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Nicd Battery charging Help.

Posted: Sun Oct 15, 2017 8:47 am
by AJB2K3
I have assembled the battery packs required to build a 14.4v 10.5Ah battery which will run off a solar panel, but I have hit a snag.

1, Can i just connect the 14.4v connection to the solar charger controllers battery port and leave it to manage the charge?
2, Is it possible to connect a secondary tap to supply 3.6v (all the pack are 3.6v connected in series to make 14.4V packs and then the 14.4v packs are connected in parrallel to make 10.5AH pack)

I feel like I am missing something here which I why I post this for the more qualified people to ask.

Re: Nicd Battery charging Help.

Posted: Sun Oct 15, 2017 9:45 am
by Burngate
1,
You haven't supplied enough information about the solar panel or the "solar charger controller", so all I can do is guess.
I'm guessing it's designed to have a 14.4v NiCd battery attached, and can successfully charge it.
But there are lots of different battery technologies, each requiring different charging schemes. Guesswork isn't really good enough - get it wrong, and you can burn down your house.

2,
No, it's not!
In each string of four 3v6 batteries, the charge current is the same for all four, and so they should all be charged to the same level.
If you take some current from just one of those, that battery will have less charge in it, so the it can end up under-charged while the other three will be over-charged.

Re: Nicd Battery charging Help.

Posted: Sun Oct 15, 2017 10:06 am
by AJB2K3
Burngate wrote:
Sun Oct 15, 2017 9:45 am
1,
You haven't supplied enough information about the solar panel or the "solar charger controller", so all I can do is guess.
I'm guessing it's designed to have a 14.4v NiCd battery attached, and can successfully charge it.
But there are lots of different battery technologies, each requiring different charging schemes. Guesswork isn't really good enough - get it wrong, and you can burn down your house.
Sorry, forgot about that. I know it can charge Yuasa batterys and car batteries without issues, I just don't know if it need some kind of BMS because it is a multi cell pack.
Burngate wrote:
Sun Oct 15, 2017 9:45 am

2,
No, it's not!
In each string of four 3v6 batteries, the charge current is the same for all four, and so they should all be charged to the same level.
If you take some current from just one of those, that battery will have less charge in it, so the it can end up under-charged while the other three will be over-charged.
Thanks. That what I thought, I just want varifacation on what I was thinking.

Re: Nicd Battery charging Help.

Posted: Mon Oct 16, 2017 9:06 am
by Burngate
Yuasa batteries and car batteries are lead-acid.
They're very tolerant of mistreatment - a car alternator just puts 14v or so across it and lets it take whatever current it wants. The automotive industry wouldn't have survived more than a century if the battery was more prone to failure. Once fully charged, extra charge electrolyses the water to hydrogen and oxygen, which is why older batteries required topping up on occasion

NiCd and NiMH batteries need more careful treatment.
They have been designed to withstand over-charging to a limited extent, with the products of electrolysis recombining within the cells. However, C/10 is generally the limit, so in your case about 1A
Each time they're overcharged, some of the electrolyte escapes, so the capacity goes down.
https://www.batterystuff.com/kb/article ... ttery.html

Re: Nicd Battery charging Help.

Posted: Mon Oct 16, 2017 4:45 pm
by AJB2K3
I assembled the first of the seven packs yesterday and it came out at 15.3 v!
I'm looking to "Underclock" the charging of the "Pack" to 12v at C/10 (thanks by the way for the link as I had been searching all weekend and google just would not show that page)
I know there are solar controllers out there that are capable of this but would I gain any "Pack" life from underrunning or should I just leave the voltage alone and adjust my Converters to the higher voltage?

Ok after stripping a dead pack in work I have found that each 3v6 pack contains 3x1v2 cells.
1 sub 14v4 pack contains 4x3v6 pack and the full pack will contain 7x14v4 packs

total of 84x1v2 (Maybe slightly off here) does this alter the calculations?
Sorry, first time dealing with battery charging.