Author Topic: battery options  (Read 14945 times)

Offline ronman

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battery options
« on: June 19, 2019, 05:33:02 PM »

3 YouTube links I thought that may be useful to people wanting to expand their UPS or inverter power delivery
You welcome to add if you have more

Just remember to add the necessary fuse and breaker switch of sorts between the batteries and the inverter / UPS after you wired your batteries


Offline chrisc

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Re: battery options
« Reply #1 on: June 19, 2019, 06:23:51 PM »
The first and third discussions were very useful.  The second not so.  Read on though

I had 8 x 12 volt lead-acid batteries connected in series to provide 24 volts.  They are also charged using a MPPT inverter powered by 8 x 3000 watt PV panels.   Worked ok, and I managed to exchange 2 of the batteries under warranty with Communica after a series of arguments with their management who I discovered bend over backwards not to honour warranties

In March I got two Blue Nova 24 volt Lithium-ion batteries and connected these in parallel.   Within 3 weeks one battery was showing "COM failure" and measuring it, it discharged at a much greater rate than the other.

I then found the BN staff ill-informed as to what to do.  The booklet that accompanies the batteries refers to a LAN connection to balance them.   There was no LAN connection which I noticed when collecting them and I was told that this facility was disabled as it was unnecessary.   The fellow who initially dealt with my complaint had no idea about this and talked about "load balancing" but did not know how to do it and asked me whether it was not described in the book (he had no idea).  He insisted that there should be a LAN connection and carried on about it until I suggested he speak to his boss

After 10 days of messing about I sent a strongly-worded email to the CEO.  His immediate response was to offer me a brand-new unit with double the capacity which would have cost R11500 extra, for R6000.  It also has a 10-year warranty and I insisted on a written guarantee explanation

I let the new battery settle down for 10 days and tested it.  With a 350 watt load at 230 volts (14 amps at 28 volts from the battery), it dropped from 99% state of charge to 60% state of charge in 14 hours.   

To my mind this is amazing performance.  It has been sunny in Cape Town these past 2 days and the battery reached 98% state of charge by 15h45 today.  For the test I configured it to charge from PV panels only, not mains.  But to enhance battery life I usually let it charge from the mains.  The real purpose of the system is for load shedding, although there has been a welcome reduction in electricity charges

I am not that keen on batteries in series without a sophisticated charge controller, having had indifferent performance due to one battery in a set failing.
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Offline ronman

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Re: battery options
« Reply #2 on: June 20, 2019, 09:15:30 AM »
Thanks for the input Chrisc. Sounds like some headaches and some victories there.

I have two 24v UPS's and three 96v UPS's. I was reviewing the APC Pro series range of UPS's which offer a separate matching battery tower for extended power use and this got me into looking at increasing battery capacity on my own UPS's, as well as conservation of these batteries. It is somewhat frustrating when you chat with suppliers and they don't know their own product. 

From what I learnt some form of lithium ion is ideally the way to go, but for most the collective price tag is a killer. Example a 7.2Ah 12v battery costs about R2300 here in Durban. Do I swap out 8 batteries per UPS for lithiums before I even look at extended battery banks, just so I have a more reliable battery for loadshedding (which currently hasn't happened in this neighbourhood since elections), or buy a silent generator which I can get for less than the combined battery costs. At the moment I'm leaning toward a generator. Not rushing into either choice.