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Looking for some battery and inverter advice


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I have installed and connected a few generators (5-150 kva) and a few inverter/battery backup systems... single and parallel... mainly as side line jobs.

I got a call from a customer because there was a really bad rotten egg smell in the house ...they pin pointed the source to the batteries in the passage cupboard ... the batteries had popped and were leaking from the terminals and the seal around the top of the battery... the installation was done by a company which specialises in solar inverter systems...the batteries are 100 amp/hr enertec lead acid deep cycle batteries.

I informed the customer that it is not a good idea to have 3 inverters and 12 batteries in the cupboard in the middle of the house... so i disconnected and removed the entire system...from the cupboard...the plan is to build a room on the side of the house  for system which will have adequate ventilation.

We took the batteries to the local battery shop and had all 12 batteries tested... only  2 batteries did not pass the test done at the battery shop ...however most of the batteries showed signs of damage at the terminals and some around the seal at the top...all the batteries were at 12.8 volts and still warm.

The batteries are 5 years old ...some would say they have served their time and its time to retire.

I took  4  best batteries and 1 of the inverters and connected them to a couple of plugs and lights and plugs...load shedding kicked in and the system managed to last 1:50 minutes and shut down at 11 VDC...the inverter indicated the batteries were charging and all seemed ok... 10 am the following morning ...the rotten egg smell was present ...so i went to site and removed the batteries and temp connection... we are going to invest in 4 new batteries so that we can get a temp. connection for the computer sand a few lights.

The questions:

What causes the batteries to overheat like this ...because they are old ...or the inverter is faulty and overcharging the batteries?

If it is the batteries please explain in detail how and why this happens ...what safety measures can be put in place to prevent this in the future. 

Which batteries you would recommend (taking cost into consideration ...24 batteries cost a pile of cash.) 

Can you equalise the batteries using the 5 kva RCT inverter (48 VDC)... i have another site with 1 x 5 kva inverter with 8 enertec lead acid batteries to 2 banks  made up of 4 batteries in each bank to make 48 VDC.

Where could i find the best settings for the inverter for the enertec 100 am/hr lead acid... bulk charge ...float etc or is it better to just leave the setting "flooded" 

I have had time to read through the forum or search for this info ...so if there is already a thread with the info please attach the links. 

 

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23 hours ago, isetech said:

Can you equalise the batteries using the 5 kva RCT inverter (48 VDC)

There are several models that fit that description. The latest models have a 64 V option, allowing a battery voltage of up to 64 V, while the inverter is still running. That means you get a poor sine wave when the battery voltage is low, however. Older models will not have the 64 V "feature", and will not have equalisation settings.

23 hours ago, isetech said:

the system managed to last 1:50 minutes and shut down at 11 VDC.

That isn't doing the batteries any favours. You need to learn about the limitations of lead acid batteries, and how to give them a decent chance at moderate life.

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I took the batteries to the battery shop to get tested ...5 of the 6 batteries  i took to the battery shop passed the test using a DHC battery system analyzer...good pass for all the tests.

So not convinced I requested a load test using the hawkins battery tester. ... 1 of the 5 batteries was still in the green at 105 amp test ...the other 4 were sitting on the fence between the green and red on the analog volt scale.

According to the spec sheet (I found when i got back to the workshop)for the enertec model 674D the load test is 315 amps for 15 seconds (above 9.3) All the batteries would have failed.

One of the staff members at the battery shop indicated that the battery felt like it was empty... so off to the scale we went... mass 23.7 kg (indicated in the spec sheet) the batteries we were testing ...between 21.5 and 22.5 kg.

The spec sheet indicates under grid design - Battery expected design life in a UPS application between 3-5 years under correct operation conditions...the batteries have a date stamp 08/2015. 

I have one of the batteries connected to a hawkins auto pro 10 to see how it will respond to the hawkins charge ...i dont expect the current to drop to zero... I am hoping to see the battery still charging tomorrow morning and hot... which will set my mind at rest indicating they are fubar and all 12 can be laid to rest.

What to do with the batteries... the battery shop is offering a R400 discount on their batteries if we swop out old with new... not sure what the scrap yard will offer for the lead in the battery ...will find out tomorrow. 

