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Old 09-05-2015, 21:25   #4501

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

evm-
You must get coffee in paper cups at Starbucks. A "coffee cup" to many of us is a heavy porcelain thing, the classic was made by Shenango and that's what diners all over the US had served for years. It always had a handle, and the hole in the handle is what makes it a torus. A coffee cup without a handle? Psshaw, that's for takeout. Even the classic paper cups in classic greek diners have fold-out paper handles.
If you can't see why topography is relevant to different viewpoints and standards...let it go past you and let's return to batteries.


How does a 4s2p battery bank, using 4 LiPo cells in each of two groups, become a 12.8V battery bank? The normal operating voltage is ~3.6 volts. That's 14.4 volts, unless you run the batteries well below 100% capacity at only 3.2V per cell?
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Old 09-05-2015, 21:58   #4502
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

FWIW, I never run my single 200 aH bank over 13.8v.
The solar (not my only source, but 99% by use) floats at 13.4v for the fridge and now Ultrasonic Antifouling CleanAHull Quad | Ultra-SoniTec Ultrasonic Antifouling system.

The normal voltage is 3.3 per cell when charged or 13.2 v.
Any higher voltage than that is rapidly bled away as the "hockey stick" in the charge curve.

I recently ran the bank down to 35% on purpose and the cells were around 3.2 v. or 12.8v for the bank. The engine was started and I couldn't tell any difference in start sounds or timing from a fully charged bank.

I have a shore charger which hasn't been used in years.
Also, the alternator is set to a fixed 13.7 v. to save on belt wear.

I'll NEVER go back to lead.

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Old 09-05-2015, 22:18   #4503
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

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Originally Posted by fallingeggs View Post
A few questions. I don't have a system yet, but have been doing to research.

1) Is there a reserve battery? How do you plan on charging it? How will it be switched (ie, the 1-both-2-off switch)?

2) Where is your starter? Bilge pump?

3) On the HVC, normally, it appears, folks have been doing the cutoff not on the whole bus bar, but individually for each source. That is, the alt gets its own HVC and so does the solar. This is because each charger likes to be HVC'ed in its own way.

4) On the BMS, have you considered the House Power? Many here have used it.

5) The bank is wired funky. It has been said that you should parallel first then series. While I mean is make four sets of 360 amp 3.2 v cells then series to 12.8 v. You will only need one fuse and the BMS works better at measuring voltage. Something about how the paralleled cells hardly get out of balance.

6) Where you buying your cells from, if you don't mine me asking.


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1) no reserve battery. I thought about putting each 180 bank on a 1,2,both switch (I have a spare switch) but I think I'll just wire the start battery on a 1, 2,off switch for emergency.

2.the engine started will have its own battery. The bilge pump will be on the house batter load bus.. It's just not labeled.

3. Good thought, I didn't think about that. I but I don't see why the cut off can't be tied to all the sources. Ex: field wire for the balmar, silent wind controller stop switch wire, etc. If this doesn't work I'll have to get separate stop relays as you say.

4. I have looked at the House Power and GWL/power bms units. Haven't decided. The gwl is a little cheaper but I haven't yet compared apples to apples yet.

5. You know I wasn't sure if I should have did what you said or what I drew. So I did it this way that way if I wanted I could utilize the switch as I said above..

6. Well someone on here was selling some used one for really cheap so I thought about that, even if they have lost some Ah, at least I will know my system works and can upgrade later with newer and/or bigger batteries.

- Ronnie...on the geaux
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Old 09-05-2015, 22:24   #4504
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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
evm-
How does a 4s2p battery bank, using 4 LiPo cells in each of two groups, become a 12.8V battery bank? The normal operating voltage is ~3.6 volts. That's 14.4 volts, unless you run the batteries well below 100% capacity at only 3.2V per cell?
The nominal voltage is 3.2 which gives 12.8. Yes 3.6 is operating voltage, I was just using the nominal voltage. I don't plan to run the batteries above 14v.

