Any battery knowledge to share here?

Can battery tenders do more harm than good? Like, the cheap $5.99 ones from Harbor Freight?

I had all my batteries on these tenders (DieHard, Exide and NAPA, plus two 'vintage style' yellow-caps) this winter. They were inside my basement workshop, vented to the outside. Just for my own info, I checked voltage randomly over the months (typically 13.70 - 13.99V), and occasionally took them off the tenders for a week to see how the voltage would stabilize (typically 12.50 to 12.80v).

In middle of March, I noticed two of the 'no-maintenance' types wept some battery acid out of their top lids.

I cleaned it up, then:

- I took one of these off the tender and let it sit. It held 12.66v. I stuck it back in its car, fired up and it seems to work fine.

- I left the other one on the tender and used it in the 67 Satellite yesterday... It measured a healthy 12.56V when taken off the tender. I stuck it in the Satellite and it cranked poorly with no start. That's not usual for this battery.

So I shot some starter gas in the carb, then it fired. It ran well and the D/C gauge showed a good charge, so I took it for an hour drive. I stopped to enjoy the view. Went back to the car.. again it cranked poorly on start-up and then died. So I had to get a jump from a friendly passersby. Then it fired. I looked but didn't really notice any more acid weeping out of the top.

Again, the D/C gauge showed a good charge that stabilized and I drove it an hour back. I parked the car in my storage garage, took the offending Exide no-maintenance battery out and brought it home. Left it on my bench. This morning it measures a healthy 12.75V.

I'll take it to the Satellite and see how it cranks this morning, but in the meantime, -

- any advice as to what's going on with the no-maint batteries?

I didn't think they'd weep anything out the top, that seems like a bad thing.

Maybe this, or both batteries have reached its service life?
Did the constant low-amp 13.9 charge cook off some battery acid?

I just don't want to harm my batteries.

Thanks,
- Art

The cheap “trickle chargers” are junk, and are nothing more than a step down transformer and a diode...they will cook your battery.

You need to buy a “smart charger” that has electronics that know when to just maintain a charge by just floating at a very, very low current. Those will not “cook” your battery by overcharging it.

Battery Tender or a Marine Pro Charger are the ones I would buy. They start at about 30.00 and go up fo 200.00

Mark

I've had my green top resto battery on a tender in the garage(continuously) since the fall of 2015. I haven't taken the car out since then. A few weeks ago I noticed one of my outlets was dead. I traced it back to the GFI outlet the tender was plugged into. I reset the GFI and plugged the tender back in. It didn't light up like normal. Either the tender crapped out or the battery did. I haven't checked the battery to see if it has a charge any more.

Thanks Mark,



I hate that.

I'll head out to check the cranking power of this battery now..
- Art

I agree that the cheap ones are junk, but there is another thing to think about.Different types of batteries have what I was told by a battery manufacture guy, is that different batteries have different full charge voltages, and that some tenders don't charge that high, and they will never cut off. Say type A battery has a charge voltage of 14 volts, and the tender only goes to 13.5, it will never see a full charge, and never shut off.

Just because the battery shows say 12.6 volts dosent mean its good.had some at work that showed great but were junk.Oh yeah the one inmy 65 last year started it like a champ.went to local cruise went to start and nothing pretty much.Jumped and alt charging.Coming home had to keep revs up so MSD would fire right.Next day charged it checked it and over 13 volts.Turn lights on and went to 2 volts.We have tenders on the harleys.Mine is at least 20 years old.Always has battery charged as does my sons.Mine is a Harley one.Also charge the tractor batterys some in winter.Rocky

Do a load test on the battery.

Thanks for the insights guys, it's an evolving lesson. A battery's voltage can be fine, but if the amps aren't there - that's a problem. So yeah - just cuz it reads 12v+ won't automatically mean it's good.



Yeah, I was going to have this done at our local AutoZone if things went badly today - but it cranked over and fired just fine.. so not clear what happened yesterday - but I'll keep jumper cables close by, and discontinue the use of the crappy tenders, that's for sure.

