djoneser

I have a 2005 C6M6. Mechanically and electrically stock except for skipshift mod, burnout mod and aftermarket exhaust.

I had a battery issue a year after purchase, the battery was still original so I replaced it with a Yellow top Optima. All was fine until I got a 2nd car recently and wanting to test the mileage after tuning it up, I kinda sorta forgot to start or drive the Vette for 3 weeks. At that time, I had no battery tender.

Went to start at the 3 week mark and nothing, totally dead. 1 week later the CTEK 3300 unit I ordered showed up, and I connected it up.

2 days of charging on the normal setting and I finally saw the green light (charged up, in trickle mode) come up, but now 2 days later after more observation, I am noticing that the trickle light does not stay lit, the unit keeps switching back into charge mode.

So my question for the forum is this. Could 3 weeks without use have actually killed the battery? From seeing the charging unit alternate between charge mode and trickle mode, and not staying in trickle mode for more than 30 minutes at a time, does this indicate that the battery is unreliable now?

The car will start, but I have no desire to be stranded by an unreliable battery, so my thought is that I should just replace it if I see that the charger indicates that it will not stay in trickle mode.

I'm a slow learner sometimes I guess, I've been seeing posts on here since I joined about needing a tender, I afraid that lesson may have just cost me a battery.

Don-Vette

Sounds like the battery needs a regular charger with higher voltage for a better "full charge" condition. I would start with there.

ant21b

Take the battery out of the car and charge it to make sure it holds a charge. See if your trickle charger will charge other batteries and is not malfunctioning. If the battery doesn't hold a charge outside the car take it back to optima for a new battery. You need to load test the battery after charging it.

Bruze

If the battery has been drained down to nothing for some time, it likely will never hold much of a charge ever again.

Take it somewhere and have it load tested to verify, and be prepared to buy a new battery.

Cherokee Nation

Some one on this forum said you need a special charger for the Optima battery??

RoadkingC6

How long ago did you purchase the new Optima battery, 3 weeks of non use won't kill a battery. if you bring it up to a full charge with a full voltage battery charger and the battery doesn't hold a charge i would get my receipt and return the battery if it's still is under warranty. also check to make sure your glove box door is fully closed and the light is off that was the problem on mine once, and i do recomend keeping it on a tender when your not using the car.

AORoads

The Ctek 3300 is a battery "maintainer" and as such, it does float between charging and not charging. Therefore, if it goes green and then an hour later goes amber, there is nothing wrong with it. And there may be little wrong with your battery other than as has been said that by letting it fully discharge you've probably compromised at least a little bit of its eventual lifespan.

I think there are several different kinds of battery chargers starting with the rapid chargers, maintainers, slow chargers, and trickle chargers. I'm not sure if the last two aren't similar or the same at times depending on who's putting the label on it.

djoneser

The battery is less than 3 years old, pretty sure I have the receipt somewhere. It's the Yellow top 34/78, which has a capacity of 55Ah (afaik!). The CTEK3300 has a heavy charge mode made for a 90Ah battery, I have been using the normal charging mode listed at 50Ah.

Maybe I should be asking if anyone with this CTEK3300 battery conditioner has the same experience of the unit switching between charging and trickle mode, with an observation that it is in charge mode more often than trickle mode?

I have a voltmeter, looks like I should be able to run a load test myself. I'll add that after.

BobBass

Mine often switches from green to orange. In fact, I swear it senses when I go in the garage because I see it change modes almost every time.

djoneser

Thanks for the input everyone. My old voltmeter does not have the min/max function so a new Fluke is on the way.

ls1121

Sorry but I just don't get it with the battery stuff.

My Montero Sport sits for 5 or 6 weeks at a time and when I get in...it starts every time.

cclive

I had heard this also...AGM batteries need a different charger. Try calling Optima and ask them.

Bruze

Or send a PM to Fort Morgan Al.

