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Old 23-05-2017, 13:26   #5836
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

Should be able to find a 12V kettle
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Old 23-05-2017, 13:30   #5837
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

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Originally Posted by exMaggieDrum View Post
Heating a water tank can be very bad for batteries and the inverter. Usually not a good idea.
I don't see why you'd do that off an inverter.

Lots of off-grid solar electric house hot water units sold, all you need is capacity, and once batteries are charged, great use for energy otherwise going to waste. Of course on a boat we don't carry as big storage tanks but. . .
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Old 23-05-2017, 15:39   #5838
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

My ProNautic stand alone charger has a custom mode that is user settable. It also has stock LiFePo4 settings of 13.8/13.2 and 14.6/13.2. There online manual says 14.8 instead of 13.8, must be a missprint cause the actual setting is 13.8. There isn't any separate sense wire though.
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Old 23-05-2017, 17:53   #5839
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

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Originally Posted by exMaggieDrum View Post
I would go with separate units and install the ProNautic charger. I plan to get one as a backup to my older combi unit. I can live without the inverter part but not without the charger. And, small chargers can be had for charging the (essential??) computers and phones, etc. Heating a water tank can be very bad for batteries and the inverter. Usually not a good idea.
We do it as standard practice. Need a shower? Excercise the 200 aH LifePo4's. They need to feel needed !
We've been doing that every summer for a couple of months on the hook ever since we have had the lithiums in what, 2008?
They're still 100% as far as I can tell. No serious capacity measurements though. 13.8, cut 'em loose. Rebulk each morning or 12.6 from solar.
Don't worry, be happy !
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Old 24-05-2017, 07:41   #5840
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

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Should be able to find a 12V kettle
I've heard they are really slow, otherwise wouldbe tempted.

I'm having a bit of a time finding a BMS now what with housepower gone - There was elitepower EMS but they only have one distributor in Canada (and don't sell direct) and he's not returning my emails.

Anyone else have any ones they'd recommend? Orion looks way too indepth for what I need it for
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Old 26-05-2017, 07:26   #5841
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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
We do it as standard practice. Need a shower? Excercise the 200 aH LifePo4's. They need to feel needed !
We've been doing that every summer for a couple of months on the hook ever since we have had the lithiums in what, 2008?
They're still 100% as far as I can tell. No serious capacity measurements though. 13.8, cut 'em loose. Rebulk each morning or 12.6 from solar.
Don't worry, be happy !
I'm glad it's working for you. I have had lots of customers who rued the day they did this. Your adequate charging is taking care of your problem, along with, I am sure, your care in not overdoing it. The lithiums are helping with their fast recharge rate but that wouldn't work for some other sailors I know who would not have as robust a charger:Ah ratio or as much care. The owner of my previous boat asked me how to convert back to allowing the inverter to power the water heater so I told him how to rewire it to do that. He wrote a few weeks later saying he was killing his batteries. They were not lithium but with having guests on his boat he would have had problems with them as well. For those who have adequate charging and pay attention and don't overdo it, you can use your batteries for anything you want.
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Old 26-05-2017, 07:31   #5842
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

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Originally Posted by john61ct View Post
I don't see why you'd do that off an inverter.

Lots of off-grid solar electric house hot water units sold, all you need is capacity, and once batteries are charged, great use for energy otherwise going to waste. Of course on a boat we don't carry as big storage tanks but. . .
Water is a good energy storage medium. The problem is insulating the storage container well enough to keep that energy and not radiate it outside (or inside) the boat. Better to store it in the lithiums and heat the water if you can do it as carefully as seniormechanico. An on-demand electric heater would be the best approach if you were to do that, or have a vacuum insulated water tank.
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Old 26-05-2017, 08:25   #5843
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

