Inverter and batteries

howardb

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So a three-phase supply, with only one phase covered by E/L all using a common neutral bar?
Seems so, and doesn't look right at all. Going to start from scratch and have it connected up properly.
 

Geoff.D

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That is more common than you would expect.

In all the houses I have stayed in (I have mover over 17 times in my adult life) lights, 3 phase stoves and geysers have anormally been left off the EL.

That is not an issue normally. I have the same.
 

Jaws677

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You want his earth leakage to trip all the time?
Then you have a faulty heating element.

I have literally never experienced a problem with a geyser protected on an earth leakage ever on an installation done correctly by the book.

But hey if you want to go against what every single expert on the subject currently say you must do be my guest.

And if you feel it's morally ok to give out advice on the internet that could potentially kill someone following your advice then it's on you.
 

Geoff.D

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Then you have a faulty heating element.

I have literally never experienced a problem with a geyser protected on an earth leakage ever on an installation done correctly by the book.

But hey if you want to go against what every single expert on the subject currently say you must do be my guest.

And if you feel it's morally ok to give out advice on the internet that could potentially kill someone following your advice then it's on you.

The EL requirement for geysers is a new one, Geysers have been in and out of E/L protection a few times. Most houses built in the 70/80's were NOT fed via the E/L, So one can't read this in isolation without verifying when the houses were built and what the regulations were then.
So, please as you seem to have the latest copy of the regulations could you check what the regs say about which regulations were in force at the time the structure was built.

The new concern is about inline water heaters under the counter water heaters in the main ( speaking under correction).
As well as what clause 6.13 states.

Thanks.
 
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Jaws677

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The EL requirement for geysers is a new one, Gyesers have in and out of E/L protection a few times. Most houses built in the 70/80's were NOT fed via the E/L, So one can't read this in isolation without verifying when the houses were built and what the regulations were then.
So, please as you seem to have the latest copy of the regulations could you check what the regs say about which regulations were in force at the time the structure was built.
As well as what clause 6.13 states.

Thanks.
Correct new addition to SANS 10142

Modern elements are much better and don't suffer from leakages.

But by now even on older geyser the element would have been replaced somewhere along the line unless your are extremely lucky.

I'll give a detailed response tomorrow from my Pc
 

Geoff.D

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Thank you very much. But replacing a geyser does not change the wiring. The only MUST is thta on a geyser replacement is that a double pole isolator must be installed, and a separate earth must be provided.
There is also the matter of those properties fitted with ripple relays and how that impacts on the regs, plus the new aspect of a integrated Solar water heating system, especially when there is a pump involved for circulating the water on a sloar installation.
 

Dairyfarmer

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Seems things are going in a lateral direction lately.

I started this thread to deal with a specific situation:
I wanted something that I could run my lights (all led now), tvs, router, etc.

The first step was to work out what I needed. The second step was to source the components. The third step was to install it. And the final step was a real life test. At no stage did I refer to this as a professional instal. That you need to discuss with your certified electrician. This thread is not to discuss whether or not a geyser needs an EL. I have already stated that the geyser is not part of the inverter installation. I have left it, as installed by a certified electrician, as i found it.

I spend time look at at systems that were already in place to see what they had did, why they had done it. The whole point of this exercise was to build a better version of those R8k "back up" boxes you buy at Makro and wire it in permanently. the only difference from the original install was to move certain breakers to a separate isolator and EL. The phase feeding this new isolator is redirected through an inverter.

So if you have concerns about putting an EL on a geyser, please feel free to mention it and start a thread about it. I do find it interesting, but it has nothing to do with this thread.
 

Dairyfarmer

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@Jaws677 and @Geoff.D

Maybe suggest a thread where a typical layout of a DB and where you need isolators and EL's. Then we can see what our DB should look like and those that are upgrading, have an idea of what work is required.
 

Dairyfarmer

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Had a "good" run this weekend with all the load shedding. Worked like a dream. Most of the time I was running less than 0.6kva, I don't think we went over 1Kva. We were not even trying to be careful with power usage. Lowest batteries go were 24.7v. the drop from the floating voltage of 27.7v to 25v was quite dramatic, be then settled down. According to the battery level icon we just dropped to 75% only after 2 hours. It's not easy to judge this as the % differs depending on the load and cell voltage. I think it tries to estimate the remaining power based on the usage.

Recharge was quick and the fan was quiet. Quiet enough to have the inverter in an adjoining room. I've heard noisier pc fans. No sign of heat on the inverter casing, batteries, cables or terminals. Plugging in the laptop and the internal temperature is reported at 58 degrees when the inverter is fully active or charging. Think it drops to 45 degrees in normal utility supply mode.

