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Old 22-06-2014, 06:36   #3751
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

Kashmir,

It would be a great idea for you to first look in the manual, and see what type of batteries your regulator was designed for. You should also gather information about multi-stage charging from the manufacturer of your LifePO4 cells.

A lot will be revealed just from gathering that information !

Alan
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Old 22-06-2014, 10:50   #3752

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

Terry, so he's going to put it all online based on...whatever.

Hey, what's the absolute worst thing that can happen? His batteries will catch fire and burn? Nope, not with LiFePO4, right? All he can do is slag down some batteries. Even in the worst case, he'll do better than Boeing did, with all their engineering prowess. (VBG)

Cause of the Boeing fires, still reported as unknown. Number of relevant known fires with LiFePO4, still zero. Right?
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Old 22-06-2014, 17:17   #3753
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

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Originally Posted by T1 Terry View Post
Are you serious? As a commercial member who is fitting up lithium batteries you should have the R&D behind you to know this information, if you don't, you shouldn't be fitting up lithium batteries as a commercial venture. Are you really going to put it all on the line using information you gained from a forum???? If I gave you a set of figures what makes you think I'm not setting you up for a major fall?

T1 Terry
Thanks for the comment Terry, Balmar regulators are not very common here. I do not have the facilities to test every single type of system out there. I know what voltages the cells I am selling require and I can alter the settings to suit what I think they should be, but I try and gather information from as many sources as possible then make my own decision about what to set them to. The use of these cells is obviously a lot more common in the US than here and I was hoping to tap into some greater wisdom.
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Old 22-06-2014, 17:40   #3754
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

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Originally Posted by hellosailor View Post
Terry, so he's going to put it all online based on...whatever.

Hey, what's the absolute worst thing that can happen? His batteries will catch fire and burn? Nope, not with LiFePO4, right? All he can do is slag down some batteries. Even in the worst case, he'll do better than Boeing did, with all their engineering prowess. (VBG)

Cause of the Boeing fires, still reported as unknown. Number of relevant known fires with LiFePO4, still zero. Right?
It won't only cost him his reputation, it may cost unsuspecting buyers a few hard earned $$ and severely damage the reputation of LiFeP04 batteries as to their expected cycle life and reliability. This is the only reason I participate in these type threads, to protect the technologies reputation from being damaged by ignorance of the technologies requirement.
Everyone can see that as a result of the hard yards done by the first adopters that lithium is the way of the future, the problem is that many will see this as a way to make a quick buck, do zero R&D and attempt to cash in on the hard work already done without contributing a cent towards it or any information they have found while doing their own R&D. This was an inevitable result, the thing to do now is not to feed those trying to cash in, make them pay the time and $$ to do R&D themselves, this type of thread is for the DIY people, not those looking to make $$ from others hard work and expense

T1 Terry
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Old 22-06-2014, 21:15   #3755
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

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Originally Posted by T1 Terry View Post
Are you serious? As a commercial member who is fitting up lithium batteries you should have the R&D behind you to know this information, if you don't, you shouldn't be fitting up lithium batteries as a commercial venture. Are you really going to put it all on the line using information you gained from a forum???? If I gave you a set of figures what makes you think I'm not setting you up for a major fall?

T1 Terry
When I saw this question, I wondered (well, maybe not) who was going to step forward to give him both barrels.

Why are you even starting from the supposedly magic little blue box? I have seen enough of them here with blown power transistors out of warranty that it is not even funny.
If it operated with a current shunt and was able to sense the current drop to stop charging, it could make it "smart", but unfortunately like all its "marine" competing alternatives, it is just an after-market VCDR (Very Costly Dumb Regulator). This one offers you Free-Range Programmable Stupidity instead of Conservative Preset Stupidity, so you can take full blame after wrecking your someone else's battery bank.
The way you get around that detail is by installing it with very conservative settings and let the dissatisfied end-user go back in and change those parameters himself.

Anyway - back on topic - claiming to provide commercial engineering services in complete technical ignorance isn't a good look - you have got that one right! Happy consulting.
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Old 23-06-2014, 02:39   #3756
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

Amazing...

A guy that sells LifePO4 cells asking these questions...

I was not expecting that !!!!

