Can a battery maintainer ruin your battery? (Page 2/4)
theogre MAY 31, 06:21 PM
I use the Battery Tender when I can't drive more then a week but don't keep it on everyday even then.

ECM and other things will kill the battery because slow drain to backup memory etc. Fiero and others means max out @ 35ma, often less, but that's enough if left for 2 to several weeks.

Newer models use AGM Batteries and bigger ones at that as stock units because has More things sucking power when vehicle is Off.
Not just those w/ crap stop/start almost every time you idle.

"Cheap" batteries won't help here.
While many hate Wmart... Max batteries w/ 3yr replacement warranty is often cheaper then cheap ones sold by AZ and most others. If dies, If/when you loose a receipt goes date made and w/o headaches. I've been using Max batteries for decades now and lifetime typically > 5-7 years and only need warranty 1 time. But this area doesn't get very hot or cold weather very often either. Upstate NY an more can see 90° to well below 0°F and everyone often gets shorter battery life because of that alone.

Note: For newer vehicle w/ OEM AGM or normal batteries... If replace even w/ same type may need a Pro "Scanner" to "reset" the PCM/BCM. Otherwise the replacement battery may not charge right.
armos MAY 31, 08:00 PM
I've never used a battery maintainer, but conceptually, I see no reason they shouldn't maintain the battery just as well as the alternator does.
Sounds like they just aren't well made.

[This message has been edited by armos (edited 05-31-2023).]

sleek fiero MAY 31, 08:13 PM
A quality battery maintainer will maintain and extend battery life if used correctly. Don't leave on indefinitely or put it on if you are using your car regularly. Room temp is best, don't leave out all winter.they are smart but you need to be smart as well. Batteries will gradually discharge over time even if they are disconnected. sleek
Patrick MAY 31, 08:26 PM

quote
Originally posted by sjmaye:

I have had pretty good results with a cut off.





I've had one on my '84 Fiero and on my Subie for years, but just within the last month I think they've contributed to some weak battery issues with both cars. I suspect because of the added contact surfaces involved, corrosion was eventually able to cause poor continuity between parts of both switches. Perhaps some preventative maintenance with some dielectric grease would've prevented any issues, but it's something to keep in mind if using one of these switches.

If you've never taken one apart, this video found online shows how they work (and where potentially bad contacts can arise).
sleek fiero MAY 31, 08:45 PM
Hi Patrick;
I tried to get i contact with you when I was in Vancouver 2 weeks ago. If you want a really good disconnect get a marine disconnect switch and mount it away from the battery so battery fumes don't contaminate it. They usually are for duel batteries but will still work for one and are a proper switch for high amperage starter use.
Patrick MAY 31, 09:19 PM

quote
Originally posted by sleek fiero:

I tried to get i contact with you when I was in Vancouver 2 weeks ago.



PM sent.
theogre MAY 31, 09:28 PM

quote
Originally posted by Patrick:


I've had one on my '84 Fiero and on my Subie for years, but just within the last month I think they've contributed to some weak battery issues with both cars. I suspect because of the added contact surfaces involved, corrosion was eventually able to cause poor continuity between parts of both switches. Perhaps some preventative maintenance with some dielectric grease would've prevented any issues, but it's something to keep in mind if using one of these switches.

Big problem is most are made of Zinc and other cheap metals and "rust" or even break. And includes many sold by car parts stores so not just Amacon or Eflay problem.

Same problem happens to "Switch type" discon's that "look like" ones made for race op's that often have Cert's saying made for the job.

Jeggs and other make real brass parts costing ~ $30 that won't rust or break easy but in Fiero w/ wet location for the battery likely still need Dielectric or Permatex Green Brake Grease to keep out road "water," washing the car, etc.

I coat most ends bolted/screwed to engine etc w/ PBG for same reason including battery cable ends.
Patrick MAY 31, 09:41 PM

quote
Originally posted by theogre:

...in Fiero w/ wet location for the battery likely still need Dielectric or Permatex Green Brake Grease to keep out road "water," washing the car, etc.

I coat most ends bolted/screwed to engine etc w/ PBG for same reason including battery cable ends.



Whenever I remove a bolt on my cars, I apply a bit of anti-seize to the threads before re-assembly... and every time I disconnect an electrical connection on my cars, I apply a bit of dielectric grease before plugging it back together... but did I apply anything on the connections of my battery cutoff switches? No. I'm not sure what happened there!
sjmaye JUN 01, 04:07 AM
the cutoff I am using is an el-cheapo from Amazon. They work, but the problem I have with them is when loosening the knob to disconnect the battery it is sort of hit or miss. see photo. In theory, as you loosen the knob the contact plates separate and remain parallel to each other negating the need to fully remove the knob to disconnect the battery. In practice, the contact plates do not remain parallel requiring me to remove the knob fully as the only way to be sure the battery is disconnected.


That aside, I agree use of disconnects do work well.
theogre JUN 01, 10:48 AM

quote
Originally posted by sjmaye:
In practice, the contact plates do not remain parallel requiring me to remove the knob fully as the only way to be sure the battery is disconnected.

Another reason to buy good ones...

Cheap ones can to that and worse because the "ears" won't hold the half sections. Now it is loose and moves but can fail and battery side gets expose so easy to short the battery that dumps 100a or more.