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To add to my monday blues... i connected the axpert 5 kva inverter as a single unit to 48 VDC battery bank to test the unit output with no load connected ...the screen switched on ...indicated 51.5 VDC ...after about 2 seconds i heard a buzzing sound ... them poof and smoke appeared out the vents ...i opened up the unit and noticed all the MOV's blown on back left side of the inverter.

Anyone know what could have caused this?

If the unit was running and a heavy load was applied to the output ...could that damage the unit?

 

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1 hour ago, isetech said:

To add to my monday blues... i connected the axpert 5 kva inverter as a single unit to 48 VDC battery bank to test the unit output with no load connected ...the screen switched on ...indicated 51.5 VDC ...after about 2 seconds i heard a buzzing sound ... them poof and smoke appeared out the vents ...i opened up the unit and noticed all the MOV's blown on back left side of the inverter.

Anyone know what could have caused this?

If the unit was running and a heavy load was applied to the output ...could that damage the unit?

What is the age and history of this inverter?

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The inverter is about 4 -5 years old ...it is one of 3 which were connected in parallel been working without any issues...suddenly the batteries became a problem on Friday last week...really bad rotten egg smell and overheating.

I removed the entire system ...connected 1 inverter to 4 batteries on friday night as a temporary measure to keep the computers working...saturday morning the 4 batteries started overheating so i disconnected the input and output and switched from the inverter with batteries only connected.. it made a buzzing sound after a couple of seconds on switching on.

Bought it back to my workshop set it up with 4 batteries...input and output connected (made sure it was connected right) switched on.

The fault light came on the screen was dim and as it clicked on bang ...smoke out the vents on the side.

opened it up and noticed the big Movs are blown.

 

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Full marks for managing the situation! 

As an electronics tech I can assure you that not all electronic equipment does the same workload. A radio receiver or calculator doesn't work hard at all!

When you are dealing with power electronics (inverters, VSDs or power amplifiers etc.) these devices work hard. The components are having to switch high voltages and currents for long periods. This stresses the power components and will have an effect on the life of the device.

There might be a reason why the inverter failed but maybe it was at that point where it was ready to fail (call it old age or whatever) but it's possible that it's as simple as this...

 

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As expected the hawkins autopro 10 is still sitting at 9 amps and the battery is hot and smells ...i am now convinced the batteries are ready to retire... i am not even going to bother connecting a small load to check how long it takes to discharge.

Now i just need to find someone in Durban to look at the inverter. 

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On 2020/02/09 at 1:50 PM, isetech said:

We took the batteries to the local battery shop and had all 12 batteries tested... only  2 batteries did not pass the test done at the battery shop ...however most of the batteries showed signs of damage at the terminals and some around the seal at the top...all the batteries were at 12.8 volts and still warm.

The batteries are 5 years old ...some would say they have served their time and its time to retire.

I took  4  best batteries and 1 of the inverters and connected them to a couple of plugs and lights and plugs...load shedding kicked in and the system managed to last 1:50 minutes and shut down at 11 VDC...the inverter indicated the batteries were charging and all seemed ok... 10 am the following morning ...the rotten egg smell was present ...so i went to site and removed the batteries and temp connection... we are going to invest in 4 new batteries so that we can get a temp. connection for the computer sand a few lights.

I'm sure you're aware of the trap here, but did you make sure these are deep cycle batteries? They look like car batteries, but they aren't and, AIUI, would require a different test.

I'm struck by the last paragraph I quote. My neighbour bought an inverter at Builder's Warehouse and then went to a local Mom and Pop store for batteries. They put car batteries in. He recently told me that the thing was useless, that he got only a few minutes out of it. I told him I used to get hours out of mine and recommended that he go to a specialist store (Maiden Electronics in Midrand, and I don't get any kickbacks from them) and get proper deep cycle batteries. I explained to him that car batteries (which said shop had fitted) are built to give a big but short burst, whilst deep cycles give less momentary power but for much longer.

He is now happy as a pig in the proverbial and his inverter gets him through a Joburg load shed with no trouble at all.

But irregardless of battery type - at 5 years those batteries have had their chips.

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I wouldnt say they all completely poked ...they could still be used to run my trolling motor on my kickboats for another year or 2  ;)

I am sure they are the right thing ...I have used deep cycle batteries for my bass boats and kickboats since 2000.

The batteries are enertec 674D 105 amp/hr premium heavy duty deep cycle batteries.

