Upgrading your Battery Banks and Alternator in 2014 is a Waste of Money.

[dlentz]

Originally Posted by Maine Sail

Rich,

I just passed 450 cycles last week, accelerated cycle testing is no small task believe me, and I conducted yet another capacity test at cycle 451. I am well into year two of this accelerated cycling but getting to 400 was hard work. It is even harder during the sailing season..

The bank is still putting up exactly what it did when new using the identical test protocol and instruments. No changes in capacity in 450 cycles. Each of these cycles has been to 80% DOD or as close to it as I can get. Sometimes we know we'll be motoring so we start charging at 70% DOD instead of 80% DOD....

Maine,
How are cells balancing with the accelerated cycling? Have you seen any/much divergence?

[sailorchic34]

Originally Posted by colemj

To replace the usable capacity of a typical 6 6V 660hr battery bank, one would typically use 400Ah of Li. This would result in ~280 fewer pounds of weight on the boat. We are a catamaran, so that is important to us, but I think even mono owners would like that loss.

I don't understand your thinking around charging sources. Li doesn't need to be charged at high C rates, and as long as your charging sources kept up with your usage with LA's, it seems like they would equally be fit for Li's. I'm talking solar, wind, good larger alternators and AC chargers - I understand that Li acceptance rates could overtax small alternators.

One only needs to put in what one takes out. If a smaller bank is taken down 80%, and that is the equivalent of taking 40% out of a larger LA bank, then it won't be any more of a problem to bring that 80% up to full charge than it would the 40%. It is all absolute - not relative.

Mark

Oh agreed, I was making a point that the high charge/ discharge rates of the LI's don't apply on boats.

As an engineer, I look at total system efficiency and complexity. My main concern, besides price of all the bits and pieces, is the additional controls needed for safe operation of LI batteries. LVC is required, so the battery is not bricked at 0v. HVC of course prevents overheating and trashing the battery of with LI is very intolerant. Then needing cell monitoring so one cell is not under or over charged. Much like a high maintenance blonde, there are many ways to fail

A boat's battery system needs to be robust. Lets just say I am concerned to the long term reliability of the electronics in a salt air environment. FLA is very simple old tech. LI requires some pretty fancy controls to keep the battery cells happy.

LI have many great benefits, no question there. When LI's get to $100 per 100 amps, I may get some.

[sailorchic34]

Originally Posted by SV THIRD DAY

Ahhhh....well....no.
Forget the weight.
Forget about the fact that they can take as much charge as you can throw at them to save on generator run time.
Forget about the face that there is no voltage sag.
Forget about having to equalize your LA batteries and burning holes in your favorite cruiser shirts.

What matters is the fact that most cruisers have a very hard time getting their LA battery EVER charged back to a full SOC when living at anchor and away from the dock. This in turn kills LA battery bank through sulfanization.

I'm replacing my 6-6v T-105's LA with with a 400AH LiOn bank as the internet experts debate it, praise it, and Poo Poo it. Progress move forward despite the naysayers and the Pioneers take the arrows.

I look forward to seeing how well your LI battery and controls hold up over the next five years. I hope it works perfect for you.

No question there are substantial benefits to LI. There are increased risks too and far more complexity. But then I'm talking to a guy who sells water makers and refrigeration, so you'r use to that complexity thingy.

[DeepFrz]

Rich; so you are going with Lithium Ion rather than LiFePO4? Is that because of availability or energy density or?

[Maine Sail]

Originally Posted by dlentz

Maine,
How are cells balancing with the accelerated cycling? Have you seen any/much divergence?

They have not been balanced since the first and only top balance. There has been zero drift and they have stayed in exceptional balance..

As of last week:

*Charging at 123A = 12mV spread
*House load of 11.4A = 4mV spread
*Resting = 4mV spread


Caveats:

My BMS does not automatically balance, I do not allow it to. If I ever wanted/needed to balance I would do so manually.

I charge to a max of 13.9V with the alt and it then steps down to 13.8V then to 13.2V, which is essentially off/no charging.

I stay well out of the upper & lower knees

I do not float. I charge then shut off all charge sources

Solar charges to 13.7V max

[SV THIRD DAY]

Sorry for the confusion DeepFrz...I just take a shortcut and type LiOn when technically it is LiFePO4. Here's a photos of the 4-400AH 3.2v cells all tied together in series for a 400AH 12.8v Battery Bank. The world hasn't ended yet, no black hole hole has opened up and sucked anyone in, and nothing has blown up yet....reports to follow.

[DeepFrz]

Thanks for the clarification, clarification...

People have been using at least 3 different namings for what I was assuming were the same thing, however I just wanted to make sure.

[piloto]

Denverdon: stock market-INTC UP ANOTHER 10 within next 40 days, F up 5 more in same period. Rest is subject to market collapse due to irrational exuberance. Keep someone in reserve for cold beverages to wash down sorrows.

[colemj]

There is one serious problem in that picture...

Mark

[SV THIRD DAY]

Originally Posted by colemj

There is one serious problem in that picture...
Mark

You mean besides the crappy wire crimp job and lack of heat shrink...or the old school use of black rather than yellow negative cabling? I got it...the stero wire size battery cables. When you post a photo....you open yourself up to the firing squad...Ready...Aim...Fire.

[colemj]

Hint: it starts with "X".

Other than that, I have no problem with those crimps or lack of heat shrink. I think some just over-obsess these things.