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Old 09-05-2015, 22:28   #4505
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

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Originally Posted by senormechanico View Post
FWIW, I never run my single 200 aH bank over 13.8v.
The solar (not my only source, but 99% by use) floats at 13.4v for the fridge and now Ultrasonic Antifouling CleanAHull Quad | Ultra-SoniTec Ultrasonic Antifouling system.

The normal voltage is 3.3 per cell when charged or 13.2 v.
Any higher voltage than that is rapidly bled away as the "hockey stick" in the charge curve.

I recently ran the bank down to 35% on purpose and the cells were around 3.2 v. or 12.8v for the bank. The engine was started and I couldn't tell any difference in start sounds or timing from a fully charged bank.

I have a shore charger which hasn't been used in years.
Also, the alternator is set to a fixed 13.7 v. to save on belt wear.

I'll NEVER go back to lead.

Nice, I plan on keep voltages below 14 as well.. Thanks for sharing your experience, I'm trying to be smitten as well.

- Ronnie...on the geaux
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Old 10-05-2015, 00:08   #4506
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

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Originally Posted by Highland Fling View Post
I am seriously curious re your reasoning thinking and logic behind the need for a dual bus. I understand the theoretical need for one but cant really work out when you woud need one in reality.

As these LFP batteries are 'new' technology <SIK> we are not going to fit and forget about them.

In fact as long distance cruisers and heavy users of our LFP batteries I would say we get a little anal with our abilities to look at and monitor individual cell voltages. ('we' being people who have LFP batteries)

I expect by next year I will be in a fit and forget mode and look at them 'occasionally' probably twice monthly but of course daily monitor fairly closely (as I have done in the past with LA batteries) Ah used, at bed time, the morning and around 14:00 hrs.
...
It is a dual bus system. A bus is a connection backbone for multiple cables, there is a charge bus and a load bus. The reasons for this configuration have been explained extensively by others. It is the only way to engineer the system properly in a marine installation as far as I am concerned.

Cell monitoring is not going to go away with lithium, liability is far too great. LiFePO4s can burn and have burned in the past, melting aluminium and glass on EVs. Who is the clown who wants to stand before a court and defend his cheap Mickey Mouse (lack of) engineering that just wiped out a few people?
Some of the systems I built have been used all the way down to the cell LVC in a complete fit-and-forget way and are charged the same way. Fit-and-forget is an outcome from good engineering, not from cutting corners or being reckless.
I never give a thought to my LiFePO4 pack and I don't look at it. I wouldn't call LiFePO4 new technology either, these cells have been mass-produced for years.
They haven't swamped the marine market because of total system cost. If you are looking at saving $10 by buying cheap BMS alpha instead of BMS beta, you are in the wrong spot.

The closest it gets to fit and forget is drop-in packs. It is bad engineering and the batteries won't last, but you can go just far enough this way to eliminate the real accident and liability, so the concept has become saleable.
They just disconnect and the user can deal with the aftermath, like the blown alternator etc. Exceed the rated current, which is often quite low due to the capacity of the disconnector, and you are on your own: you shouldn't have, you should have fused etc. Your fault.

The future of LiFePO4 systems is in well-engineered solutions.
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Old 10-05-2015, 00:42   #4507
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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
evm-
You must get coffee in paper cups at Starbucks. A "coffee cup" to many of us is a heavy porcelain thing, the classic was made by Shenango and that's what diners all over the US had served for years. It always had a handle, and the hole in the handle is what makes it a torus. A coffee cup without a handle? Psshaw, that's for takeout. Even the classic paper cups in classic greek diners have fold-out paper handles.
If you can't see why topography is relevant to different viewpoints and standards...let it go past you and let's return to batteries.