Scrap yard offering R8.50 per kg ...the battery shop R3- 400 per battery if swapped out ... had to laugh at the sales guy ...i call on Saturday ...he offers me replacement lead acid batteries at R1700 with a replacement battery... when i take the batteries to get tested i dont tell him i called on Saturday ... ask for a price to replace ...he offers me the batteries at R1850 because i am an installer ...so i ask him if that is without batteries ...his reply no installer price including batteries... I just smiled and walked away. 

 

 

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Some feedback from the person looking into the inverter...it seems a cap popped and the voltage ramped and boom it is in sy moer in ...another R11 k plus the batteries ...thanks eeeeeiiiishkom ...another R40-R50 K if we go the cheap battery route :(

I am too nervous to test the other 2 inverters. ...and still the big question did the inverter over charge the batteries and destroy them or where the batteries just old and needed to be replaced. ..i suppose we will never know.

So how bad is this load shedding...collected some goods at a wholesaler today  12 pm the power comes back on and booooom ...you hear loud noise from the back of the building and only half the lights switch on ...computers and everything nothing ...one phase blew. 

If you selling generators...solar panels...inverter panels etc etc ... you smiling all the way to the bank ...if not and you run production lines and have staff sitting around because you cant afford a ! million plus generator and the running cost...lets see how many small businesses are going to survive.

For most of us its actually a pleasure to have 2 hours of quiet time.

America has a fall out with China... suddenly people in China are sick and the economy is taking a massive hit... We have products in China ...suddenly communication has gone quiet....how is this going to affect the prices ...you cant buy inverters for example directly from China at the moment...but you can get inverters from Italy ...but they dont ship to SA. 

America scratches in everyone's salad ...nobody is allowed to scratch in America's salad.

 

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I decided to knock the top plastic cover off the enertec maintenance free battery and have  a look inside... as expected the water level is low ... the battery is still fully charged after all this time. 

I have been trying to find someone to look at the RCT inverter ...got hold of Rectron (RCT) they are not interested ....unless i have proof of purchase from them and the unit is still under warranty ...not interested as they do not do repairs.

So i contacted Mustek who supply the meccer unit ...very helpful ...they also have technical people who do repairs to the units under warranty ...but because this unit is not a meccer the person gave me a number for a company who handles out of warranty repairs.

This is certainly going to help make a decision on which unit to purchase in the future... i wouldnt even consider Rectron unless their price is half that of mustek. 

Meccer ...RCT same thing just a different name.

 

 

 

 

 

 

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Something to consider ...Apparently kodak inverters  have a 2 year warranty ...if the unit is faulty during the warranty period ...they will collect the unit form the site...courier it to their service centre and repair it ...and apparently they carry spares for their units which i am told are made up of both solis and voltronic components... making it a better option ...as i mentioned ...this is all hear say ...i can only rely on information shared from distributors....that is why apparently is used frequently

It seems that everyone selling inverters are experts. 

 

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Been spending hours doing research into solar ...inverters and batteries... something i thought was a smart idea ...the person had taken clear PVC tube... fitted it to the breather outlet of his lead acid batteries and run it outside the building...especially if you have no option but to install lead acid batteries in a confined space.

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I see bluenava have just launched their Racpower solution... BN52V-100-5,2K

A rack or wall mounted option (compatible with victron peripherals) 

As i learn more and more about inverters and batteries ...this is certainly gona be an option i will be looking into.

Until recently i just couldnt see  why people would throw hard earned money at these expensive options...however as the systems i work on get older and older ...i am seeing the consequences of using lead acid and cheap inverters... you may be saving in the short term ...and if that is all you looking for ...it certainly is way cheaper ...however 3 x R11 000.00 and 12 X R2000 plus plus plus ...in the long run its gona bit you. 

IF you are installing a quick short term solution and only plan to spend  around R 10 000.00  ...understand that it is only going to be a 3-5 year plan...it is about what people are getting out of their cheap systems.

However it is not that simple...most of these cheap systems are not maintenance free ...you cannot just leave the unit in the cupboard and forget about it until the next round of load shedding ...just like the generators ...it requires route startups ...it requires draining the fuel when there is a pause in the laod shedding... you cant just leave the unit in the cupboard and forget about it... you must fully charge the battery and disconnect it and then make sure you check how long it takes to discharge.

 

 

 

 

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