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Author Topic: Battery Bank  (Read 8097 times)
tz0c0s
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« Reply #15 on: March 03, 2011, 05:24:07 AM »

Outtasight,
   I have tried the switch the freezer off thing to push energy use into economy 7 periods, sort of the opposite of you. After pushing my luck too far & experiencing the wraith of SWMBO, I have for the moment taken a break, she thinks.

This leads me to recalling the "chest fridge", made out of a chest freezer. Probably a good thing to do & could help you to use less power through the night.

Regards Andy
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Justme
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« Reply #16 on: March 03, 2011, 09:25:59 AM »


This leads me to recalling the "chest fridge", made out of a chest freezer. Probably a good thing to do & could help you to use less power through the night.

Regards Andy

In that instance it will make no difference (unless you are a secret lemonade drinker). Its only a factor when the door is being opened & all the lovely energy (cold) falls out the bottom.
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Navitron solar thermal system
30 x 58mm panel 259L TS
1200watts solar 120vdc
FX80 Solar controller
Victron 12v 3000w 120a
6kva genny
6 x 2v cells 1550amp/h 5C
24 x 2v cells 700amp/h 5C
Total bank 4350 amp/h 5C
tz0c0s
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« Reply #17 on: March 03, 2011, 10:35:38 AM »

My understanding was due to the increased temperature differential, a freezer had a more effectice level of insulation. This would help night & day with energy usage. The door being on top I agree would have no increased benefit overnight.

You are old enough to recall R.Whites  Smiley Me too.

Regards Andy
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Justme
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« Reply #18 on: March 03, 2011, 12:55:40 PM »

You could be right about the insulation factor. But then how often does a fridge come on over night any way?
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Navitron solar thermal system
30 x 58mm panel 259L TS
1200watts solar 120vdc
FX80 Solar controller
Victron 12v 3000w 120a
6kva genny
6 x 2v cells 1550amp/h 5C
24 x 2v cells 700amp/h 5C
Total bank 4350 amp/h 5C
Billy
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« Reply #19 on: March 03, 2011, 03:44:07 PM »

Quote
how often does a fridge come on over night

Mine comes on quite a lot actually.  The ambient room temperature is around 22C and even when the door is not opened it does a 2 minute cycle about every 12 or so minutes night and day.  It is a LEC model 24volted by Shoreline and I don't think the case is very well insulated and the door seals are always a weak point.

billy

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profp
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« Reply #20 on: March 03, 2011, 06:41:17 PM »

Quote
how often does a fridge come on over night

Mine comes on quite a lot actually.  The ambient room temperature is around 22C and even when the door is not opened it does a 2 minute cycle about every 12 or so minutes night and day.  It is a LEC model 24volted by Shoreline and I don't think the case is very well insulated and the door seals are always a weak point.

billy

 Grin
Get a new one then - seriously. Inverter + relatively inexpensive 240v A+ rated fridge will be hugely more efficient if it's cycling that frequently. I'd measure the duty cycle of mine, but it'll be a month or two before we're in the 20's :-)
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eabadger
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« Reply #21 on: March 03, 2011, 07:24:34 PM »

Regarding the battery bank and discharge, I get confused, as my Exide manual for my new batteries states that a “cycle” is classed as any recharge cycle, and not to recharge unless required.
The batteries are forklift type, and instruction base each discharge as 80% so 20% remaining, this they say will give 1500 cycles, at full capacity?
But the document infers that charging at 50% will still only give 1500 cycles, they base battery decay on recharge and not discharge, hence the term deep cycle?
I appreciate that some “leisure” type would best be kept almost full, but on big proper banks?
The cells I now have are rated at 840a at c5 rate, so I assume given my usage will not be so drastic as c5 I could get close to 1000a ?? but assuming 840 in a 24v bank that should achieve 20,160w. any thoughts?
But with my 110a charger this will take a long time to put back in, by the way the 110a charger is what was supplied with the battery bank.
So we are putting a Kw of solar on bank and 1Kw wind turbine, float charge them if nothing else.
But going back to first part of post, get usage down, on grid we are using 18kw per day, aiming at 6kw maximum off grid, but last week off grid saw 6kw used in two hours! Education to the family required, but the deep fried chips were great, and have now put used cooking oil back in the system.

steve
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1600w PV main array at 24v, excide 2v 1000a forklift cells now x 2, 320w PV secondary array at 12v. Enfield 1944 ex RAF 5.6kw diesel genset (now in pieces, big ends gone), Petter AC1 28v diesel charging set at 2.8kw.
1kw wind turbine.
26kw wood stove back boiler to underfloor heating and dhw
Justme
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« Reply #22 on: March 03, 2011, 07:32:20 PM »

Chip pan is prob about 2kw. You would only need it on for about 20 mins & some of that it will be off due to the stat.

So prob about 0.5kWh actually used. Unless they put the fryer on when they start cooking & leave it on till needed.