Quote:
Originally Posted by exMaggieDrum View Post
I'm glad it's working for you. I have had lots of customers who rued the day they did this. Your adequate charging is taking care of your problem, along with, I am sure, your care in not overdoing it. The lithiums are helping with their fast recharge rate but that wouldn't work for some other sailors I know who would not have as robust a charger:Ah ratio or as much care. The owner of my previous boat asked me how to convert back to allowing the inverter to power the water heater so I told him how to rewire it to do that. He wrote a few weeks later saying he was killing his batteries. They were not lithium but with having guests on his boat he would have had problems with them as well. For those who have adequate charging and pay attention and don't overdo it, you can use your batteries for anything you want.
Isn't this what Lithium is great for though? High loads for a short period of time. As long as you don't discharge below 20% they should be fine. Half the reason I'd be doing it is to help stop my battery bank chilling at 90%+ SOC for long periods of time
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Old 26-05-2017, 08:35   #5844
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

Re Hot water tank insulation:
I stripped off the 1995 vintage fiberglass insulation, and spiral wound my tank (nice high quality SS) with about 5 layers of 10mm Aerogel.
I then spiral wound that with fiberglass tape to seal it.
If we motored someplace and reached 180 f., it holds for a nice hot shower for almost two days.
When I heat the 1kw element via inverter for 20 minutes, it's good for at least a day's use for dishes and a shower.

It's good to look at the insulation side of the equation as well as the power side.
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Old 26-05-2017, 08:52   #5845
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

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Originally Posted by exMaggieDrum View Post
An on-demand electric heater would be the best approach if you were to do that, or have a vacuum insulated water tank.
I was talking about using otherwise-wasted surplus PV. So unless you're willing to schedule washing self, clothes & dishes around your charge cycle, most people would want the time-shifting enabled by well-insulated tanks.

I admit you could do a lot more with the idea on land.
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Old 27-05-2017, 03:53   #5846
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

I've invented a new method of balancing.

To put it simply, have a primary and secondary set of cells. The primary cells are permanently wired in series. The secondary cells can switch between parallel with the primary cells, or disconnect from the primary cells and parallel with each other

https://youtu.be/WNQ-TyxS6kE
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Old 27-05-2017, 07:02   #5847
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

Quote:
Originally Posted by senormechanico View Post
Re Hot water tank insulation:
I stripped off the 1995 vintage fiberglass insulation, and spiral wound my tank (nice high quality SS) with about 5 layers of 10mm Aerogel.
I then spiral wound that with fiberglass tape to seal it.
If we motored someplace and reached 180 f., it holds for a nice hot shower for almost two days.
When I heat the 1kw element via inverter for 20 minutes, it's good for at least a day's use for dishes and a shower.

It's good to look at the insulation side of the equation as well as the power side.
Most excellent Senor. That was the missing part of the equation.

Relative to lithium versus any other type of battery and use for heavy loads on a constant basis: if you have a charge deficit you will not be able to do the heavy loads on a constant basis. Heavy loads don't have to be very heavy for some sailors with limited charging. Lithiums are better suited for using the whole capacity and heavy discharges but at some point you still have to keep them at 20% or whatever. Just mathematics. That was my point, not that you can't do it. I have personal friends who have not yet mastered that issue. They would ruin lithiums in short order just as they have wet and AGM batteries, and no hot water heating either.
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Old 27-05-2017, 09:15   #5848
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

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I've invented a new method of balancing.
Interesting, look forward to seeing test results. What relays have you ordered? (link please)

But big picture question, is this even a problem needs solving in practice?

My understanding is only initial balancing is needed under normal low-current House usage.

Assuming max charging volts @~3.45 and staying well away from both top and bottom "shoulders", I haven't seen reports of any ongoing active balancing needed.

Some say they manually balance as part of routine maintenance, annually?

Some go so far as to say per-cell BMS can cause imbalances.

Maybe just midpoint monitoring is enough?
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Old 27-05-2017, 09:35   #5849
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

Ok now I'm totally on board with ABYC getting involved LiPo4Fe standards.
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Old 30-05-2017, 11:55   #5850
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

So the cheapest BMS I've managed to find so far is over 700 CAD. Sigh.

Does anyone have any good options that were priced around the same as the Housepower BMS?
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