Battery chat

[Bossrox]

Hydrogen hazard with lead acid batteries, here the solution.

I had a couple 200 a/hr lead acid batteries in my setup for almost a year but now I have 8 more of those batteries & the possibility of a hydrogen build up that could blow up my shed was weighing heavy on me with all the clicking & arcing relays I have running the system.

Thinking ahead knowing I might need this 1 day, I had gotten a hydrogen sniffer alarm on ebay way back when I started this project off but procrastinated getting it hooked up.

1st thing I did was test it by opening a cap on the battery & stuck a funnel in it, then dropped the sensor in the funnel while it was charging & it didn't take long to go off, so this chinese gadget really works & best of all, it's was only $20 on ebay. Cheap insurance.

Since hydrogen is lighter than air, it will rise as high as it can & if it has nowhere to escape, it'll just accumulate, so I mounted the sensor in the peak off my roof, hooked it up & guess what? There was gas accumulating up there. Apparently not in high enough concentration for an explosion & all this time, I didn't have the sniffer up so it must be pretty sensitive or the shed would have been history by now.

Anyways, so now I have a problem I gotta deal with & fortunately my roof peak has a louvered vent to the outside right above where my batteries are & I needed to push that accumulated gas out thru the vent & just happened to have a 9" box fan I grabbed & mounted over the vent.

The sensor has a built in relay so I employed that to fire up the fan when the alarm went off & most of the time that did the trick but that was when the batteries were on a light charge. A heavy charge makes a lot more gas & under those conditions, more gas was being made than the fan could dispose of in automatic mode & just kept firing back up shortly after shutting down so the fan had to be switched on continuously.

So for now I'll have to manually switch the fan from auto to full on from observing the charging mode visually but I have an adjustable off delay switch to keep the fan running longer after the alarm goes off that I'm going to employ to see if it will solve the issue but if that's still not good enough, then my next project will be to come up with a circuit that will detect when the batteries are in heavy charge mode to fire up the fan regardless if the alarm hasn't gone off so stay tuned for that gadget if it needs done.

Update: I decided to build a separate shed for the batteries for 2 reasons, 1st is I can separate them from the electronics nearby thus eliminating any arcing relay issues then piped in a blower motor into the new shed from the main shed to feed it fresh air with a delay off timer so it will run longer when the alarm triggers which has been working great & being the main shed is either heated or cooled seasonally, it'll keep the batteries in the shed from getting too hot or cold.

2nd is I got a source for some huge batteries pretty cheap so I'm springing for more to up my bank size from it's current 2700 amp/hrs to about 4700 amp/hrs & later 6300 a/hrs but I don't have the space in the current shed to get that many batteries in there plus that much weight in there might be more than it can stand without collapsing something. Some pics of the new shed will be forthcoming when it's done.

[Bossrox]

A new battery shed on the way for a 6300 a/hr (75kw) bank

Well with my battery bank soon to be massive, I had to make another space to house them & I don't think my old shed is built tough enough to hold almost 2 tons of weight without collapsing or mangling up something & my hydrogen sniffer is always going off even with an automated fan to blow the gas buildup outside, so I needed to get the batteries away from all the ignition sources in the shed that might destroy it.

So I'm building a shed just for the batteries with everything screwed together with extra sturdy supports to hopefully house them safely & get better protection from a possible hydrogen gas explosion.

It will be on the other side of my current shed wall about a foot apart from where all my solar electronics are located to cut down on excessive wiring runs. It will be fully insulated with thermostatically controlled heating pads under the batteries to keep them from getting too cold for winter along with gas heat piped in from the main shed on really cold nights & it will be under a run of solar panels protected from the sun in summer along with a blower fan piping in A/C for summer to keep them from getting too hot along with a hydrogen sniffer that will engage a more powerful booster blower to force any dangerous build up of gas out a dryer vent when needed.

I'm using 24v inverters right now but a 48 volt is on the horizon so to save the pain in the ass of rewiring all the batteries, I'm configuring them into 8 - 24v banks so all I'll have to do is jump the 24v banks in series then parallel them together for 48v & also allows me to still use my 8 - 24v desulfators rather than buying new 48v versions, then if I need to go back to 24v, just reverse it with no fuss!

