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Old 30-05-2014, 19:28   #1
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Wind with LifePO4

Hello,

Last night at the yacht club, there was a huge raffle prize drawing. I won a Rutland 914i, and so did my girlfriend.

I have two 12v wind turbines now, and we have the Hatteras 43 Double Cabin that happens to be all 12v.

I have a CALB LifePO4 12v 500Ah house bank, and the 2 12v Lead Acid engine banks.

If I were to install a "Normally Closed" 500A relay in parallel with the "Normally Open" relay that is in place on the BMS now for the HVC. When HVC is reached, the BMS would be able to direct the current to the engine banks, or a 12vDC water heater element.

I do not find much information online about people using wind turbines in a LifePO4 system. Mainly Solar.

The Normally Open relay would handle the redirecting the current, and continue to keep the turbine under load.

Alan
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Old 01-06-2014, 08:21   #2
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Re: Wind with LifePO4

Hello,

It is obvious that no one has tried it...

I have installed the relays to the BMS. Tomorrow We let one Rutland 914i spin to see how she works.

According to the forecast from the observatory... Mild winds, but enough to generate enough to see if it works.

I have a 30v DC water heater element in place of the previous AC element as the dump load.

The BMS will save the day, or I will
Be buying 4 new CALB cells !!!

I am enjoying these un chartered waters.., hahaha.., sad that no one else is curious to do the same !

Alan
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Old 01-06-2014, 09:25   #3
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Re: Wind with LifePO4

From your description it is unclear how you want to connect the relays, could you attach a drawing?

If I understand correctly, your plan is to use the HVC condition signal as a means to trigger redirect to a dump load. In my opinion this is not good, because it means that HV condition will be reached regularly, while it is intended to be a last ditch effort to save the bank. Regular charging process should terminate (or start to dump in this case) well before HVC.
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Old 01-06-2014, 20:44   #4
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Re: Wind with LifePO4

Hello,

Happy Dragon Boat Festival !!!

Here is a quick diagram how the dual pole relay will be directing power from the BMS house board when the HVC is reached.

The wind turbine will always be under load... Charging the bank, or the DC water heater element.

Should work !

Alan
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Old 02-06-2014, 01:56   #5
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Re: Wind with LifePO4

Hello,

Before connecting to the LFP bank. The controller has the dump load where I can set the voltage that will trigger the diversion... Having both running in parallel is the safety I am looking for !! Will be testing on 2 Trojan T-105's to make sure it works !
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Old 02-06-2014, 03:07   #6
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Re: Wind with LifePO4

Alan,

re circuit diagram:
  1. it is redundant and unnecessary to switch both positive and negative leads. Usually negative is permanently connected to a negative (common reference) bus bar and any switching/diverting is done on plus side of the circuit;
  2. unless I am mistaken on how House Power BMS relay control outputs work, I think you may have to swap NO/NC for the intended operation.
However, and please accept my apologies for being blunt:

Quote:
Originally Posted by Hkalan View Post
Before connecting to the LFP bank. The controller has the dump load where I can set the voltage that will trigger the diversion... Having both running in parallel is the safety I am looking for !!
your approach is simply wrong (if I understand you correctly). HVC event should never be triggered under normal charging of your bank. If HVC is triggered, it means that one or more charge controllers is either set too high or is malfunctioning. Let me repeat: normal charging/discharging regime does NOT involve HVC/LVC events! So, having both _running_ (== active/triggered in my understanding) is wrong.
The controller has a dump load and under normal conditions should start dumping well before HVC happens.

One more remark, how is the water heater element connected to the rest of the circuit? Is it _only_ ever used as a dump load, or is it also used to heat water during normal operations?
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Old 02-06-2014, 04:22   #7
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Re: Wind with LifePO4

Hello,

The HVC from the BMS control board is what normally turns off the AC powered charger or an alternator in normal situations. That is why there is a mini BMS on each cell that is looped to the main board. When the mini BMS says it is full, the HVC relay from the main board stops a charge to the bank.

I do not know of any other way that the BMS stops the bank from charging when it is full.

The LVC connects to the relay to disconnect the inverter.

The control board also has another relay out to cut all DC from the bank if the main LVC fails.

The DC water heater element is only connected as a diversion load. Nothing else feeds it. A dedicated resistance.

I am a firm believer in redundancy on my vessel...

Alan
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Old 02-06-2014, 04:56   #8
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Re: Wind with LifePO4

Hello,

This is how the 12v House Power BMS control board works, I am quite confident that the HVC is the only way the system will stop any charge to the bank.

Alan
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Old 02-06-2014, 05:39   #9
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Re: Wind with LifePO4

Quote:
Originally Posted by Hkalan View Post
Hello,

This is how the 12v House Power BMS control board works, I am quite confident that the HVC is the only way the system will stop any charge to the bank.

Alan
Alan,

I studied the House Power BMS docs too, and I think they are misleading. What they fail to make clear is, that HVC is to protect from a runaway (malfunctioning) charger. Instead, they make you believe that HVC event is a normal method of charge termination, which is plain wrong and dangerous.

