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Old 07-08-2014, 21:38   #61
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Re: Baqon drop-in LiFePo battery systems with BMS

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Originally Posted by DumnMad View Post
I like this thinking. Makes sense to me but I know little about these things.
Would the LiFePO4 charging rate be seriously penalized at 13.4 vs 13.8?
I guess we have to play lexicographer and define what we mean by “seriously penalized”, so we can answer that question. As Mail Sail properly pointed out and other with real life systems have noted using the lower 13.4v charge rate does make you hit the charge limiting point faster than using a voltage of 13.8v so there is one negative. This means that 13.4v may only take you to about a 80% state of charge, BUT most people recommend staying out of the 90% SOC knee anyway, so is it really the end of the world (or seriously penalized) to really lose another 10% of your banks capacity (40Ah from a 400AH bank)? Is playing in the 10% to 80% SOC area going to nut-you-up or can you live with that? I guess that is your individual call to make, to me it is worth it to keep things as KISS as possible, to others, I’m clubbing baby fur seals with a baseball bat….so you decide.

A one piece of data I think we know is that your LiFePO4 bank will not be harmed or damaged by using the 13.4v vs 13.8v or 14.0v. So that’s good. We also know that you won’t harm your bank by playing in the 10% to 80% area rather than the 10% to 90% area…so again…what is the downside? Well it’s clear that if I’m running a generator for charging or alternator then I won’t be pushing as much current into the battery at 13.4v as 13.8v so I could have to charge for longer….how much longer I can’t say. I can't say because with 1380W of solar on my boat I’m not burning diesel to charge anyway, so it's not as important to me. What matters to me more is not over-charging the bank and getting into the >90% knee, where we do have data showing negative affects on the bank. I love and respect the engineering types that want to build an automated black box to shunt this and ballance that, but sometimes we can lose sight of the forest for the trees and make things more complicated than they need to be. Maybe Main Sail or someone else can help to actually quantify the 13.4v vs 13.8v charging time difference.
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Old 07-08-2014, 21:53   #62
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Re: Baqon drop-in LiFePo battery systems with BMS

I like it Third Day.
We spend all sorts of money on safety issues so putting in 800AH ranging 10% to 80%, (560AH useable) instead of 700AH ranging 10% to 90%, (560AH useable) to avoid complications and risks seems a no brainer to me.
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Old 07-08-2014, 23:06   #63
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Re: Baqon drop-in LiFePo battery systems with BMS

In my view, there is always a tendency to over complicate things. We fight it with our water makers and refrigeration products. When a client calls and offers us a lot of money to design and build him a custom automated App for his Ipad/Iphone to measure fresh water production on the water maker or compressor speed and refrigerant loop superheat on the refrigeration units there is a pressure to say,
“Sure you are paying for it, we will do it”.

But in the end we TRY and say no. Not because I’m smarter than the client, heck I’m just a self-professed Cruising bozo running a business aboard a boat from Mexico or California - wherever we happen to be floating at the moment. We say no because I know I will have to service and stand behind anything I put our company logo on. Sure I’m just a not all that impressive nerd science guy/inventor turned cruiser, but my biz partner Charlie has over 30yrs at Solar Turbines, a division of Caterpillar, where he designed, installed and started-up turbine facilities around the world (power generation, gas compression, cryogenic plants, anywhere a turbine burned fuel). So adding wipe-your-rear-end automation and controls is what he knows how to do and wakes up dreaming about. I’m always telling him NO because if I let him he would over engineer and automate my damn cast iron fish fry pan! It’s what engineers do, God love them, they can’t help it, it’s in there DNA and pocket protector decoder badge.

“Rich, what in the world does that have to do with anything about LiFePO4 battery banks?”

Well I’m trying to address what I think a big problem is with internet chat room type advice, which is, you don’t have a context or world view of the person giving the advice or making the comment. Sure you still may think I’m crazy but you will at least understand from where I am standing viewing the problem and how I like to approach things. Sum me up as an Anti-Conventional-Wisdom-Smart-Ass-KISS-Man, who hates dark chocolate and attempts to keep boat systems as simple and “bozo boater proof” as possible.

A) Because I’m a Bozo Cruiser myself and understand the language
And
B) Because I speak to Bozo clients all the time to provide them with customer service. (No offence to my Bozo clients…I love you all…even the ones on the east coast that can’t figure out why my voice sounds scratchy when they call me at 4AM my time and ask me if I’m awake yet. If you had to ask, then NO I wasn't awake yet!)

I’m also doing something here that every public relations company on the planet and common sense says not to do. I’m sharing my honest thoughts on a public forum for all the world to see the fillers, salts and nitrates being added to the sausage. Rule 187 in the PR books says that all communications with the outside world must be sanitized, run through Legal, poll tested, and made damn sure not to offend. Well I guess there is just too much “Don’t Give A **** What the World Thinks Cruiser” in me to play that role and my partner hasn’t banned me from internet chat rooms yet, so here I am.

So here is my ideal LiFePO4 KISS System and How I'm rolling on our boat with a 400AH bank. I would love some feedback on what I’m missing or how I’m screwing up from those far smarter and with more experience than I have.