Last year I had only two tenders, so I took the 5 batteries out of the cars , brought them inside, and rotated the tenders to different batteries every month roughly. At the end, I put them on a 2amp charger for an hour. They all worked normally.

Cheers,
- Art

my car batteries have lasted this long, not gonna start now, once every few months i go and charge up my batteries to freshen them up...heard stories of fires, burning out the wall sockets to drawing more electric per month for those on a fixed budget...just saying..

I have used multiple Battery Tenders for many years with good success..
Except last year I went out into the garage and was surprised to find 1 of the Battery Tenders was super hot... A closer examination showed that it had an internal short and its bottom case had actually come apart due to its extreme heat exposing all of its internal components and transformer.
I called Battery Tender to report the problem since it had a 5 year warranty and they asked me to send them some photos of the defective Battery Tender. I did and they responded they have never seen a unit having this type of defect???

Anyway they sent me a new replacement Battery Tender which I never used and gave to my son. After having the original Battery Tender shorting out I discontinued using any Battery Tender. Funny about 2 weeks later, Battery Tender contacted me and requested I return the defective for their inspection and failure mode analysis... However I had already threw the defective unit in the trash..

So in the end I would caution anyone using a Battery Tender to check it occasionally for overheating as to avoid a possible fire.

Just my $0.02...

I never trust them. I just disconnect my car batteries not in use for the winter & ocassionally fire them up throughout the odd seasons. Any of my cordless drills etc. I always unplug when I am not out in the garage. I have heard & read too many horror stories about them either over charging & causing fires or shorting out & causing fires.

IMO this is a better charger, safer and better for your battery's.
LINK to battery minders.

I use one of these every 1-2 months for 48 hours.

Once its 100% LED lights the power consumption drops to 2 watts as measured by a Kilo-A-Watt power meter on the 120 volt outlet. At this low level it should not be overcharging a 12v lead acid battery.

https://www.pulsetech.net/xc100-p-xtreme-charge-12v-battery-maintenance-charger-desulfator.html/

I have thought about buying one of these
to check the health of the battery “guts”
beyond what my MAC 130 amp load tester can do:

https://www.amazon.com/Associated-Equipm...uct_top?ie=UTF8

While your talking about batteries, I have a fairly new marine deep cycle battery that won`t go above 75% charged. I assume the plates are sulfated. Any way to get it back or is toast? I used my good optima charger on it and still won`t go above 75%. I thought the trickle charger would of helped it through the winter but I guess not.

look at the battery minders, my link above^^^

Bingo...

All my batteries go in the basement when not in use...


When needed, a little time on the charger, then back in the 'tray'...

If a pulse type charger will not bring a marine battery to full charge,
find the bad cell(s) with one of these:

https://www.amazon.com/East-Penn-Manu-Ba...9H2RG54DRMZYEJW

Then use an ounce of this:

https://www.batterystuff.com/battery-restoration/fluid/BE12oz.html

Just in the one bad cell.

Hook the battery back up to the pulse charger for 2-5 days.

This is kinda “last ditch” first aid for a wet 12v battery but more than half the time will extend the working life.

Thanks, will give it a try.

A few years ago I asked my automotive battery supplier about which kind of battery charger was best to use. They said they only sell one battery charger and this is it. I have used it long term(3-4 months at a time) with no problems. FWIW Smart charger.


From hanging around airplanes I learned about battery minders...but I use this new to me 28 volt power supply to test and maintain the battery in this cessna. It provides plenty of amps to test lights and radios without the engine running.
Going flying tonight in a about an hour.

I have owned and used 2 different load testers like you show above, neither was worth a sh!t because they really can't put the correct load on a battery. I have used my hand held load testers and all three batterys show good. But in the truck you can tell something is wrong. I take them out and to the battery supplier and they test them with a real load tester and find one bad. Waste of money the hand held ones IMO.
You are just as good to put a volt meter on your battery and have someone crank the engine and watch the voltage.

This is still the only real way to load test your battery. The battery store has one and they test every battery I replace in my truck fleet. My trucks have 3 batterys each and I buy my far share of battery's.
LINK