Alum Battery Conversion - Beginner Questions

[Joster]

Hi All!

Converted my first alum battery the other day but with mixed results. The battery I used was an old Energizer 700 CCA Deep Cycle Marine Battery. It was a junk battery given to me by a friend. Before the conversion it stood at about 5V. Just for fun I put in on the output of my SG and something interesting happened. At first, all my neons where lit even though the battery was connected. Then 1 by 1 they started going out until they where all not lit. I disconnected the battery just for a sec and sure enough they all lit up. Can anyone tell me what was happening there?

After that, I poured the acid out which was pretty much black. I rinsed it three times until the distilled water ran mostly clear. I heated up some water and mixed in 195 grams of alum (not sure how much water I used and I didn't end up using all the solution, next time I do this I will be sure to do way better measurements haha). I filled up each cell. At this point the battery was standing at 8V.

I don't have a battery charger (except the SG) so I used a transformer and rectifier to put current onto the battery (about 2.5 amps). The voltage while charging is about 16V and you can see the attached curve to see what it does under load. This curve is after charging @ 2.5 amps for 4 hrs. I only got 1A for about 20 minutes. The graph might be a bit hard to see but the big notch there is at about 7V.

1. Is there something physically wrong with the battery I'm pretty sure there where no shorted cells as I measured the voltage of each cell before the conversation at about 1.3V, or maybe the plates are just too sulfated)
2. Maybe my mix is not strong enough?
3. Maybe I need a better charger. Perhaps just use the SG or dump a cap into it from the SG

One last thing. I'm pretty sure this is normal but when it is charging I can see the solution bubbling and I can hear it fizzing too. I can also smell a slight vinegary odor near the battery. Is this ok?

Anyway, as you can probably tell I'm just getting into this so any advice would be a huge help!

Cheers!

JM

[BobZilla]

Hi JM,

At first, all my neons where lit even though the battery was connected. Then 1 by 1 they started going out until they where all not lit. I disconnected the battery just for a sec and sure enough they all lit up. Can anyone tell me what was happening there?

Yes I can tell you, and it is the same reason you have not had much success. It is an old battery with massive sulphate buildup on the plates. The battery was at a very high impedance when you connected it and was only accepting a very slight bit of the energy. That is why the neons lit up because the energy had to go somewhere since the battery would not accept it. As it ran for awhile the impedance dropped and the pent up voltage lowered below the neons trigger voltage so they went out. You had started to clean the plates just a tiny bit that point.

The rest of your work did not go well because of the same issue. What you need to do if your working with old batteries is re-condition them with your SG first. You may be able to still salvage it but it is going to take a lot of cycles.

[Dominus]

Running the SG without a load, fries the transistors