1. Set all your ships Charging Devices to 13.4v (ok we can debate 13.4v 13.?)
2. High Voltage Bank Alarm (14.0V)
3. Low Voltage Bank Alarm (12.0V)
4. Individual Cell Monitoring, so you can see the individual cell voltages on a screen along with the bank voltage.

Now for the safety for when one of your charging devices fails, because remember folks we are on a boat and **** happens all the time.

5. High Voltage Charge Cut-off (14.5v...still not sure about)
6. Low Voltage Load Cut-off (11.5v....still not sure about)

Done…now go enjoy your boat.

What about Auto-Balancing of cells? Well I figure that if a Joe Average Cruiser can’t do that manually once every few years then he doesn’t have a chance of lasting as a cruiser anyway quite frankly and will sell the boat to someone that will long before the cells need balancing. Come on…even if you think I’m crazy…you know I’m partially right on that one!
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Old 08-08-2014, 06:36   #64
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Re: Baqon drop-in LiFePo battery systems with BMS

Rich
+1

I face the "because we can, we must" syndrome every day…and I have a pocket protector. :-)

When trying to dissuade a client from doing something that may be cool, looked good in the last issue of Passagemaker, or looked very impressive when demonstrated at the boat show but, in the whole scheme of things, is the wrong thing to do from a sensibility, maintainability, serviceability, and reliability standpoint, I point out the pitfalls and finally say, IYB (It's Your Boat).

Quote:
So here is my ideal LiFePO4 KISS System and How I'm rolling on our boat with a 400AH bank. I would love some feedback on what I’m missing or how I’m screwing up from those far smarter and with more experience than I have.

1. Set all your ships Charging Devices to 13.4v (ok we can debate 13.4v 13.?)
2. High Voltage Bank Alarm (14.0V)
3. Low Voltage Bank Alarm (12.0V)
4. Individual Cell Monitoring, so you can see the individual cell voltages on a screen along with the bank voltage.

Now for the safety for when one of your charging devices fails, because remember folks we are on a boat and **** happens all the time.

5. High Voltage Charge Cut-off (14.5v...still not sure about)
6. Low Voltage Load Cut-off (11.5v....still not sure about)
Your points 2, 3, 4, 5, and 6 nearly define the BMS that I use. The only additional point is a signal from the BMS to the charging devices to turn them off before HVC if the charging devices organic control system does not.

Quote:
What about Auto-Balancing of cells? Well I figure that if a Joe Average Cruiser can’t do that manually once every few years then he doesn’t have a chance of lasting as a cruiser anyway quite frankly and will sell the boat to someone that will long before the cells need balancing. Come on…even if you think I’m crazy…you know I’m partially right on that one!
+1
At fractional C charge and discharge rates the cells will stay in balance for hundreds and hundreds of cycles so balancing, top or bottom, is an as required action. Maine Sail has absolutely proven this as have my systems in the wild.
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Old 08-08-2014, 10:28   #65
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Re: Baqon drop-in LiFePo battery systems with BMS

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At fractional C charge and discharge rates the cells will stay in balance for hundreds and hundreds of cycles so balancing, top or bottom, is an as required action. Maine Sail has absolutely proven this as have my systems in the wild.

So is the general consensus that at 0.5c charge and 0.2c discharge rates things are still stable in regards to balancing?

Data logging of cell voltages might not be too hard to implement and then simply do a manual balance when it needed to be done?

I'm one of those guys that struggles with KISS. I would enjoy working with the technology as long as it is essentially built fail safe without too many sub systems so you don't need to worry about a big problem caused from a small one. Automatic shunting circuits is probably not the best thing to have around on a boat.
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Old 08-08-2014, 12:00   #66
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Re: Baqon drop-in LiFePo battery systems with BMS

So this drop in solution is no good? I'm waiting for a drop in solution. It sounds like it needs a backplane with all the sensors and disconnects and then a module battery bay where batteries can be swapped out as needed without replacing the entire unit. You could even have a hot spare cell so if you have a cell die it can switch that cell off and connect the spare to the bank.
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Old 08-08-2014, 12:02   #67
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Re: Baqon drop-in LiFePo battery systems with BMS

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Originally Posted by SV THIRD DAY View Post
Now for the safety for when one of your charging devices fails, because remember folks we are on a boat and **** happens all the time.

5. High Voltage Charge Cut-off (14.5v...still not sure about)
6. Low Voltage Load Cut-off (11.5v....still not sure about)
Warning: I don't know much about LiFePO, but I am learning. However, if one cuts the input to the bank while an alternator is running, won't this pretty much destroy the alternator?

Wouldn't it be better to cut the field to the alternator instead?

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Old 08-08-2014, 12:17   #68
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Re: Baqon drop-in LiFePo battery systems with BMS

Quote:
So is the general consensus that at 0.5c charge and 0.2c discharge rates things are still stable in regards to balancing?
That has been the experience of three operating systems that I am aware of.

Quote:
Data logging of cell voltages might not be too hard to implement and then simply do a manual balance when it needed to be done?
Absolutely. And by "data logging" I look to the owner to take is DMM to the battery bank periodically and check and record the parallel string voltage as well as the bank voltage. Top balance only if the string voltages are starting to diverge. Experience shows that this doesn't happen with fractional C charge/discharges.

