Your opinion of these batteries please?

Re: Your opinion of these batteries please?

Welcome to the forum Blitz!

I recently acquired 6 "DataSafe" 12HX-300-FR batteries, that were kept in a telecom environment, and under constant float charge 13.6 v.
They are all hot, in pretty good shape, and since I have had them I have been charging them with a xantrex tru charge 40.

I want to use at least 4 of them in the truck, and maybe all 6.

they are rated at 70 Ah each,
and here are the detailed specs.
http://www.cogenient.com/mfc-refdocs/EnerSys/VRLA/HX/DataSafe%20HX%20Brochure.pdf

what is your opinion of these batteries?

They are designed for "float" service and generally only are expected to last a few cycles if deep discharged (my guess). That is why the phone companies replace them every year (need reliable emergency backup power, replace them once they get cycled very much).

A pair of 6 volt @ ~220 AH deep cycle golf cart batteries are pretty nice for starting with solar--But it is difficult to argue with "free" batteries--At least to experiment.

AGMs are nice batteries (for lead acid types). Very high surge current support and no mess (if not over charged).

for charging,
right now I am using the TruCharge 40, and I'm pretty happy with how that is all working out.

Should be a nice charger for those batteries (set to AGM type). 40 amps could keep upwards of 160 AH of 12 volt AGMs pretty happy (5% rate of charge).

I also have a xantex freedom 458 (25 ) dual input, dual output inverter charger, that i have not hooked up yet, besides for just testing its operation.
it will put out 130 amps of charging power, and I want to incorporate this inverter/ charger into my system.
Manual PDF: http://www.xantrex.com/documents/Inverter-Chargers/Freedom-458/Freedom%20458%20Addendum(976-0137-01-01_Rev-A).pdf

I'm currently using a xantex 3000 pro watt as my main inverter, with a separate charger ( the tru charge 40 ).

The issues with batteries is they do not like to supply a huge amount of current and (especially these batteries) do not like to be deeply cycled (call taking them below 75% state of charge or 25% depth of discharge a "comfortable" cycle for them.

When you put large AC inverters on these batteries, they take a lot of power.

For example, a 3,000 Watt @ 24 volt AC inverter, if you are to run it at full power over all battery charge conditions:

3,000 Watts * 1/10.5 voltage cutoff * 1/0.85 inverter eff * 1.25 NEC derating for DC wiring+fuse/breaker = 420 Amps @ 12 volt DC Branch circuit rating

That, obviously, is a lot of current. Heavy/short DC wiring needed, and a lot of current from those batteries.

Those batteries are rated for ~102 Watts per cell for 60 minutes (until battery is dead--and probably not recover). Each 12 volt battery has 6 cells, so that would be a 600 Watt load.

To run 3,000 Watts, at least 5 of those 12 volt batteries in parallel would run the 3kWatt inverter ~1 hour at full load.

And, what this is all really coming back down to--Is what are your needs. Most off grid Lead Acid battery banks do not supply that much power for very long. A 3kWatt genset will run ~2 hours on a gallon of gasoline. Much longer than that battery bank+AC inverter is really capable of.

Because this is a mobile application, and will not be used even weekly, For now I will be staying with shore power to charge the system, but eventually will be sizing a panel or two to fit this system.

So, I guess I'm looking for opinions and advice.

I have these batteries... so I'm gonna use them.

at 70 Ah in an 8 hr period... without derating...
would you use all 6 or just put 4 in the bank?

Where battery (and solar) power is great--For smaller loads that you need to run for many hours with no noise/starting genset, etc. (like a cabin/small home in the evening when you want lights+computer+TV and no generator==And the ability to just flip on a switch to get power).

I have really good interconnects and anderson connectors, and know how to design the bank to draw evenly from all of the batteries at the same time.
from reading here : http://www.smartgauge.co.uk/batt_con.html
I dont have a shortage of 1/0 2/0 3/0 and even some mcm cable and connectors up to SB 350's 175's mostly...

If the batteries+AC inverter meet your needs--Why not. But I would be suggesting that you look at your loads and break them down. Such as smaller amount of 24x7 emergency/off grid power (few hundred watts). And for the big power (jobsite, heavy day time loads like pumping water, running shop tools, etc.), continue to use a genset for the time being.

I'm weak in math,
I'm new at doing this seriously

We can help you here--But this first post is trying to set expectations--Both ours based on what your needs are, and for you to understand that solar power is not cheap--And it is difficult to buy equipment/supplies and connect them together in a "useful system" (more luck than planning if it does meet your needs).

so what kind of power am I really looking at here?
420 AH max with out derating on 6 batteries,
or 280 AH with 4 batteries.

