Cen-Tech battery charger -Harbor Freight

[mmcmdl]

I blew my old time charger up 2 years back and ended up with a Schumaker (sp) jump box from TSC . This has jumped everything so far , other than me . I think my internal battery is shot .

 

[arvidj]

I've always assumed the "does not know a battery is there" was one end of the spectrum of smarts my chargers have with the other end of the spectrum being "turn off or at least way down when charged so you don't cook the battery dry".

Of course a product designer who actually used his device might have added a 'push this button to get a completely dead battery off the ground' but they probably never actually use their pruducts in real life situations. The test lab batteries alway have enough of a charge to get things started so real situations are never tested.

Sorry, got a little carried away with the sarcasm

 

[projectnut]

We had a similar problem with the coach batteries in our motorhome a couple years ago. In our case we were on the road in Alaska when the onboard charger decided it was time to give it up. The batteries probably weren't quite as bad as the ones in your travel trailer, but they were far to weak to even turn on the LED lights.

I went online to the NAPA Auto Parts website and found this battery charger:

https://www.napaonline.com/en/p/SORPL2320C?partTypeName=Battery+Charger&keywordInput=battery+charger

It isn't the cheapest in the world, but it's in a different league than the Harbor Freight ones I have at home. It's now become my go to charger for everything from a garden tractor to the motorhome. I've even used it on my end loader that hadn't moved in nearly a year. The battery was so dead it wouldn't light up a 1157 bulb, but the charger detected it and was able to charge it.

I do have an older Schumacher commercial 2/40/200 charger/starter in the garage. It's been a good machine, but even it doesn't compare to the new Pro Logix one for charging a dead or nearly dead battery. It's the old style bulk charger with no capacity for multistage charging. I keep telling myself it's time to dump the old Harbor Freight models that barely worked when they were new.

 

[RJSakowski]

I left a circuit on in my boat last summer and when I discovered it, the deep cycle battery was dead flat. I managed to put somewhat of a charge on it but it never recovered. Over the winter, it went flat again, presumably die to an internal short, and froze. Dead meat!

 

[markba633csi]

Some cordless tool chargers won't charge a totally flat battery either, what a goofy feature
-Mark

 

[Janderso]

I took the battery to work this morning. I hooked it up to our smart charger. It's a Midtronics product. they run about $1,300.
Watching it go through the diagnostics and watching the display was interesting.
It started out at 1.7 volts DC. That was after a 12 hour charge with my 2 amp charger.
It's so dead it needs a jolt but it's a deep cycle type marine battery.
This charger started a 2 hour charge. The initial ramp was 12 volts at 5 amps. As you watch the screen the amps came up by tenths every minute or so. It stopped at 59.1 amps and 15.6 volts. This was after about 35 minutes. The battery was very warm to the touch. I let this go a bit more then moved it to a 12v slow charger.
I now have 12.6 volts after it sits for half an hour.
I think it will be OK.
I don't think the other battery will charge driving down the highway. I might just leave it home or disconnected until I can get a proper charge on it.
I'm curious what my new Cen-Tech does when I test it tonight when I get home?
At least I will see if it works.

 

[Janderso]

The charger worked as designed.
You guys are right. If the battery is really dead there will be no output, no red light, nothing.
I connected the fresh charge with the stone dead battery. The charger came alive.
I put a ten amp charge for an hour then separated the two.
Now I have 12 volts on the second battery.
I’ll charge it by itself for a couple hours now.
Done!
Revived.
I need to make sure to disconnect the battery circuit when I store it.

 

[DavidR8]

Batteries are a deep topic.
When I owned a sailboat I did extensive research into DC charging systems.
A fully charged 12v battery will read about 12.9v and about 11.9v when fully discharged.

Anything less than approximately 12.4v leads to sulfatation which is the death knell for lead-acid batteries. If a lead-acid battery is left in a discharged state for long periods they cannot be revived to have anything close to original amp-hour capacity.

I recommend getting a solar trickle charger to maintain charge when the RV is not in regular use. Put it in a south facing window and connect it to the batteries as directly as possible.


Sent from my iPhone using Tapatalk

 

[Janderso]

Good idea David. I have hesitated because I thought it would get stolen. I never thought of putting it inside.
Wont the tinted windows cut the UV’s?

 

[Flyinfool]

The windows will cut the output a bit, but it will still work.
I have had a small solar panel on my RV and the battery is now 15 years old and going strong.
I put my panel up on the roof, Not attached just toss it up there right above the entry door. Just inside the door is a 12V outlet that I plug it in to.
Just remember to take the panel off the roof BEFORE you start driving,

Be careful trying to charge a really dead battery while driving. As you noticed it got hot and was pulling in 56 amps, That is a lot of load for a long time on the tow vehicle alternator and has a danger from an overheated battery. I have seen alternators have a short service life when doing a lot of heavy charging.