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BFL13

Victoria, BC

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Posted: 11/30/20 10:12am Link  |  Quote  |  Print  |  Notify Moderator

Still does not explain what is meant by "floating voltage" in the battery specs.

PD ISTR has the feature that if you are using the RV it will be at 13.6 "normal" and after a period of no (or is it low--how low?) "activity" it drops to 13.2v. If you go in the Rv and turn on a light or two it goes back to 13.6.

All those on long term shore power living in their RVs would be at 13.6 and their batteries are not disconnected.

If you keep your RV at home plugged in between trips what are you supposed to do? Is that "storage"? I go in ours a lot to do upgrades or whatever. I could disconnect the batts and be on converter but I have not been doing that.

According to Trojan, with flooded and once home and recharged, I should not leave them on Float if using the RV next week, but I should if not using it next week. If I have AGMs then I should not go on a float once they are recharged unless the next trip is more than a month later.

On solar full-time off grid, the controller will drop to 13.6 after it stays at 14.x for a time. You don't want to be at 14.x overly long, but you do want to be there till the batts are full.

I tried dropping to 13.2 in the afternoon after the batts were full and it was unsat. Got minus amps showing and voltage 13.1. RV was still being used. Turned it back to 13.6 and no problem. I think that is why they have 13.6 as "normal"

So what is "standby use" where they want you to do "float charging"?
Is there a draw on a standby battery from what it is connected to in a UPS scenario? Otherwise, why choose the higher float voltage instead of the storage voltage?

My SiO2 modified AGM battery guide says do not leave it with a small load on it or it will sulphate slowly. So would any battery in an RV with the disconnect open but the LP alarm still on.--if you don't take the wires off the battery and have a small load like that on, should you be at 13.2 or is that "using" the RV so you should be at 13.6?

The various battery guides are clear on what to do with a disconnected battery, but are not clear at all IMO what an RVer should do between trips. Even winter storage is confusing where some storage yards have power and some don't and with those some guys use solar "maintenance charging"

So that's another one--"maintenance" to go with "storage" and "floating"


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BFL13

Victoria, BC

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Posted: 12/06/20 06:54pm Link  |  Quote  |  Print  |  Notify Moderator

Was setting up the TC again and ran into where I had to pick to have the converter able to run the rig with the battery wires off so the battery is not on a float (which it is not supposed to be unless not using the rig for more than a month per AGM routine) the TC gets used a couple times a month but has a modified AGM (SiO2) battery bank. That means never being on a float according to Trojan.

So that brings up anybody with an Inverter/charger. You can't run the rig on the charger part and leave the batteries disconnected, no load, so to meet the Trojan battery guide "rules".

That means you must float the battery bank no matter what when on shore power for however long. If that ruins your batteries, too bad!

Itinerant1

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Posted: 12/06/20 07:32pm Link  |  Quote  |  Print  |  Notify Moderator

BFL13 wrote:

Was setting up the TC again and ran into where I had to pick to have the converter able to run the rig with the battery wires off so the battery is not on a float (which it is not supposed to be unless not using the rig for more than a month per AGM routine) the TC gets used a couple times a month but has a modified AGM (SiO2) battery bank. That means never being on a float according to Trojan.

So that brings up anybody with an Inverter/charger. You can't run the rig on the charger part and leave the batteries disconnected, no load, so to meet the Trojan battery guide "rules".

That means you must float the battery bank no matter what when on shore power for however long. If that ruins your batteries, too bad!


With my Magnum inverter/ charger if on shore power I turn off the charging so the 120v is passing through powering the 5th wheel and the batteries are powering the 12v items, I could turn off (disconnect) the solar but leave it so it can recharge what little power that was used during this period of time (7-15ah, nightly), float till night. But then I guess lfp don't have the same constraints as lead.


12v 500ah (5,120Wh usable) , 20 cells_ 4s5p (GBS LFMP battery system). 8 CTI 160 watt panels (1,280 watts) 2s4p. Panels mounted flat on the roof. Magnum PT100 controller, Magnum 3012 hybrid inverter, ME-ARC 50. Installed 4/2016 been on 24/7/365

BFL13

Victoria, BC

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Posted: 12/06/20 09:10pm Link  |  Quote  |  Print  |  Notify Moderator

ISTR a debate over whether you should float Li batts. When not in use (storage?) they should be at around 60% SOC. (true?) RV use does not seem to be covered by the float or not guidelines for any battery type seems like. Keeps the battery makers happy I suppose.