Quote:
Automatic shunting circuits is probably not the best thing to have around on a boat.
Absolutely! Top (or bottom) balancing has not shown to be warranted.

Quote:
So this drop in solution is no good?
In my opinion, it is not good.
1. No interface between the installed BMS and sources or loads.
2. Fixed capacity.

Quote:
Wouldn't it be better to cut the field to the alternator instead?
Disconnecting the alternator output from the battery bank will probably destroy the diode pack in the alternator. That is why we don't use that method.

The preferred method for stopping the output of an alternator with an external regulator is to turn the power to the regulator off. This will not harm the regulator or the alternator and can be very easily accomplished with a simple Bosch relay.
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Old 08-08-2014, 12:26   #69
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Re: Baqon drop-in LiFePo battery systems with BMS

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Wouldn't it be better to cut the field to the alternator instead?

Mark
I think this was meant more to make a point than to be specific, but yes, your right.
If one merely has a high voltage cut out that functions as a disconnect, then of course I guess that could fry the alt. One assumes though that there would be a high voltage alarm first, sort of like the low oil pressure alarm that would go off prior to the cut-out functioning.
I think it depends on how much automation your willing to accept and to pay for.
Assuming reaching the high voltage cut off point is a one in a million occurrence, so what, you fry an alt.
What happens to a battery bank that does not have a high voltage cut off, when the safe voltage is exceeded on a DIY system?
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Old 08-08-2014, 16:55   #70
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Re: Baqon drop-in LiFePo battery systems with BMS

I understand that there are several members and professional members working hard to figure all this out and it is great to say that a company who has decided to package these cells in a "drop in" solution is missing a lot of things that are essential.

My simplistic mind runs to, "So what are the consequences?"

This outfit is providing a 5 year warranty on their batteries and if I abide by their charging recommendations I presume theyr will stand by their warranty.

So without individual cell monitoring, balancing and over-volt cutoffs and all that - does my boat burn to the ground one night?

I can't believe Baqon would expose themselves to that. Maybe the bank is damaged or something and at these prices that is a tragedy but I am skeptical about the doom a gloom aspect of these discussions.

There is always a better mouse trap - my question is does this "drop in" solution trap mice better than Lead Acid?

There are going to be a lot of cruisers/boaters who don't read the doom and gloom threads here that are going to drop these batteries in and do nothing with their charge systems. Should we be expecting more boat fires in a year?
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Old 08-08-2014, 17:14   #71
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Re: Baqon drop-in LiFePo battery systems with BMS

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Originally Posted by colemj View Post
if one cuts the input to the bank while an alternator is running, won't this pretty much destroy the alternator?

Wouldn't it be better to cut the field to the alternator instead?
Absolutely, the Cut Off approach needs to be taylored for the source to be cut off and for the alternator that would mean cutting off the field.

I look at it as a three stage system:
1. An external alternator regulator set-point of 13.4v (ok ok maybe 13.6v or your favorite voltage)
2. A high voltage alarm to sound a buzzer
then as a last failsafe
3. A voltage sensing relay to cut the alternator field to the alternator and shut it down.

So far I've never had the high voltage buzzer or cut off "go off" except when doing testing to intentionally make it happen. So unless something fails with the alternator regulator, battery charger, solar charger, or wind generator regulator, the hope is I never will, except for testing!

Quote:
Originally Posted by Ex-Calif View Post
This outfit is providing a 5 year warranty on their batteries and if I abide by their charging recommendations I presume theyr will stand by their warranty.
Talking from experience, a warranty is only as good to the customer as the fine print defines and the Company offering it can stand behind it. So just because a Company has a 5yr warranty doesn't mean that they KNOW their product will really last for 5yrs. It just means they won't lose money on the "Prorated Warranty" due to their profit Margins on the product to start with. For example, I know the cost of a RO Membrane and at the prices some water maker companies charge for them they can still make over a 100% profit margin on a prorated warrany replacement membrane....so at that...what's the risk to the company? Nada.
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Old 09-08-2014, 06:37   #72
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Re: Baqon drop-in LiFePo battery systems with BMS

I will say again, the preferred method of stopping alternator output (verified with Balmar) is to turn the external regulator off, not to break the field wire.
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Old 09-08-2014, 07:11   #73
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Re: Baqon drop-in LiFePo battery systems with BMS

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I will say again, the preferred method of stopping alternator output (verified with Balmar) is to turn the external regulator off, not to break the field wire.

Yep!!!!! With Balmar you cut REGULATOR B+, not field....
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Old 09-08-2014, 07:25   #74
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Re: Baqon drop-in LiFePo battery systems with BMS

OK, when I wrote "cut the field" I meant make the alternator stop producing current before disconnecting the bank. Cutting the regulator B+ still requires some type of relay system to ensure that the alternator stops producing before the output is disconnected.

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Old 09-08-2014, 08:21   #75
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Re: Baqon drop-in LiFePo battery systems with BMS

The Devil is in the details.
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