Cruisers Forum
 


Join CruisersForum Today

Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on Cruisers Forums. Advertise Here
 
Thread Tools Search this Thread Rate Thread Display Modes
Old 09-02-2018, 17:05   #1
Registered User

Join Date: Nov 2011
Location: On Evenstar
Boat: Hallberg-Rassy 53
Posts: 135
Send a message via Skype™ to Evenstar
AirX Marine Windgen and LiFePO4

I've recently completed most of the upgrades to LFP technology on the boat. Specific details are complex, but it's a 24V, 720Ah system with a dual power bus and a CAN Enabled Emus BMS. All we need to know about the BMS really is that it can't control non-CAN chargers, so I have to connect non-CAN sources like my windgen to the load bus. There is no easy way to close the charge contactor without the CAN chargers on...stupid design but I have to live with it for now. The wind generator's Voltage Regulation Setpoint will be lowered to a little below fully charged voltage, so it won't try to raise the voltage high enough to damage things, but will add current to supply house loads when the batteries aren't completely charged. That's not what I'm trying to sort - this 400W generator is not enough normally to actually *charge* anything, just defray consumption.

What I am trying to sort out here is protecting the wind generator from a protection event where the load contactor shuts off. The AirX marine on an open circuit will freewheel itself to death if it's not put in brake mode. So if there is a protection event when I am off the boat and the batteries turn off, the wind generator will freewheel until someone shuts it off manually.

The Windgen has a + and - leads. You short them together in order to brake the system or turn it off.

What I would like to do is use a simple SPDT relay to automatically short out the windgen power leads and brake it in the even of a power off condition.

Below is the diagram - at the top is the recommended installation method with a break-then-make switch.

At the bottom is my proposed solution - a SPDT relay that runs a wire between the windgen's + and - thread on the Normally Closed circuit. It is powered from the house power, which means that when the load contactor is closed (all is normal) the relay is activated and the circuit is open.

If the Load Contactor opens, the wind generator will be put into Open Circuit mode and start freewheeling. But the relay will lose power, which then closes the wire that crosses the + and - wires on the wind generator, braking the wind generator until power is restored.

Click image for larger version

Name:	windgen.png
Views:	152
Size:	31.2 KB
ID:	163812

Does this seem like a stupid or dangerous solution to the problem? Does anyone have any other brilliant ideas how to protect the wind generator?
__________________

__________________
S/V Evenstar - Hallberg-Rassy 53 Hull #34
Our travel blog, or "Embarrassing things I do to myself around boats"...
Evenstar is offline   Reply With Quote
Old 11-05-2018, 02:28   #2
Registered User

Join Date: Apr 2013
Posts: 35
Re: AirX Marine Windgen and LiFePO4

This is exactly what Iím investigating at the moment and came to the same solution as you. My big concern is that the relay would be energised most of the time. I would really like a solution where the relay is open when the wind generator is charging and closed, (energised), when the BMS says the battery is full.
__________________

Timd_chapman is offline   Reply With Quote
Old 11-05-2018, 04:14   #3
Registered User
 
travellerw's Avatar

Join Date: Jan 2014
Location: Grenada
Boat: Fortuna Island Spirit 40
Posts: 2,291
Re: AirX Marine Windgen and LiFePO4

Quote:
Originally Posted by Timd_chapman View Post
This is exactly what I’m investigating at the moment and came to the same solution as you. My big concern is that the relay would be energised most of the time. I would really like a solution where the relay is open when the wind generator is charging and closed, (energised), when the BMS says the battery is full.
Thats a dangerous design. If the relay fails, %95 of the time they fail in their off state (unless the contacts get welded). If you design it like that, then a failed relay will disable the charging cutoff. This could possibly lead to damaged batteries, or at least a HVD event.

Even high quality relays fail more than I would be comfortable with.
travellerw is offline   Reply With Quote
Old 11-05-2018, 05:47   #4
Registered User

Join Date: May 2014
Boat: Morgan Out Island 41
Posts: 1,040
Images: 2
Re: AirX Marine Windgen and LiFePO4

There is a problem with the design. in order for the wind gen to charge, the manual switch needs to be in the "on" position instead of the shorted position. By inserting the relay the way you indicate, when the relay closes, you not only short the wind generator, but you also short the BATTERY as well.......
pcmm is offline   Reply With Quote
Old 11-05-2018, 06:26   #5
Registered User
 
boat_alexandra's Avatar

Join Date: Aug 2009
Location: charleston
Boat: bristol 27
Posts: 3,483
Re: AirX Marine Windgen and LiFePO4

If you already invest in expensive batteries and management systems, why do you want to use the cheapest wind generator available?

There are other wind generators that are a lot better in basically every way including the ability to integrate with your batteries.
boat_alexandra is offline   Reply With Quote
Old 11-05-2018, 06:41   #6
Registered User
 
travellerw's Avatar

Join Date: Jan 2014
Location: Grenada
Boat: Fortuna Island Spirit 40
Posts: 2,291
Re: AirX Marine Windgen and LiFePO4

Quote:
Originally Posted by boat_alexandra View Post
If you already invest in expensive batteries and management systems, why do you want to use the cheapest wind generator available?

There are other wind generators that are a lot better in basically every way including the ability to integrate with your batteries.
Please enlighten us as to which wind generators will integrate with LiFePo4 batteries. I'm genuinly curious as I don't know of any.
travellerw is offline   Reply With Quote
Old 12-05-2018, 17:52   #7
Moderator
 
Jim Cate's Avatar

Join Date: May 2008
Location: cruising SW Pacific
Boat: Jon Sayer 1-off 46 ft fract rig sloop strip plank in W Red Cedar
Posts: 14,965
Re: AirX Marine Windgen and LiFePO4

Perhaps I'm missing something here, but our AirX's internal regulator shuts the system down (via an internal short) when the voltage reaches the set point. This will happen quickly when it sees an open circuit. In practice, when it reaches the set voltage it begins to PWM the output to limit the voltage and if it continues to rise (as when seeing an open circuit) shuts it down completely. It then periodically restarts, the voltage rapidly rises and it again shuts down.

