.3Ohm resistance between maintenance-free car battery terminals - Page 1
Forum section: electronics / repair

author: m.m.m
author_rank: Regular Contributor
timestamp: February 06, 2015, 03:11:23 pm
content: hi, I my car battery has internally shorted, and when I connect my ohm meter to it, it shows 0.3Ohms, and when I connect a charger to it, the charger just overheats as it's shorted out. what can I do for it?p.s.:I have replaced the battery with a new one so please don't tell me to buy a new one.

author: c4757p
author_rank: Super Contributor
timestamp: February 06, 2015, 03:18:42 pm
content: You bought a replacement and that's shorted too?

author: m.m.m
author_rank: Regular Contributor
timestamp: February 06, 2015, 03:20:21 pm
content: Quote from: c4757p on February 06, 2015, 03:18:42 pmno, I mean I have replaced that but I want to know what's wrong with the old one.

author: wraper
author_rank: Unknown
timestamp: February 06, 2015, 03:26:05 pm
content: Quote from: m.m.m on February 06, 2015, 03:11:23 pmDispose it?

author: Mechatrommer
author_rank: Super Contributor
timestamp: February 06, 2015, 03:34:11 pm
content: Quote from: m.m.m on February 06, 2015, 03:20:21 pmwhats wrong with it? the old one is internally shorted. what can you do about it? depend on what condition.condition1: if you have sometime to waste: open it up, find out what causes it, fix it and glue it back together again.condition2: if you dont have sometime to waste: put it in the rightful place.fyi i keep all my broken batteries, the big ones are for bracing or holding something in place, the smaller ones are for throwing out monkeys or dogs that usually sneak in my backyard stealing fruits and messing out the food-waste-bin. only very few 1 or 2 in the beginning that met condition 1 but ended up in condition 2. but most people will advice recycling facility. fwiw.

author: SeanB
author_rank: Super Contributor
timestamp: February 06, 2015, 03:39:31 pm
content: Very likely the internal plates buckled and shorted out through the separator plastic cloth of one cell, and then the cell discharged itself through this until depleted. The other cells then had overvoltage applied as the alternator was still trying to charge the now 5 cell battery to 14.4V, and this then boiled off the electrolyte in the remaining cells, drying them out. As it got dry the top of the plates now got hot from the current flow ( they are a grid of thin castings with a paste on them) so they melted through the separator until all the cells were dry and shorted out. The last probably happened after you parked using the last energy in the cell to short itself.Taking it apart will just show buckled plates and some damaged separators, though the removal will likely remove the shorted sections. Sealed battery is just a regular battery in most cases with a label over the cell covers to hide them. Remove label, open the cells and add water to the new battery, and it will last you a lot longer. they use water because they are almost always in a very hot engine compartment, with large temperature cycles and vibration. The heat boils off water and the vibration causes the plates to shed active material.

author: m.m.m
author_rank: Regular Contributor
timestamp: February 06, 2015, 04:07:19 pm
content: Quote from: SeanB on February 06, 2015, 03:39:31 pmthank you all, it's a ca/ca battery, ain't it dangerous to open? also this is how the top of the battery looks like, seems a bit hard to open:

author: DIPLover
author_rank: Regular Contributor
timestamp: February 06, 2015, 04:34:39 pm
content: Just recycle the thing and get on with your life...

author: Richard Crowley
author_rank: Super Contributor
timestamp: February 06, 2015, 04:48:22 pm
content: Dunno know what "ca/ca" means?But it looks like an ordinary vehicle lead-acid battery, and OF COURSE it is dangerous.It almost certainly contains HAZARDOUS substances in all three states:It contains solid lead plates which are subject to recycling properly in most civilized parts of the world.It contains liquid acid which is quite dangerous to handle without proper precautions and materials.It could contain dangerous gasses in some sealed varieties.Not recommended to mess with it unless you really know what you are doing and now to handle especially the liquid acid.

author: SeanB
author_rank: Super Contributor
timestamp: February 06, 2015, 05:05:27 pm
content: They placed a plastic cover on and glued it. Recycle it, or prise the cover off ( the part under all the labels, it will have a seam on the side to the top casing) and you will see all the cells are dry. Adding water now will not help, it will still self discharge fast.Yes it contains both lead metal, lead oxide ( black and reddish coatings on the plates) and a fill of strong sulphuric acid, which is corrosive to skin, can transport lead through the skin and which destroys pretty much anything organic with time. Battery casing is resistant to it, but even it will fail with time, and you only will get around $0.70 per kilo of battery. Recycle at the scrap yard or the supplier of the new battery, do not just dump it.

