Battery Cable Question

Discussion about the OutBack Energy Cell Batteries
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manerack
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Posts: 3
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My RE system: Canadian Solar CS6P-260P (4 panels)
OutBack FM80-150VDC, MPPT Charge Controller
Outback EnergyCell 106RE (5 batteries)
Xantrex Prowatt SW 2000 Inverter

Battery Cable Question

Post by manerack » Fri Sep 18, 2015 7:58 am

I am configuring a 5 battery (106RE) array in parallel (12V). Can I daisy chain them with 4/0 cable or do I need to connect each to a common bus bar? How long can the total length of 4/0 cable be (battery to DC interconnect box to inverter)? The DC box will have a 250 amp breaker. Thanks.

larrywa
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Battery:48v @ 130Ahr Crown batteries, deep cycle <$380 for 6.25kWh

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Re: Battery Cable Question

Post by larrywa » Fri Sep 18, 2015 9:29 am

manerack wrote:I am configuring a 5 battery (106RE) array in parallel (12V). Can I daisy chain them with 4/0 cable or do I need to connect each to a common bus bar? How long can the total length of 4/0 cable be (battery to DC interconnect box to inverter)? The DC box will have a 250 amp breaker. Thanks.
This is really not a good idea. Each battery will need to be the same brand, age and impedance and eventually one battery will hog all the charge and the others will die.

If you really must I would common both positive and negative at one single point, ie. splitter busbar and run very long leads to each battery in order to get an equal amount of impedance to each bank so that all charging and loading is shared. Large fuses may work somewhat with their built in impedance. Then my DC clamp meter would come out regularly to insure unequal charging isn't happening. PITA.

A diode and resistor array come to mind to insure equal charging and draining but with a 12v system the losses are prohibitive. I wouldn't attempt it.

Is there no way for you to change your system voltage to a higher voltage?

manerack
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Posts: 3
Joined: Mon Sep 14, 2015 10:10 pm
My RE system: Canadian Solar CS6P-260P (4 panels)
OutBack FM80-150VDC, MPPT Charge Controller
Outback EnergyCell 106RE (5 batteries)
Xantrex Prowatt SW 2000 Inverter

Re: Battery Cable Question

Post by manerack » Fri Sep 18, 2015 10:10 am

My inverter has a maximum input of 13v, so I can't reconfigure the batteries for higher voltage.

Vic
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Re: Battery Cable Question

Post by Vic » Fri Sep 18, 2015 10:59 am

manerack wrote:My inverter has a maximum input of 13v ....
I sure hope that the 13 V maximum voltage into the inverter is a TYPO!!

If this is not a TYPO, then, you really need a new, GOOD inverter. My opinions, Vic
4/20/08: 18 Shell SQ 175-106 Vmpp, Stacked 5548 SW+, 1350 AH Surrette 4KS25's, MX-60, Kubota SQ-3250 25 KVA Polyphase Diesel genset. Thanks OutBack for this Forum + the great Support and Service.

manerack
Forum Junior Member
Posts: 3
Joined: Mon Sep 14, 2015 10:10 pm
My RE system: Canadian Solar CS6P-260P (4 panels)
OutBack FM80-150VDC, MPPT Charge Controller
Outback EnergyCell 106RE (5 batteries)
Xantrex Prowatt SW 2000 Inverter

Re: Battery Cable Question

Post by manerack » Fri Sep 18, 2015 12:19 pm

Xantrex Prowatt SW 2000 Inverter

Vic
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Re: Battery Cable Question

Post by Vic » Fri Sep 18, 2015 1:23 pm

manerack wrote:Xantrex Prowatt SW 2000 Inverter
Just looked at the Spec for this inverter, it does say, " input Voltage Range: 10.5 - 15.5 VDC".

Spec:
http://www.xantrex.com/documents/Power- ... 0_2000.pdf

Of course, with any Temperature Compensation for a cold battery can still cause a shutdown, and so on.
FWIW, Vic
4/20/08: 18 Shell SQ 175-106 Vmpp, Stacked 5548 SW+, 1350 AH Surrette 4KS25's, MX-60, Kubota SQ-3250 25 KVA Polyphase Diesel genset. Thanks OutBack for this Forum + the great Support and Service.

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Kurt Lundquist
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Re: Battery Cable Question

Post by Kurt Lundquist » Fri Sep 25, 2015 8:08 am

Here is an informative link on wiring batteries http://www.smartgauge.co.uk/batt_con.html. Someone posted that link in the forum years ago. With 5 batteries you will need to follow method #3. As larrywa points out, the five parallel strings of batteries is not an ideal situation. Inevitably the charge between the five strings will be unbalanced which will lead to pre-mature cell failure. I also agree that having one fuse per string is a good idea. Many manufacturers make fuses that mount right on the battery terminal block for easy integration. You will probably want a 200A fuse for each battery.

If possible I would consider trying to get a 24V inverter instead. You will need one more 106RE battery to make a 24V bank with 3 parallel strings of batteries. The system will operate more efficiently and the batteries should last longer. Also you could easily add two more 260W modules in the future if you want to expand the PV array.

-Kurt
Kurt Lundquist
Renewable Energy Project Engineer
http://alphaenergy.us/

larrywa
Forum Guru
Posts: 354
Joined: Thu Jun 25, 2015 11:25 am
My RE system: FlexPower Two
2 x GVFX3648s,
2 x FM80s,
FNDC w/3 shunts,
Mate3 v3.015.005 (works excellent!)
Hub 10.3,
PV:1000W east@45, 600W west@45, 2400W south@19 deg.
Battery:48v @ 130Ahr Crown batteries, deep cycle <$380 for 6.25kWh

ISY994i HA, Insteon, X10, Philips Hue, MiLight bulbs & RGBW strips
WebControl 8 as weather station stuffing
ISY994 variables via REST interface

Raspberry Pi3 x 2, Pi1 B+

Re: Battery Cable Question

Post by larrywa » Fri Sep 25, 2015 5:18 pm

A few years back when I hooked up my 48v battery bank to be a little safer I took a 200A fuse with the flat blades on each end and drilled a hole in each copper blade. I used one end for the battery terminal connection and the other for the heavy wire.

This would make it safer but also the small resistance in a fuse would help the charge and discharge share the current to each battery cluster.

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