As to the cycles. I was told that a part cycle was just that. So you could get double the cycles at half the DOD. Or half the cycles at double the DOD.
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Navitron solar thermal system
30 x 58mm panel 259L TS
1200watts solar 120vdc
FX80 Solar controller
Victron 12v 3000w 120a
6kva genny
6 x 2v cells 1550amp/h 5C
24 x 2v cells 700amp/h 5C
Total bank 4350 amp/h 5C
eabadger
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« Reply #23 on: March 03, 2011, 08:20:06 PM »

We had chargers and heaters/imersion on as well, I have fitted KwHr ampy meter to the diesel generator, so was monitoring usage, about 2kw of chargers and a couple of oil radiators, try and run genset at near capacity to stop bore glazing.
Excide seem specific about charge cycles, I am try to upload document, it even advise about charging forklift in lunch hours, or other odd times, fit the correct battery and recharge once a day, even the warranty gives these details.
It states battery decay happens due to charge cycle.
I will keep trying to upload.

I forgot to take in to account the 80%dod when doing my sums above, so battery capacity about 16Kw at C5 rate, but no way will we be discharging at 160amphr very often, if ever.
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1600w PV main array at 24v, excide 2v 1000a forklift cells now x 2, 320w PV secondary array at 12v. Enfield 1944 ex RAF 5.6kw diesel genset (now in pieces, big ends gone), Petter AC1 28v diesel charging set at 2.8kw.
1kw wind turbine.
26kw wood stove back boiler to underfloor heating and dhw
EccentricAnomaly
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« Reply #24 on: March 04, 2011, 09:48:08 AM »

The cells I now have are rated at 840a at c5 rate,

840 Ah

Quote
so I assume given my usage will not be so drastic as c5 I could get close to 1000a ??

1000 Ah

Quote
but assuming 840 in a 24v bank that should achieve 20,160w. any thoughts?

20,160 Wh

Quote
I forgot to take in to account the 80%dod when doing my sums above, so battery capacity about 16Kw at C5 rate,

16 kWh

Quote
but no way will we be discharging at 160amphr very often, if ever.

160 amp

Both the amp and the watt are units for measuring the rate of transfer of charge and energy, respectively. There are standard SI units for those quantities: coulombs for charge and joules for energy so an amp is 1 C/s, a watt is 1 J/s, a coulomb is 1 As (amp·second) and joule is 1 Ws (watt·second). These quantities are quite small, though, so it is common to use the amount of charge or energy which would be transferred in a hour at the unit rates as the unit of quantity. An Ah is the amount of charge which would be transferred in an hour (3600 seconds) by a current of 1 A so it is 3600 C. Similarly, a Wh is 3600 J or 3.6 kJ and a kWh is 3'600'000 J or 3.6 MJ.
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eabadger
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« Reply #25 on: March 04, 2011, 11:51:49 AM »

do i have to do lines?

Maybe we or rather you could campaign battery manufactures to list all energy values in joules, make it better?

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1600w PV main array at 24v, excide 2v 1000a forklift cells now x 2, 320w PV secondary array at 12v. Enfield 1944 ex RAF 5.6kw diesel genset (now in pieces, big ends gone), Petter AC1 28v diesel charging set at 2.8kw.
1kw wind turbine.
26kw wood stove back boiler to underfloor heating and dhw
Billy
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« Reply #26 on: March 04, 2011, 12:15:11 PM »

No lines Steve, just an hour in the naughty corner.   facepalm

He's right of course but we know what we are trying to say don't we, it's just that we say it wrong innit blad.

billy

 Grin Grin Grin
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EccentricAnomaly
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« Reply #27 on: March 04, 2011, 04:36:49 PM »

do i have to do lines?

There's no need for sarcasm. I was just correcting a minor slip which would tend to spread and reinforce a common confusion. It's worth trying to get it right because it's quite common for posts to be a bit ambiguous and doubt about the correct use of units only adds to uncertainty.

Quote
Maybe we or rather you could campaign battery manufactures to list all energy values in joules, make it better?

In a way it would be better as many people do seem to have a bit of difficulty with the idea of amp-hours and watt-hours.
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eabadger
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« Reply #28 on: March 04, 2011, 05:14:09 PM »

Look, mistakes are made, I should not have made the mistake given my job, but we know what (watt) we mean, sloppy maybe of me.

However we do all make mistakes, the correct way of indication kw x hour is in fact
Kw•h

Not Kwh

And A•h not Ah.

The SI is clear on that, which is why I shouldn’t have got this wrong, as ratified by IEEE. Wont be able to hold my own at the next dinner do.

Hours over now, out from the corner.
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1600w PV main array at 24v, excide 2v 1000a forklift cells now x 2, 320w PV secondary array at 12v. Enfield 1944 ex RAF 5.6kw diesel genset (now in pieces, big ends gone), Petter AC1 28v diesel charging set at 2.8kw.
1kw wind turbine.
26kw wood stove back boiler to underfloor heating and dhw
Billy
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« Reply #29 on: March 04, 2011, 07:10:45 PM »

 Grin
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