Safe to do pulse repair without disconnecting battery?

[DavidOfMA]

I tried a pulse repair on my five-year-old car battery and, to my surprise, the first pass brought the battery health from 74% to 84% and a second pass a few days later brought it up to 90%. Because I use the car infrequently, I'd like to use this on a regular basis.

I'd prefer not to disconnect the battery and have to re-program the radio, clock, audio settings, etc. The charger's manual doesn't say I need to disconnect it, but opinions on an Internet search were mixed. I'd appreciate hearing from people here who have tried a pulse repair with the battery still connected.

Thanks!

 

[Rand]

I'd reply on the instructions more than internet noise.

 

[DavidOfMA]

The instructions, which are minimal, don't say one way or the other. I'm here because I'm looking for someone who has actually tried it.

 

[eljefino]

Depends on the charger, depends on the voltage, depends on the health of your battery.

If your battery is supposed to absorb the pulses a certain way, but is too aged to allow this, those pulses are going into everything else electronic in your car.

I look at it like disconnecting the battery when running to "test" the alternator. Yes, anecdotally, someone got away with it, but it's not a good idea.

 

[f355spider]

I imagine it depends on the car...I run Battery Minder and Granite Digital "Save a Battery" battery tenders with various battery desulfation modes that send pulses and are connected to my cars all the time for the past four or more years without issue. I have bluetooth battery monitor on one of my cars that tracks a 15 day charging history by voltage and I can see the pulses in the graph. List of cars in my signature line.

But the lack of instructions with the device you are using is a bit disconcerting. I would call or email them.

 

[barryh]

It depends on what voltage the charger produces in desulfation mode. The handbook for my car stipulates that the battery must be disconnected if the charging voltage is to exceed 14.8 volts So that's what I would take notice of, not the battery charger instructions.

 

[Astro14]

Safe? I doubt it.

Can you get away with it? Probably.

I would not leave my battery connected, though. Why risk it?

 

[kschachn]

Safe? I doubt it.

Can you get away with it? Probably.

I would not leave my battery connected, though. Why risk it?

Exactly.

 

[SubLGT]

Depends on the charger. Some, like the Optimate, can pulse at 22V. In which case I would disconnect the battery.

 

[berniedd]

I would disconnect the battery. High voltage pulsed spikes from the desulfator-charger can damage electronics. Left connected to the car electronics, a shunting effect might occur on the pulses and decrease their intended effect. In other words, if you disconnect a battery cable the pulses will be applied only to the battery and nothing else, probably enhancing their effects.

 

[DavidOfMA]

Thanks, everyone, for your input. I'll play it safe and leave it disconnected when I do a pulse repair charge.

 

[Carmudgeon]

FWIW, the manual for my CTEK says it pulses at 15.8V during the first desulphation stage, which never lasts more than a few seconds on a normal battery, but can go up to 8h, depending on mode, and condition.

In normal use, with a battery in ok condition, the first mode only lasts for a few seconds before moving on the next stage.

Under any other condition, like purposely trying to "repair" a battery, I'd disconnect.

 

[Nesterenko]

Thanks, everyone, for your input. I'll play it safe and leave it disconnected when I do a pulse repair charge.

Agreed, too risky .

 

[DavidOfMA]

I am impressed by the ability of pulse repair mode to desulphate. After two cycles, my battery went from 74% to, today after two days sitting, 92%, according to the Topdon battery tester, and it passed the cranking test with flying colors.

 

[zzyzzx]

I imagine it depends on the car.

This, and if it's really a problem there are work arounds like putting a quick disconnect on the battery and using an alternate power source for the car when the battery is disconnected (like another battery, like a riding lawn mower battery, etc.)

 

[f355spider]

This, and if it's really a problem there are work arounds like putting a quick disconnect on the battery and using an alternate power source for the car when the battery is disconnected (like another battery, like a riding lawn mower battery, etc.)

What I learned from a little research, there seems to be two types of "pulse" or desulfation modes. Some battery tenders and chargers have a specific, separate mode that is much stronger and probably designed to be used with the battery disconnected from the car.

The ones on my Battery Minder and Granite Digital "Save a Battery" battery tenders are continuously operating during the maintenance or "float" mode and the battery can be connected to the car per the user manual.

 

[bonjo]

if by pulse repair you mean desulfation, then most charger from establishe brands are safe to use with the battery connected.
You don't say the make of your charger?
Take on board what "BarryH" posted.
If the pulse is higher than 15.8V (CTEK), I would definitely disconnect the battery

 

[Tony_P]

I attempted a pulse repair with a cheap Chinese eBay charger while the battery was still connected and it fried the diodes in my alternator. It's a 2010 Mazda 3 with only 100,000 km (65,000 miles) on it. Well looked after car, a very mild weather environment where it's lived it's whole life, everything points to the charger being the culprit.

 

[DavidOfMA]

Good to know, and sorry that happened. I've been disconnecting the battery and it sounds like that was a good idea. Although, I'm also unimpressed with Mazda's quality control. At 53K, my 2014 Mazda 3 exhaust manifold cracked, necessitating an out-of-warranty, $2200 repair last year.

I decided to get around the infrequently-driven battery problem by installing a remote cutoff switch and, soon, an AGM battery because they can withstand deeper discharges without significant sulphation, so for me the question is now moot.

 

[f355spider]

I attempted a pulse repair with a cheap Chinese eBay charger while the battery was still connected and it fried the diodes in my alternator. It's a 2010 Mazda 3 with only 100,000 km (65,000 miles) on it. Well looked after car, a very mild weather environment where it's lived it's whole life, everything points to the charger being the culprit.

I think this is very dependent on the brand you use. I have used Battery Tender and Granite Digital Save a Battery tenders and they both continuously pulse repair/desulfate. They are designed to be connected to the battery in the car. I have been using them for years connected to my cars almost continuously whenever parked at home...no issues.