LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

[neelie]

That is the question.

( Its a given that adequate LV and HV cell level protections and alarms will be in place)

1) Do most of you have a BMS and if so what manufacturer?

Did you consciously choose to have a BMS or was simply the default choice?

Are you happy with the performance, quality and documentation of your BMS?

2) If no BMS does any one use cell loggers to control & monitor cell protection?

3) Is having a BMS an ABYC requirement or an insurance requirement?

I appreciate this is a contentious issue, so I'm hoping for polite, courteous discourse...please.

---------------------
FYI - my mini science project - LFP101 which consists of 4 x 100AH Sinopoly cells is going swimmingly well and has proved to be a great learning experience and it has sold me on the value of LFPs ... Many, many thanks to Ebaugh and T1Terry for their unstinting advice and encouragement . Couldnt have done it without you.

The best advice I can offer any newbie is to get 4 cells and screw around at home with them manually trying to balance the cells while in series .. it was like herding cats as T1 Terry put it.

Bit by bit, the fog lifts and slowly everything written on this thread begins to make sense. Its worth the investment in time and energy.

In 5 months time I intend to scale up to a 1000 AH house bank. I would really prefer not to have a BMS.

[ebaugh]

Originally Posted by neelie

That is the question.

( Its a given that adequate LV and HV cell level protections and alarms will be in place)

1) Do most of you have a BMS and if so what manufacturer?

Did you consciously choose to have a BMS or was simply the default choice?

Are you happy with the performance, quality and documentation of your BMS?

2) If no BMS does any one use cell loggers to control & monitor cell protection?

3) Is having a BMS an ABYC requirement or an insurance requirement?

I appreciate this is a contentious issue, so I'm hoping for polite, courteous discourse...please.

---------------------
FYI - my mini science project - LFP101 which consists of 4 x 100AH Sinopoly cells is going swimmingly well and has proved to be a great learning experience and it has sold me on the value of LFPs ... Many, many thanks to Ebaugh and T1Terry for their unstinting advice and encouragement . Couldnt have done it without you.A

The best advice I can offer any newbie is to get 4 cells and screw around at home with them manually trying to balance the cells while in series .. it was like herding cats as T1 Terry put it.

Bit by bit, the fog lifts and slowly everything written on this thread begins to make sense. Its worth the investment in time and energy.

In 5 months time I intend to scale up to a 1000 AH house bank. I would really prefer not to have a BMS.

As of now, I don't think there are any specific ABYC requirements, certainly not one for a BMS. But they do have people talking internally about changes needed for Li banks. There was a draft "guideline" expected a couple of months back, I don't know if it ever got distributed. Maybe one of the guys more plugged in to ABYC can give us an update.

[Lagoon4us]

In base terms using a cell logger with alarms,Volt and Amp monitoring, fuel gauge, charge cutoff and load cutoff forms a basic BMS.
I believe temperature monitoring isn't needed so the main thing missing from what has largely been discussed here is the automated balancing.
Am i correct?

[daddle]

Temperature monitoring may be a good idea because charging at below 0C (32F, freezing) is either "not permitted" or "significantly shortens life."

[Lagoon4us]

Apologies but low temp isn't an Aussie's problem.

I think the LiFeYPO4 handle temp better, might be wrong?

[daddle]

Originally Posted by Lagoon4us

Apologies but low temp isn't an Aussie's problem.
I think the LiFeYPO4 handle temp better, might be wrong?

* Sometimes boats move to different climates, even catamarans
* Life begins to be diminished around 5C to 10C.
* When life is important the temp is maintained between 20C and 45C.
* Some unfortunate CF'ers experience cold weather, say in Croatia.
* This characteristic is a negative compared to LA and should be considered.

[mrm]

Originally Posted by daddle

* Sometimes boats move to different climates, even catamarans
* Life begins to be diminished around 5C to 10C.
* When life is important the temp is maintained between 20C and 45C.
* Some unfortunate CF'ers experience cold weather, say in Croatia.
* This characteristic is a negative compared to LA and should be considered.

Currently published Winston specs for LiYFePO give charging temperature range between -45C and +85C.

Winston Battery Limited

[Lagoon4us]

Croatia, where we are, pulls up at say 0deg windchill aside, I ain't sailing anywhere where it's -45 of that i'm sure !!!!

[daddle]

Originally Posted by mrm

Currently published Winston specs for LiYFePO give charging temperature range between -45C and +85C.

Winston Battery Limited

That's impressive. The chemists have been busy. But the battery data sheets are less than forthcoming on proper specification: there is no cycles/temp chart and the other charts are at "normal temperature", whatever that is.

For us electronics geeks data sheets are supposed to describe characteristics for the entire range of test conditions, not cherry picked. But that's the state of the battery business. The research papers will eventually confirm or tell the real story.

