reverse battery charging

[mellowyellow]

my 15yr old son was chargin the lawnmower battery<br />and had the charger hooked up backwards. <br />is the battery fried now? should I expect any<br />other problems too???<br />wish he'd learn these lessons on his own eqpmt!<br />thanks in advance,<br />M.Y.

 

[rwise]

Re: reverse battery charging

mellowyellow<br />I think I'd be happy that it did not explode! Try recharging it correctly, but for $16 + gov I'd just put a new one in it, (yea right) Good luck!<br />Richard

 

[dkondelik]

Re: reverse battery charging

ARGH!<br />I've got one too (a 15 yr old that is) and know EXACTLY what your goin' thru. <br />Heck, i even bought him his own set of tools cause i was tired of him loosing mine. Few months later he was loosing mine again cause he already lost all of his.<br /><br />The battery thing kind of hits home too. last fall he took out the Basstracker. A friend of his pulled the battery off of the charger and dropped the charging leads together. Now i got a shiney new battery charger. Along with whats left of my tools, it too is now under lock-&-Key.<br /><br />Don't know about the condition of your battery. Guess you'll just try to see if it will take and hold a charge. The other question might be "did the charger survive?"<br /><br />From what i remember/understand, in just a few years, he'll grow out of this

 

[FLATHEAD]

Re: reverse battery charging

Aint that always the way!! 50/50 chance of getting it right but it always seems to go the other way.

 

[mellowyellow]

Re: reverse battery charging

misery loves company guys, thanks!<br />know all about missing tools and the like.<br />santa brought me a new craftsman box full o'<br />tools and it is locked! he got a wallyworld<br />set of 130+ pieces so he doesn't even ask to<br />borrow mine anymore.... 'cept when he can't find<br />one of his LOL<br />new battery, no biggie.<br />new charger? <br />electrical damage to the old Deer?

 

[Fishbusters]

Re: reverse battery charging

Had a friend that we never let borrow tools to work on his car because if you followed behind him while driving long enough you could watch them fall out of the undercarrage.<br />As far as the battery personally I would get a new one out of his allowance.

 

[jee70611]

Re: reverse battery charging

MY,<br /><br />If the acid in the battery is still acid and hasn't been turned to water by the charger then you probrably have a good chance at it being fine. Just so long as their wasn't a whole lot of extra build up on the plates that would short out the cells. You could test the battery acid in each cell with litmus paper and see if it turns red. If it does, then as long as the cells aren't shorted out, It should take a charge. However, if the acid has changed to water (yellow litmus = pH7) the only hope would be to empty and replace the acid with 60/40 sulfuric acid/water mix. Then it should work if the cells aren't shorted out. It will most likely pull a huge draw though and take quite a while to charge up if he "de" charged it for a long time. I would try to leave it on trickle charge for a while before throwing full power to it. You don't want it to blow . In other words, try to charge it and if it don't take then just replace it . Now for the mower, the charging stator could be bad, but since the battery was still connected it might be fine. As a safety precaution I would replace the diode before reconnecting a fully charged battery to prevent frying the stator. They aren't cheap. Let us know how it goes and Good Luck!!!<br /><br />James

 

[petryshyn]

Re: reverse battery charging

mellowyellow<br /><br />>First off, determine if the battery polarity has been reversed. Do this by checking with a voltmeter to see if a "minus sign" appears in front of the voltage reading.<br />>If not, likely no harm done<br />>If it reads opposite, connect up an old headlight across the battery until it is "stone" dead. Then recharge in the proper polarity.<br />>Do NOT add electrolyte at any time. (only water if low) acid never leaves the battery.....<br />>disconnect the battery leads. Connect to the leads with an analog ohmmeter or digital with a diode test function. If you get a reading from lead to lead one way and not the other, the diode is likely ok. (be sure all accessories are off when testing)<br />

 

[jee70611]

Re: reverse battery charging

schematic,<br /><br />I thought that when the SO2 leaves the water that it is dissolved in that it changes from H2SO4 to H2O. It has been a while since I had chemistry class but could you refresh my mind a little. I didn't think that the redox reaction could go the other way. Hmm.. Oh well, I guess if you don't use it you loose it . I should study up on it a little to refresh my mind huh?