All in all we had no disruption to our day other than forgetting to set the bread machine to coincide with loadshedding. Even at night the spots were working the whole time. I have decided to not increase the battery bank, but rather replace the batteries at a later stage with better (more expensive) batteries. I'll save up some money every month till I have enough to buy 2 x 12v 200ah gel batteries.

I have decided to also put up some solar panels later in the year if load shedding continues. This will help keep the battery usage as low as possible during the day.
 

Dairyfarmer

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Oh how I am so glad I got everything sorted at the start of the month. kept simulating load shedding to see if everything worked. Then the real thing started.

What worries me now is when we go into Stage 5 and we get a 5:00 block and 2 x 2:30 of load shedding in a day. My batteries will dip below 50% dod in less than 5 hours. Maybe time to get those solar panels sooner.

On solar panels, a friend was asking me about inverters. I suddenly realised that some 3kv hybrid inverters can only accommodate 600w of pv, while others can accommodate 1500w. 600 is fine for a 500w load when the panels are performing at their best. If the load increases to 1000v then you start using battery reserves.

And a final note, what is the feeling on using a battery balancer? Is it worth the R1200?
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Geoff.D

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Do you have copies of the discharge curves for the batteries? That should help you decide in how deep you can allow the DOD to go to. Conventional wisdom states that the DOD should never fall below 20%.
Battery balancing is a technique to ensure that each battery in a string discharges equally. Battery balancing extends the life cycles of batteries. It can pay for itself quite quickly. Battery balancing also helps detect issues you may have with any cabling and connections. So I would go for it, bearing in mind the investment cost of batteries. The more expensive the batteries the more important battery balancing becomes.
 

RedViking

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Oh how I am so glad I got everything sorted at the start of the month. kept simulating load shedding to see if everything worked. Then the real thing started.

What worries me now is when we go into Stage 5 and we get a 5:00 block and 2 x 2:30 of load shedding in a day. My batteries will dip below 50% dod in less than 5 hours. Maybe time to get those solar panels sooner.

On solar panels, a friend was asking me about inverters. I suddenly realised that some 3kv hybrid inverters can only accommodate 600w of pv, while others can accommodate 1500w. 600 is fine for a 500w load when the panels are performing at their best. If the load increases to 1000v then you start using battery reserves.

And a final note, what is the feeling on using a battery balancer? Is it worth the R1200?
View attachment 635508
How much can your inverter support?
 

Dairyfarmer

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Anyone know why the mid point negative poles are bridged? And doesn't this affect the voltage of each string of batteries?
 
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Dairyfarmer

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As was discussed in load shedding whats needed to keep watching I do need to add in how to calculate the battery pack you need

volts x Ah / watts / dod x 0.85

Volts is the battery. i.e 12, 24 or 48v
Ah is the Ah of the string, i.e 102, 105, 2000
watts is your load, i.e. 1500w
DOD = depth of discharge. 2 = 50%, 3 = 33.3%, 5 = 20%
2 is to account for a maximum target of 50% depth of discharge of the batteries
0.85 is the efficiency of the inverter, i.e loss due to converting ac to dc to ac and maintaining float charge in batteries

So in my case:
I have 4 x 12V 102Ah batteries in series and parallel making a total of 24v and 204Ah.
My load is around 500w but can go up to 1500w

24 x 204 / 500 / 2 x 0.85 = 4h10m
24 x 204 / 750 / 2 x 0.85 = 2h45m
24 x 204 / 1000 / 2 x 0.85 = 2h05m
24 x 204 / 1500 / 2 x 0.85 = 1h25m

(edit: type the equation into a calculator as written from left to right. Although the order doesn't matter as long as you don't start with one of the dividers, in which case you need to start with 1/divider.....)

So if I am running at 750w I can easily get 2h30m, or one load shedding block. I have yet to break 500w (without the fridge) average during load shedding and this reflects in the battery level indicator after 2h15m load shedding only dropping 25%. I'm about to install a new plug point for the fridge that will be on the inverter side of the db board. This will add 300w when the fridge is actively working and an average of 100w at idle. I have made this decision to preserve the fridge motor rather than as a need to keep the fridge working during load shedding.
 
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The_Traveller

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Aug 9, 2008
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Do you have copies of the discharge curves for the batteries? That should help you decide in how deep you can allow the DOD to go to. Conventional wisdom states that the DOD should never fall below 20%.
Battery balancing is a technique to ensure that each battery in a string discharges equally. Battery balancing extends the life cycles of batteries. It can pay for itself quite quickly. Battery balancing also helps detect issues you may have with any cabling and connections. So I would go for it, bearing in mind the investment cost of batteries. The more expensive the batteries the more important battery balancing becomes.
What kind of battery balancer would you recommend ? Please link the specific component . Thanks
 
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