[ebaugh]

Originally Posted by daddle

* Sometimes boats move to different climates, even catamarans
* Life begins to be diminished around 5C to 10C.
* When life is important the temp is maintained between 20C and 45C.
* Some unfortunate CF'ers experience cold weather, say in Croatia.
* This characteristic is a negative compared to LA and should be considered.

Many more cruisers, especially us stink pots with batteries in the engine room have a much bigger problem with high temps which are proven to kill LA.

[mrybas]

Hi,
I'm in Central America and would like to replace my 6 year old AGM's before leaving for the S. Pacific. Are LiFePO4 batteries ready for the sailor with average understanding of electrical systems, or still a few years until they're ready for 'the market'?

[mbianka]

Originally Posted by ebaugh

I suggest you study the EV forums at DIY Electric Car and EVTV.ME to get an appreciation of the differences between AGM/LA and LiFePO4 from an audience with similar applications. I don't know if range is important to you or not, but if so, the differences in EV cars is astounding. It's the difference between going to the market vs a daily commute to the office much further away. You have I think more of a hybrid solution, so it may not all apply. Nevertheless I think it would be interesting. Those guys, the EV community, are the true pioneers of this, not marine house banks.

Yeah, I agree the EV guys have been doing this for a long time. I did poke around some of the ev boards when I was first thinking of coverting to EP. That's where I found about the Paktrakr which I used to monitor the batteries at first. Though I have rethought using it these days. I was amused when of the ev guys spoke of using some used free batteries in his vehicle and nonchalantly talked about how one of them exploding and how he needed to get around to replace it. Those guys went through a lot of trial and errors for sure. I also got a lot of info from the crowd working on electric boats too. Watched as some people got burned (financially) when they laid out money for motors in underwater pods that did not exactly perform as advertised.

Range was a concern when I first thought about converting to electric propulsion. But, I always reminded myself that my boat is a "sailboat" first and foremost. That's how I like to propel it. Though my system is speced at 20 miles at 4 knots I've never have had to do that. Since I usually operate under battery until the battery capacity has dropped 30%. Which is about two and half hours of motoring. Then switch to hybrid mode and can run as long as the Honda 2000 has fuel. Range worries are no longer a concern. Most of the time motoring is limited until the wind returns usually within a half hour or getting in and out of an occasional marina. Though I did have to motor 40 miles last fall on one particular windless day. It was a quiet 40 miles too.
THE BIANKA LOG BLOG: ELECTRO SAILING AROUND NEW YORK: PART ONE

Considering the way I operate I still don't see the economics working for me to change out to Lith's at this time. I could replace my four 200 amp AGM's for $1,900. Lith's would cost double and that's before I start adding chargers and BMS to the costs too. That does not mean I'm not interested in them. Just I'd still like to see a bank that makes it to 1,500 charge cycles like is claimed and the balance issues be not so hands on. For now my AGM bank is pretty much hands off and I like that.

[mrm]

Originally Posted by mbianka

Considering the way I operate I still don't see the economics working for me to change out to Lith's at this time. I could replace my four 200 amp AGM's for $1,900. Lith's would cost double and that's before I start adding chargers and BMS to the costs too.

You stated previously, that for best longevity you like to utilise only 30% of your bank capacity. This means, that 200Ah AGM bank gives you 0.3*200 = 60Ah of usable capacity.

LiFePO delivers 70% of its capacity while claiming 7000 cycles (or 80% claiming 5000 cycles). This means that you will get the same or better usable capacity from 100Ah cells (0.7*100 = 70Ah).

To make a 48V bank you will need 15 LiFePO cells.

At current nominal (not clearance!) prices, it amounts to 15 * $110 = $1650.

So you still have $250 to spend on cell loggers, mini BMS and such

That does not mean I'm not interested in them. Just I'd still like to see a bank that makes it to 1,500 charge cycles like is claimed and the balance issues be not so hands on. For now my AGM bank is pretty much hands off and I like that.

We see much better claims at present
As for 'hands off' - I have a feeling we will get there quite soon.

[noelex 77]

Does anyone know the name of the input plug/socket for this cell logger.

Google doesn't give up the secret in this case.
Thanks
EV-Power | Cell Logger 8 cells / 1 battery (USB port)

[NahanniV]

Originally Posted by noelex 77

Does anyone know the name of the input plug/socket for this cell logger.

Google doesn't give up the secret in this case.
Thanks
EV-Power | Cell Logger 8 cells / 1 battery (USB port)

It's a "JST-XH" connector (.1" spacing). I got a 5 pin (for 4 cells) cable from a local hobby store that caters to electric Remote Control Hobbies. This is commonly called a balance connector in the hobby world.