Recomendation for RV battery upgrade

[Dontknow]

I've been lurking and learning. Thank you for the information

We (family of 4) started with top end 2-6V for 240Ah AGM in our 5th wheel trailer. These gave us 80-90Ah usable from 12.7V down to 12.0V(under load). Our next move was to pull the AGM out and go with 4x6V (440Ah) generic FLA. The FLA keeps us going for 2-3 days in the summer but on winter ski trips with the heater running, being inside more and colder batteries the bank needs to be charged after 24hours or the voltage drops below 12.0V the next morning.

The batteries may be charged to 90% SOC but never to 100%SOC due to amount of generator run time that is needed. The 1.3Kw of solar being added will be of limited use in the winter.

A 24V or 48V bank was a consideration but the trailer has a leveling system with four 12VDC motors that draw 70amps each, 140amps when the motors run in tandem.

Charging was done with a 50amp (with temp sensor) charger. A Victron 12/3000/120 (oversize for our needs) inverter charger, GX control, 150/100 controller is being added.


The battery bank was located in a side compartment at the front of the trailer with no heat. At 5 degrees F the compartment will be 20F

To keep the batteries warm I utilized some dead space between the frame rail to build a compartment that is 6" W x 22" L x 15"H. It has 3" of XPS foam around it. A warm air duct that heats the tanks also heats the compartment but it may not be enough to keep lithium above 35F when it is 10F or colder outside.

Depending on battery size the new compartment can hold between 800Ah(6V Golf Cart) and 2000Ah(Lithium cells)


Considerations:
- FLA - Least expensive. Longest life. More weight. Requires a watering system. Sealed & vented battery box has to be built. Charges below 32F

- AGM - 50% more $ than FLA. Safest. More weight. Easiest to install / change out. Charges below 32F

- Factory built LiPo4 - 300-400% more $ than FLA. - 100-150% more $ than AGM. Not enough data to determine life expectancy/payoff. Requires a heating system and temperature cut off for charging. Less weight. Fast charging. Less generator time - 80% SOC is Ok

- Used EV lithium converted to 12V bank ??

-Other options?

[Mike90250]

> AGM - 50% more $ than FLA. Safest. More weight. Easiest to install / change out. Charges below 32F

is not the safest, when old, the AGM can easily go into thermal runaway and blow. Still requires vented enclosure.

I'd suggest stick with FLA till more work has been down with Li. Used car battery packs can be troublesome in an RV where you live with them, and if they start up a fire, it's not getting put out.

[Dontknow]

> AGM - 50% more $ than FLA. Safest. More weight. Easiest to install / change out. Charges below 32F

is not the safest, when old, the AGM can easily go into thermal runaway and blow. Still requires vented enclosure.

I'd suggest stick with FLA till more work has been down with Li. Used car battery packs can be troublesome in an RV where you live with them, and if they start up a fire, it's not getting put out.

Thanks Mike.

Can't find any 2V FLA that are short (<15") enough to fit the compartment.

The choices are:
- 8 - 6V FLA in 4 (12V) stings for 880Ah
- 6 - 2V Concord AGM for 900Ah.

2V Concord would be good but these are 300% more than a generic (East Penn) 6V. The payback doesn't work.

Each string will be connected to a common bus with the same length of wire but this isn't going to deal with internal resistance. Any suggestions? Maybe a disconnect on each bank so the banks can be individually charged?

[Mike90250]

Why do you need such a huge amount of power ? Does your rig have an onboard genset ? For the winter, I'd suggest going to the 4, 6V batteries wired series/parallel, and use something like a honda eu1000 to keep them topped off daily. Generator days, batteries nights. Sometimes, trying to do it all with batteries is much harder than 1 gallon of gas daily.

[Dontknow]

No on board generator. A fuel cell was a consideration then a friend bought one for his boat. He still runs the generator every day but for less time.

I hate running a generator but is sure makes things easy. Instead of having to run it I want to give myself some leeway as to when it runs thus the 880Ah. I may add another 1kw of portable solar to try extend the time between when the generator runs.

We had Honda 3000i but it idled for hours during absorption. The same for Honda 2000i we currently use. I've been looking at Honda 1000i or something smaller that will fit into a small sound enclosure.

[Mike90250]

Do not try to "fit" any of the honda eu series generators into some sound reducing enclosure, they are quite likely to overheat. The eu1000 is very quiet, clones are not so quiet.

Generally with solar, you run the generator for an hour in the morning to charge batteries to 80% full, and then let the solar charge all the way up, no need to idle a genset for hours when the sun can do it. If no sun, then you NEED the genset

[Dontknow]

Appreciate the warning Mike
The sound enclosure I make aern't the YouTube variety. Mine have 70cfm (30db) CPU fans that are baffled to reduce noise and a temp. alarm.

I was checking the 1 year old generic 6V (EastPenn) batteries yesterday. Something didn't seem right so I connected a 10A light bar to one of the banks. Voltage dropped from 12.6 to 12.0 in a min. Ran the charger overnight. This mornig the charger was 1.1A@14.8V. When I hooked the light bar up the starting voltage was 13.6. In 5min it was 11.9V. The label may read 220Ah but that isn't what is coming out. Tommorow I'll pick up 2 Crown GC2H 6V to test the light bar on.

