Balancing used AGM

[Hedges]

I picked up 24x FullRiver DC250-6 AGM batteries, somewhat used. They had powered a couple Tuk-tuk for tourists. 76 lbs. each, so 1800 lbs.

DC250-6 Battery from Fullriver Battery

fullriverbattery.com

Most measured 6.26 ~ 6.29V, but a couple were lower, lowest being 6.05V (40% SoC per manual)
I set aside the highest 16 batteries for one 8s2p (or 2p8s) bank. That will supply 2x Sunny Island split phase. The 35 mm^2 cables that came with them should marginally fit the requirement.

The other 8 will supply 3x Sunny Island 3-phase system, will make heavier jumpers for them.
I hooked a 6V trickle charger to the lowest ones for about a week.
I've now paired them up, 2s4p with matched pairs in series, to charge at 12V.
12V automatic charger was too gentle, so now setting up MPPT SCC with adjustable parameters to do 14.8V absorption, 13.7V float.

Outback MX60 with Outback breaker panel, 15A for PV and 63A for battery.
Only one SunPower 327W panel connected for the moment. Voltage too high in series for MX60 (120V limit), will get Y cable and connect two in parallel.

Once all are up to same voltage and SoC, will connect in series for 48V and hook to Sunny Island, which can keep them at float with grid power.

 

[SamDeleted]

I picked up 24x FullRiver DC250-6 AGM batteries, somewhat used. They had powered a couple Tuk-tuk for tourists. 76 lbs. each, so 1800 lbs.

How's your back after shifting them lol ?

 

[Hedges]

Shifting is OK, lifting is not for me.
These don't come with rope handles, although they do have clips to hold a strap centered.

I brought ramps and appliance dolly. Due to steepness of ramp, I really struggled to roll the first couple up the ramp, standing on the ramp as I went. Might have actually been easier if shorter/steeper so I could stand on tailgate while pulling dolly, like when I move something up a couple steps.

An employee at the seller's site lifted the rest for me, said he wouldn't have to go to the gym that night.

Unloading, I backed my pickup up to an upslope driveway, which made slope shallow enough they were easy to dolly off. I can handle loads up to twice the weight of these, with difficulty, that way.

Cheapest and easiest way to keep panels working during a power outage

Yes, this is the correct way to do it. But those inverters start at $3k and go up from there Do you know of any? Would a Ecoflow smart panel work?

diysolarforum.com

 

[SamDeleted]

Unloading, I backed my pickup up to an upslope driveway, which made slope shallow enough they were easy to dolly off. I can handle loads up to twice the weight of these, with difficulty, that way.

All sound very clever , it's good to find easy ways round hard jobs


A controlled fall is a lot easier than a lift !

 

[Crowz]

Ive found the easiest way to move batteries around my place is my zero turn lawn mower. That front part where you feet go is an ideal platform for moving anything from batteries to window air conditioners

 

[SamDeleted]

Ive found the easiest way to move batteries around my place is my zero turn lawn mower. That front part where you feet go is an ideal platform for moving anything from batteries to window air conditioners

I normally use a sack barrow, often across poor ground and through the mud

Well I say " I " ... I paid a mate to do it last time ?

 

[Crowz]

I normally use a sack barrow, often across poor ground and through the mud

Well I say " I " ... I paid a mate to do it last time ?

View attachment 181109

Those are hand trucks on this side of the pond.

 

[SamDeleted]

Those are hand trucks on this side of the pond.

Ah that's it, and bloody useful too

 

[Hedges]

Or "Appliance Dolly"

Mine is like the orange one lower right, cost $40 a few decades ago. Have replaced cracked and leaking tires a couple times.
Some have stair climbers, fan belts on a few rollers as shown. I just grunt mine up steps, or place boards/bricks or a ramp when taking something heavy up a couple.

Moving 140 # inverters, I've learned to use a strap if it will tilt sideways; rolled off and dented a corner.

Full size fridge is too heavy for me to tilt back onto the wheels, but bigger guys can move them that way.

 

[SamDeleted]

Moving 140 # inverters, I've learned to use a strap if it will tilt sideways; rolled off and dented a corner.

Ouch , straps are a good idea

Full size fridge is too heavy for me to tilt back onto the wheels, but bigger guys can move them that way.

Depends what you call a full size fridge! Some of your American fridges can be HUGE

 

[hwy17]

I understood already having an AGM bank, but really buying more?

This isn't trendy, Hedges.

 

[Hedges]

With a strap around, I throw my weight back and it comes up slightly, then tilts back and lifts me off the ground.
If I had those rear tilt-out wheels, I might accomplish this with an extension handle.
My neighbor had moved it in for me. I tilted and placed a flat dolly underneath to move out, and walked it over a curb.

 

[Hedges]

I understood already having an AGM bank, but really buying more?

This isn't trendy, Hedges.

Luddite - Wikipedia

en.wikipedia.org

I have one 4x Sunny Island system with 405 Ah AGM, a 3x system (3-phase) with worn out 15 year old 100 Ah bank, and will be installing a 2x system.

The cost was 15% of new, which brings it under cost of LiFePO4 based on kWh cycle life.