These batteries (again, my guess), are not designed for deep cycling. Shallow cycling, they will probably do OK (less than 25% power draw). And if you want to experiment with solar/off grid power--They can certainly be educational.

In the future, at a 10 % or 13% charge rate... what wattage of panels will I need to properly charge this system ( and I know I need a charge controller )

In round numbers a 10-13% rate of charge for Lead Acid batteries is actually quite a nice rate of charge/balanced with bank capacity/capabilities. Roughly, such an array would look like:

420 AH * 14.2 volts charging * 1/0.77 solar panel+charge controller deratings * 0.10 rate of charge = 775 Watt solar array

If you get around 4 hours of sun minimum for ~9+ months a year (excluding winter--In summer you may get 5-6 hours of noon time equivalent sun per day--based on your location/amount of shading by trees/etc.):

775 Watt solar array * 4 hours of sun (average) per day * 0.52 off grid AC system derating = 1,612 WH per day (plus or minus)

I'm already kinda stuck in 12 volts, with out putting out more cash... for other inverters...
So I just want to use what I have for now, and upgrade to at least 24 volts at a later date.

thanks for Your opinions.

remember I'm new... so be nice :")

Blitz

We always try to be nice... But we also try to level set expectations. Off Grid solar power is not cheap, and the systems are heavy/bulky, and they need maintenance (batteries replaced every ~4-8 years or so, new electronics every 10+ years, etc.).

If you have random power needs (portable power, 2 weeks or less emergency power after an ice storm, etc.), a good quality AC genset and some stored fuel is usually a better bet.

Not to scare you away--But to get you thinking about your loads first, and conservation. To learn more about your AC loads, a Kill-a-Watt type meter is well worth the money for experimentation and conservation projects.

Once we have a better idea about your loads, usage, location of system, etc., we can probably give you some better help. However--We are not going to make solar power "Cheap"...

Take care,
-Bill

Re: Your opinion of these batteries please?

More or less, 4 hours per day for ~9 months of the year would give you:

300 Watts * 0.61 off grid DC power system eff * 4 hours = 732 Watt*Hours of DC power per day
732 WH per day / 12 volts = ~61 AH of 12 VDC power per day...

Is that useful? In dead of winter, you might look at 2 hours of sun per day. And during stormy/dark weather, pretty close to zero hours of sun for a few days of very dark winter weather.

-Bill

Re: Your opinion of these batteries please?

I am not sure where you are at--But lets say Houston Texas, using PV Watts with the array set flat, we get:




Month
Solar Radiation
(kWh/m²/day)


1
2.71


2
3.36


3
4.27


4
4.92


5
5.62


6
6.12


7
5.88


8
5.52



9
4.89


10
4.22


11
3.17


12
2.42


Year
4.43



You will get more than 4.0 hours of sun per day (long term average--Some days more, some days less).

We recommend 5% to 13% rate of charge--For seasonal/random usage/AGM batteries--5% rate of charge can work just fine:

300 Watts * 1/14.1 volts charging * 0.77 panel+controller derating * 1/0.05 rate of charge = 328 AH @ 12 volt battery bank maximum "recommended" AH capacity

So, you could put 4.7x 70 AH @ 12 volt batteries on there pretty easily (5 or so). You could try 6x -- Free batteries are free.

Yes--The battery bank is just a storage tank for electricity. You pump in XX AH in a day, and YY AH the next--Until the battery bank is full. At that point, you cannot fill it any more (if the charge controller is working correctly).

You decide the weight, peak power, etc. that makes sense for your needs.

-Bill

Re: Your opinion of these batteries please?

Blitz wrote: »

I was thinking that a large bank of batteries would need lots of amps to even begin to charge them... Like 40 +. To even begin to charge them.

Yes, large battery banks do better with large charging current. Cost/size/weight of batteries is why we try to keep banks "smaller".

However, AGM batteries have lower internal resistance, and lower self discharge rates--So, they can do a bit better with lower charging current.

We really aim at designing a "balanced" system (battery matches loads, solar array matches battery+loads, etc.). the hardware is expensive--So having an oversized system hurts your wallet. But, on the other hand, an undersized system is a complete waste of money too.

Regarding Amp*Hours... Turns out that Lead Acid batteries are nearly 100% current efficient. Take out 10 AH, return 10 AH to fill it back up.

Note that as you get >90% or so state of charge (for AGM), charging efficient does drop.

Technical question:

when everything is set up in the truck, the batteries, 458, a charge controller and a single panel ( to start with )

*** Will I need to remove/ or anderson disconnect the Solar charge controller before I plug into shore power ? ***

( Obviously, using Solar alone, I will not be able to be plugged into shore power at the same time... "out in the fields" or parked at the cedar shed)

In general, you can parallel charge controllers and leave the solar controller connected all of the time. There can be a limit (several large Amp capacity chargers can supply too much current to a battery bank and such)--But for your system, solar+AC charging is not a problem.