 

[petryshyn]

Re: reverse battery charging

jee70611<br /><br />When a battery is being discharged, the H2SO4 combines with the Pb and PbO2 plates to form PbSO4, H and O2. The hydrogen and oxygen can easily escape the battery causing the need to replenish the water. The SO4 is removed from the plates and recombines with the water when we charge the battery.(unless we leave it sit around too long which allows solidification of the PbSO4)<br /><br />Acid never needs to be added cause it doesn't evaporate. Its either in the electrolyte or the plates.....

 

[mellowyellow]

Re: reverse battery charging

thanks for the education guys!

 

[grandx]

Re: reverse battery charging

You can lose acid if your battery boils over, via over charging etc.

 

[petryshyn]

Re: reverse battery charging

sorry grandx<br />battery acid doesn't leave the battery (in any noticeable quantity) unless it was overfilled to begin with, or tipped over, leaks etc. When charging or discharging lowers the level, only the water is missing. Only water should be added. If a battery actually boils, it is ruined beyond use. Anything over 120f warps the plates, breaking off the useable lead material off of grids (substrates). Many people mistake "gassing" as boiling. Gassing occurs when charging and discharging. It is normal. It looks like boiling, but its just the H and O2 migrating up through the electrolyte.<br />General rule of thumb.......if a battery is warm to the touch, your charge rate is too high and/or too long.

 

[ebbtide176]

Re: reverse battery charging

its nice to see schem here. and this is good stuff, so i'm "touching" it (using an old unix term- to update a file)<br /><br />good info, great info... but i'm a little cautious on the part of a warm battery meaning overcharging. maybe i've been overly lucky with batteries all my life, 'cause i get them pretty warm, and often at that. <br /><br />i waited til the replies came in to say - that i've seen people do what MY's son did. and putting them back on correct polarity reversed the polarity back to work almost as normal in a few instances. i would put a rubber doormat over them while charging, for safety sake tho.

 

[petryshyn]

Re: reverse battery charging

hi ebb<br />Lead/acid batteries have plates which are kinda neat. To increase surface area, they use a grid or frame (much like stucco wire) and trowel a porous lead paste onto it. This gets hard and brittle once applied. If the battery is overcharged to the point where its temp exceeds approx 120F, the expansion of the plate assembly cause distortion of the plate which results in the brittle lead breaking away from the grid. If it falls to the bottom of the battery, it no longer contributes to the electrical capacity of the battery. This may not render the battery useless, but each time you exceed safe temperatures, the battery loses capacity. This means that the limiting factor to charging rates is temperature. Although not practical, the best way to adjust charge rates would be to monitor cell temperature. Thats why fast chargers must only be used a for a short time so as not to exceed safe temp levels.<br />Maintenance free batteries are a little more tolerant to overcharging, as their plates are encased in an insulative envelope which holds in place the broken away material. Therefore the material still maintains electrical connection to the plate assembly and continues to contribute electrically.<br /><br />Most lead/acid batteries would live for 7-10 years if they weren't murdered long before. I've seen some that have lasted just under 20!

 

[DJ]

Re: reverse battery charging

Schematic,<br /><br />You are sooooooooo, correct. <br /><br />It's a falsity that cold kills batteries. <br /><br />It just so happens that the cold (harder cranking engines, etc.) is what finally tells the operator that he has a weak battery. <br /><br />Heat is the true enemy. More batteries are sold in the southern climates than in the northern ones. How about that?<br /><br />It's not unusual for ambient temps. to exceed 115 degrees F., here in AZ. Underhood temps can approach 300.