[bcroe]

Appreciate the warning Mike, The sound enclosure I make aern't the YouTube
variety. Mine have 70cfm (30db) CPU fans that are baffled to reduce noise and a temp. alarm.

You may know, a large fan running slowly is A LOT quieter than a small fan running fast.
Bruce (designed some fan controllers) Roe

[Sunking]

Considerations:
- FLA - Least expensive. Longest life. More weight. Requires a watering system. Sealed & vented battery box has to be built. Charges below 32F

Does not require a watering system. Nice to have, but not required. That is what wife and kids are for. Gives them something to do once a month

- AGM - 50% more $ than FLA. Safest. More weight. Easiest to install / change out. Charges below 32F

How is AGM safer? FLA does not go into thermal runaway like AGM can. In reality in an RV or even a home system AGM and FLA are equally safe. For an AGM to go into thermal runaway takes a fairly large DC charger on line 24 x 7 x 365. Thermal runaway is a concern for Telecom, not a home or RV user.

[/QUOTE]- Factory built LiPo4 - 300-400% more $ than FLA. - 100-150% more $ than AGM. Not enough data to determine life expectancy/payoff. Requires a heating system and temperature cut off for charging. Less weight. Fast charging. Less generator time - 80% SOC is Ok

- Used EV lithium converted to 12V bank ??[/QUOTE]

Stay away from Lithium of any kind. They cost way more than Pb batteries and have shorter life cycle span. Additionally cold weather performance suks big time and could start a fire in cold weather

-Other options?

Stick with Pb batteries.

FLA will give you the most bang for your dollar, and the longest cycle life possible is cared for. But be careful you get what you pay for. There are Golf Cart and L16 batteries made for 2 years, and there are Golf Cart and L16 batteries made to last 7 to 10 years.

AGM have there niche applications. Catch is as you have observed cost about twice as much as FLA, and they only last half as long as FLA. So the cost is higher than you think. So the cost should be justified. What are the justifications?

1. In mobile applications where spills cannot be tolerated, or where unusual mounting orientation will be required like on their sides. AGM were developed for Aerospace where a spill would be disaster.

2. Where very high charge/discharge rates exceed C/4. Example in a solar system if you live in a chit hole like Seattle WS where you only receive less than 2 Sun Hours in Winter is going to require extremely high charge rate 5 months out of every year.

3. Extremely cold climates of -40 degrees. Trust me you are not going into that kind of extreme. FLA can tolerate -40 if fully charged. So this does not really apply to you.

[VancleVector]

I have never used solar generator. But I got diesel genset.
I've been researching (gawd I'm bored) generators and came across reviews of the Predator 4000/3500 generator. $699.00 or maybe $649.00 with their coupon. I found this manufacturer might be good.
dieselgeneratortech.com

[Dontknow]

I was checking the 1 year old generic 6V (EastPenn) batteries yesterday. Something didn't seem right so I connected a 10A light bar to one of the banks. Voltage dropped from 12.6 to 12.0 in a min. Ran the charger overnight. This mornig the charger was 1.1A@14.8V. When I hooked the light bar up the starting voltage was 13.6. In 5min it was 11.9V. The label may read 220Ah but that isn't what is coming out. Tommorow I'll pick up 2 Crown GC2H 6V to test the light bar on.

Decided to run an equalize charge and test the SG before getting the Crown batteries.
Resting at full charge the string of 2-6V(East Penn) is 12.8V. and the SP is over 1275.
After 5 min with a 9.5A load the battery voltage drops to 12.3V and the SP remains over 1275.
After 8 hours with the 9.5A load the battery voltage is 12.1V and a SP of 1225.
There seems to be some life in these.

What would cause the rapid voltage drop at the start with only a 9.5A load? Being cheap batteries maybe the design?

[Sunking]

What would cause the rapid voltage drop at the start with only a 9.5A load? Being cheap batteries maybe the design?

Internal resistance. You cannot use voltage to determine SOC on a battery that is in operation. It only works on a well rested battery on an open circuit. The hydrometer is the only thing to measure real time and accurately.

In other words to use voltage, disconnect the batteries, let them rest 24 hours, and then measure the OCV.

[Dontknow]

One of the generic 6V is pooched.....12months+ 4days and only 10-15 (20-50% DOC) cycles

Options for 4 - 12V strings. Each string will have disconnect:

4 - new generic (East Penn?) 220Ah (GC2H) plus 4 ( three 1 year old & 1 new warranty replacement) - 1 year warranty

8 - Trojan T105( Jan 2018 build date) 220Ah (GC2) -1 year warranty - cost 10% more per battery than generic

8 - Crown CR-260 (Oct. 2017 build date) 260Ah (GC2H) -1 year warranty - 18% more capacity and cost 43% more per battery than generic

8 - Rolls S330 ( Jan 2018 build date) 250Ah (GC2H) -2+5 year warranty - 14% more capacity and cost 46% more per battery than generic


The additional (rated) capacity and quality of the Crown or Rolls is appealing but since I have 4 of the generic batteries these allow the bank to built and save 70% of the cost.

By using the generic is this a case of being penny wise, dollar poor?