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 > complete build, good setup? questions

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pianotuna

Regina, SK, Canada

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Posted: 07/11/18 01:51pm Link  |  Quote  |  Print  |  Notify Moderator

Itinerant1,

It is my understanding that LI batteries are NOT forgiving of overcharging. Any BMS should be designed to prevent that.


Regards, Don
Full Time in a 28 foot Class C, 256 watts solar, 556 amp hours of AGM in two battery banks 12 volt batteries, 3000 watt Magnum hybrid inverter, Sola Basic Autoformer, Microair Easy Start.

Mako Kupo

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Posted: 07/11/18 03:10pm Link  |  Quote  |  Print  |  Notify Moderator

Itinerant1 wrote:

I know the magnum inverter/ charger is programmable not sure of his solar controller but if it is overcharging should not be an issue. While actually using the camper(batteries) after fully charge, float and use solar during the day for loads and batteries through night or poor solar days. When storing the camper long term deplete batteries 50% +/-.

Properly set parameters he should be able to enjoy camping and not fret over batteries.


this is the idea. I have dry camped(boondocked) every single night minus 3 or 4 since January, and need more power! the mppt controller is victron, fully programmable and is recommended for lithium. so much help here, amazing thank you all so much! starting new thread for something else now too!

Itinerant1

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Posted: 07/11/18 03:10pm Link  |  Quote  |  Print  |  Notify Moderator

True they don't like to be overcharged beyond the recommended limits just like any battery. But if you can progam the limits of the charge there shouldn't be an issue, if there is an issue the bms should shut the battery down.

If a person is going to spend big dollars on Lifepo4 batteries why cheap out on the charger/ controller?

Itinerant1

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Posted: 07/11/18 03:20pm Link  |  Quote  |  Print  |  Notify Moderator

Mako Kupo wrote:

Itinerant1 wrote:

I know the magnum inverter/ charger is programmable not sure of his solar controller but if it is overcharging should not be an issue. While actually using the camper(batteries) after fully charge, float and use solar during the day for loads and batteries through night or poor solar days. When storing the camper long term deplete batteries 50% +/-.

Properly set parameters he should be able to enjoy camping and not fret over batteries.


this is the idea. I have dry camped(boondocked) every single night minus 3 or 4 since January, and need more power! the mppt controller is victron, fully programmable and is recommended for lithium. so much help here, amazing thank you all so much! starting new thread for something else now too!


My Lifepo4 are 500ah GBS with magnum 3000 hybrid/ magnum PT100, 1280w solar. Ive boondocked 755 days out of the past 819 so plenty of time using Lifepo4. Properly set the limits and enjoy the ease.

* This post was edited 07/11/18 03:53pm by Itinerant1 *

Almot

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Posted: 07/11/18 05:19pm Link  |  Quote  |  Print  |  Notify Moderator

pianotuna wrote:


It is my understanding that LI batteries are NOT forgiving of overcharging. Any BMS should be designed to prevent that.

Correct.

But, besides plain overcharging - when it's 100% and you keep applying 14V or whatever it's max voltage is - it has been proven that charging to 85-90% is better for Li battery longevity. Also, keeping it 40-60% full when in storage for several months.

Don't know whether Magnum inverter-charger can be programmed to stop charging at 90%, and doubt that 120V charger sold on Battleborn site can.

Itinerant1

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Posted: 07/11/18 07:14pm Link  |  Quote  |  Print  |  Notify Moderator

Almot wrote:


But, besides plain overcharging - when it's 100% and you keep applying 14V or whatever it's max voltage is - it has been proven that charging to 85-90% is better for Li battery longevity. Also, keeping it 40-60% full when in storage for several months.

Don't know whether Magnum inverter-charger can be programmed to stop charging at 90%, and doubt that 120V charger sold on Battleborn site can.


What voltage are you calling 100%, 85-90%?

Are you saying if charging with solar you would charge to 85-90% then stop charging and run off the battery cycling it while the sun is up and could be powering misc items?

pianotuna

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Posted: 07/11/18 08:02pm Link  |  Quote  |  Print  |  Notify Moderator

Itinerant1,

What do you do when the LI's are full and there is still solar to be harvested? I.E. how do you protect the LI from overcharging? I'd love to have your 1280 watts [emoticon]

Almot

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Posted: 07/11/18 08:49pm Link  |  Quote  |  Print  |  Notify Moderator

Itinerant1 wrote:


What voltage are you calling 100%, 85-90%?

Are you saying if charging with solar you would charge to 85-90% then stop charging and run off the battery cycling it while the sun is up and could be powering misc items?

Whatever the manufacturer says the voltage is at 85, 90, or 100%.
90% is easier to determine with battery monitor, not a voltmeter, because in Li it's almost flat at this point.

Yes, it's better not to let it go higher than 90%. Can be done by terminating the charger input to battery, or by running the loads. Ideally, Li charger should be able to be programmed accurately to achieve this.

pianotuna

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Posted: 07/11/18 10:29pm Link  |  Quote  |  Print  |  Notify Moderator

Even the scangauge which is a very fancy voltage "reader" (60 times per second) can't accurately show the voltage on an LI.

If I were in a climate where I could safely use LI technology, I'd probably use 30% to 90%. I do try to do that with my phone.

Itinerant1

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Posted: 07/12/18 08:22am Link  |  Quote  |  Print  |  Notify Moderator

pianotuna wrote:

Itinerant1,

What do you do when the LI's are full and there is still solar to be harvested? I.E. how do you protect the LI from overcharging? I'd love to have your 1280 watts [emoticon]


Charging has been set at 14.1 bulk (CC), 14.2 absorb (CV)(10 minute is minimum, can't be turned off), float 13.6 (CV) since day one (27 months ago) and the system has not been turned off since. Living on solar/ Lifepo4. Figuring at least 780+ 30% cycles. With a few totaling 70% DOD discharges after many consecutive days of rain/ overcast.
During these 27 months generator was used roughly dozen times for 2 hour each time putting a 200ah hold over charge into the batteries.

Magnum has sufficient programability along with the Magnum PV solar charge controller. Which follows the inverter/charger programming. If anything happens that would cause conditions beyond programmed limits the BMS will disconnect the charge source or loads.
**Over voltage (highest cell is over 3.8V after a 3 second delay)
** Under voltage (lowest cell is below 2.8V after a 30 second delay)
** Over current (current exceeds 10C for 10 seconds)
**Over temperature (highest cell exceeds 150°F or 65°C)
**Under temperature (lowest cell is below 32°F or 0°C, charging is not allowed)
**Ground fault (There is a high voltage leakage greater than 2mA to the chassis pin)
**Unmanaged cells (The programmed number of cells does not equal the number of cells read)

When the batteries are at "my" full SoC they'll float and solar is powering norcold fridge, tv/dvd, charging phones/ laptop/ tablet, fans.
During the late spring, summer, early fall these items might be on starting as early as 8-9 and still have the batteries full by 12:30 or so depending on solar harvest.
I suppose the best part is if the batteries get full great if not no problem they'll work just as well at a lower SoC for long periods of time also.

If you would like to see misc recorded readings from the Me-Arc display & BMS display at various soc, voltages, amps in/ out what items running. Attached is an excel sheet I put together.

DC display readings

During the period of June 16-20 overcast/ rainy days is where Lifepo4 shows their stuff. June 15 started the evening 99%, June 21 back to 99%.

2018 PT data

Mako Kupa sorry for the hijack

* This post was last edited 07/12/18 10:14am by Itinerant1 *   View edit history

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