in this forum.  If it is at all possible, always try to have only 1 string of batteries or cells.

In layman's terms, you are going to have 2 x 180Ah strings in parallel and might want to add another string, currently you have 360Ah and you will have 540Ah when you have 3 strings in parallel.  Rather try to get 540Ah or similar batteries (4V / 6V / 8V / 12V batteries, does not matter) or 540Ah or similar 2V cells and connect them in 1 serial string to make up your battery bank.

 

 

 

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5 hours ago, superdiy said:

If it is not too late yet, try to arrange with your supplier to exchange the 8 batteries for single batteries of higher capacity (Ah values) or even 2V cells of higher capacity.

It is not advisable to have multiple parallel battery strings for various reasons and discussed many times before in this forum.  If it is at all possible, always try to have only 1 string of batteries or cells.

In layman's terms, you are going to have 2 x 180Ah strings in parallel and might want to add another string, currently you have 360Ah and you will have 540Ah when you have 3 strings in parallel.  Rather try to get 540Ah or similar batteries (4V / 6V / 8V / 12V batteries, does not matter) or 540Ah or similar 2V cells and connect them in 1 serial string to make up your battery bank.

Reply:

When I was talking to a so called expert in JHB, he advised me not to buy 24 x 2v batteries, as for the occasion where one would go faulty and my complete battery bank would be out of action. His recommendation was 2 or 3 strings in parallel, as to be able to disconnect a certain string when a specific battery fails.

I am really very new in this and would also like to test my theory:

a.  4 x 180ah @12v in series = 180ah x 48v   = 8640w

    4 x 180ah @12v in series = 180ah x 48v   = 8640w

                                                          Total:    = 17280w        360ah x 48v

B. 24 x 360ah @ 2v in series = 360ah x 48v = 17280w

The amount of power available in both the above banks are very similar or not ?

Thanks

 

5 hours ago, superdiy said:

 

 

 

 

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Hi Chris. Yes will post a pic of the DB room when it's finished. I have batteries but I have the system grid tied so batteries only get used as backup when Eskom goes down, my batteries are just to keep the system alive and maybe a few Led lights. I have 4x 100 ah 12v lead Chrystal. Batteries are the weak link so I decided to go minimal. Apparently Lead Chrystal batteries can be discharged to 80% DOD and have many more cycles in them than lead acids.


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On 10/25/2016 at 0:40 AM, Chris Rossouw said:

When I was talking to a so called expert in JHB, he advised me not to buy 24 x 2v batteries, as for the occasion where one would go faulty and my complete battery bank would be out of action. His recommendation was 2 or 3 strings in parallel, as to be able to disconnect a certain string when a specific battery fails.

I am really very new in this and would also like to test my theory:

a.  4 x 180ah @12v in series = 180ah x 48v   = 8640w

    4 x 180ah @12v in series = 180ah x 48v   = 8640w

                                                          Total:    = 17280w        360ah x 48v

B. 24 x 360ah @ 2v in series = 360ah x 48v = 17280w

The amount of power available in both the above banks are very similar or not ?

Thanks

 

Yes, the power available, or in other words the Ah, of both banks are exactly the same.

Except maybe for the redundancy thing there is no other pros to parallel strings, but a lot of cons:

  • If one or more cells in one or more batteries in parallel strings fail, large currents will flow between the strings and the batteries in the string(s) containing the faulty cell(s) will overheat and might even cause a fire or explode - I've had first hand experience, but I was lucky enough to discover it in time and was able to disconnect the faulty string before anything serious happened - it could have been catastrophic if I discovered it minutes later - one of the batteries was so hot I burned myself when I touched it.
  • It is much more complicated and expensive to do battery balancing on parallel strings than with one string.
  • If you are going to connect a battery monitor with midpoint measurement e.g. a BMV702, the midpoint connections needs to be fused between the strings to try to prevent fireworks in case of cell/battery failures.

 

 

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On ‎2016‎/‎10‎/‎25 at 2:48 PM, Neb said:

Hi Chris. Yes will post a pic of the DB room when it's finished. I have batteries but I have the system grid tied so batteries only get used as backup when Eskom goes down, my batteries are just to keep the system alive and maybe a few Led lights. I have 4x 100 ah 12v lead Chrystal. Batteries are the weak link so I decided to go minimal. Apparently Lead Chrystal batteries can be discharged to 80% DOD and have many more cycles in them than lead acids.


Sent from my iPhone using Tapatalk

Thanks Neb

quite interested in your installation as it is very similar to mine. Will appreciate photo's if you can, might just get an idea or two.

 

Cheers

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Regarding cells going bad in a long string: You can take the cell out and convert your 48V string into a 46V string, just adjust the charge voltages slightly, so it won't leave you without power even if a cell goes bad. You can also replace that cell -- forklift people do it all the time -- but it will degrade very quickly to match the rest of the string and you won't get the full life out of it. Still better than replacing the whole thing.

So the redundancy argument seems somewhat flawed to me.

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10 hours ago, plonkster said:


On the farm we ran a 34v bank on a 36v inverter for YEARS...

Sent from my GT-I9195 using Tapatalk
 

I really thought an inverter will only use the battery bank if it is the full 48v or whatever. This is new to me, but thanks

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18 minutes ago, Chris Rossouw said:

I really thought an inverter will only use the battery bank if it is the full 48v or whatever. This is new to me, but thanks

Well, it will shut down a little sooner... :-) The popular Axpert inverter, for example, has a lower limit of 40VDC, which is ample.

