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

[Maine Sail]

Originally Posted by goboatingnow

The last thing you want is Gels, tricky finicky cells

Dave

When properly charged these are some of the longest lasting LA batteries I see and work on in the marine environment. I've got a set that came new on a Tartan delivered 13 years ago and many others well beyond 9 years with no maintenance, no equalizing just set the charge voltages per the manufacturers instructions and let them go.... Not difficult to charge at all just don't go beyond 14.1V (or manufacturers recommendations), use temp compensation, and they will last for a long, long time...

AGM's I agree but GEL's are good robust batteries. Unfortunately GEL's got a bad rap because people did not want to change alternator regulators and many shore chargers lacked a proper GEL voltage setting. When charged properly they are really good batteries... Heck Deka/East Penn produces FLA, AGM and GEL they rate their GEL batteries are double the cycle life of their AGM's....

[Maine Sail]

WARNING - Lesson Learned / Glow Plugs

Ok our Westerbeke/Mitsubishi engine has four glow plugs, one for each cylinder. Unfortunately the duration I press the button NEEDS TO BE SHORTER with LiFePO4....... Sadly this never occurred to me until all four glow plugs were toasted over the last few weeks of cold weather sailing.

I suspect I burned one out, then pressed a little longer on the remaining three, then burned another then finally popped the remaining plug/plugs.. In the summer I don't even really use glow but when the engine is sitting at 30-40f they can be nice.... Because I stay in and sail late in the season my glow plugs really help in the cold weather...

If anyone wants to know a Westerbeke 44B will start at 29F without any glow plugs, it just takes a little more cranking.... Still I prefer to have the glow plugs...

When I realized it it today, what I had done wrong, it totally dawned on me as a Doh' moment......

Many 12V glow plugs on Japanese engines are rated at 10.5V for 15 seconds. This is all well and good with a single LA battery where voltage sag drops battery voltage to a safe range for the 15 second press of the button. This is NOT a safe duration when using LiFePO4 and feeding them 13.2V +/-...

It did not dawn on me until I toasted the plugs that my LiFePO4 voltage simply does not sag under the load of the glow plugs, like my old LA bank did. Because of this "lack of sag" the glow plugs were seeing significantly higher voltages for the same press duration, over heating and finally failed.....

Fortunately they take about 5 minutes to replace and cost $6.50 each so no big deal but I figured I would pass it on.

I do plan to install a diode, or even two, in the glow circuit to intentionally drop the voltage. I will also glow for about 5 -8 seconds not the 15 I had been doing for years...

Sometimes even the little details sneak by so I figured I would pass this little one on. 99% of the devices on-board LOVE the lack of voltage sag, the 1% that don't are the glow plugs.....

With glow plugs on LiFePO4 press for about half what you did with LA or throw a diode in the B+ to the plugs.

[deckofficer]

Good catch Maine. Our cells don't sag. What is the amp draw of those glow plugs? I like numbers, so if each pulls 15 amps and expects to see 10.5 volts, that would be 630 watts warming those 4 combustion chambers. Almost 800 watts at lithium voltage.

[senormechanico]

You're right about no sag.
Dead cold starting my Volvo MD 2020 in winter in the PNW, I give the glowplugs a count of 6 and it fires right up.

[T1 Terry]

The batteries are that strong you can actually crank on hold the glow at the same time. This stops over doing the glow plug time and it is surprising just how quick they fire up when done this way.

T1 Terry

[Opie91]

Maine Sail or anyone else doing this for a living,

Have you started to install these in boats other than your own?

[CharlieJ]

I have designed three systems, installed two and I am about to start designing and installing the fourth system. First system was nominal 800Ahr using Thundersky 180Ahr cells; second system was also nominal 800Ahr using CALB 180Ahr cells. The third system is designed and the cells are in hand but not installed is 2 x 1000Ahr banks using Forzatec 100Ahr cells. The fourth system will probably be in the 1000 to 1600Ahr range and will probably use CALB 180Ahr or 400Ahr cells.

[roetter]

Originally Posted by Opie91

Maine Sail or anyone else doing this for a living, Have you started to install these in boats other than your own?

I have done one 360Ah system for myself and another for a friend using 180Ah Winston.

I am in the process of doing another system of 1400Ah using 700Ah Winston cells for myself. Will install the same system on another friends boat next April.

I am also getting ready to order some small cells for a small electric dinghy for my wife. Just for short and slow runs to the beach. She gets nervous about being g unable to start the outboard.

[Cotemar]

Originally Posted by roetter

I am also getting ready to order some small cells for a small electric dinghy for my wife. Just for short and slow runs to the beach. She gets nervous about being g unable to start the outboard.

Do you have more details as to your electic dinghy? Will you just splice your custom LiFePO4 battery to a Torqeedo Travel motor?

My Cat dinghy will be perfect for electric as it needs little hp to even row let alone motor. It flys with a 6 hp.

http://www.cruisersforum.com/forums/...ml#post1347622

[Stumble]

I have tried to read thru this thread, and sadly it gets to technical for me quite quickly. I am trying to figure out what type of work I would be looking at to replace my current 300ah lead acid system with a LiFePO system? We had an on the dock electrical spike that fried the battery charger, and the batteries are 5 years old, so I don't mind replacing them. So at this point my installed system is pretty much toast and before I spend a lot to replace it with what I have I would like to understand my options.

Secondly would a system like this require significant monitoring or is it a replace it and forget it system. I don't mind periodic maintenance, but I don't want to have to manually try to balance different cells. I don't have the patience for that.

Finally the current boat profile is mostly daysailing, with a few weekends a year we will anchor out for 2-3 days. The installed 300ah of lead acid is fine for our current demands, so could I go to a smaller battery bank because of the deeper discharge allowed on LiFePO?