Alan
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Old 23-06-2014, 11:32   #3757
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

After 4 years using my Li banks, one concern I have is about the alternator.
As the Li batteries can accept an high C charge during almost all the charging time , the alternator become pretty hot and my concern is its lifetime.
It is a 75Amp 24V Leece neuville "heavy duty", feeding 2 *130Ahbatteries and I derated the alternator to 60Amp max. Added a blower to pick up "cold " air from the bildge, but still pretty hot.
Any suggestion how to size an alternator to keep a raisonable charging time and a good lifetime. I do understand that all alternators are NOT designed to run at 80% of the nominal capacity.... but ...
cheers
gael
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Old 23-06-2014, 11:37   #3758
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

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Originally Posted by OceanSeaSpray View Post
It is also one of the most stupid way of doing it without destroying anything - for a start - and it would take one massive resistor. If the system goes over-voltage and you dump the resulting excess power instead of addressing the root cause - something has gone very wrong - you open the road for much more damage including fire.
If the regulator fails shorted, alternator output becomes proportional to engine revs. Happy cooking.

Definitely NOT the way of addressing a regulation failure issue.

I don't think you quite get V=IR and load dumping on alternator disconnects .


Here a piece from a suitable manufacturer of load dumming resistors alternator

"
The more conventional alternator systems frequently require “Load Dump”resistors to prevent damaging high voltage transients when a load is suddenly removed or the engine is switched off from high speed. This resistor is usually connected in series with an avalanche diode; it sees a low average power but must withstand fast rising high power transients. A wirewound part such as SQP or WP-S series is needed here."

it can even be automated using avalanche diodes if you like, then you can just open the load.

Note : that European cars have alternators that can handle such load dumps by law.

http://www.ttieurope.com/docs/CP/6488/automotive.pdf

Please dont tell me how to suck eggs, thanks


dave
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Old 23-06-2014, 11:44   #3759
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

Quote:
Originally Posted by gael View Post
After 4 years using my Li banks, one concern I have is about the alternator.
As the Li batteries can accept an high C charge during almost all the charging time , the alternator become pretty hot and my concern is its lifetime.
It is a 75Amp 24V Leece neuville "heavy duty", feeding 2 *130Ahbatteries and I derated the alternator to 60Amp max. Added a blower to pick up "cold " air from the bildge, but still pretty hot.
Any suggestion how to size an alternator to keep a raisonable charging time and a good lifetime. I do understand that all alternators are NOT designed to run at 80% of the nominal capacity.... but ...
cheers
gael

You really need good alternator temperature based sensing controlled charging. Balmar do some systems of that ( as do others)
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Old 23-06-2014, 12:03   #3760
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

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Originally Posted by Hkalan View Post
Hi Eric,

I did have the relay on the AC side, I recently put it the dual coil on the DC side because I ordered several more single and double pole relays to stow, and will have the AC side relay back in by the end of next week. All relays will match and from the same factory. (the ac side relay was a local purchase and was not confident in it).

I was reading on another forum how an El-Cheapo-Charger short circuit, and even when the AC side was cut, the DC was back feeding into the charger that started a minor fire (don't understand how)... so for all safety sake I will cut both AC and DC sides. Cant hurt !

Alan
This level of protection is carrying things to the bizarre, I mean today we do not habitually protect the AC side of a charger ( or do field coil switching) . You might as well install a full auto fire suppression system, have breathing apparatus on stand by etc.

The main thing is simply a Cell logger/BMS logic that detects a CELL level HVC event and disconnects the input feed to the battery. I would not recommend removing the load, as having the load actually helps things.

For alternators, you can switch the field off, but thats often very hard to rig up on certain systems. Load dumping is a solution followed by an alarm and obviously manual alternator shutdown. ( nones is doing unattended engine charging right ...!)

HVC should be manually resettable only.

LVC can be done on total battery voltage , but again I would prefer to see cell level LVC. A major cause of problems in Lithiums is recharging cells that have been allowed to go very flat. This actually is more dangerous then overcharging.

Again I would suggest that LVCs are manually reset as you need to inspect each cell to see where the problem is.

If you get a cell with a very low voltage then you need to do a " pre-qualifiying " charge on that cell, typically at 1/100 - 1/50 C until the lower knee voltage is reached, fast charging dead lithium's is dangerous.