I am curious about the wire gauge, though. Hard to tell from the pic, but that looks like 2AWG (maybe 6?), which seems pretty skimpy. We are wired with 4/0.

Also, why does it look like there is a spare one disconnected at the top of the pic?

Mark

[SV THIRD DAY]

Originally Posted by colemj

Hint: it starts with "X".

Well ok...I know...but this was just a quick little test run so I didn't hook up the xantrex temp sensor correctly. There goes what little credibility I had...

Originally Posted by colemj

Also, why does it look like there is a spare one disconnected at the top of the pic?

Damn, can't get anything past your eyes. Shhhhhh...that's the bottom of a second 400AH bank that we are playing with in series with the first for a total of 800AH....and if my wife finds out about it I'm screwed, there goes my R&D play money for sure!

[Maine Sail]

Originally Posted by SV THIRD DAY

Well ok...I know...but this was just a quick little test run so I didn't hook up the xantrex temp sensor correctly. There goes what little credibility I had...

Rich,

The is NO temp compensation on LFP....

[SV THIRD DAY]

Originally Posted by Maine Sail

Rich,

I just passed 450 cycles last week, accelerated cycle testing is no small task believe me, and I conducted yet another capacity test at cycle 451. I am well into year two of this accelerated cycling but getting to 400 was hard work. It is even harder during the sailing season..

The bank is still putting up exactly what it did when new using the identical test protocol and instruments. No changes in capacity in 450 cycles. Each of these cycles has been to 80% DOD or as close to it as I can get. Sometimes we know we'll be motoring so we start charging at 70% DOD instead of 80% DOD....

When we come back to the mooring I leave it where it is. I could care less if it is at 20% SOC 40% SOC or 60% SOC as it is not phased by this.. I also don't leave the solar on, no need to... Last weekend was good sailing (well ok decent sailing) so it is currently at 18% SOC, after today's round of heat shrinking.. If our bank is sitting for any period of time, it is rarely if ever left above 70% SOC...

I was working on another boat in the anchorage today and needed to heat shrink about 17 2/0 & some 4/0 battery lugs, with both adhesive lined shrink and then clear over that with labels between. The owners bank was crapping out on low voltage after two shrinks. I told him last year his batts were beyond dead... Running the engine would have helped but it was too hot to be sitting in an engine bay next to an 800 pound heat sink. His solar panels were no help, batts are beyond gone.....

I took my skiff over to our boat and shrunk the remaining 15 with our inverter, no engine running.. This was done at approx 20% SOC on the LFP bank and the voltage hardly sagged enough to even be noticeable even with a 145A load at approx 20% SOC....

Our bank has performed exactly as it was designed to, amazingly well.....

Originally Posted by Maine Sail

They have not been balanced since the first and only top balance. There has been zero drift and they have stayed in exceptional balance..

As of last week:

*Charging at 123A = 12mV spread
*House load of 11.4A = 4mV spread
*Resting = 4mV spread


Caveats:

My BMS does not automatically balance, I do not allow it to. If I ever wanted/needed to balance I would do so manually.

I charge to a max of 13.9V with the alt and it then steps down to 13.8V then to 13.2V, which is essentially off/no charging.

I stay well out of the upper & lower knees

I do not float. I charge then shut off all charge sources

Solar charges to 13.7V max

Great Data!
Since we live aboard on the mooring, once I throw the switch from LA to LFP my family of 4 will be living our daily lives on the bank with wind, solar and the as needed Honda 2000/Sterling ProCharge 60A battery charger (the xantrex in the photo is not my charger). I will keep good data to track performance, but I don't plan to run the 20%/80% SOC cycle tests in the same way you have been painstakingly doing. I'm looking at it from a little different approach.

Based on our power usage history, we will use around 150AH per day. So my plan is to let the batteries see the charge/discharge profile that a normal cruising boat would see for living aboard cruisers with as few interventions as possible. Of course I’ll have the high and low voltage cut off/alarms, and individual cell monitoring to protect the battery, but my goal with the battery management system that Grasser is making for me is to have as much of a hands off approach as possible. Just keep out of the knees and leave it alone. The controller will monitor individual cell voltage, I’ll take your approach and not have the controller automatically balance but do it myself if the need arises. So far that issue looks over-blown from the test data I'm seeing from the manufacturer, your data and others who are reporting good ballance of the cells. Why complicate the controller to add a feature that I (or an average cruiser can easily do themselves is my approach).

Basically the “Black Box Controller” will have input lugs for Solar, Wind, Alternator, and Battery charger going to the battery and then have Output lugs going to the DC distribution panel from the battery. While data gathering is certainly a goal of the project, we also want to make it as “leave it alone” as possible because in the end it’s not the techy geeks like us that like taking data that matter, it’s the average Joe Cruiser who just wants it to work without hassle and too much baby-sitting. I think we are about at the point where that can happen if the system and controller is done right.

[Steve Lavigne]

Originally Posted by SV THIRD DAY

Basically the “Black Box Controller” will have input lugs for Solar, Wind, Alternator, and Battery charger going to the battery and then have Output lugs going to the DC distribution panel from the battery. While data gathering is certainly a goal of the project, we also want to make it as “leave it alone” as possible because in the end it’s not the techy geeks like us that like taking data that matter, it’s the average Joe Cruiser who just wants it to work without hassle and too much baby-sitting. I think we are about at the point where that can happen if the system and controller is done right.

So, you are developing a product that will make the entire Lifepo4 management simple and cost effective. Sounds awesome! Hope it works out and you bring it to market.