Matching VFX3524M and Battery Specs

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Matching VFX3524M and Battery Specs

Postby Woodman9 on Fri Jun 01, 2012 6:26 am

I need technical help understanding some basics. Specifically I want to know our charging configuration settings and also how to know that batteries are sufficiently charged. Here is my configuration on our houseboat:

Outback Inverter: VFX3524M

Batteries: 16 Lifeline GPL-6CT Gel Cell Batteries
Battery Specs:
Nominal Voltage: 6 Volts
Amp Hour Cap @ 20 hour rate: 300 amp hour
Recommended Charge Voltage: Bulk Charge 7.10-7.30volts, Absorption/Acceptance Charge 7.10-7.30 volts, Float Charge 6.55 - 6.70 volts

I watched the "FX Charger Set Points" training video on your website and saw that the amps made available to the charger was 14.0 aac. I assume this is sufficient for our configuration above? I don't know. Next I see "Absorb Setpoint" set to 26.6vdc. I have no way of knowing if that number is correct for my batteries based on the above battery specifications. What should this value be set to? Next I see "Absorb time limit" at 1.0 hours. I have no idea if this is right or not. Next I see "Float Setpoint" at 25.6vdc. I suppose with all of this I should call the battery manufacturer???

A bigger issue I have is I DON'T KNOW AT WHAT POINT THE BATTERIES ARE CHARGED. I assume that the "Status" section of the Mate should tell me how charged the batteries are? Am I looking for a voltage value? What am I looking for to know how charged or discharged our battery bank is at any given time? The battery specification numbers above do not align with values I'm seeing on the Mate! Very frustrated.

Sorry but I'm lost in all these numbers and figures and I do not have an EE degree. :)
Woodman
Woodman9
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Re: Matching VFX3524M and Battery Specs

Postby dhamilton on Thu Jun 14, 2012 3:33 pm

For your voltage settings you will want to call your battery manufacture to get those set points. I am assuming that you have your battery bank wired in four stings or four? If that is the case then you have 1200 Amp Hours and your absorb time for the inverter you have will be 5.9 hours. If you have a FLEXnetDC you would be able to see the state of charge for your battery bank, otherwise you will be looking for a voltage.
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My RE system: 2x VFXR3524A, FLEXmax80, 6x EnergyCell 106NC, Mate3

Re: Matching VFX3524M and Battery Specs

Postby Vic on Fri Jun 15, 2012 5:06 pm

Hi Woodman,

OK, welcome to the forum, almost never look in this section of the forum ... sorry for the delays.

If you have 16 6-volt batteries on a 24 volt system, then you have four strings at 300 Ah each for a bank of 1200 Ah.

You mentioned "recommended" charge parameters, SO this must be from the manufacturer.

I would choose the mid-point of these ranges, or a bit below the midpoint. So Midpoints as I see it are: Bulk/Asorb 28.80, and Float 26.48 volts.

You MUST use the Remote Temperature Sensor on each charging source. Sealed batteries will NOT tolerate overcharging. Gells are the most sensitive batteries. They also cannot tolerate excessive charging currents. Either of these NO NOs can permenantly damage these batteries.

If you do have four strings of batteries in parallel, All of the battery interconnecting cables must be identical in length, and construction. All the connections to the batteries must be tight an not corroded.

You will want a Battery Monitor to monitor State Of Charge for the bank. You will need a Clamp-On DC Ammeter to try to measure the charge/discharge currents in each string of batteries in an attempt to balance these currents.

Honestly, a single string of batteries is the ideal, two strings can be OK if you monitor things carefully, More than two strings is BAD. Sealed batteries are difficult to monitor as you cannot measure the SOC of batteries. These are just my opinions. More Later, 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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Re: Matching VFX3524M and Battery Specs

Postby Vic on Fri Jun 15, 2012 5:11 pm

Wm, Will look further, but is it possible that your batteries are really AGMs? The number you posted says AGM in several links from Googling.

If they are AGMs, then they are somewhat less sensitive than Gells. Any sealed battery ( AGM or Gel) are sensitive to overcharging. The AGMs normally will take high rate charge currents.
EDIT: woodman, you may have seen this pdf Manual, ... it has more details on your batteries:
http://www.lifelinebatteries.com/manual.pdf
Note in section 5.4, that this Battery Manual states the charge voltage as 7.15+/--0.05 volts times 4 for the number of batteries per string.
Good Luck, 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.
Vic
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Posts: 979
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Location: San Joajuin County, CA


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