new battery question

[MNice]

I bought a new battery at cabelas for my vex, 12 volt 7 amp. When I got home I tested it and it was up to 17 volts?? I used it yesterday for about 2 hours and it down to 16 so I didn't charge it. I am planning on waiting till it gets below 12 to charge. any thoughts??

[Sgt. Rock]

Buy yourself one of the little battery status indicators that you can hook to it and show it's charge status. Will show full, 1/2, 1/4 etc. Not voltage. I've found that I can run a long time before charging.

[MNice]

I guess I didn't phrase my question ery well. I've often read you should never overcharge a battery, yet somehow this battery is way overcharged. Will this ruin my battery, or do you think it'll be ok.

[Ed Carlson]

I suspect it will level out to 13-14V peek charge after a few uses and charges.

Draw it down to 1/2 a couple of times and charge it up as directed and it should be fine.

[Giant_Jackpot]

17 volts on one of these batteries is not normal. If you are certain your voltmeter is reading correctly, I would take the battery back and get a new one. As for the battery indicators that show % of charge, they DO measure voltage and they are notoriously inaccurate. I would go to radio shack and spend $15 to $20 on a digital voltmeter before spending the money on the “gauge”. I have posted some other battery info below that I have posted at other times out here when battery questions come up.

Here is the scoop on the Vexilar type batteries. Since I used to work for a company that made smart chargers for these types of batteries, I can say the info I am giving you is good stuff.

First of all, the batteries are sealed lead acid and just like the battery in your car, they like to be charged. Charge the battery after each use and you can get them to last 4 or more years. The worst thing you can do to a lead acid battery, is run it down and not charge it as soon as possible. Also charge the battery every month or so during the off season.

With that said the cheap chargers that come with these batteries will cook the battery and shorten its life if you leave charger on the battery for extended periods. The advice someone was giving Ebass about leaving the charger on the battery for 3 days is poor advice (unless the charger is a smart charger). If you really want to take care of the battery, connect a voltmeter to the battery during charging. When the battery reaches about 14.8 volts disconnect the charger. Otherwise don’t leave the charger connected for more than 24 hours.

The smart chargers are a good idea if they are doing the right thing. They should charge the battery to about 14.8 volts and then drop into a maintenance or float mode at about 13.2 volts. The next time I am at Gander I will check one of the Marcum chargers out and see if it is really a good thing.

As far as the LED battery indicators go, don’t believe everything you see. The components used in an inexpensive device like this can have tolerance swings of up to 20%. On a properly charged battery, one indicator may read fully charged while another might say ¾. Just something to keep in mind.

Let me know if you have any other questions.........

[BradB]

Good stuff, Giant_Jackpot! I appreciate your advice. I've been using a Battery MINDer on my larger deep cycle batteries for the past few years, with good results. Is this the kind of smart charger you are writing about? I just leave them on all the time when I am not using the batteries.

Having burned out a couple of the "cheap" chargers over the past several years, I bought a Vector 2/10/20/35 Amp Smart Charger . I use this to bring the batteries up to charge after use, and then if I'm not going to use them I put them on the Battery Minder on wood blocks in the basement.

[sorry, I had to remove the unauthorized links. M-H]

[Giant_Jackpot]

Brad,

Do you use the Battery Mindr for just your small Vexilar 12 volt batteries or your big boat batteries too? The reason I ask is that although the info on their web site looks good, I have a hard time believing that a 1 amp charger could charge a big deep cycle battery within a reasonable time period. I do like the idea of one of these for the smaller batteries though. Having a charger that goes into a float mode will extend the life of a battery. That de-sulfating part sounds a bit like snake oil to me but I can’t say that it doesn’t work either.

Bottom line is that my opinion is they are good for the Vex battery but I would use a bigger “on board” style charger for the big batteries. There are a lot of the chargers for the big batteries that do the float thing as well.