After all the shelves are filled with batteries, I'll have around 4700 a/hrs @ about 1 1/2 tons weight with 20 - 200 a/hr CAT size 4d's @ 115 lbs each & 6 - 120 a/hr V-Max AGM's @ 70 lbs each, all tightly packed in a 4x4 shed. About $10,000 worth of batteries if bought new but thanx to craigslist, I snagged it all for less than 3 grand.

Well I couldn't stop there, after figuring out my summer nite time demand, to keep from draining my bank more than 20%, even with all those batteries, I would still need more, so another side pocket to my new shed is in the works to hold 8 more 200 a/hr batteries that'll give me a whopping 6300 a/hrs or about 75 kw capacity for which a 20% drain would be about 15kw & more than enough to cover my typical sundown to sun up winter usage, for summer, it's yet to see, so except for system breakdowns, I'll essentially be energy independent except with that humungus battery capacity, more solar panels & another charge controller is in the works too to feed those hungry beasts.

At 1 point I had a hankering for getting ahold of some Tesla car battery packs. I can't remember the kw stats for those but the Tesla powerwall made for solar use has a max output of about 13.5kw to full discharge but given the price is around 10 grand & I'll easily have 15kw @ a 20% drain plus some hefty reserve if I want to dip in past that for about 3 1/2 grand, I'd say I did pretty good. You think?

The battery shed is now full. Just added 6 more 200 a/hrs batteries with the other 14 & 6 120 a/hr AGM's, jacking me up to 4700 a/hrs. Now I'm in the comfortable range of having 11 kw of energy I can draw off the bank & keeping the drain to under 20%. With my typical sunset to sunrise drain of about 10 kw, I'm pretty content for now but looking forward the next 8 / 210 a/hr set I will hopefully be acquiring in January to bring it up to 6300 a/hrs with a 20% drain of 15kw.

Here's some pics & a video coming in the near future to show it off, stay tuned.

Triple locked door


With 4 levels, 2 batteries per shelf on the sides or 8 per side, 4 in the center & 6 on the floor.


Each shelf lit up with led strip lights when door opens

[Bossrox]

Sizing your bank correctly to your demand

Now that Fall is here, the A/C's are just about no longer needed which leaves an abundance of panel power that isn't being utilized.

I've just recently upped my battery bank & with the excess panel power from the A/C's now offline, I now have a place to store more of it, where before I had to wait til morning to fire up the inverter, I can now start it up usually around midnite but more batteries will be added shortly which I believe will give me the ability to run all night off the inverter minus bad solar days.

The point is, if you can't make use of most of the panel output potential, you're not getting the best bang for your buck so if you have more panel capability than your energy demand, the best logic is to boost your bank size to store it.

I have about 2300 a/hrs currently & with new batteries coming, it will to jump to 3500 a/hrs. At night after my panels quit putting out, my inverter uses an average of 50 to 60 amps per hour. Between 6pm & 9am is no tangible solar activity so after I add the extra batteries, it'll all be on battery power for those 15 hours which will be about 750 - 900 amp hours. In deep Winter that'll be a few hours more tho.

Now the question is, to preserve battery longevity, is that a safe drain level to prevent discharging more than 20%. Let's see if that works out here.... 10% of 3500 is 350 amps, 20% is 700 amps, 30% is 1050 amps so I can see now that 750 - 900 amps is hovering around the 25% mark of 3500 amps, a tad more than I'd like to go.

But another 1200 a/hrs will be added on top of that in the near future for 4700 a/hrs total that would make the typical drain about a 15% overnite. That's great news for us lead/acid users knowing you can expect a good healthy lifespan out of your bank plus having 6 desulfators like I have on my system will enhance the longevity even more & they do work, I can vouch for that.

The 3500 a/hr set up was done today, this will be the 1st night to run off batteries all nite. Will find out in the morning my total kw usage & the volt reading to see how drained they got & how long it'll take to bring 'em back to full charge, tomorrow will be a sunny day I'm told so this should be an intresting test. Will get those figures up here for you to see.