How does a 4s2p battery bank, using 4 LiPo cells in each of two groups, become a 12.8V battery bank? The normal operating voltage is ~3.6 volts. That's 14.4 volts, unless you run the batteries well below 100% capacity at only 3.2V per cell?
Perhaps you forgot that the post I responded to was regarding whether it was one bus that was segmented or 2 buses that were joined. You know sometimes I get a little annoyed at posts like these, as I did at this one. It added nothing to the conversation I say again.

And I let my annoyance show by responding to your comments (that were in error) regarding cups and torus....

So first take a sphere, flatten it into a plate, then bend the outer potion of the plate up into a cup shape. While we are at it take a torus and attach it to the side of the cup. Cups of course do not need to have handles.

The heavy porcelain thing you reference is more properly called a mug.

And what is up with the Starbucks ad hominem? I'm sure you know that Starbucks will serve your coffee in a cup/mug if you have the time to stay and drink it in their store.

Stop on by next time you are here and the coffee is on me. We can discuss your red herring then.
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Old 10-05-2015, 01:39   #4508
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

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Originally Posted by OceanPlanet View Post
...
Of course some devices are both source and load (such as an inverter-charger). Typically we recommend inverter-chargers to be on the load bus as the most common issue with those is running down to an LVC with AirCon, etc. Depends on what the most likely use is, if primarily for charging then we put on the charge bus.

Attached is a generic dual-bus diagram, and also some various common system configuration diagrams showing dual bus setups.
...


It is another unfortunate example of corner-cutting and bad engineering. On a lithium installation with a dual bus system, you don't use combined inverter/charger devices, period. They are unsuitable for this type of application. It doesn't matter how it is done:
  • Put the charger on the load bus and your overcharge protection is gone. Shore chargers are some of the riskiest charging sources as they are capable of high currents and supply never runs out.
  • Put the inverter on the charge bus and not only you can run the bank down flat making it completely unsafe to recharge afterwards, but what happens in case of HV disconnect is not ok either.
How some switch-mode DC chargers feel if you disconnect the DC output at full load is another question too... the spike could wipe out the entire output circuitry not to mention everything else hooked up to the charge bus. Such a device should be cut on the AC side first, with the DC disconnector only acting as an ultimate protection, very much like cutting the field of an alternator.
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Old 10-05-2015, 07:12   #4509
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

An inverter/charger can be on the DC load bus as long as the HVC opens an AC mains relay to the unit. That is not more dangerous that having separate charger and inverter.
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Old 10-05-2015, 08:05   #4510
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

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Originally Posted by SailRedemption View Post
1) no reserve battery. I thought about putting each 180 bank on a 1,2,both switch (I have a spare switch) but I think I'll just wire the start battery on a 1, 2,off switch for emergency.

2.the engine started will have its own battery. The bilge pump will be on the house batter load bus.. It's just not labeled.

3. Good thought, I didn't think about that. I but I don't see why the cut off can't be tied to all the sources. Ex: field wire for the balmar, silent wind controller stop switch wire, etc. If this doesn't work I'll have to get separate stop relays as you say.

4. I have looked at the House Power and GWL/power bms units. Haven't decided. The gwl is a little cheaper but I haven't yet compared apples to apples yet.

5. You know I wasn't sure if I should have did what you said or what I drew. So I did it this way that way if I wanted I could utilize the switch as I said above..

6. Well someone on here was selling some used one for really cheap so I thought about that, even if they have lost some Ah, at least I will know my system works and can upgrade later with newer and/or bigger batteries.

- Ronnie...on the geaux

Running two house banks on a small boat doesn't seem worth the added complexity. Just build the single system right.

As for the starter bank, that is what I was getting after with the reserve question. What type of battery will it be? How will you charge it? It's not an easy problem, at least for an automated solution.

The way I figure it, if a starter bank is going to be a pain to charge, I'm better off with out it. The house bank will have zero issues starting the small marine engines.


