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07-15-2018, 04:53 PM
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#1
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Senior Member
Join Date: Oct 2015
Location: Sarasota, FL
Posts: 163
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Dual Inverters - Not the same?
Our rig currently has 2 Xantrex Freedom 458 2k Watt inverter / chargers. One of them (#1) has failed, but #2 continues to work fine, and has minimal load on it. I have no interest in replacing the failed unit with the same Xantrex again. I'd like to replace the failed #1 with the Victron Multiplus unit (so my residential fridge can be on pure sine wave), while keeping the old Xantrex #2 in place. Ideally, when #2 bites it, I'll replace that with a Victron Multiplus also
My question is, could this cause charging issues, given all 8 of my 6V batteries and the 2 current inverters are connected together on the DC side? Essentially they both pull from the full battery bank, and both of them charge that bank together. I'm trying to make sure the old Xantrex inverter and new Victron inverter don't fight each other trying to charge the bank of batteries. The 8 250amp/hr 6V batteries we have give us great performance and don't want to screw them up.
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07-15-2018, 06:21 PM
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#2
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Senior Member
Join Date: Jul 2014
Posts: 35,317
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As long as you set the charging voltages close to the same on both inverters all will be fine.
If one is set a bit higher, it will do the absorb and float charging when the batteries are near topped off. At that point, you dont need the amp output of two chargers anyway.
In bulk charging, both will be at full output amps, or what ever you limit them to, until the battery bank reaches the absorb voltage.
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07-15-2018, 07:34 PM
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#3
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Senior Member
Join Date: Dec 2012
Location: Swoope, VA
Posts: 362
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I agree with twinboat.
Or, you could disable the charger on one inverter. I doubt you'd really need both of them unless you have a huge battery bank.
__________________
2022 Jayco Eagle 284BHOK, 2022 GMC CC Dually D/A, 2009 2500 Suburban, 2004 Rinker Captiva 232 boat
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07-15-2018, 09:13 PM
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#4
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Senior Member
Join Date: Oct 2015
Location: Sarasota, FL
Posts: 163
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Quote:
Originally Posted by twinboat
As long as you set the charging voltages close to the same on both inverters all will be fine.
If one is set a bit higher, it will do the absorb and float charging when the batteries are near topped off. At that point, you dont need the amp output of two chargers anyway.
In bulk charging, both will be at full output amps, or what ever you limit them to, until the battery bank reaches the absorb voltage.
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Ok...thanks. The 8 batteries together are putting 1004 amp-hours. At about 50% depth of discharge, the 2 Xantrex Freedom 458's would charge them in about 70-90 minutes on 50A. It's been a good size for us.
I did some more research. And found specs on both inverts in my future setup:
Xantrex Freedom 458:
Bulk Charge Voltage: 14.3
Float Charge Voltage: 13.4
Equalize Charge Voltage: 16.3
Victron Multiplus 12/3000/120
Absorption Charge Voltage: 14.4
Float Charge Voltage 13.8
Storage Mode: 13.2
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07-16-2018, 02:46 PM
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#5
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Senior Member
Join Date: Oct 2015
Location: Sarasota, FL
Posts: 163
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The wiring will look like this:
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07-16-2018, 04:18 PM
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#6
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Senior Member
Join Date: Jul 2014
Posts: 35,317
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You can we what Xantrex call bulk voltage, Victron calls absorbsion voltage.
They are only a tenth of a volt different and will be fine working together.
As far as the bulk or absorb voltages, both chargers are in constant current mode, pushing ad many amps as the batteries will accept, until the batteries voltage comes up to 14.3 or 4.
That's when both chargers will go into constant voltage mode and start tapering off the amp output, while maintaining the voltage.
They will remain at that voltage for a pre-determined time ( absorb time ) before tapering back to float voltage.
You need to check your battery specs to see if the float voltage is OK for your batteries. If not, there should be a way to adjust it.
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07-16-2018, 04:29 PM
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#7
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Senior Member
Join Date: Oct 2015
Location: Sarasota, FL
Posts: 163
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Quote:
Originally Posted by twinboat
You can we what Xantrex call bulk voltage, Victron calls absorbsion voltage.
They are only a tenth of a volt different and will be fine working together.
As far as the bulk or absorb voltages, both chargers are in constant current mode, pushing ad many amps as the batteries will accept, until the batteries voltage comes up to 14.3 or 4.
That's when both chargers will go into constant voltage mode and start tapering off the amp output, while maintaining the voltage.
They will remain at that voltage for a pre-determined time ( absorb time ) before tapering back to float voltage.
You need to check your battery specs to see if the float voltage is OK for your batteries. If not, there should be a way to adjust it.
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Good point! I checked with US Battery and they stated below. Looks like I'll have to see if I can wind the Float charge back some to meet their spec:
Following is the charging recommendation and charging profile using 2 stage chargers for US Battery deep cycle products.
*Equalization and float charge modes are not considered to be one of the stages in a charging profile.
1. Bulk Charge Constant current @~10% of C/20 Ah in amps to 2.45+/-0.05 volts per cell
(e.g. 7.35 volts +/-0.15 volts per 6 volt battery)
2. Absorption Charge Constant voltage (2.45+/-0.05 vpc) to 3% of C/20 Ah in amps then hold for 2-3 hours and terminate charge
Charge termination can be by maximum time (2-4 hr) or dV/dt (4 mv/cell per hour)
• (Optional Float Charge) Constant voltage 2.17 vpc (6.51 volts per 6 volt battery) for unlimited time
• Equalization Charge**Constant voltage (2.55+/-0.05 vpc) extended for 1-3 hours after normal charge cycle (repeat every 30 days)
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