If my understanding of the system is correct, don't see how it will harm your batteries or system.

Jim
__________________
Jim and Ann s/v Insatiable II on the hard at the Boat Works
Jim Cate is offline   Reply With Quote
Old 12-05-2018, 18:41   #8
Registered User
 
travellerw's Avatar

Join Date: Jan 2014
Location: Grenada
Boat: Fortuna Island Spirit 40
Posts: 2,291
Re: AirX Marine Windgen and LiFePO4

Quote:
Originally Posted by Jim Cate View Post
Perhaps I'm missing something here, but our AirX's internal regulator shuts the system down (via an internal short) when the voltage reaches the set point. This will happen quickly when it sees an open circuit. In practice, when it reaches the set voltage it begins to PWM the output to limit the voltage and if it continues to rise (as when seeing an open circuit) shuts it down completely. It then periodically restarts, the voltage rapidly rises and it again shuts down.

If my understanding of the system is correct, don't see how it will harm your batteries or system.

Jim
What voltage does that happen at?

Of course there are lots of schools of thoughts on LiFePo4... but for me, I don't want my system over 13.8V. I also don't want my system held at over %90 charged for a long period of time.

In a strong wind situation (not uncommon here in the Caribbean), the wind generator could push past the 14V mark (maybe even as high as 14.4V) before cutting out.
travellerw is offline   Reply With Quote
Old 12-05-2018, 19:25   #9
Registered User
 
boat_alexandra's Avatar

Join Date: Aug 2009
Location: charleston
Boat: bristol 27
Posts: 3,483
Re: AirX Marine Windgen and LiFePO4

Quote:
Originally Posted by travellerw View Post
Please enlighten us as to which wind generators will integrate with LiFePo4 batteries. I'm genuinly curious as I don't know of any.
Something with an external regulator. I wouldn't really trust the air-x regulator with lithium batteries, but I suppose in theory it would work.

You can probably modify the air-x by removing the internal regulator and using rectifiers, or maybe just turn the knob all the way to maximum voltage and you could run it into another regulator preferably with a dump load to prevent overcharging.

The air-x regulator tends to stop the blades quickly and takes a while to start again.. a better regulator could instead slow the blades while continuing to produce some power.

The air-x is probably the worst of the commonly used wind generators, I think because it's the cheapest.
boat_alexandra is offline   Reply With Quote
Old 12-05-2018, 20:14   #10
Moderator
 
Jim Cate's Avatar

Join Date: May 2008
Location: cruising SW Pacific
Boat: Jon Sayer 1-off 46 ft fract rig sloop strip plank in W Red Cedar
Posts: 14,965
Re: AirX Marine Windgen and LiFePO4

Quote:
Originally Posted by travellerw View Post
What voltage does that happen at?

Of course there are lots of schools of thoughts on LiFePo4... but for me, I don't want my system over 13.8V. I also don't want my system held at over %90 charged for a long period of time.

In a strong wind situation (not uncommon here in the Caribbean), the wind generator could push past the 14V mark (maybe even as high as 14.4V) before cutting out.
The Airx regulator is user adjustable via a pot on the outside of the housing, so readily accessible. You can set it for whatever voltage you wish.

Dunno how you would deal with the 90% charge issue, but that's true with solar as well, isn't it?

Jim
__________________
Jim and Ann s/v Insatiable II on the hard at the Boat Works
Jim Cate is offline   Reply With Quote
Old 13-05-2018, 04:12   #11
Registered User
 
travellerw's Avatar

Join Date: Jan 2014
Location: Grenada
Boat: Fortuna Island Spirit 40
Posts: 2,291
Re: AirX Marine Windgen and LiFePO4

Quote:
Originally Posted by Jim Cate View Post
The Airx regulator is user adjustable via a pot on the outside of the housing, so readily accessible. You can set it for whatever voltage you wish.

Dunno how you would deal with the 90% charge issue, but that's true with solar as well, isn't it?

Jim
Ahh I didn't realize the Air-X had an adjustable voltage cutoff.

As to the %90 issue. For solar it really depends on the controllers you have. If you have a fully programable controller its not an issue. You simply set a voltage to charge to, then stop (no float).

Frankly I think the OP is going to find this a "non-issue". If his solar bank is sized appropriately, then I'm guessing his wind generator will be manually switched off %90 of the time. The extra power is just not required with LiFePo4 batteries. Sure, the extra power is nice on rainy/cloudy days to help carry the load. On sunny days, the solar should easily fill everything back up since there is no long absorbtion phase.
__________________

travellerw is offline   Reply With Quote
Reply

Tags
lifepo4, marine, wind

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
For Sale: AirX marine wind generator Z28YJ General Classifieds (no boats) 5 28-11-2016 15:42
Installimg and using my new 400 watt Airx Wind Generator on my Hunter 30 Tom ONeill Electrical: Batteries, Generators & Solar 2 08-01-2012 04:46
Windgen and Magnetic Compass Interference Sailmonkey Electrical: Batteries, Generators & Solar 25 16-04-2010 06:22
New AirX 400 Watt Generators $580 johnar Electrical: Batteries, Generators & Solar 2 07-01-2010 20:35
Opinions Needed: Used KISS vs New AirX brianontheroad Electrical: Batteries, Generators & Solar 10 29-11-2009 08:57



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 20:08.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2019, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.