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BANGKOK 12 December 2018 06:36
Arjen

And then are the batteries gone....

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I deploy a LOT of SLA batteries in the field for my line of work (

Which kind of batteries of do you find are best and which would you avoid?

 

You are probably the exact person to give correct advice and diagnosis of problems. I have been doing my best and hope that I haven't made any major errors.

 

As PV is becoming more widely used a primer (for the DIYer and check to see if the shops are selling what is needed) on the subject of batteries, what type, how to locate, maximum heat, maximum charging voltage, minimum voltage before disconnecting,, use of, sizes of, sources of peltiers etc.  Would be of enormous help and if you can find the time should be pinned in the this

 

 

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This is just manufacturers covering themselves. There is actually some research into this (sorry it's too late and I'm too tired to Google it, I'm just enjoying a beer after work and reading through ThaiVisa). An SLA will take as much current as you can supply it during charge. It won't take more than it can handle. Giving it as much current as it wants to charge with might actually do it good. WATCH THE VOLTS THOUGH. . . I never supply any of my SLAs with more than 13.5 volts (or 27 volts for my 24 volt systems) but give them as much current as they want when charging. There's a big difference between forcing the current in with volts, or allowing the battery to take to what it wants. . .

 

About the OP, one of those pictures above appears to be in direct sunlight, maybe the light on your camera, I don't know, but those batteries sure look older than 2 years. Regardless, it sure looks like you've allowed your bank to overheat. It's dead, forget about repair, just bite the bullet and replace. I deploy a LOT of SLA batteries in the field for my line of work (networking and telephony equipment in outdoor cases in direct sunlight). I generally use forced air to maintain case temps at ambient. Occasionally I will use peltiers to keep the temp lower than ambient but only when there are routers and switches involved. The higher the battery temp the lower the float charge. It looks like this is where you're blown it. My cases generally hit 38 degrees most of the year where I'm using forced air and if my batteries last less than 3 years something is VERY WRONG. Generally I get 5 years +.

 

Another thing to watch out for is the manufacturing date on SLAs. If they've been sitting on a shelf for two years and the open circuit charge allowed to drop too far there's a good chance the batteries are permanently damaged, even if you just bought them. My limit is 12.7 volts. If it's below that, I don't buy. Don't be shy to test the voltage in the shop, and check the manufacturing date.

 

"Deep cycle" doesn't give you carte blanche to deep cycle. I never let my batteries go below 11.4 volts when discharging and that's when they'll disconnect automatically. They have a very long life as a result. If I need a system to run for 8 hours without mains power, I'll spec it for 16.

 

 

 

 

 

Thank you very much for this great information. I will not spend much more time on these batteries, and will purchase new ones after doing some more research.

 

About cooling with peltiers, I use these for an other application, and I am afraid when I use them to cool a battery bank I will pull 100's of Amps.

 

But I wil install (a lot of) fans to keep the temperature at or around ambient temperature.

 

Thank you again!

 

Arjen.

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Which kind of batteries of do you find are best and which would you avoid?

 

You are probably the exact person to give correct advice and diagnosis of problems. I have been doing my best and hope that I haven't made any major errors.

 

As PV is becoming more widely used a primer (for the DIYer and check to see if the shops are selling what is needed) on the subject of batteries, what type, how to locate, maximum heat, maximum charging voltage, minimum voltage before disconnecting,, use of, sizes of, sources of peltiers etc.  Would be of enormous help and if you can find the time should be pinned in the this

 

 

Yes, yes yes!!!

 

Please more information!

 

Probably a new (pinned, Crossy?) topic?

 

Arjen.

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Honestly, I have very little experience with solar systems, but I occasionally deploy remote microwave links that are entirely solar powered. The thing is, I'm not fussy about long charge times and low float charging voltages, I don't need rapid charging and this arrangement greatly simplifies charging circuits (which I also construct myself) but if you're using in a domestic environment, you'll obviously want to charge as fast as possible when the sun is out, maximizing the voltage for rapid charge and then tapering down. I never do that, so my advice in this case is probably not much good to you. . . but I can say that if you're batteries are being so stressed during charge or discharge that they deform in such a way, then the system has been BADLY designed for the environment it's been deployed in.

 

To give you an idea of what I do (I'm an IT consultant but in my case this is a broad brush), here's a remote IP camera system I recently installed on a hotel's access road, a pretty basic install with 3 IP cameras, a wireless link back to base, and 4 high powered 12 volt infra-red floodlights. . .

 

DSC_0564.thumb.JPG.65985b14f2d6f280509233dec88ef848.JPG

 

DSC_0566.thumb.JPG.441c39d03df92c983615433302572dad.JPG

 

 

 

The rest of these pictures our from a few of my own private systems, so I didn't pay much attention to cosmetics, but I'm just trying to make the point that all of the stuff is cheaply and readily available on ebay. You don't need to pay someone like me big bucks to build these systems if you're confident in your own soldering iron and fingers. Lead acid technology is old and well understood, and charging is pretty straighforward.

 

About what type of SLA I'm not really fussy, but I've been getting good results with the lead calcium NV batteries being cranked out in HomePro . 

 

As I said, the following are my private systems, so no laughing at the cosmetics and heavy use of hot glue. I throw these together with scraps and leftovers. . .

 

DSC_0540.thumb.JPG.6e8f8bb72313bf0c54857a964e5d8b60.JPG

 

 

DSC_0537.thumb.JPG.ff9f0ad857d2e782899155015f67bf22.JPG

 

 

DSC_0539.thumb.JPG.ee705300fdca8884890f2aaf007574f2.JPG

 

 

DSC_0529.thumb.JPG.19bec6053f5dbfac31b622f03be37430.JPG

Edited by NilSS

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I forgot to add to the above, these are highly redundant, highly reliable systems I deploy for customers. Even though the electricity blinks all the time, daily, hourly, or even more frequently, I remotely monitor switches and servers in boxes like this that have been up for years without a reboot. YEARS!

 

 

 

 

 

Edited by NilSS

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In fact I did not really design, I just bought PV modules, charger, inverter an batteries from one supplier. It turns out that the batteries do not fit with the charger....

 

I do not need fast charging. I have designed my system as a whole house UPS. When the grid fails, I use my own supply. When the batteries are full, before charging stops, I switch also over to my own supply, to reduce our electricity bill a bit. (but that is not the main reason from my system, it is desgned as an UPS)

 

In the past we had black-outs, and brown-outs nearly daily, for several hours. Now we have maybe once every ten days a black-out, from maximum two hours. Only at night it takes sometimes longer to restore the grid. We are close to the fuses, and usally they make a loud BANG, and then we are in the dark. Then I need about 4-6 seconds to start my own supply. When I switch over to the grid, or to my own supply when grid is available switching time is milli-seconds. Even the lights do not blink. I can hear it on things like refrigerators and fans, as switching does not happen with synchronised phases. Brown-outs maybe still occur, but since I have an AVR, I do not notice these so much.

 

In normal use I switch back to the grid when batteries are at 25V. That leaves enough for around 20 hours of usage, when I power off some pumps. When I leave all on, it is enough for around 5 hours.

 

I have 20 100Ah batteries, connected in 24V. Sometimes there is announced that they will cut off power supply. In that case I will charge the batteries as far as possible, and that gives me, when I am very carefull around 48 hours of usage.

 

Thank you very much for your ideas!

 

Arjen.

 

 

 

 

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