He would know.

bolivar

A voltmeter cannot do a load test. You need a specialized load test meter, it will actually put a high amp load on the battery. The voltage doesn't tell you much about the battery capacity. It could show 12.6 volts, but have no power in it.

Take the battery to some shop that can do an actual load test on it.

As someone else said, if the battery has been totally discharged, it will never recharge to its 'new' condition.

FortMorganAl

A yellowtop is a deep cycle battery which means it is designed to be more like a battery used for a golf cart or trolling motor than for starting a car. With that in mind, a single discharge shouldn't hurt it as much as a single discharge hurts "normal" batteries. But it will take some life out of it.

So let's recap - you have a 2005 with skipshift (irrelevant), "burnout mod" (if that is a linelock - irrelevant), and new mufflers (irrelevant). You killed your first battery in a year but we don't really know when that was, only that you have an 10 year old car that has seen 2 batteries in its life. The first battery supposedly lasted more than 7 years and was replaced less than 3 years ago. Battery was dead after 3 weeks in the car and then sat for another week while you waited for a tender. It took 2 days for the CTEK to recharge a totally dead battery (not unusual) but it is cycling every 30 minutes.

Now for your questions - Can 3 weeks without a tender kill a battery? YES. Is this battery unreliable? Yes. It isn't so much the cycling of the charger as it is the fact that you have been abusing the battery for 3 years. That alone is going to make it unreliable. A Yellowtop is designed for deep cycling which means (ads to the contrary) that it isn't as good at starting but will take more abuse. You need a new "normal" battery. The CTEK cycling might be normal but the abuse, unfortunately, is what is killing this battery.

Can you do a load test yourself with a voltmeter? Not really. With a recording voltmeter you can use the car starter to apply a load and measure the lowest voltage during starting. That isn't a real load test but it can tell you that a battery is definitely bad. If the car starts quickly a pretty bad battery can still show OK with this kind of test. A real load test requires pulling 200-300 amps for 15 seconds or so. That is several KW and so requires a resistor capable of dissipating a lot of heat.

Do AGM batteries need a special charger. Yes but... An AGM battery has a slightly higher voltage at full charge but the CTEK is designed to provide that. The CTEK is not designed to bring back a fully discharged battery but it will do it. It just takes a lot longer.

cclive

To add to FortMorganAl, while a tender can very slowly bring a dead battery back to a full charge, it is not meant to do so. A real charger should be used to charge it up, then the tender used to keep it there.

Bruze

Unless things have changed from the old days, we only used a fast charge in an emergency type situation or when we were in a rush.

Supposedly, the slower the charge rate the better it is for the battery (and the deeper the charge will be, assuming the battery isn't shot).

But this was just information passed down from the old timers, don't know if it's true or not but it seems logical.

ant21b

You buy a centec or solar battery tester you input the cold cranking amp rating of the battery and it tests the cold cranking amperage of the battery and tells you if its good or should be replaced. You must fully charge the battery first of course. Its a small light weight tester and is the latest in battery testing. Works great it told me to replace my delco battery at 5 years old.

cclive

I didn't mean to imply a big 50 amp charger...I was thinking a 2 or 5 amp rate, neither of which is too much for a battery that size. But both of these are considerably faster than a tender that puts out 1/5 of an amp. Heat is the enemy...as long as it is charged slow enough not to generate heat in the battery..it's all good.

djoneser

OK, I cancelled the Fluke order, and looking online I will just hit up a Harbor Freight nearby and find an actual battery load tester. I see some listed for 100 amp load for under $50.

FortMorganAl: You say I have been abusing the battery, by that you mean having the battery in the wrong vehicle type? Or did you mean abuse by not having it already tendered? I had read on this forum about the yellow top as a decent choice, it seems you are indicating I was misinformed. Which Optima battery model is the "correct" one in my situation? Or do you have an alternative recommendation over Optima? Also, will the above mentioned 100 amp battery tester be worth purchasing? or do I need to find a 200+ model as you stated?

Thanks for your reply, very well stated :-)