1st nite was pretty mild & didn't need to fire up the floor or bed heaters so about 5kw was used sundown to sunrise & today, not a cloud to be seen. Tonite tho will be much cooler & those heaters along with the battery shed heaters will get some action tonite. I expect something more like 7 kw or more usage by morning & about 7.5 kw would amount to about 20% drain of my newly upsized battery bank.

If that's what gets used, then that's not bad if I can stay within that range but the additional 1200 a/hrs I'm planning for will certainly give me a better comfort zone & more room to run more stuff. As far as charging time with the added 1200 a/hrs of batteries, it took to around 2pm to replace what was used overnite, about 2 hours more than before the expansion so it looks like when I jump it up another 1200 a/hrs, I shouldn't have any trouble fully charging the bank with the current amount of solar panels I have now on a good sunny day. Tomorrows report to come.

Well as expected last nights drain was about 7kw but even with a good spell of cloudiness today plus ran a load of clothes, the batteries reached full charge before the sun gave out & the panels produced 17kw. The 3500 a/hrs of batteries looks to be about the minimum to break even so when the next 1200 a/hrs of batteries gets put in, that'll for sure put me over the top.

Well just added the new batch of batts for another 1200 a/hrs, now up to 4700 a/hrs & what a difference in what the overnight voltage in the morning was, in the lower 24's to now in the upper 24's. So now that leaves the last 1600 a/hrs to be my final achievement, hopefully sometime early next year for the 6300 a/hrs I'm headed for.

[Bossrox]

How to equalize batteries & not damage them.

This info was pulled from Battery University's website.

Stationary batteries are almost exclusively lead acid and some maintenance is required, one of which is equalizing charge. Applying a periodic equalizing charge brings all cells to similar levels by increasing the voltage to 2.50V/cell, or 10 percent higher than the recommended charge voltage.

An equalizing charge is nothing more than a deliberate overcharge to remove sulfate crystals that build up on the plates over time. Left unchecked, sulfation can reduce the overall capacity of the battery and render the battery unserviceable in extreme cases. An equalizing charge also reverses acid stratification, a condition where acid concentration is greater at the bottom of the battery than at the top.

Experts recommend equalizing services once a month to once or twice a year. A better method is to apply a fully saturated charge and then compare the specific gravity readings (SG) on the individual cells of a flooded lead acid battery with a hydrometer. Only apply equalization if the SG difference between the cells is 0.030.

During equalizing charge, check the changes in the SG reading every hour and disconnect the charge when the gravity no longer rises. This is the time when no further improvement is possible and a continued charge would have a negative effect on the battery.

[Bossrox]

Kilowatt to amp hour reference

If you're running totally on lead-acid battery power, I thought it would be good to have a quick guide of the battery capacity to aim for @ your typical energy use that would give your bank a good lifespan. The following is based on 12 volts but if you're using 24 or 48 volts, just divide the a/hrs by 2 or 4 respectively but won't change the kw rating or the bank size you'll need.


1kw = 83 a/hrs / Required capacity for 10% drain = 830 a/hrs, @ 25% drain = 622 a/hrs

2kw = 167 a/hrs / Required capacity for 10% drain = 1670 a/hrs, @ 25% drain = 1252 a/hrs

3kw = 250 a/hrs / Required capacity for 10% drain = 2500 a/hrs, @ 25% drain = 1875 a/hrs

4kw = 335 a/hrs / Required capacity for 10% drain = 3350 a/hrs, @ 25% drain = 2512 a/hrs

5kw = 416 a/hrs / Required capacity for 10% drain = 4160 a/hrs, @ 25% drain = 3120 a/hrs

6kw = 500 a/hrs / Required capacity for 10% drain = 5000 a/hrs, @ 25% drain = 3750 a/hrs

7kw = 583 a/hrs / Required capacity for 10% drain = 5830 a/hrs, @ 25% drain = 4373 a/hrs

8kw = 667 a/hrs / Required capacity for 10% drain = 6670 a/hrs, @ 25% drain = 5000 a/hrs

9kw = 750 a/hrs / Required capacity for 10% drain = 7500 a/hrs, @ 25% drain = 5625 a/hrs

10kw = 833 a/hrs / Required capacity for 10% drain = 8330 a/hrs, @ 25% drain = 6240 a/hrs

If you're fortunate enough to fork out the $$$ for lithium, on a majority of them you can take out about a 90% drain without serious degradation so your bank size would only need to be around 10% higher than the a/hrs listed per kw rating.

