Another dead battery

[patrickh]

I have a 24V troll motor. Two 12s in series. I always thought that you should drain batts down as much as possible before recharging so I dont charge everytime I bring boat back. Battery memory or something. I have a 12V charger that I put on 2amp setting with deep cycle setting as well. I charge both batteries for about the same amount of time each. I charge each individually but while hooked up to the other. Is this wrong? I have replaced one battery twice already and went to charge it yesterday and it would not take a charge again. Same battery every time. What am I doing wrong?

 

[LubeDude]

Re: Another dead battery

After thinking about this for awhile, the only things I can see that you are doing wrong is not keeping them charged all the time and charging them everytime you get home, and not charging them with an adaquate charger. I originally posted that you had to disconnect them, but you shouldnt have to. The memory issue is a MYTH. Also, you really should use batteries that are of the same type, quality and age. Every time you turn your trolling motor on your batteries become one and they will try and equal out, The good battery sucking from the bad or week one, even in a 24 volt situation.

 

[Drowned Rat]

Re: Another dead battery

I agree with LubeDude. Recharge your batts. everytime, even if you only use them for a short time. You never want to let the batts get below 50% charge or about 10 volts. About charging them individually, but while they're hooked to one another. Why are you doing this? Are the batts. still in the boat when you charge them? Do you have anything hooked up to them when you charge them? They really should be disconnected from each other when charging. It's true there's no way for the batts, tied in series, to equalize if their is no load applied, but I don't think it's good for the battery that's not being charged to be hooked up, especially when you're charging the batt that has the wire going to the positive terminal.

 

[LubeDude]

Re: Another dead battery

When I first posted, I said the same thing about the batteries being hooked together, but I thought about it and decided there could be nothing going to the other battery with just the one wire. Might be a good Idea to disconnect just to be sure.

 

[Boatist]

Re: Another dead battery

PatRickH<br />I agree with everyone, charge your batteries as soon as you get home with the boat. If you allow a deep cycle battery to discharge more than 50 percent it will do damage. If it a starting battery then will be dammaged by discharging below 80 percent. 50 percent of charge is not 6 volts but more like 12.4 volts at 70 degrees.<br /><br />I also think you need a bigger battery charger. I would get a 10 amp automatic charger that will taper to zero as the battery charges. Even with a 10 amp automatic charger it will take near 24 hours to fully charge a group 27 deep cycle. You can leave your batteries connected while charging but must be carfull to hook the charger up right. Connect your charger to the plus and minus posts of each battery and fully charge.<br /><br />You also could buy a 24 volt automatic charger for your boat and charge both batteries at once.<br /><br />Your batteries can be damage by charging too little or by over charging that why I strongly reccommend a good automatic charger that knows when to shut off.<br /><br />Charge your batteries at least once a month weather you use them or not. All batteries self diacharge and sulfate if not at least once a month. They discharge faster in hot weather than cold.<br /><br />Batteries in serries should be same size, capacity and condition.<br /><br />Here is a link that I think was better before they expanded it so much. Still good infomation if you have the time to dig it out.<br /><br /> http://www.uuhome.de/william.darden/carfaq.htm

 

[raymondmoyer]

Re: Another dead battery

Battery memory isn't a myth. It's just dealing with a different kind of batteries than what we use. The memory occurs in NIckel CADmium batteries, not lead acid or gel cell batteries like used in cars and boats. I agree with everyone else recharge them suckers as soon as you get home.

 

[rickdb1boat]

Re: Another dead battery

As Lubedude said, The moral of the story, is never let your batteries discharge ALL the way, before re-charging them. And there is no reason to disconnect them when charging. They will last a long time if properly cared for...<br /><br />Boatist, never heard this one:

They discharge faster in hot weather than cold.<br />

Could you elaborate? Curious why...

 

[18rabbit]

Re: Another dead battery

The memory occurs in NIckel CADmium batteries...

The “myth” is that NiCad’s have memory. They don’t.

 

[patrickh]

Re: Another dead battery

Thanks everybody. All good info. I will charge early, charge often. Also, I have always wanted to get an automatic charger that stays in the boat. Hard mount and waterproof/resistant. Any recommendations?

 

[kd6nem]

Re: Another dead battery

18Rabbit,<br />Are you saying that all NiCd's do not have a memory? I understand that is hardly ever a problem any more, but did this not used to be true especially with cheaper NiCd batteries? I've found some very credible technical publications which agree they've improved tremendously but would deny that this was mere myth for this battery type. I'm interested to hear why you say this. Have we all been wrong all this time? Or is this just a phenomenon of the past?<br /><br />You work in electronics? I have noticed that you seem to have a very good grasp of electrical/radio. I play fairly seriously with it, but you sound like maybe you do it for a living?<br /><br />RB, I'll take a very shallow SWAG at the discharge issue- warmer temps increase the speed of chemical reaction, so discharge is accellerated. True of flashlight batteries, too. Some folks store their household dry cells in the freezer to make them last longer. I have no idea how effective it really is, but it makes sense in principle. NiCd's, by the way, don't have big a problem working in very cold temps, unlike many other kinds.