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Old 23-06-2014, 12:13   #3761
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

Quote:
Originally Posted by gael View Post
After 4 years using my Li banks, one concern I have is about the alternator.
As the Li batteries can accept an high C charge during almost all the charging time , the alternator become pretty hot and my concern is its lifetime.
It is a 75Amp 24V Leece neuville "heavy duty", feeding 2 *130Ahbatteries and I derated the alternator to 60Amp max. Added a blower to pick up "cold " air from the bildge, but still pretty hot.
Any suggestion how to size an alternator to keep a raisonable charging time and a good lifetime. I do understand that all alternators are NOT designed to run at 80% of the nominal capacity.... but ...
cheers
gael
What is "pretty hot"?


I don't know the NEMA ratings your winding's insulation is, A, B, F, or H, but if H then that is good to 180 C / 356 F, a whole lot hotter than I would put my hand on.

That is the beauty of our LiFePO4 cells, less charge time due to high charge acceptance. It does test the charging system though.
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Old 23-06-2014, 16:51   #3762
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

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Originally Posted by goboatingnow View Post
Here a piece from a suitable manufacturer of load dumming resistors alternator

"
The more conventional alternator systems frequently require “Load Dump”resistors to prevent damaging high voltage transients when a load is suddenly removed or the engine is switched off from high speed. This resistor is usually connected in series with an avalanche diode; it sees a low average power but must withstand fast rising high power transients. A wirewound part such as SQP or WP-S series is needed here."
...
Please dont tell me how to suck eggs, thanks

dave
...and suddenly removing the load is of course most common on marine systems because the battery banks "disappear" all the time on any normal installation - as we all know. Switching off the engine from high-speed is also standard practice, just shift in reverse at full throttle as you dock and kill the engine as soon as you come to a standstill.

Incidentally - and at the risk of teaching you necessary egg-sucking - when you stop a marine diesel engine, you do so by cutting the fuel off and power remains on the alternator circuit until after the engine is stopped. This will never, and can't possibly, cause any voltage spike, no matter what.
The situation is completely different on a car, where ignition and power get cut off first to stop the engine, while the alternator is still running.

So keep sucking eggs, but something could be said about techno-babbling and commenting at all cost without adding value.
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Old 24-06-2014, 13:53   #3763
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LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

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Originally Posted by OceanSeaSpray View Post
...and suddenly removing the load is of course most common on marine systems because the battery banks "disappear" all the time on any normal installation - as we all know. Switching off the engine from high-speed is also standard practice, just shift in reverse at full throttle as you dock and kill the engine as soon as you come to a standstill.

Incidentally - and at the risk of teaching you necessary egg-sucking - when you stop a marine diesel engine, you do so by cutting the fuel off and power remains on the alternator circuit until after the engine is stopped. This will never, and can't possibly, cause any voltage spike, no matter what.
The situation is completely different on a car, where ignition and power get cut off first to stop the engine, while the alternator is still running.

So keep sucking eggs, but something could be said about techno-babbling and commenting at all cost without adding value.

Modern car systems now by law must handle load dumping. This is defined as removing the battery while the alternator is loaded. Ie still a load in place. Your cars electrical systems can handle that and they do it with simple clamping systems.

Equally in a HVC protection system, first by switching in a load and deploying a simple clamping device ( which many alternators have ) you can disconnect the alternator. I suggest this because accessing the field coil is not easy on many systems.

Load spiking occurs regularly on boats electrical systems. Especially during starting and other high current loads. In fact more load dumping occurs then in cars.

As to shutting down cars , you seem to forget diesel cars !

A HVC event on a boat is a serious event one that should in reality never happen. Unlike LVC events which could be quite common. Hence I personally would risk an alternator rather then damage a Li cell set. As I said with a few fairly cheap components you can disconnect a loaded alternator and manage the resultant transient.

Dave


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Old 24-06-2014, 17:15   #3764
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

Quote:
Originally Posted by gael View Post
After 4 years using my Li banks, one concern I have is about the alternator.
As the Li batteries can accept an high C charge during almost all the charging time , the alternator become pretty hot and my concern is its lifetime.
It is a 75Amp 24V Leece neuville "heavy duty", feeding 2 *130Ahbatteries and I derated the alternator to 60Amp max. Added a blower to pick up "cold " air from the bildge, but still pretty hot.
Any suggestion how to size an alternator to keep a raisonable charging time and a good lifetime. I do understand that all alternators are NOT designed to run at 80% of the nominal capacity.... but ...
cheers
gael
Realistically, any alternator is going to dump everything it can produce into a lithium bank if it controls off the voltage of the bank, this means it is going to get hot, possibly up to the point where it starts protecting itself by cutting back.