I was lucky enough to find a source for excellent used batteries so my cost for a bank of 6300 a/hrs came in around 2 1/2 grand but here's something I found intresting.... When I tallied the cost of my 28 Cat 200 a/hrs at the new price of $400 each, that comes to $11,400 & 6 120 a/hr AGM's @ $300 a piece = $1800 that would total $13,200.

But for example if I was to go for some new battle born 100 a/hr lithiums @ a grand a piece, I would only need 10 for $10,000 to equal the kw capacity of the lead acid, then get a more efficient charge absorption & a better lifespan statistically. So if you're buying new, the lithiums, surprisingly they come out cheaper, take a charge more efficiently & should last longer if it's a stable reliable battery system, but there's a caveat about them that bothers me.......

One thing that nags at me about lithium, is the BMS electronics controlling the charge parameters, are they bullet proof or prone to problems. I don't know that. Plus you have all those cells & if 1 degrades more than the others, it shuts down or severely limits that entire battery, then you'd have to tear it apart to locate a bad cell. It's a way more complicated battery scheme that requires stricter parameters to function properly & gives lead acid an advantage somewhat with it's simplicity & a track record of stability.

[Bossrox]

How well can lead acid keep its load capacity?

I thought I would start a history to monitor the strength lead acids can hang onto over time but I'm not finished adding to my bank yet to start this & when that happens, for my 1st ledger here, I will do a 10kw drain off a fully charged bank & see what the ending voltage drop reveals. Then about every 6 months do the same test to see if the bank can produce the same stats. That should give a pretty clear indication if there's any degradation, so this project will get started sometime in the spring of 2021 after I get the remainder of my bank completed.

[Bossrox]

Wiring size you'll need to handle inverter & charging loads

1 AWG 50 amps @ 37.7 ft, 100 amps @ 18.9 ft, 150 amps @ 12.6 ft, 200 amps a@ 9.4 ft, 300 amps @ 6.3 ft.	2 AWG 50 amps @ 29.8 ft, 100 amps @ 14.9 ft, 150 amps @ 9.9 ft. 200 amps @ 7.4 ft, 300 amps @ 4.9 ft.	4 AWG 50 amps @ 18.8 ft, 100 amps @ 9.4 ft. 150 amps @ 6.3 ft, 200 amps @ 4.7 ft, 300 amps @ 3.1 ft.	6 AWG 50 amps @ 11.8 ft, 100 amps @ 5.9 ft, 150 amps @ 4.4 ft, 200 amps @ 2.9 ft, 300 amps @ 2.2 ft.
1/0 AWG 50 amps @ 47.5 ft, 100 amps @ 23.8 ft, 150 amps @ 15.9 ft, 200 amps @ 11.9 ft, 300 amps @ 7.9 ft.	2/0 AWG 50 amps @ 60 ft, 100 amps @ 30 ft, 150 amps @ 20 ft, 200 amps @ 15 ft, 300 amps @ 10 ft.	3/0 AWG 50 amps @ 75.6 ft, 100 amps @ 37.8 ft, 150 amps @ 25.2 ft, 200 amps @ 18.9 ft, 300 amps @ 12.6 ft.	4/0 AWG 50 amps @ 95.2 ft, 100 amps @ 47.6 ft, 150 amps @ 31.7 ft, 200 amps @ 23.8 ft, 300 amps @ 15.8 ft.

[Bossrox]

Mixing different batteries, what I just learned about the damage it could cause & how I will deal with it

I got an important heads up from another person I hadn't considered with my bank being mixed with 110 a/hr & 190 a/hr batteries that would lead to early failure for the smaller batts if I didn't configure them different.