AGM fits the bill for grid-backup. About 700 cycles to 70% DoD is more than enough for a decade of power failures over its float life. (cycled nightly would be only 2 years.)
If sized for 3 days without sun, would cycle 15% most nights, good for about a decade.
Looks like FullRiver's Gel batteries would do 15 years or so at 15% DoD, approaching the 20 years of FLA forklift batteries.

Lead-acid is good for the 22kW, 33kW, or 44kW surge capability of my various systems. Of course lithium would be too, if BMS sized to handle it. But these are also good for the load-dump of an AC coupled PV system, regardless of battery capacity. AGM can take 5C for a while. Lithium, bank needs to be sized large enough and kept balanced and below 100% to accept load-dump charging.

What I would like is AC coupled lithium battery, keeping lead-acid battery at float, and charging with surplus, as commanded by frequency-watts.
Hoping Sunny Boy Smart Energy does that. Never found out how Sunny Boy Storage charging responds to frequency-watts, only know it has Rule-21 curtailment.

 

[SamDeleted]

@Hedges how many amps of 48v AGM do you have total ?

 

[Hedges]

1260 Ah @ 48V.
(1155 Ah usable, 105 Ah are 15 years old and worn out, OK to light up an inverter for testing.)

 

[Hedges]

I bought 105 Ah for $1200 around 2009.
Later in 2020 I bought 405 Ah for $5000 (think it would cost $6000 today.) Having just installed 4x Sunny Island, figured it needed at least a modest bank. The lithium I saw (LG RESU) was 5x the price per kWh, for 5x the cycle life.

Only reason I bought 750 Ah more last month was I saw a deal on used ones, came to around $1800 with tax.

And I should have said 1155 Ah still good; usable at 70% DoD would be 808 Ah, more like three sets of 280 Ah lithium (which others here have.)
Mine are to be spread across three systems, two properties.

 

[Hedges]

After a few cycles of 12V charging 2 in series, gently "equalizing" with MX-60 SCC as 12V pair, charging individual 6V batteries with non-regulated charger and timer, I decided they were close enough. Something like 6.39V lowest, 6.42V most of them. The regulated supply that was handy only put out 1A, not enough to equalize. The 6V battery charger was starting to push it above 7.7V, hit 8V, didn't want to keep doing that.

Using 35mm^2 cables that came with the batteries and a couple jumpers made from 4 awg (I think) battery cable, I wires them 8s, through one fuse, and to 3x Sunny Island 5048 3-phase 120/208Y. Those cables are undersize for full load but sufficient for low power testing and running my 2 HP air compressor (3-phase for now.)

Later I'll buy a crimper and make 4/0 cables to go between batteries. Also something suitable for the smaller dual lugs in this model SI. Also have "semiconductor" fuses, so will precharge through SI's PTC fuses before closing breakers. But for now, standard fuse so just throw the breakers.

The 22 cables I got with the batteries I'll use for a 2p8s bank, series and cross connected. That will have 2x SI.

250 Ah 48V AGM. Set SI for 62A charge current, 2.45V absorption for 2 hours, 2.27V float.
Full River says terminate absorption at 0.012 to 0.002C tail current, but SI doesn't implement that.
SunXtender says 2 hours if typically < 30% DoD, 4 hours if typically > 50% DoD. Check tail current and adjust time to achieve 0.005C



(No, I have no problems with OCD. Maybe a little nagging voice, but not problems.)

There's a laptop, Sunny WebBox out of view, and TriPower not currently connected to PV.
The Outback MX60 I was using is now floating the old SunXtender 4x 105Ah 12V wired in parallel.

 

[nycamper62]

Last summer I picked up 4x Tel 12-170FGa AGM's, my back remembers them well.

 

[SpongeboB Sinewave]

For AGM, a nice and strong (high current) balancer is a great idea if you can find one.

Ya know... AGMs are kind of like hot dogs. They plump when you cook 'em

boB

 

[Hedges]

The 16 batteries closest matched in voltage I have now placed in the basement, wired 8s2p. Before making the parallel connection, I checked voltage of each 8s, and they were within 9 mV of each other.

Connecting diagonal corners, I put a 400A class T fuse at battery+ and wired to Sunny Island 5048US. Inverter has breaker; fuse is just for catastrophic shorts. Wire is large enough to blow the fuse (base on grounding conductor size for such OCP) but not to carry 400A continuous.

Temperature sensor taped to one battery. Ground wire to house panel. AC1 & AC2 connections to a breaker panel with fuse for grid connection; that goes to a 15A plug (therefore the extra ground for when unplugged.) Single cord R/B/W/G to SI, red is grid.

It started out drawing about 5 ~ 7A at 120V as it topped up the 500 Ah 48V bank. Later I'll enter Full River's Absorb and Float voltages, which are a bit higher than default settings and the SunXtender I use in another system.

SI uses time rather than tail current (as FullRiver recommends) to terminate absorption. But it keeps track of cycles and periodically does an extended absorption. Their own proprietary method for care and feeding of lead-acid.

This will hold the batteries fully charged until I put it to use with Sunny Boys. In the mean time, can serve as UPS. I have an isolation transformer I could wire as auto-transformer to make split-phase as desired.

Old 2007 firmware in this unit, during quickstart a single entry specified both single SI configuration and grid backup. Later firmware has separate parameters for those two. But this one does support SIC-40 140Vpv SCC (configuration mentions this), and I might connect that.