Battery Charging Mishap

Sounds like you have a shorted cell(s) in one of the batteries.

IMHO...

If the wire that smoked and melted were the conditioner leads, then it sounds like you confused the wiring, and either put the batteries in series, or attached the conditioner with polarity backwards.

If the jumpers on the batteries were melting and smoking, then probably you shorted the batteries by incorrecty attaching the jumpers.

You may have a dead or shorted battery as suggested by WJMFIRE. Charge them sepeartely, then test them.

KJK, I think you have provided the answer. Previously, when I used the external charger, I disconnected the batteries from their 24V configuration and then connected the jumpers for a 12V charging setup. This time I left the batteries connected in 24V (series?) and then made the connections for the charger for 12V charging. Stupid mistake. Any simple way, for a novice with a $20 multi-meter, to check the viability of my almost new batteries? As I mentioned before, the voltage reading is good.

Don,

Glad to have helped!

As far as checking the batteries, pick up a cheap "Battery Load Tester" from your local Pep Boys, Auto Zone, Farm and Fleet, ect. I have seen them as low as $22.00.

For what you will be using it on, a cheap one will be fine.

Happy fishing to you!

Or save the $22 by taking the batteries to the store. They have testers that check with and without load.

Advance Auto Parts also does this.

You simply made a great short circuit!! Probably only across one battery.....

Sadly, it appears that you have no fuses in the circuit!! This is one of the times when having a few strategically placed fuses would have "saved your bacon!"

May I say that charging in parallel is not a good idea (understatement of the year!!), either charge seperately (and you can leave them connected to the boat's electrics then), or buy a second charger....

Never, ever simply attach the charger in parallel mode AND still have the boats electrics connected, always disconnet from anything else first!!!!

Depending upon the type/style of battery, there are several other "Do's and Don'ts" that you may need to follow.....

By the way, you first said that you did everything the same as all the other times, that was simply untrue......think about it!!!

Would you explain your concerns about charging in parallel? My boat AC/DC charger is hooked up to charge in a parallel and connected to the electrical system. My engine alternator is also hooked up in the same fashion.

I seem to be missing something in your statement or I am misinterpreting it.

Charging in parallel is not a good way to charge LA batteries, but will work, but does not take into account any differences/tolerances, even in identical batteries, from the same company, with the same charge code.......this will accelerate cell aging.

It even happens within a 12 volt battery to a degree as not all cells are absolutely identical. A way to reduce the possible aging effect is to charge only to 70% of capacity.

In your case, with 2 x 12 volt batteries, you would be far better off in getting a charger for 24 volts.....surely the supplied charger is just such a version, the one that does not charge anymore....

To charge in parallel two batteries from a 12 volt charger needs a selector switch to switch between charging an running.....someone posted some good diags in an earlier post that demonstrated that well. You cannot charge with 12 volts AND "run" with 24 volts.......trying to do this will make the short circuit you experienced......simple.

Also, the charger you are using was not (if I understood you correctly) made for the job in hand, so it may not be of the correct range of current for your batteries, it also might be of a type used to boost a car battery occasionally and therefore it has no proper charge control.

Charging LA batteries is a little "science" of its own, don't do it properly and you end up with dead batteries within 2 years, or even 2 months......

Even "fully charging to 100% capacity" an LA battery severely reduces its life span.........which is why most car batteries do not live longer than 3-5 years, when correct handling/charging could mean 10 years plus.......

Gassing an LA battery also reduces its lifespan.....even a Sealed LA.....

You have not posted enough detailed information about the charger and your batteries to make accurate posting by myself or any other person possible.....its all guesswork at this time.

As you are probably realizing now, if you look at KJKs schematics, when you parallel series-connected batteries you cause a dead short.

If the voltage rating of your batteries is still over 12, they should be fine. You can charge either independently by connecting a 12 volt charger to each one, but not both at the same time. Trying to balance their voltages is a good idea, and that can only be done by independent charging. (In more expensive systems a battery management system serves to keep the batteries balanced.) To keep the batteries in good shape, charge them routinely with a 24 v charger, and periodically check the voltages after the batteries have had a chance to settle down after charging (2 hours later, or so). If one battery ends up at lower voltage than the other, charge it alone for a while with a 12 v charger. (Otherwise, the imbalance tends to be self-reinforcing, with one battery becoming overcharged, and the other undercharged.)

GA

I should have mentioned previously that the batteries are new. I used them on a fishing trip yesterday and they worked fine. Today I tested them before the attempted charging and they both read 12.46V. Prior to use, they read 12.65V. There is an on board charger but I disconnected it as it was not providing any charge. I guess my making wrong connections is a possibility. After using my fire extinguisher and disconnecting all battery wires I tested both batteries and they still read 12.46V.

Testing a battery that is not under load tells you very little about the health of the battery.

Don, When you mentioned the fire extinguisher it made me wonder what size wire you are using for the jumpers. Trolling motors can pull quite a few amps. The amp draw is why you need heavy gauge wire. Did the wires to the charger cook too? I was also kind of curious where the second jumper came from if this was a "stock" 24 volt installation. Check the output voltage of your onboard charger too. It may have been hooked up wrong. With those voltages known, someone here could help. Maybe with diagrams like the ones above. (Nice post KJK)

Also, if you had it hooked parallel and the motor worked fine you may have a 12 volt motor.

Barchetta, I don't think I explained myself too well. When I fried my wires I think it fried my brain a little also. The batteries are wired in series for 24V. However, when I use the external charger I wire the charger in parallel to the batteries. This time I left the batteries wired in series and charged in parellel. Oops! I just hope the batteries are OK. They show good voltage but I'm not sure how to test "under load". Thanks.