I don't have any data for how much it would cost an RVer to float when ideally he should not be floating. Just part of doing business, so why worry about it?

pianotuna

Regina, SK, Canada

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Posted: 12/06/20 09:19pm Link  |  Quote  |  Print  |  Notify Moderator

Hi BFL13,

I've heard, for greatest longevity, long term storage for Li is 40 to 50% state of charge. Not what I want.


Regards, Don
My ride is 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.

BFL13

Victoria, BC

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Posted: 12/06/20 09:41pm Link  |  Quote  |  Print  |  Notify Moderator

pianotuna wrote:

Hi BFL13,

I've heard, for greatest longevity, long term storage for Li is 40 to 50% state of charge. Not what I want.


If you are on shore power for a while, you can do that if you have a converter to make your 12v, but not if you have an inverter/charger. (An inverter /charger must be connected to the battery to operate at all--it needs the 12v from the battery to run its own systems)

It might be worth the approx $130 for a converter to rig up and by-pass the inverter/charger for 120v too somehow. If all you have is a single 12v Walmart batt, then it would not be worth the bother probably. What if you have a $3,000 Li battery bank and are spending the winter on shore power at some resort?

MrWizard

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Posted: 12/07/20 01:50am Link  |  Quote  |  Print  |  Notify Moderator

At one time in my life, I was an electrician at a stateside international airport, airline terminals have lots of emergency lighting
To me Float means the battery is connected to service ready equipment, whether that is lighting or aN INDUSTRIAL U.P.S.,
Storage is just that stored away somewhere and not in use, not expected to suddenly supply power for an unknown period of time, RV storage is just that, the RV is being stored, until used in the future time, could be weeks could be months, the batteries do not need to be floated, unless you expect that future use is emergency use, and must have full power capability
As do what Trojan or pd mean when they say float IDK


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Itinerant1

Itinerant

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Posted: 12/07/20 05:43am Link  |  Quote  |  Print  |  Notify Moderator

BFL13 wrote:

ISTR a debate over whether you should float Li batts. When not in use (storage?) they should be at around 60% SOC. (true?) RV use does not seem to be covered by the float or not guidelines for any battery type seems like. Keeps the battery makers happy I suppose.

I don't have any data for how much it would cost an RVer to float when ideally he should not be floating. Just part of doing business, so why worry about it?


As far as lfp goes if I was putting my rv away for winter or a long period of no use the batteries would be at a 50-60% SoC. Plus I would remove all the senseboards connected to the cells, they're part of the bms. They have a power draw on the cells, very little but it's still there.

If the rv was being stored with occasionally use and no hookups I would just shut everything down turn the batteries off and disconnect the solar (breaker). If the batteries are somewhere above 50% SOC good enough.

This is what I would do for "my" system today if the storage scenario came up.

BFL13

Victoria, BC

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Posted: 12/07/20 07:57am Link  |  Quote  |  Print  |  Notify Moderator

Can you disconnect the BMS in a "drop-in" Li batt? If not and they are in storage at say 60% SOC, do they give you a time limit before they are so low they must be recharged? Would the BMS activate the low voltage? What happens after that?

One thing going for SiO2 is no BMS IMO. I would be worried a BMS would develop a fault of some sort. That's just me though.

I have changed my routine with the Wet 6s so now I will have the wires off between trips if that will be more than a week. We use the C at least once a month all year but not every week, so no actual storage ever happens.

I have decided to treat the SiO2s as a type of AGM for floating rules. The TC is used more often than the C so going over a month with no usage never happens. That means they too will be disconnected between trips. Both rigs will be on stick house shore power between trips and running on converter for 12v.

We sometimes have power failures for the stick house when a tree falls on a power line somewhere, so the RVs are available if the power failure lasts too long. That means turning the 12v back on battery in the dark, so a flashlight would be needed for that.

Itinerant1

Itinerant

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Posted: 12/07/20 08:50am Link  |  Quote  |  Print  |  Notify Moderator

A drop in lfp battery is a sealed unit, no access to the bms. Each manufacturer might have their own specs for storage. Lifeblue states "Storage Method 50% SoC, test @ 90 Days, recharge if below 13.0V".

What happens for low voltage in the dropins is they shutdown.

Do you worry about your house, car, class c or whatever else that has electrical components developing faults. Deal with it if and when it happens, lifes to short.

Your batteries are for recreational use and trying to just get longevity. It's not like your a fulltimer boondocker living off the batteries/ system, I personally want power at any time and any SOC to run my wants without having to figure generator run time or running to a rv park for a pedestal so full charge or equalization can be done, my personal choice for lfp.

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