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

[ebaugh]

I don't think the chemistry has anything to do with it? Supposedly these were the first cells to pass some complicated Chinese safety test for EV cars that includes all sorts of punishment without creating a fire.

I figured who can argue with safety fuses? Especially since fire is the worst nightmare possible on a boat so I added them. They don't protect the pack as a whole, but there is a big fuse for that right after the BMS solenoid disconnect.

They sell the 4 screw system as an enhancement promoting better connections, but I wonder about that. I guess if there was any wiggle in the cell interconnects, that would impact a single bolt more than the 4 screws, but they aren't supposed to move any.

[T1 Terry]

Do you have a photo of one of the fuses? Sounds interesting, as you say, there is no harm in adding an additional safety item as long as it doesn't add another possible poor connection or corrosion point.
The first time I saw the plastic cover plates I thought they looked like a great innovation, the biggest fear is dropping something across the terminals, there is a huge amount of energy available in those cells just waiting to catch the unsuspecting punter. We covered the spanners that were to be used on the batteries with heat shrink to minimise the chance of shorting across a terminal or the the body work.

T1 Terry

[ebaugh]

I used ANL fuses, generally available inexpensively from car stereo suppliers. I think it was about a buck apiece. They mount between the terminals sandwiched between buss bars or between a buss bar and a terminal. I had to drill out the rivets since the case got in the way. You end up with the same thing you described a filed down buss bar, but at least supposedly calibrated to melt at a specific current flow.

This would not work well for the single bolt batteries unless they just happened to fit. Or work well for higher capacity cells, but all of these connections handle less than 20A in my installation.

[ebaugh]

Hey Terry!

I believe I've finally found the culprit behind the low cell in my installation. (described back a few posts in this thread). One of the EMS/BMS sense boards was drawing 148 milliamperes, but still otherwise worked as advertised. A good board drew 2 milliamperes.

Perhaps that only reinforces the "who needs a BMS concept"! I had a spare, so I've installed that for the time being. It will take a month or so to be 100% sure, but I'm pretty sure. Found it with an IR gun, it was running about 10 degrees F over ambient which led to further investigation.

Bob

[deckofficer]

Good point Bob. The (8) 100 amp cells that are due to arrive this week I'll be using as (2) 12.8 volt batteries, one with a BMS and one without. Both will see the same type of service and I'll check each cell's voltage as regular maintenance just to see if BMS is needed for users that charge and discharge these cells properly.

[T1 Terry]

Originally Posted by ebaugh

Hey Terry!

I believe I've finally found the culprit behind the low cell in my installation. (described back a few posts in this thread). One of the EMS/BMS sense boards was drawing 148 milliamperes, but still otherwise worked as advertised. A good board drew 2 milliamperes.

Perhaps that only reinforces the "who needs a BMS concept"! I had a spare, so I've installed that for the time being. It will take a month or so to be 100% sure, but I'm pretty sure. Found it with an IR gun, it was running about 10 degrees F over ambient which led to further investigation.

Bob

Glad you found it before it damaged those cells. It's the most common way the BMS modules fail, the other way is when the control a battery charger and for what ever reason fail to turn it off boiling the cells. On another forum an electric vehicle owner looks to have lost quite a bit of his battery pack through the BMS not reducing the over voltage or shutting down the charger yet all th lights were flashing.

T1 Terry

[jff]

Greetings all

I'm new here, but it look like this thread has a wealth of knowledgeable contributors.
I have just installed 16 GBS 200ah cells, arranged as 2 24v batteries with Elites BMS system.

The major issue I have is with charging, in a marina my Victron 50A charger works fine, and is turned off by the bms system,but anchoring out is a problem.
The boat has a Steyr diesel with a watercooled flywheel generator that provides in theory 2 24v 80A outputs. Certainly when I tested the system in the marina it looked good, with the BMS reporting around 140a going into the cells. That was with the pack being at around 80% charged.

When I tried to recharge when the cells dropped below 3.2v, I ran into a brick wall. It seems that the regulator doesnt like being asked for more amps than it can provide, initially drops the output to around 30A, then shuts down completely. Not exactly the ideal situation.

I tried contacting Steyr who advised "the unit is operating correctly, we do not recommend using lithium batteries with this unit" which was a bit suprising since they offr a hybrid drive as well using the same alternator.
Does anyone know of a device that I can put between the cells and the alternator to limit the load on the alternator?

cheers

John

[senormechanico]

If all it's doing is producing DC, can you limit the generator's RPM via the throttle linkage?

[s/v Thea]

Originally Posted by jff

Greetings all

I'm new here, but it look like this thread has a wealth of knowledgeable contributors.
I have just installed 16 GBS 200ah cells, arranged as 2 24v batteries with Elites BMS system.

The major issue I have is with charging, in a marina my Victron 50A charger works fine, and is turned off by the bms system,but anchoring out is a problem.
The boat has a Steyr diesel with a watercooled flywheel generator that provides in theory 2 24v 80A outputs. Certainly when I tested the system in the marina it looked good, with the BMS reporting around 140a going into the cells. That was with the pack being at around 80% charged.

When I tried to recharge when the cells dropped below 3.2v, I ran into a brick wall. It seems that the regulator doesnt like being asked for more amps than it can provide, initially drops the output to around 30A, then shuts down completely. Not exactly the ideal situation.

I tried contacting Steyr who advised "the unit is operating correctly, we do not recommend using lithium batteries with this unit" which was a bit suprising since they offr a hybrid drive as well using the same alternator.
Does anyone know of a device that I can put between the cells and the alternator to limit the load on the alternator?

cheers

John

You could put a high amperage diode in the charging circuit, they have a 1v +/- voltage drop.

