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Re: Battery Tender Jr

Posted: Tue Oct 31, 2017 4:20 pm
by brotherjethro
It sounds like you're trying to use your Battery Tender while you're also charging the car. I wouldn't recommend that, because the built-in 12v converter is also trying to output 13-14 volts at that time. If your battery tender is showing strange light patterns, it's probably a sign that it knows something odd is happening.

(BTW, you didn't mention which model you have, but the Jr only has one light and can't show both red and green at the same time)

Re: Battery Tender Jr

Posted: Tue Oct 31, 2017 4:44 pm
by LeftieBiker
It sounds like you're trying to use your Battery Tender while you're also charging the car. I wouldn't recommend that, because the built-in 12v converter is also trying to output 13-14 volts at that time.
I do this all the time, and it works fine.

Re: Battery Tender Jr

Posted: Tue Oct 31, 2017 5:25 pm
by brotherjethro
LeftieBiker wrote:
It sounds like you're trying to use your Battery Tender while you're also charging the car. I wouldn't recommend that, because the built-in 12v converter is also trying to output 13-14 volts at that time.
I do this all the time, and it works fine.
Interesting. What does it do? Does the Battery Tender finish all of its phases while the car is still charging?

Re: Battery Tender Jr

Posted: Tue Oct 31, 2017 8:59 pm
by LeftieBiker
Interesting. What does it do? Does the Battery Tender finish all of its phases while the car is still charging?
Yes. Mine is hardwired to an SAE connector through the charge port compartment, but I believe it will act normally even if clipped on.

Re: Battery Tender Jr

Posted: Wed Nov 01, 2017 5:33 am
by jjeff
brotherjethro wrote:It sounds like you're trying to use your Battery Tender while you're also charging the car. I wouldn't recommend that, because the built-in 12v converter is also trying to output 13-14 volts at that time. If your battery tender is showing strange light patterns, it's probably a sign that it knows something odd is happening.

(BTW, you didn't mention which model you have, but the Jr only has one light and can't show both red and green at the same time)
Yes my model of Battery Tender after charging is complete, desulphaphies?? the battery. I believe a red LED means it's hooked to the battery, a solid green LED means it's charging and a flashing LED means it's in the de-sulification mode, where it will stay until unplugged. What I don't know is once it's in the de-sulfication mode(flashing green LED) if the battery gets low will it start charging again......I know once the green LED flashes, the only way to get it to stop is to power cycle the Battery Tender, even if disconnected from the battery it will still flash, until unplugged.

Re: Battery Tender Jr

Posted: Wed Nov 01, 2017 6:08 am
by LeftieBiker
Yes my model of Battery Tender after charging is complete, desulphaphies?? the battery. I believe a red LED means it's hooked to the battery, a solid green LED means it's charging and a flashing LED means it's in the de-sulification mode, where it will stay until unplugged.
Maybe there's a newer model that does this, but for most BTJs the solid red light means bulk charging at full power, the flashing green means it's in finish charging mode at reduced power*, and then it goes solid green when the battery is full charged, and stays there.

* Maybe the flashing green means a de-sulfating mode, because 0.75 amps isn't that much, but since these are designed for small batteries as well as larger ones, I think that this mode is to keep small motorcycle-sized batteries from charging too quickly from 90% to 100%.

Re: Battery Tender Jr

Posted: Wed Nov 01, 2017 6:43 am
by brotherjethro
jjeff wrote:What I don't know is once it's in the de-sulfication mode(flashing green LED) if the battery gets low will it start charging again......I know once the green LED flashes, the only way to get it to stop is to power cycle the Battery Tender, even if disconnected from the battery it will still flash, until unplugged.
Yes, the BTJ monitors the battery voltage in both green modes (solid & flashing) and will switch back to bulk charge "solid red" mode and start over if needed. You can see this happen by turning on the headlights while in either green mode.

Re: Battery Tender Jr

Posted: Wed Nov 01, 2017 6:47 am
by brotherjethro
LeftieBiker wrote:
Interesting. What does it do? Does the Battery Tender finish all of its phases while the car is still charging?
Yes. Mine is hardwired to an SAE connector through the charge port compartment, but I believe it will act normally even if clipped on.
Good to know! I've been curious, but didn't want to try it.

(And mine is wired the same way, LOL).

Re: Battery Tender Jr

Posted: Wed Nov 01, 2017 8:42 am
by ebeighe
LeftieBiker wrote:12.8 volts isn't really "quite full." I've never had a BT JR fail, and I have several of them. Give it a bit longer.
BrockWI wrote:Yup, your battery was likely just that low. I can't remember if the newer ones time out after 24 hours or not, but it wouldn't surprise me if it took more than 12 hours to get he battery back to full.
yes, as you predicted... just needed several more hours. all good.

Re: Battery Tender Jr

Posted: Wed Nov 01, 2017 12:36 pm
by RegGuheert
jjeff wrote:...de-sulphfying?
jjeff wrote:...desulphaphies??
Jeff wrote:...de-sulification mode,..
I love these! :D

Yes, it's a weird word. Briefly, lead sulfate forms as a white paste when a lead-acid battery discharges. When the battery is recharged, the lead sulfate is separated back into metallic lead and sulfuric acid. If the battery stays partially discharged for some amount of time (depending on temperature, etc.), some of the lead sulfate converts from the paste form into a crystal. Once the lead sulfate crystallizes, it is not as easily split back into metallic lead and sulfuric acid. In other words, it ties up both electrolyte and lead that originally was available in the charge-discharge reactions of the battery, thus reducing the capacity. Desulfating chargers typically use either higher voltages or pulses or both to try to break up the lead sulfate crystals to restore some or all of the original capacity of the battery. This typically takes more than one recharge cycle, but the battery can eventually come back close to like-new condition if such chargers are used consistently (and electrolyte levels are maintained).

So...

...desulfating.

...desulfates.

...desulfation.