A properly functioning charge source will stop charging on its own, well before the bank voltage will reach the HVC alarm level.

Similarly, the LVC event cuts loads as a last level of protection. User, however, should have been alerted that the bank is nearing empty and some action is necessary, well before the voltage drops to LV condition level.

I tried to explain and help, but ultimately it is your boat, your batteries, and your money. I will rest my case.
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Old 02-06-2014, 06:14   #10
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Re: Wind with LifePO4

Thank you very much !
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Old 02-06-2014, 15:32   #11
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Re: Wind with LifePO4

mrm is correct. Your charger should be set to never apply a dangerous voltage to your batteries. For LiFePO4, I suggest the charger be set to 14.0V. That is high enough to reasonably charge the batteries and low enough that it can be applied for years without destroying the batteries.
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Old 02-06-2014, 19:06   #12
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Re: Wind with LifePO4

Good Morning,

Nice thing about having my vessel birthed in Hong Kong... I can call CALB directly at low costs, and speak to the engineers in their language :-) I had to actually visit their office the other month to get the business cards of their engineers to be able to call them today LOL.

CALB says... and I Quote: The Upper Charging Limit for your CA series 400Ah cells is 3.65v. Meaning an upper charge limit of 14.6v for the four cells in series. If the BMS relay you have is cutting the charge when 14.2v limit is reached, There is absolutely no problem at that charge voltage limit on our cells. The "CleanPower" BMS does have the overall main cell protection of 3.75v, that should really be adjusted to 3.65v. keep in mind you want a safe and healthy charge cut off. See about changing that one to 3.65v (14.6V for 4 cell max charge limit). As I look at the diagram you sent me. You need to manually reset the BMS. A car BMS is rest after you turn the ignition. You are continuously using the bank, and have solar available. Does the CleanPower House BMS have a voltage level regulated accessory that can be attached in the place of a momentary manual rest button. Chances are in your situation on a yacht, you would hit LVC because you don't have a gauge in front of you like when driving an electric car. No one likes to hear alarms when having an enjoyable day on the water, to realise you need to charge the bank ! End Quote

I know so many here have LifePO4 banks, this is just my conversation with the people that made my cells. Only sharing what I learned, and what is relevant to my situation.

We talked about other things, but that was relevant to this thread... Thanks for letting me share the info, and hope other may look into alternative ways to charge their banks like I want !

Alan
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Old 02-06-2014, 20:27   #13
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Re: Wind with LifePO4

Hello Again,

Exchanging a few emails with the builders of the HousePower Controller and miniBMS boards.

My miniBMS boards are 3.6v, so the overall protection of the controller board is at 14.4v. That is below the 3.65v as stated by CALB.

The contact HVC relay "C" is at 14.2v. That is also in the safe range as stated by CALB.

I am exploring the adjustments with the solar & wind controller as well today. I have been able to adjust the controller to go into diversion mode at 14.0v, and the current goes directly out the "dump load" connecting port to the water heater element. The wind turbine would be under content load as I want.

If the solar & wind controller is dumping at 14.0v or even 14.1v, the BMS will not go into HVC. I would not have to worry about the reset or a LVC alarm.

Options and Redundancy work for me LOL

Thanks,

Alan
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Old 02-06-2014, 21:20   #14
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Re: Wind with LifePO4

About the Dump Load...

I contacted a factory near by, and on the same concept of a 3 phase water heater element. I had them put 3 independent 30vDC 900W elements into the one screw in base that has the same thread as my Quick 10.6 gallon Marine water heater (w/heat exchange coil) in the engine room. We mainly use a 12L tankless LPG water heater that has 12v ignition and exhaust blower, so the AC element does nothing but sit in the unit. Now the DC element is working for me at no cost for power, and keep the LFP safe.

Connecting to one element will dump 900W, two in parallel will dump 1,800w, and three in parallel will allow a max of 2,700W. I will use these on a 24v LFP bank I want to put on the Bertram 46.6 FBMY doing the same as this 12v setup.

Cost for one unit $16 dollars ! Not to bad in my opinion !!!!

In closing, CALB confirms my settings, and warranty for the cells will stay valid with this set up. Life is good at the mooring, cruising, and on the hook !!! Without the sound of a generator or shore power cables :-)

That is until the little lady wants the air conditioner turned on.... LOL

Alan
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Old 02-06-2014, 22:55   #15
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Re: Wind with LifePO4

Quote:
Originally Posted by Hkalan View Post
CALB says... and I Quote: The Upper Charging Limit for your CA series 400Ah cells is 3.65v. Meaning an upper charge limit of 14.6v for the four cells in series.
Did they say that it's ok to charge at 3.65V until the cells are charged and then stop? Or did they say that it's ok to apply 3.65V indefinitely?

I like simple, safe, and reliable, so I limit charging to 3.50V to ensure that my cells will stay in balance. They reach virtually the same level of charge, just more slowly, so I'm not giving up any significant capacity.
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