author: jlmoon
author_rank: Unknown
timestamp: February 06, 2015, 05:09:24 pm
content: Quote from: SeanB on February 06, 2015, 03:39:31 pmI refer to that as lead droop, where the plates get thin and fold over on each other. Usually happens where the terminals connect the groups together.

author: m.m.m
author_rank: Regular Contributor
timestamp: February 06, 2015, 05:37:25 pm
content: Thanks again, I just broke a little piece of it, here is what I see: A cap for the cell, and some liquids floating around that, I viewed several videos on refilling lead-acid batteries, non of them had that liquid floating near the cap! is that acid? have I broke too much into the cell itself?!

author: Leadfootin
author_rank: Contributor
timestamp: February 06, 2015, 05:50:42 pm
content: That would be sulphuric acid!Big question is what caused the failure, overcharging or vibration being the main culprits.

author: m.m.m
author_rank: Regular Contributor
timestamp: February 06, 2015, 06:12:11 pm
content: Also the plastic over the caps are stuck to it, so I can't break the plastic completely. have anyone had this situation?

author: SeanB
author_rank: Super Contributor
timestamp: February 06, 2015, 06:12:49 pm
content: That is the sulphuric acid which has been blown out of the cell during it's death. As the inner cell now has dried out it will never recover. Only way is to send it to China to be taken apart and made into lead again and new batteries.The plastic cover is solvent welded on that one, so it will not come off easy.

author: Richard Crowley
author_rank: Super Contributor
timestamp: February 06, 2015, 06:17:22 pm
content: It is NORMAL to see the liquid (acid) level ABOVE the plates. It is REQUIRED for proper operation. Letting the liquid leak or vaporize/boil off exposes the plates which is a BAD thing.Back in the bad old days of unsealed batteries, a regular maintenance task was to open the caps and confirm that you could see the surface of the liquid, confirming there was an adequate amount.I suspect that the videos on YouTube all show broken batteries with little or no liquid acid fill remaining.

author: m.m.m
author_rank: Regular Contributor
timestamp: February 06, 2015, 06:25:43 pm
content: I don't think it's dried out, when I move it it sounds like a lot of liquid floating around, maybe just the caps need to be replaced?and also, how can I fix the internal short circuit when I remove the plastic cover? is the short inside the cells or just above them inside the plastic cover? I just couldn't understand what you said in the 5th reply.thanks a lot.

author: Richard Crowley
author_rank: Super Contributor
timestamp: February 06, 2015, 06:29:56 pm
content: Note that ALL the cells must be immersed in the acid fluid.Frankly, if you are asking these kinds of questions, you are probably NOT qualified to attempt this kind of repair because you are not properly fearful of the hazards.The fact that you have such a low resistance indicates one or more shorted cells in your battery, and that would require major work to repair.It could easily cost more to repair than to replace, not even considering the great hazards from the materials in the battery. NOT RECOMMENDED!Furthermore, even if you WERE qualified, those sealed batteries were not designed to do that kind of repairs. They were designed to be simply recycled and replaced.

author: gilbenl
author_rank: Regular Contributor
timestamp: February 06, 2015, 11:37:04 pm
content: I'm afraid that your battery is indeed dead beyond all hopes of repair, despite the inaccuracies these folks have attempted to pass as facts. Here's what has really occurred:After a long and difficult life under the hood of your car, the electrons inhabiting your battery grew lazy and complacent. They once buzzed with potential, but now, when your multimeter tried to excite them with a current, they just passed the ampere right along without a care in the world, returning it unimpeded. They longed to be free!Back in the day, electrons had a decidedly different work ethic. They would toil happily, forever cycling from anode to cathode only expecting the occasional nourishment in return for their efforts. Electrons today are over-indulged and full of entitlement. Discontent with the banal work performed by their ancestors, they want to go off and see the world, backpack through Europe, and crap like that. It is because of this insatiable wanderlust that battery manufacturers resorted to sealing the case.Upon opening your battery, all of the "new age" electrons found their opportunity and escaped. Heisenberg uncertainty principal makes it so that you will never know where they are or where they are going, so any attempt to reclaim your electrons is hopeless. I'm deeply sorry for your loss.