PWM battery charging settings

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PWM battery charging settings

Postby tkosam » Thu Feb 11, 2016 9:23 pm

Hello everyone,

I just set up a new hybrid wind/solar charge controller:

http://www.aliexpress.com/item/800W-24V ... 27582.html


There are menus for wind, solar, battery, dump....

In the system/battery menu what should I put if I have a 24v system with 4 batteries 12v, serially connected:

1. battery capacity: 190 Ah
2. energy accumulates: ADD
3. battery over-discharge limit voltage: ???? V
4. battery over-discharge limit recovery voltage: ??? V
5. battery over-charge limit voltage: ??? V
6. battery over-charge limit recovery voltage: ???? V
7. Floating voltage: ???? V
8. over-load limit voltage: ???? V
9. over-load limit recovery voltage: ???? V

thanks in advance

tkosam
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Re: Battery MPPT functions

Postby Gordon-Loomberah » Thu Feb 11, 2016 9:45 pm

We'd need to know the battery type and specifications first.
When you say 4 12V batteries serially connected, surely that would be 48V? Or do you mean 2S 2P?
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Re: Battery MPPT functions

Postby tkosam » Thu Feb 11, 2016 9:51 pm

It is GEL battery, and they are connected in order to get 24v, so I suppose it is 2S 2P.
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Re: Battery MPPT functions

Postby davidg » Fri Feb 12, 2016 6:40 am

MPPT no,

PWM yes.

way too cheap for real MPPT controller, #just saying :?
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Re: PWM battery charging settings

Postby Gordon-Loomberah » Fri Feb 12, 2016 7:16 am

Not just PWM David, it's Double PWM! ;)

I'll fix the topic name.
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Re: PWM battery charging settings

Postby APR » Fri Feb 12, 2016 9:02 am

tkosam wrote:In the system/battery menu what should I put if I have a 24v system with 4 batteries 12v, serially connected:

1. battery capacity: 190 Ah This is correct
2. energy accumulates: ADD I don't know what this one is about.
3. battery over-discharge limit voltage: ???? V For this value I would start at say 25 volt (12.5v/battery) and assess how the batteries meet your needs. 12.5 volt per battery is going to leave your batteries at above 60% to 65% SOC. The lower the discharge voltage the less life you will get from the batteries. To have the controller stop discharging the batteries too far, the load must be connected to the controller, not straight across the battery terminals
4. battery over-discharge limit recovery voltage: ??? V Once the controller is recharging the batteries, this is the voltage at which the controller will again start supplying the load connected to the controller load terminals. You only need to set this voltage a little higher than the Over-Discharge Limit voltage.
5. battery over-charge limit voltage: ??? V I assume this voltage is the "Bulk" charge voltage. This voltage will depend upon your battery, and getting it wrong could shorten the life of your batteries. Without info specific for the battery brand and type, I would set this voltage at no more than 28.8 volts (14.4 volt per battery) or perhaps a little lower.
6. battery over-charge limit recovery voltage: ???? V I don't understand why this value is needed. It suggest that the charge controller is not precisely controlling it's charge voltage. This value will need to be lower than the "Over-Charge Limit Voltage". Perhaps try 0.2 volts lower, say 28.6 volt or 28.4 volt. Bulk charging is done by current limiting until the voltage reaches a set point, and then the current will taper off. It sounds like the bulk charge voltage is going to cycle between these two voltages, but I am probably wrong on this.
7. Floating voltage: ???? V This value will be in the battery manufacturers specifications. If you cannot find this value I would be setting it at 27.2 volts.
8. over-load limit voltage: ???? V I don't understand what this is trying to limit.
9. over-load limit recovery voltage: ???? V Same for this parameter.


tkosam, if you can get your hands on the manufacturers specifications for the batteries you have, the specs will give accurate charge voltages to set in the charge controller. One issue is that as the battery temperature varies the ideal charging voltages also vary. The voltage adjustment with temperature variation will also be in the battery specifications. As a rough guide, at a battery temperature of 40 deg C the bulk charge voltage would typically be reduced by around 0.1 V, and at a temperature of around 10 deg C the battery bulk charge voltage would typically be increased by around 0.05 volt. See if you can pull up the charging voltage specs for the batteries you have as the battery life can be significantly reduced if you get these voltages wrong.
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Re: PWM battery charging settings

Postby tkosam » Sat Feb 13, 2016 6:48 am

Hello,

First, thank you for all the trouble for answering my questions.

I went to the battery shop and they told me this:

the charge voltage "absorption" should be 27,6 V

the charge voltage float should be also 27.6 V

low voltage disconnect should be at 23,6 V

The batteries are GEL batteries, and the salesman told me that all GEL batteries work the same.

So in the controller I put all voltage as you told me, only the voltage under 3. and 4. Them I put 23.6 V for number 3. and a little higher as you suggested for number 4., that is 23.8 V. when i put your suggested voltage for numbers 3. and 4. then the batteries show me 0% Low, in the display. but when i put your voltage the controller is showing that batteries are 90% full, which is impossible because the other controller, which is connected to the same batteries shows that the batteries are around 25% full.



Thanks
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Re: PWM battery charging settings

Postby tkosam » Sat Feb 13, 2016 6:49 am

Also, the controller doesnt show any Amps going out of the system, it says zero the whole time, which is impossible because I'm using electricity.

What to do?
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Re: PWM battery charging settings

Postby APR » Sat Feb 13, 2016 7:10 am

tkosam wrote:What to do?


Hi tkosam, do you have a multimeter you can use to measure the battery voltage?

You are discharging the batteries too far if you are discharging them to 25% SOC. The batteries will last a lot longer when you only discharge them to around 80% to 70% SOC, so they are always close to full.

Do you have the load connected to the load terminals of the controller? If you have, the controller should be displaying the amps being drawn from the batteries.
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Re: PWM battery charging settings

Postby tkosam » Sat Feb 13, 2016 8:16 am

the controller is connected to the battery and from the battery the inverter is connected.

There is no load connected to the battery. By load, i suppose you mean "dump load" from the controller?

I have no multimeter. The display on the controller shows 24.2V and 90% full.

Also, what does SOC mean?

I calculated and experienced that i can use around 80 W (laptop plus internet antena plus a few LED lamps. They take around 80-90 watts) for around 25 hours. without charging. But the day usually gives some amps.
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