Doug

[witzgall]

Is the regulator external to the alternator? It should be, and they should be able to modify the program parameters to work with your cells. I would politely let them know how disappointed you are with their response, and don't be afraid to push things up their chain of command. The setup you have is very expensive, and state of the art. To say that you can't use them with state of the art batteries is a cop out.

Chris

Originally Posted by jff

Greetings all

I'm new here, but it look like this thread has a wealth of knowledgeable contributors.
I have just installed 16 GBS 200ah cells, arranged as 2 24v batteries with Elites BMS system.

The major issue I have is with charging, in a marina my Victron 50A charger works fine, and is turned off by the bms system,but anchoring out is a problem.
The boat has a Steyr diesel with a watercooled flywheel generator that provides in theory 2 24v 80A outputs. Certainly when I tested the system in the marina it looked good, with the BMS reporting around 140a going into the cells. That was with the pack being at around 80% charged.

When I tried to recharge when the cells dropped below 3.2v, I ran into a brick wall. It seems that the regulator doesnt like being asked for more amps than it can provide, initially drops the output to around 30A, then shuts down completely. Not exactly the ideal situation.

I tried contacting Steyr who advised "the unit is operating correctly, we do not recommend using lithium batteries with this unit" which was a bit suprising since they offr a hybrid drive as well using the same alternator.
Does anyone know of a device that I can put between the cells and the alternator to limit the load on the alternator?

cheers

John

[jff]

Originally Posted by witzgall

Is the regulator external to the alternator? It should be, and they should be able to modify the program parameters to work with your cells. I would politely let them know how disappointed you are with their response, and don't be afraid to push things up their chain of command. The setup you have is very expensive, and state of the art. To say that you can't use them with state of the art batteries is a cop out.

Chris

The regulator is external and your right,I'm exceedingly disappointed. Particularly when the Australian Steyr service agent told me the flywheel generator was "perfect" for lithium. Normally, I'd just pull the regulator and have it modified. But I'm in Italy and my Italian is pitiful.

I did find these motor controllers that might do the job Hydrogen (HHO) DC PWM Controllers High Current

[ebaugh]

The GBS batteries accept all the charge the system can provide. Voltage rise is very slow. But I'm not sure why that's different than a large capacity but depleted regular battery.

I read the brochure on they system you have, but all I could find is a glossy. Do you have more details? Or a link to an installation/service manual?

The other already provided advice is sound...push the manufacturer to actually support the product.

[jff]

Here's all the information on the IFG I've been able to extract
http://dl.dropbox.com/u/26395671/Z0010410_1_06.pdf

Its actually made by ISKRA in Slovenia, but they are just contractors and dont want to know I'll certainly be hassling Steyr, particularly given that they are working with Mastervolt on a serial hybrid. In the long run, that should produce the best result.
However, I hate marinas, and I need to get the boat over to the Canaries before setting over the Atlantic.

The truly bizarre thing is the only 12v systems on the boat are the engine management, starter, and alternator. I'm thinking I might change the alternator & starter to 24v to giv some redundancy. The ems can run from a converter

[Dsanduril]

Steyr/Iskra IFG into LiFePO, wow, I'm envious, and glad at the same time to not be that close to the edge.

The "problem" with permanent magnet is that all the controls are on the output, you can't control the magnetic field as you can with the field current on a traditional alternator. And you can't do much to control the current, the PMA increases voltage as RPM go up.

From reading between the lines, Iskra/Steyr are using a constant voltage regulation routine, and with the LiFePO they get to full current before they reach the constant voltage. They're counting on the voltage rise that occurs in LA during charging. The manual you posted even notes that it shouldn't be run on a deeply discharged bank, probably for the same reason. Bottom line, you're at the mercy of crappy software in the controller. Can't believe you can't send it a setpoint on the CANbus (maybe you can, but no one wants to tell you).

Quick and dirty, I would consider the suggestion above of inducing about a 1V drop in the lines from the generator to see if you can fool the regulator (from all drawings it looks like it does not have separate voltage sensing lines). A 1N3290 diode is rated at 100A and 1.5V and runs about $15. You'd have to find a good heat sink, and you'd be wasting 120W or so per channel at full output, but might be a cheap way to verify that everything is doing what you expect. Hate workarounds like that, but then, what is cruising other than sailing from one workaround to the next

If you want to play with the very expensive equipment, it looks like they use a jumper to switch between 13.8 and 14.3 constant voltage. I wonder if that jumper is just bypassing a resistor in the internal sensing circuit? If that's the case you might be able to open the thing up and change the resistance value. I would want to do that kind of tinkering, but there's a lot of $/£/€ on the line, and they're not mine, so that's easy to say.

[ebaugh]

I got the manual and read through it. Interesting concept, but I'm not so sure I like all the water (saltwater I think) running through things I don't have on a schedule for replacement.

You said there were 2 24V banks, the literature says they can't be in parallel without isolation diodes, do you have those installed if required. Unless you used 2 BMS systems, they come together somewhere.

Even if not needed with 2 BMS systems, the diodes may help your situation as previously mentioned.

But the bigger issue is the entire design is a single stage, essentially unregulated charger. Not a great idea for charging lithium. You do have the BMS to save the batteries, but for marine use, I think it should be a for insurance only since usually you're using the system the same time you are charging it underway.

I've scratched my head for an hour and don't have anything brilliant to suggest.

It's probably cost prohibitive, but switching to the AC version and using controllable battery chargers would work.

Assuming the diodes work in the present system, try to make sure the voltage is limited to absolutely no more than 3.4V per cell when operated full time, 3.34 would be even better to maximize battery life.

Wish I could be more help......