I'm now considering the scratched panel @ 275 watts on the site, just for this setup.
seems I cant go wrong... its just not 300 watts.

Solar power numbers if you are within 10% of the "numbers"--That is pretty much "the same" numbers.

And a PWM charge controller, but I need to read up on the RF interference...just because I use 2 way radios in the truck, as well as SW.

Most VHF radios (commercial, HAM, etc.) are FM--Which is pretty noise resistant, especially at shorter ranges (line of site) common to VHF.

For Short Wave/AM, yea--You can have real problems with RF Hash from any fast/high power switching systems.

There are PWM charge controllers with special low frequency operation (intended for telecom systems and keep the audio noise low). However, most >200 Watt panels are Vmp~30 volts (or other non "12 volt friendly" voltages). PWM controllers are not a great match for those panels.

MPPT charge controllers digital switching power supplies which can have lots of hash. Some controllers are FCC Class A listed--And are usually quieter than non-FCC A/B listed/tested units.

And if a Prius drives anywhere within a few miles--There goes your Short Wave.

I'm already designing a large watertight box for the 458, but one I can vent when in use.
( the truck bed is also covered.. with 5 feet of headroom )

Keeping power electronics cool/well ventilated is always a good idea (so is keeping them dry too).

Thinking about the battery interconnect configuration for a bank of 6, being "balanced"
the class T fuses and cables.. and I have some very large insulated buss bars to go from my bank to dual MCM cable to the inverter. ( overkill I'm sure )

Not really--Keep the cables short. For a 12 VDC system, you want no more than ~0.5 volt drop for your wiring.

Depending on your actual power needs--You may want to look at some large DC breakers instead of fuses. It is nice to just turn off the breaker to kill all your loads. And large T fuses+holders are not cheap either.

Couple of 250 Amp breakers.

unplug the charge controller before I plug into shore power ?
i'm sure it depends on which model I choose?

Nope, don't worry.

Re: Your opinion of these batteries please?

AH rating is sort of the total energy available from the battery at a specific current flow (AH * Voltage = Watt*Hour which is the actual energy available--But voltage vaires over discharge--AH is a bit more consistent).

So, if you have a 70 AH battery at 8 hour rate, you may have a 100 AH Battery at 20 Hour rate.... I.e., the total energy delivered is more at lower current levels (less energy is going up as heat due to internal resistance which is P=I²R and other secondary chemical reactions in the plates).

That is that the Peukart Factor is attempting to quantify... The faster (harder) you discharge the battery bank, the less energy (AH) available.

https://en.wikipedia.org/wiki/Peukert%27s_law

Peukert's law, presented by the German scientist W. Peukert in 1897, expresses the capacity of a battery in terms of the rate at which it is discharged. As the rate increases, the battery's available capacity decreases.
Manufacturers rate the capacity of a battery with reference to a discharge time. For example, a battery might be rated at 100 A·h when discharged at a rate that will fully discharge the battery in 20 hours. In this example, the discharge current would be 5 amperes. If the battery is discharged in a shorter time, with a higher current, the delivered capacity is less. Peukert's law describes a power relationship between the discharge current (normalized to some base rated current) and delivered capacity (normalized to the rated capacity) over some specified range of discharge currents. If the exponent constant k was one, the delivered capacity would be independent of the current. For a lead–acid battery, however, the value of k is typically between 1.1 and 1.3.

It generally ranges from 1.05 to 1.15 for VRSLAB AGM batteries, from 1.1 to 1.25 for gel, and from 1.2 to 1.6 for flooded batteries.^[1] The Peukert constant varies according to the age of the battery, generally increasing with age. Application at low discharge rates must take into account the battery self-discharge current. At very high currents, practical batteries will give even less capacity than predicted from a fixed exponent. The equation does not account for the effect of temperature on battery capacity.

Formula

For a one-ampere discharge rate, Peukert's law is often stated as
where:
is the capacity at a one-ampere discharge rate, which must be expressed in ampere-hours,
is the actual discharge current (i.e. current drawn from a load) in amperes,
is the actual time to discharge the battery, which must be expressed in hours.
is the Peukert constant (dimensionless),

We tend to use C₂₀ for off grid home applications... basically, if you assume 5 hour discharge per night, for 2 nights and 50% maximum discharge, that is the 20 hour discharge rate.

For a fork lift, with an 8 hour work day, you may see C₈ or C₆ discharge rates--As that is more representative of their usage.

-Bill