The way the smaller batts were wired up was charging them faster than the big 1's, thus when the small batts got fully charged, the big batts were still catching up. Meanwhile the small batts are still getting the full absorption charge when they needed to be in the float stage & overcharging will damage battery life.

So here's my solution that won't be perfect but balance it out better so losing those small batts should no longer be an issue.

Being the big batts are 190 a/hrs & the smalls 110 a/hrs, I'll need to parallel 2 of the smalls to form a 220 a/hr battery to get close to matching the 190's, then series them from there into 24v.

This way, now the big batts will get fully charged a bit before the smalls & the 30 amp difference should have a negligible impact on battery life.

[Bossrox]

High capacity lithium phosphate just got attractive

Battery hunters might find this intresting. Just watched this video on a Gyll brand, rack mountable lithium phosphate 48v 100 a/hr battery for $1500.

That really grabbed me 'cuz Battle Born's are going for a grand a piece for a 12v 100 a/hr battery which would be $4000 for the same power as this Gyll 48 volter. That's a huge difference!

I'm set pretty good right now with a giant lead acid bank but if they wear out I'm now considering a move to Lipo4 after seeing this. Here's the video on this brand.

[Bossrox]

Experimental equalizing findings & results

I had to build a new cabinet for my batts bank. The old 1 was just to hard to check & service if needed so now they're all on a single level, way easier now to deal with.

Anyways, I got a new 48 volt inverter on order & while waiting for it, I got a hydrometer & checked the status of my batts, finding a wide difference in each batts cells specific gravity on what was suppose to be fully charged batts..

So I started equalizing experimenting with different voltages & amps to see if it would have any effect on restoring the batts.

I ended finding that pumping 28 volts @ 100 amps for 1 hour sessions gave significant improvement balancing the cells. Some of the batts did great on the 1st session but most I'm having to do multiples.

That much amps forced into a batt heats them up pretty warm after a hour & would likely be hazardous to let them go any further & these batts are BEARS tho, so they can handle that much power but on a regular car batt would likely be highly dangerous & would need to moderate the amps for smaller batts.

I got all 20 of my batts used so I had no idea what condition they were in & after the initial testing found that I probably had cumulatively about 50% of a new batts capacity but will see how well they all turn out when I'm finished.

After finishing up the equalization experiment, I made substantial improvement to the bank, ended up getting 18 out of the 20 batts with the specific gravity balanced on all cells. 8 were restored to 100% & 10 to 75%, 1 unrecoverable with a dead cell & the last 1 with 2 unbalanced cells, the dealer will be swapping out.

I also did some experimenting with epsom salt to see if there was anything to some of the stories I've seen of it reviving dead or tired batts you can watch in the vid's below.

As mentioned earlier, all these batts were used that cost me about $90 a piece that cost $400 new & in my system for 6 months before I decided to give 'em a thorough test that looked horrible.

So what it looks like, I got about an 80% capacity bank for 1/4 of the new price & I'm pretty content with that!

I video'd these tests & here's the results of test 1 & 2.



Test 2

[Bossrox]

Lithium now in reach & beats lead acid cost & power for a DIY build

This is mindblowing! I just did some figuring on the difference between my huge lead acid bank & just 2 sets of 48v 280 a/hr batts & here's the mindblower.....

My 20 190 a/hr batts which are at about 65% of capacity that comes to 615 a/hrs of which limiting the drain to 30% will give me 185 a/hrs of usable power or 9kw. Those batts can be had new for about $200 a piece times 20 is 4 grand.

Building 2 sets of LiFePO4 48v 280 a/hr batts with an upper limit cost of $800 & a pair for $1600..... Not a big cost difference so far but here's the energy I'll get from them limiting the charge/drain cycles to 70%. 560 a/hrs x 70% = 390 a/hrs or 18.5kw, double the kw capacity of the lead acid needing 8 grand worth of lead acids to do the same & a lifespan 4 times or more of the lead acid.....

That's mindblowing & now knowing this, it's foolish even screwing around with lead acid anymore!