Don,

You've already used the $20 voltmeter as much as you can with this scenario. At 12.46 volts across the battery, the six individual cells are averaging 2.076 volts, which is fine for a lead-acid battery on open circuit. A fully discharged battery is about 1.75 volts/cell. If you had caused an internal short in one of the cells the voltage would be about 2 volts lower. An open cell would give you zero voltage across the battery.

I suspect you may have taken a few cycles off their lifespan, but the batteries are probably fine for use. The following tests will help verify that.

1. Buy a cheap hydrometer (available at most auto parts stores) and check the specific gravity of each cell. Most deep-cycle batteries run about 1.275 on full charge. At the stated voltage I would guess you should see somewhere around 1.250. If you're really cheap, the floating-ball type of hydrometer will also work.

2. Visually inspect for the following:

a) Look at the exterior of the battery jar. A bulging or bowed wall may indicate overheating.

b) Uncap and look into the fill hole of each cell. It should look like sheets of paper and rubber sandwiched between thin plates of lead. The lead plates should be straight and even, and the separators in between should be of uniform color and shape.

Unless you see something grossly out of whack, I'd say charge both batteries (correctly this time!), watching the charging rate for any abnormal activity. Once they're charged, go fishing. The worst that will happen is that the batteries will die sooner than you expected and you'll have to use your gas engine to get back in - after all the beer is consumed, of course.

Tony

HI Don, I think that your short circuit did show that the batteries were in good condition, but I would not recomend this sort of load test.

Cheers

Joe

LOL!!

Followup: The only wires that cooked are the 18 guage jumper wires (as recommended by the battery maintainer manuf.) connecting the two batteries together. I've used the 18g wires before and they worked fine. But, I had everything else dissconnected! The maintainer is 1.0 amps. The battery maintainer wires, and the wires leading from the battery to the trolling motor foot pedal switch are OK.

Thanks

GA's to KJK and Barchetta. Thanks!

Your welcome, the important thing is you can get back to fishing soon! It might even quit raining.

A very simple way to "load test" your batteries is to connect them in the correct manner for powering the trolling motor, connect the trolling motor to the batteries in the usual manner and then run the trolling motor. If the trolling motor can be placed in a drum of water or a suitable sized tub all the better but not mandatory. Run the motor and test each battery with your volt meter (multi-meter). If each battery is around 12 volts fully charged they are OK. Much less than that and you may have fried that one.

If you don't have the container to place the trolling motor in with water don't worry, run the motor in air BUT BE SURE NOT TO GET TOO CLOSE TO THE PROP! This will also put a load on the batteries but not as much due to difference in density of water and air.

Deep cycle batteries can take a lot of abuse usually. On several occasions I have used my boat battery (sailboat so it is deep cycle) as an emergency power source for arc welding during the winter when the boat is out of the water. Not beautiful welds but it got the machine working again. Then used the same battery in my truck after the truck battery failed due to age. The deep cycle battery was then in the truck for at least 4 years. The boat always gets the newest and best battery, its my pride and joy so I have to treat it right.

Good Luck, Old Salt

Some seals need water as a lubricant and as a coolant......

NEVER RUN YOUR TROLLEROUT OF WATER UNLESS THE MANUFACTURER HAS STATED THAT IT IS A GOOD IDEA AND SAFE....OK?

Yes, I realize this. I wasn't thinking in terms of more than a minute of run time, only long enough to get a reading off the volt meter. Prudence would have the operator connect the meter and do all other prep work before starting the motor. That way run time would be a minimum, perhaps only 10 seconds or so.

For the short run time that it is necessary, a garden hose at about 1 gal/min draining onto the shaft at the seal location would be adequate.

Personally, I have a 55 gal open head drum that I use whenever running an outboard or trolling motor on land. Only problem with it is that other people want to borrow it but some don't return it until I ask for it back.

Thats exactly how I used to test a 2 stroke outboard of my Father's many years ago!!! Works really well!!

Hi Don, I would have to agree you made a mistake with the connections when charging the batteries, but I have not thought what I am about to say completely through, but after this problem you may also have problems with your on-board charging system, you may have blown the diodes in your on board charging system. To test this is, it is quite simple measure the voltage with your $20 tester, record the voltage and then start your engine that recharges the batteries, then record the voltage again.

Is the second recording higher than the first recording? is it at least about 2 volts, if so every thing should be OK, Happy Fishing.

Cheers

Joe Sparky

Sir,

It seems that the connections at battery are ok as per your normal way. However check the load side of the battery. If in the load side of battery there is some wrong connection which is providing a short circuit path between + & - Then this can occur instantly. + Terminal if short with the body could also be a condition.

Regards.

It strikes me as odd that the wiring became fusible links before blowing a fuse in one of the components.

This follows Murphy's first law of electronics that the transistor will invariably fail to save the fuse.

otha, your comment concerning a fuse is food for thought. Actually there is a re-setable link at one of the positive battery terminals and it does function. I had to re-set it a couple of times during my fishing trip when the prop got tangled in seaweed. However, the separate wires that I had connecting the batteries together for charging did not have a fuse. I guess it would be good practice to include one or more for future use. Thanks.

After finished reading these posts, I think to myself that everything is possible to happen even the small or stupid mistake. Hey, it does not mention about anybody because everybody may have same issue.

have thought about the answer after reading it but try to hold to see what is really the issue. And it is correct.

Thank you,