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Old 10-05-2015, 09:18   #4511
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

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An inverter/charger can be on the DC load bus as long as the HVC opens an AC mains relay to the unit. That is not more dangerous that having separate charger and inverter.
Yes this would create a mitigation. I still wouldn't do it by design because you are still charging into the load bus. If you somehow dropped the load bus with the charger going, the charger output would suddenly find itself connected directly into the loads with the voltage shooting up.

In the correct topology, there are two disconnectors in series between sources and loads.
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Old 10-05-2015, 14:43   #4512
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

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Originally Posted by fallingeggs View Post
Running two house banks on a small boat doesn't seem worth the added complexity. Just build the single system right.

As for the starter bank, that is what I was getting after with the reserve question. What type of battery will it be? How will you charge it? It's not an easy problem, at least for an automated solution.

The way I figure it, if a starter bank is going to be a pain to charge, I'm better off with out it. The house bank will have zero issues starting the small marine engines.


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I see what you're saying, I'll have to put the two banks in parallel then series. I'll only need one bms, fuse, etc. and the wiring won't be so wonky.

I was going to use a simple group 27 gel battery with a duo charger from the house. The voltages and charging are similar. I also have a sterling ProCharge ultra 20a charger for when plugged in. Unless I spend a little more and get a small lithium bank so they are exactly the same, I'd do that. That way the victron can just "triclke"(company term, not actual trickle charge) to the start battery.

Shouldn't be a pain to charge, the only time it would charge is when the boat is at the dock or when engine is running in which the start battery will charge back up rather quickly. If this somehow becomes complex, I'll look into just starting off the main house batteries.

- Ronnie...on the geaux
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Old 12-05-2015, 03:25   #4513
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

Hi,

I dont want to disturbe the flow but thought I could pick your brains. I think about installing the following system on board (see attached picture - hope it is visible). I have 4x 115 Wp solar panels. Two are connected in line and will go into one of the two MPPT chargers. I have no AC on board and only a 15Ah max additionally from my 30hp outboard engine that could / will load the batteries. There is no additional starter battery. I was told I might need two DC/DC Converter. One to feed the battery from the outboard engine and one after the battery to protect electronic equipment from the higher voltage of the LFP battery. Is that correct?

Would be great to get you feefback.

Thanks and cheers

Achim
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Old 12-05-2015, 04:01   #4514
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

Hi, not sure if the upload of the picture failed so here are the components:

Victron LiFePO4 Battery 12,8V/200Ah

Victron Battery Management System BMS 12/200

Victron BlueSolar MPPT 100/50 (12/24V-50A)

Victron Fuse holder for MEGA-fuse
Victron MEGA-fuse 100A/32V (package of 5pcs)

Victron Battery Monitor BMV-700

Do I need anything else and/or does the above make sense?

I have a 25Ah 12 V watermaker on board, a 1,5 Ah Autopilot and 30A per day fridge. Do you think one 200 Ah LiFePo will be enough or better two or better more solar panels?

Can I sufficiently see how many Ah are still in the Battery with the BMV 700 using a LiFePo battery?

Cheers,
Achim
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Old 12-05-2015, 11:08   #4515

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

Achim-
You don't need a DC-to-DC converter. Wrong word.
Most outboards do not regulate their voltage output, they rely on the battery absorbing excess voltage, which is a gamble. So you would want a "regulator" in between the outboard and the battery. If you can't find one for an outboard, find a cheap solar panel "controller" which takes in typically up to 22 volts from a "12" volt panel, but regulates it down to 14.4-13.8 volts to the battery. (Assuming your engine will not put out more than 22 volts, you'll have to check.)


That might seem like overkill but it will completely protect the entire system from your engine's charger output, including both the batteries and the electronics. There should also be a fuse in between the engine and that regulator.


"Can I sufficiently see how many Ah are still in the Battery " You will have to check the manual for your equipment, most as available online if you haven't bought it yet. There are issues as to how precisely what equipment shows state of charge, Maine Sail has some good articles on the Compass Marine web site, part of the question is whether you need answer that is within 2%, or within 15%, i.e. what accuracy you are looking for.
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