You have a few options:
  • One I have used in different circumstances is inserting a power resistor into the alternator field circuit (cut in at one of the brushes), so output is reduced accordingly. It will still go up with engine revs, but not as quickly. It is usually necessary to experiment a bit with resistor values, starting with a few ohms. You can combine this with using a larger frame alternator to get a truly de-rated unit. The resistor needs to be able to handle a bit of power, it gets warm at times.
  • If your alternator is internally sensed (only!), then the size of the wiring between the B+ post and the battery bank has a lot to do with maximum effective output. Dropping a small amount of voltage along the way can do a lot in terms of limiting maximum effective alternator output, but don't run your wiring hot! It is just a contributing factor, especially if you have a huge B+ cable at present.
  • Sense your voltage "elsewhere" if your alternator has a voltage sensing terminal. People have reported good results with sensing the lead-acid starting bank instead of the lithiums over splitting diodes. This is because the starting bank is normally full and reads a higher voltage than the house bank during charging. This slows charging down however.
Because alternator temperature is a function of current, you are not going to achieve lower temperatures and keep the same charging time unless you go to a de-rated larger frame alternator no matter what. However, as heat is proportional to the square of the current, a further small current reduction could go quite a long way with lowering temperature without impacting charging time by much: 55A instead of 60A would give you 15% less heat for 9% longer charging time. This is where I would start before thinking about a larger alternator, technically simple zero-cost options first.



But are you really at a point where you need to worry about it? Does it get hot to the point where it starts dropping current to cool down?
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Old 24-06-2014, 20:40   #3765
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

Quote:
Originally Posted by goboatingnow View Post
Here a piece from a suitable manufacturer of load dumming resistors alternator

"The more conventional alternator systems frequently require “Load Dump”resistors to prevent damaging high voltage transients when a load is suddenly removed or the engine is switched off from high speed. This resistor is usually connected in series with an avalanche diode; it sees a low average power but must withstand fast rising high power transients. A wirewound part such as SQP or WP-S series is needed here."

it can even be automated using avalanche diodes if you like, then you can just open the load.
...
http://www.ttieurope.com/docs/CP/6488/automotive.pdf

dave
Let's see:

"A wirewound part such as SQP or WP-S series is needed here":

From the link above:
SQP Series: Low cost ceramic box type 0R1 to 1M, 2 to 20W
WP-S Series: General purpose WW/cement parts, 0R01 to 10K, 1W to 7W

14V/100A alternator at full output: 1400W
14V/100A alternator with failed regulator: several kilowatts potentially at excessive voltage until something blows

Still from the link above, the circuit diagram offered ("this resistor is usually connected in series with an avalanche diode") does absolutely nothing if the alternator regulator fails. It is not going to save the day either if it doesn't fail and the batteries are disconnected under load. Its purpose is completely different.

It is not and was never intended as a dump load for the alternator output as claimed. It clamps voltage spikes on D+, not B+. If the charging battery bank is disconnected under load, the magnetic field in the stator will still collapse abruptly as the current suddenly has nowhere to go, causing a voltage spike on B+ as usual. Here with the whole boat electrical system still connected to B+ and no batteries left to damp the surge, it would most likely take out just about everything on board connected at the time.

Quote:
Originally Posted by goboatingnow View Post
A HVC event on a boat is a serious event one that should in reality never happen. Unlike LVC events which could be quite common. Hence I personally would risk an alternator rather then damage a Li cell set. As I said with a few fairly cheap components you can disconnect a loaded alternator and manage the resultant transient.
No you can't disconnect this way, the alternator output still has nowhere to go and you are not managing anything. On a vehicle, all of the electronics have to be designed to withstand the load dump pulse of 100V or more, because the pulse does take place no matter what.
Marine electronics are not up to it, and by a long way, so you don't drop the battery out of the circuit.

So back to the start:

Most (not all) alternators are designed to be maintained without excessive grief and brushes are accessible without dismantling the unit. Sometimes, removing the built-in regulator on the back is required to get to the brush holder assembly underneath.
Disconnect one of the wires to the brushes, bring that circuit (field circuit) out and insert a small relay in there, controlled by the BMS.
In case of overcharge or runaway condition, opening this circuit instantly disables the alternator, whether it is good or faulty, 100% reliable.
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