 

[Paul Moir]

Re: Another dead battery

Bearcat - More than you ever wanted to know about NICADS. <br /><br />You might want to look around the www.repairfaq.org site a bit.

 

[kd6nem]

Re: Another dead battery

Paul, most interesting. <br />I am still scratching my head at the disparity between some of the equally technical(or nearly so) articles I've read in the past. I realized that charging rate was an issue, and used to do the old charged capacitor across the battery trick to kill the dendrites. Much of the conventional wisdom I subscribed to has served well. Gonna have to rethink this a bit, although I don't have many NiCd's around these days, except maybe in power tools.<br />Again, sorry for the hijack.

 

[18rabbit]

Re: Another dead battery

Bearcat, the short answer is ‘yes’. Or maybe you are just the last to know. <br /><br />What happens is a reverse of the charge state of one of the 1.2v cells. This can happen when all the cells in a battery pack are below .8v and one cell tries to go below 0v. It does not necessarily cause permanent damage, but until corrected the performance of the battery pack is tanked. Not so much a memory* problem as a bi-polar personality issue. <br /><br />NiCad’s suffered from a physical breakdown by overcharging. This is due to the heat generated by charging beyond 100% capacity. The electrolyte ‘cooks off’ as it were, venting from the battery. The result is an un-recoverable loss of capacity.<br /><br />There is a unique voltage spike that occurs with NiCads just as they are reaching their full charge state. Newer chargers sense that voltage ‘flash’ and shut down to a trickle charge to prevent overheating the cells.<br /><br />Btw, you are correct about the temp’s affect on the physical properties of a bat’s chemistry. A higher quality charger will sense the bats temp and adjust voltage accordingly. Fwiw, NiCads just have a lower temp threshold. Never freeze any battery.<br /><br />Refrigeration does nothing to preserve the life of an alkaline battery. Unless performing electro-message therapy on a head of lettuce, bats don’t need to be in the refrigerator. Another myth…probably started by a lonely head of lettuce. <br /><br />* Technically, NiCads have exhibited something called a memory. It is still a phenomenon that only occurred with very precise, systematic charge/discharge cycles when used on orbiting satellites with solar chargers in the early 60’s. Any change in the charge/discharge cycle immediate corrects the memory symptoms. The ability to recreate the memory effect is very rarely achieved under the best laboratory environment, and never seen with use by people.

 

[18rabbit]

Re: Another dead battery

Never mind. Paul's link is better.

 

[Boatist]

Re: Another dead battery

RB<br />Almost any chemical reaction is accelerated as temperatures rise. Reaction is slowed as temperatures get colder. This is true of lead acid batteries for sure. At the same time voltage will rise as temperature rises. A cold battery will supply less voltage and current. By everything I have read self discharge and sulfation increase as temperation rises. Biggest killer of batteries is people with unregulated dumb chargers and self discharge/sulfation from not keeping the battery charge. <br /><br />Many sites on the net about batteries problems. I will post one at the end and look at least 13 and 13.2. <br /><br />I have been very lucky with batteries on my boat as never had a battery that did not last 6 years. On the boat I carry two batteries, one starting battery used to run everything needed to run the boat.<br />Starter, Ingition, Navigation lights, Bildge Blower, Horn, Wiper, Compass and dash lights, Trim motors, and Bildge pump. <br /><br />Second a deep cycle used for all the rest. VHF Radio, Loran C, Gps, Depth Finder, Lighter outlets, VHF handheld charger, ect.<br /><br />Both batteries are charged with a 35 amp alternator on a 140hp I/O thru a battery isolator.<br /><br />Still when I get home with the boat first thing I do is hook up the charger at my charger connection at the front of the boat. Often when pulling boat have left on the radios, Loran C, GPS, depth finder ect. After hooking up the 10 amp automatic charger shared by both batteries we unload the boat. By the time we get every thing unloaded both batteries are charged up but usually leave it on until get fish cleaned also.<br /><br />My boat in stored in the summer sun with a Sunbrella cover and in the afternoon temperature offten reaches 140 degrees inside but I will never charge the batties when that hot.<br /><br />Here is one site, read 13 and 13.2<br /><br /> http://www.uuhome.de/william.darden/carfaq.htm

 

[TELMANMN]

Re: Another dead battery

I too got tired of dead batteries, especially after sitting over the winter even though I would recharge monthly. <br /> I have been using a battery minder this winter and it appears to work great. I have used a couple of the batteries for ice fishing and they seem to be better than ever.<br /> Go to http://www.vdcelectronics.com/about.htm for info. about battery charging, sulfation etc.

 

[rickdb1boat]

Re: Another dead battery

Thanks for the info Boatist! Good link, too!