battery question

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lived666

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Received my 3000watt UPS inverter today.
Now I need some batteries. It is a 12V-220V inverter, should I get 102 AH 12V batteries or 122AH 6V batteries and criss cross them so they 12V - the 122AH 6V cost about R1100 and the 105AH 12V around R1600.
I know jack **** about this stuff
 
3000W ? From 12 V? That doesn't sound right. Normally inverters over 1kW tend to have higher input voltages - like 24 V or 48 V.
 
greg_SA said:
3000W ? From 12 V? That doesn't sound right. Normally inverters over 1kW tend to have higher input voltages - like 24 V or 48 V.
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what do i know, they asked if I want 12v, 24v or 48v, I said 12V and its definitely 12V its got the pretty dials and what not that shows 12V. Anyhow with regards to battery....
 
I would go for the 12V but i do not have experience with inverters .
Is this an on grid or off grid inverter ?
The charger is very important with regards to how long the battery's(especially deep cycle) last as mentioned by some one on a previous post .
 
Last edited:
Go with the 12v batteries in parallel - having multiple 6v batteries in a series/parallel configuration adds complexity and introduces challenges if one of the batteries fail. This obviously depends on affordability and how big the battery bank would be.
 
quovadis said:
Go with the 12v batteries in parallel - having multiple 6v batteries in a series/parallel configuration adds complexity and introduces challenges if one of the batteries fail. This obviously depends on affordability and how big the battery bank would be.
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cool, thanks. didn't think of a failure, so yeh 12v

anyone know of a decent supplier jhb/pta areas?
 
lived666 said:
Received my 3000watt UPS inverter today.
Now I need some batteries. It is a 12V-220V inverter, should I get 102 AH 12V batteries or 122AH 6V batteries and criss cross them so they 12V - the 122AH 6V cost about R1100 and the 105AH 12V around R1600.
I know jack **** about this stuff
Click to expand...

considering you will have to buy 2 6V and connect them in series to make it 12V (with AH remaining at 122) might as well by 1 12 for now, you can then later buy a second 12V connect it in parallel and up the AH (I think? )
 
lived666 said:
Received my 3000watt UPS inverter today.
Now I need some batteries. It is a 12V-220V inverter, should I get 102 AH 12V batteries or 122AH 6V batteries and criss cross them so they 12V - the 122AH 6V cost about R1100 and the 105AH 12V around R1600.
I know jack **** about this stuff
Click to expand...

Just curious...what brand and where did you purchase the UPS?

Thanks
 
The problem with a parallel set up is that one battery will tend to deliver the current over the other and worse since no two batteries are the same one might actually discharge the other. If you do go this route link the batteries +ve to +ve and -ve to -ve but make sure that you take your load positive from the one battery and the negative from the other. If you have two batteries of the same make and age as well as having a constant float charge this probably won't amount to a problem.

The advantages of using the batteries in series is that it is in essence just making the battery bigger by combining cells in series. I've also been told that 6v batteries tend to have thicker plates and therefore last longer but thats just what I've been told, probably an american thing derived from golf carts or something. But isie is right in that if one battery goes at least you have a backup whereas if one battery goes in a series connection you are out of the game until you replace it.

Just remember that the 2x105 12V @ 12V = 210ah or 2520Wh or R15.23 per ah (1600*2/210)
2x122ah 6V @ 12V = 122ah or 1464Wh or R18.03 per ah (1100*2/122)

So it may be slightly more expensive to buy the 12v once off but you're actually saving per amp hour.

BTW, where are you getting your batteries and what type are they? Battery centre sells deep cycle silver calcium 105ah batteries for just under R1.5k.

Lastly just make sure that your DC side of the inverter (the battery links and the load connection) has decent size cables and you keep them as short as possible since it is a 12V system. Using 3000W on 12V equates to drawing 250 Amps through those cables. Even with thick cables, make sure they aren't heating up too much. To give you and idea, if you geyser is 2200W (pretty typical size) its only drawing 10amps when in use so 250 amps is not a small amount of current.
 
When I asked for a 3kw 12v system , supplier said I 'have to' use 250Ah batteries .
 
Your batteries have a discharge rate which is related to the capacity which is why they would recommend that.
 
Need to add nothing here. Mybb have covered all angles. Well done for once.
 
contrastflash said:
BTW, where are you getting your batteries and what type are they? Battery centre sells deep cycle silver calcium 105ah batteries for just under R1.5k.
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I called 3 different branches and they all Quoted over R2k?

If I start with 2 102AH batteries what kind of power/wattage will I generate and for how long?
 
contrastflash said:
If you do go this route link the batteries +ve to +ve and -ve to -ve but make sure that you take your load positive from the one battery and the negative from the other.
Click to expand...
Now I connect +ve to +ve and -ve to -ve both with a really massive copperbar or similar why should it matter where I connect my load? Won't a dedicated seperate point where one, two or more batteries are connected to and there goes the load too be better, alone for being able to remove/disconnect one battery easily so needed?
 
I spoke to someone who told me to look out that the batteries are not HD or HC as in High cycle and not deep cycle, which is cool, I almost went to go and buy what would have been high cycle - anyhow going to get some Enertec Deep cycles on Monday for R1386 ex vat or R1580, that's the best I can find for a brand name with 2 year warranty:
http://www.rgsbatteries.co.za/
 
lived666 said:
I called 3 different branches and they all Quoted over R2k?

If I start with 2 102AH batteries what kind of power/wattage will I generate and for how long?
Click to expand...

Hi, typically with a deep cycle battery you don't want to discharge past 50% so 2x102x0.5=102ah worth of use, multiply by 12 = 1224Wh ie. you can run something which draws 1224 watts for an hour, or 612 watts for 2 hours etc.

you'll probably average a load of about 600 watts (lights, tv etc) so it'll get you through the typical load shedding stint

EDIT:

I stay in Secunda, the local battery centre charges R1450 for a 105ah First National Battery brand, ask them for a discount?
 
sovielenamen said:
Now I connect +ve to +ve and -ve to -ve both with a really massive copperbar or similar why should it matter where I connect my load? Won't a dedicated seperate point where one, two or more batteries are connected to and there goes the load too be better, alone for being able to remove/disconnect one battery easily so needed?
Click to expand...

The idea is that you distribute the inter-battery connection's resistance to prevent the connection's wire/bar resistance (no matter how small) from making one battery deliver more current than the other. It's recommended practice, whether you choose to do it or not is totally up to you.
 
contrastflash said:
I stay in Secunda, the local battery centre charges R1450 for a 105ah First National Battery brand, ask them for a discount?
Click to expand...

asking for a discount could be my middle name........didn't work, though they didn't have that brand.
Anyhow great info all round, muchas gracias!
 
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