sla battery end voltage strange behavior

[knagtegl]

Hi,

I finally build my ssg to the original specs (could not get a bike wheel and the right magnets because I was in eastern europe a few months)
but now I have a good wheel 11 min freespin and 18 magnes superpoled (magnets are a litle smaller 4 cm x 2cm x 1 cm) but since they are pushed together I dont think there is a significant difference.
I am using just one 3055 transistor (I am stil waiting for a delivery of 10 mj's) it is pulling 230 mA when tunned and it is charging quite good as far as I can see. (did only one charge cycle yet).

100 4395 - YouTube

the coil core is about 2 cm diamater and 7,5 cm long 4 wires I gues around 19 awg (got it from an old motor) and a 20 AWG trigger all around 50 meters long and twisted.

The thing I want to mention is that when I charge a sla battery (10A/h gel cel for wheelchair) it charges to lets say 14 volt it than does not go much further up at least very slow. When I disconnect and wait some time and connect it again it is going over 15 volt very fast.
Can anybody explain this or has someone seen this same thing too?

the normal lead acid batteries do not have this behavior and go right up to 15 volts.

[John_Koorn]

It sounds like your SLA is sulfating or dried out. How old is it?

John K.

[Tachyon Catcher]

All my SLAs react in that fashion when rested after a charge. After a few charges with my energizer, they usually go over 17volts if I do as you did and rest them after a charge, then charge them again. I have over-charged a few batteries, rested and charged again only to see the voltage go over 24v, then all my neons light up and the battery is ruined with an impedance off the charts. I am working with 7Ah SLAs. I have charged/rejuvinated around 30 SLAs. I think this is normal.
Randy

[knagtegl]

Hi John,

I bought 3 of them in january 2012 and did not use them much just did a few cycles with them and kept them full as much as possible.
they are from cell power, cpc-10-12 valve regulated sealed lead acid

It almost seems that they have some sort of overload protection that you override when let it rest and charge again.

[Faraday88]

Hi,

Have you pre-loaded this battery? the reason why i'm asking you this is, if its been peak charged prior to you hooking it up to the Energiser, then what you observed is preaty straight forward. a Peak charged battery on the SSG will cold -boil and gas exessively ..
rgds,
Faraday88.

[knagtegl]

Farady88,

I don't know exactly what you mean by 'pre-loaded' but It is just taking quite a long time to charge this battery compared to the 5 amp/h motorcycle lead acid battery. when I put the 5a/h on a load to discharge, I hook the 10 a/h sla on the energyzer but when I need the energyzer for the 5 A/h I disconnect the 10 A/h before it is at 14,5V. When the 5 A/h is full again I put the 10A/h back on the energyzer and continue the charging but than it is going to over 15 volts very rapidly.
Much faster than when I would charge it in one session, it seems that it does not accept the charge in the second session and thinks it is fully charged.
But I believe Randy has experienced this aswell.

Karel

[Tachyon Catcher]

Karel,
Be careful letting those batteries set around. The sulfate in them needs moved around through charge/discharge. Letting them set at the same charge state causes the sulfate to harden on the plates regardless of charge state. Hardened sulfate is non-conductive. If enough of it builds up on the plates they become non-conductive. The energizer will break up the sulfate, but must be done gradually with many cycles. A fully sulfated battery if forced with a energizer to fast, can cause chemical "holes" in the plates and changes the chemistry in the battery. These are not literally holes, but areas on the plates where the doping is removed so the plates do not react chemically with the electrolyte. The experience I described above with the voltage of the battery going over 24 volts is a result of "forcing" a charge on the sulfated battery too fast. My energizer is a multi-coiler that can pound those little 7Ah SLAs quickly.
Randy

[Faraday88]

Hi,

Try this method: In a 2 battery system, Load the Primary with a resistive (LightBulb) element and also at the same time drive the Energizer off this primary to charge a secondary, after the secondary is charged, cycle themt .
you will get rid of the sulfate even faster by this method.

rgds,
Faraday88.

[caldovicd]

So, you are saying that constantly swapping batteries is not causing any harm to batteries with this method (with Light Bulb)? If I am not mistaken, I have read somewhere, or heard JB saying that you can not swap batteries, because one is charged by negative energy, other by positive?