[hellosailor]

Stumble-
"Secondly would a system like this require significant monitoring or is it a replace it and forget it system." The literature I've seen, including correspondence specifically asking about a 12-volt preassembled battery that is sold as a drop-in replacement, all says you must use a BMS. Must.
The only exception to this is from one company selling drop-in replacements with a built-in BMS, at an incredible price per unit.

So the question may not be what the system requires, but rather, do you want the opinion of hobbyists, or the opinion of the manufacturers, and if you go for the latter, can you find any that say you can "forget it", with or without the BMS. After all, even conventional wet lead batteries can't be totally neglected, unless they are sealed you'd still want to check the electrolyte level once in a while.

[roetter]

Originally Posted by hellosailor

Stumble- "Secondly would a system like this require significant monitoring or is it a replace it and forget it system." The literature I've seen, including correspondence specifically asking about a 12-volt preassembled battery that is sold as a drop-in replacement, all says you must use a BMS. Must. The only exception to this is from one company selling drop-in replacements with a built-in BMS, at an incredible price per unit. So the question may not be what the system requires, but rather, do you want the opinion of hobbyists, or the opinion of the manufacturers, and if you go for the latter, can you find any that say you can "forget it", with or without the BMS. After all, even conventional wet lead batteries can't be totally neglected, unless they are sealed you'd still want to check the electrolyte level once in a while.

Hello Sailor - You must own stock in lead acid companies.


Stumble:
LiFePo are much easier to use and keep alive for a long time than all the discussions here might suggest. We are all guys that like to tinker with this kind of stuff and go to the extreme.

No balancing is required if:
A- you do not push them hard ( less than 1C, boat house banks usually run at 1/10C)
B- and you do not drive them from really full to really empty. leave 10% at the upper and lower end and they will live a long, long time.
You information suggests that you are a very light user for what the LiFePo can deliver.

The shore charger should be adjustable to 13.8V or maximum 14V.

Just once in a while (every 2-3 months) measure and record the voltages of each cell. Best to do it when you are charging with a shore charger and they are near full (80+). Any cheap digital voltmeter will do. The absolute voltage is not that important. Important is the voltage difference between the cells. If you get more than 0.1V difference between the lowest and the highest cell, then you need to balance.

To balance:
Best to do this when charging and near full.
Charge with your regular shore power charger.
Measure the cell voltages when near full. At this point voltages of the high cells will go above 3.45V when the battery starts getting full, if you are using about a 10A charge current for every 100Ah in battery capacity.
Get a 12V automotive head light lamp. Put short cables and alligator clips on it.
If you have one high cell, put the lamp on that one cell. The lamp will only light dimly as you are driving it only with 3.4 or so volts.
If you have two or three cells high and they are next to each other put the lamp on those.
It will take some time to bleed some excess amperes out of the high cells, but this is what the fancy BMS systems do, also rather slowly.
Just don't forget to take the lamp off.
You are good when the high cells have dropped to closer than 0.1V of the lowest cells, after you have taken the lamp of.
Make sure none of the cells goes above 3.7V ( your are still in the very safe zone). If one does, stop the charger and keep the light bulb on it for a while. Then start charging again.

Four 160Ah cells would do the trick for you to replace the 300Ah lead acid you have. They are $176 each at Balqon at the moment. At an RV store I saw Exide deep cycle lead acid 80Ah for $100 each. That make $400 for 320Ah LA vs $704 for the LiFePo at more usable capacity.

[roetter]

Originally Posted by Cotemar

Do you have more details as to your electic dinghy? Will you just splice a your custom LiFePO4 battery to a Torqeedo Travel motor? My Cat dinghy will be perfect for electric as it needs little hp to even row let alone motor. It flys with a 6 hp. http://www.cruisersforum.com/forums/...ml#post1347622

At this moment I am going really simple. I have a small inflatable dinghy with soft bottom, that we used when travelling with our motor home. It can be rolled up quite small and has a bag. With that we used a small cheap 12V trolling motor from a fishing store. We will see how it works and the. Go from there. We a dinghy with a 20Hp Honda as our main car. The electric one will only be used by my wife when I can not take her and the dog to shore.

[T1 Terry]

Originally Posted by hellosailor

Stumble-
"Secondly would a system like this require significant monitoring or is it a replace it and forget it system." The literature I've seen, including correspondence specifically asking about a 12-volt preassembled battery that is sold as a drop-in replacement, all says you must use a BMS. Must.
The only exception to this is from one company selling drop-in replacements with a built-in BMS, at an incredible price per unit.

So the question may not be what the system requires, but rather, do you want the opinion of hobbyists, or the opinion of the manufacturers, and if you go for the latter, can you find any that say you can "forget it", with or without the BMS. After all, even conventional wet lead batteries can't be totally neglected, unless they are sealed you'd still want to check the electrolyte level once in a while.

Then you have to consider this advice is from someone who is quoting from "all he has read" They may be hobbyists but they do have the hands on knowledge and do not have an reason to push an add on product they just happen to make and sell. So the real question is, do you want a reliable battery system, and do you want fries with that? Or will you be happy to stay with the old stand-by that everyone knows everything about

T1 Terry

[Stumble]

Roetter,

Actually ISAF has changed the rules to require all rechargeable batteries be sealed, so the open top flooded lead acid batteries can't be installed anymore (as of 1/1/12 see OSR 3.28.4 b), so the price is actually much more competitive. To save the weight (and my back), gain useful capacity, and cost about the same, it is becoming harder to justify not buying LIFEPO's. I just want to make sure I understand what I am getting into.

So assuming I am going to use a battery monitor does anyone have a recomendation?