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1 minute ago, Chris Rossouw said:

Any experience on what an Imeon 9.12 will do?

I assume the DC cut-off voltage is configurable, as are the charge settings. Lowering all of them by 2V should "just work" (tm). Can't say for sure, but I'd be very surprised if they don't.

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I bought 8 x 12v 180ah batteries already. Superdiy stated above that using 2 or 3 strings of batteries in parrallel could be very dangerous. I contacted the supplier which at first was not very eager to swop the batteries for 24 x 2v cells. Yesterday they agreed to do so , but the pricing is totally out of line. Much more than lots of other 660ah 2v cells on the market. Looks to me I'm stuck with the 12 volts or in for a big surprise!

Questions:

1. Is there anyway I could protect the batteries from excessive heat, possible explosion etc. by means of any device such as fuses etc? In    the event of a single battery going down?

2. If I install a 702 victron monitor system, will this also do the battery balancing or do I need another device. Do they work with all inverters and could I therefore use this with the Imeon 9.12

3. The above devices are they required per string?

Will appreciate it a lot if someone out there can help me with all these unanswered questions.

Thanks

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@Chris Rossouw I quickly scanned the thread and cannot seem to find why you needed to buy so many batteries.

2v batteries are very expensive as you found out. 

The question that should first be discussed: What is the load you want powered from batteries and for how long does the load need to be powered?

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47 minutes ago, Chris Rossouw said:

2 or 3 strings of batteries in parrallel could be very dangerous

That might be overstating it a bit. It really isn't that bad, the telecoms industry does this sort of thing ALL THE TIME. It has drawbacks. A single battery can fail, blow up, etc, but that is why you fuse them properly. The important bit is that you know the drawbacks and work with them.

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the Imeon is an 48v inverter. If not 8 x 12v the other option would be 24 x 2v . Am I correct?

Fact is I have the batteries now and to swop them will be very costly.

I am going to use a hybrid system and should be able to push quite a lot of power during daytime back into the grid, which I hopefully would be able to use during night time.

I use about 2000kw/h per month on the farm, about 7km from town. Batteries will only be for a backup if the sun is not available and the grid is down. My wife and daughter + MIL is many times alone on the farm, I travel a lot! I cannot afford to have no electricity at anytime for 2 reasons. 1. Security and secondly MIL needs oxygen 24 hrs a day and without electricity it becomes a big problem.

In short the background to the system

 

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Or 4 x 12v. ;)

Your need for no power disruption puts a whole new take on the need for batteries.

But let me put it like this. 2000kw/h per month on the farm does not tell me how much the batteries must power in the event of a power failure.

For the higher that load and the longer the period the batteries must supply power, the more expensive the battery bank gets to the point where 2v batteries become a must.

Let me explain.

If you need to power 2000w during a power failure lasting 2 hours on a regular basis, like we had before, letting the bank drain to 50% capacity, having 1 days backup just in case, you will need 4 x 180ah batteries
If you want to go down to max a of 20% DOD, then you need 16 x 180ah batteries.

6 panels just to recharge the batteries.

You can power 4000w for 2 hours per day on 12 x 180ah batteries down to 50% DOD IF there is a power failure, with 1 days reserve - need 14 panels just to re-charge the batteries the next day.

See where I am heading?

 

FWIW: Pushing back into the grid is not a given at all. Maybe a bonus a while, or not, for we have discussed on the forum the issues about feeding illegally back on a meter than may or may not handle that. ;) 

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2 hours ago, Chris Rossouw said:

Questions:

1. Is there anyway I could protect the batteries from excessive heat, possible explosion etc. by means of any device such as fuses etc? In    the event of a single battery going down?

2. If I install a 702 victron monitor system, will this also do the battery balancing or do I need another device. Do they work with all inverters and could I therefore use this with the Imeon 9.12

3. The above devices are they required per string?

Will appreciate it a lot if someone out there can help me with all these unanswered questions.

Thanks

1. One fuse per string and another fuse/breaker between the battery bank and inverter - that is about the best you can do.

2. The BMV702 or similar is only a battery monitor. You'll have to get battery balancers separately. Victron has a simple option, one balancer for every 2 batteries in a string, thus 3 balancers per string of 4 batteries. Then you have to multiply that by the number of strings. Battery balancers are inverter independent.

3. Yes, per string. Some people interconnect each battery in a string and balance the lot with 3 Victron balancers, but then your chances of fireworks are much much more in case a cell in one of the batteries die. The single fuse per string mentioned in 1. above would actually then also be worthless.

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2 hours ago, superdiy said:

Victron has a simple option, one balancer for every 2 batteries in a string, thus 3 balancers per string of 4 batteries. Then you have to multiply that by the number of strings. Battery balancers are inverter independent.

I use a Chinese balancer, think it's called HA-02. Bought two of them from Aliexpress. They work brilliantly, battery voltages differ by less than 0.03V. You need one HA-02 balancer for every 4 batteries. They are about R1000 including shipping (depending on exchange rate). I think Chris here on the forum also uses them.

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1 hour ago, cvzyl said:

I think Chris here on the forum also uses them.

I do. I have the HA01. The HA02 that I could find was more expensive than 3 x HA01s so I went with the HA01s. Money well spent. I wish I had battery balancers before I had batteries so that I could use them from day 1. Next time around I will order battery balancers before I even start shopping around for the other kit.

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