Jumping 12V Battery direct from Battery

No sorry, it doesn't "mean" that at all.

It MEANS that you should not connect a charging source that will force more than 4.2 amps into it.

As a practical matter, and if you can see the charging current on a meter, most any smart, automatic charger should be OK.......because it won't come anywhere near it's max. current capacity unless the battery is completely DEAD with some shorted cells.

Of course, if you won't have a meter to look at (usually ON the charger), the safe thing to do is get a charger with a capacity no higher than about 5 amps.

 

I have actual experience using a 6 A rated charger (mode). Charger said complete, disconnect and immediately reconnect, started charging again/not fully charged. I could repeat this ad infinitum but kinda got tiring after a while. (Schumacher XC75W-CA if it matters). Switched to below 4.2 A spec charger, and it charged fully, disconnect and immediately reconnect, still full...

moto g(7) power ?

 

That experience you had with one specific charger means nothing as far as the advice from Toyota about charging rate.
In neither case did you KNOW what the charging rate actually was.

One more time: The max. rated charging capacity of a charger means virtually NOTHING in most normal circumstances because the charging current usually will not come anywhere near the max. capacity.

As a matter of fact, a really LOT of automatic chargers will do what you observed and it is not necessarily a problem.
The subsequent charging should only last a few minutes......as the charger makes SURE that it really is full.

 

Since it's dead yes 4 amps is preferred. Don't know of a 4.2 amp or 4.1 amp charger. It would take longer otherwise...

moto g(7) power ?

 

looks like a good unit

 

Others share that tendency.......a LOT of others.
Just be sure it is an automatic battery maintainer......and NOT a cheap trickle charger.

I've had good luck with Schumacher's.
Go for it.

 

I'm so sorry I did not see this question until now. I was busy trying to warn against possible issues with a charger rated above 4.2 A that I have. I know you're planning on getting the Schumacher unit and I've selected "Like" as approval. The Duracell unit does not mention "smart" but does explain features of smart chargers, one being it will not overcharge if left connected for extended periods. Anyone considering it I do believe it is a smart charger.

moto g(7) power ?

 

And....do you now understand that a charger will almost NEVER actually supply the full rated current ?
And that recommendation is for actual current.......and NOT the max. capacity of the charger ??

 

Sam do you seriously think when the Owner's Manual stipulates a max charging rate that's the intended message? If you just take the amperage mentioned in the Owner's Manual as the charger rating, you'll have a charger that'll work fine, get the job done. Maybe doubly safe, if your take holds water, but what does it matter?

 

Yes. Because that is what it SAYS.

It does NOT say "Do not use a charger with a capacity of more than XX amps."
It just doesn't.

And what else it doesn't say is "for an extended time".
Using a smart 10 amp charger, for instance, that provides 6 or 7 amps for the first minute or so is perfectly fine IF it drops down to around 4 for the remainder of the charging time.

I think that a max. capacity of 6 amps is probably ideal.
That has the potential to give it a little extra if the battery is REALLY low, without having the capacity to hit it REALLY hard.

 

"Never add water nor charge quickly." The first line.

Sam, you're making a determination here that can affect someone buying a charger for the first time.

For me, I have 8 cars on various brands, models, even versions of chargers/maintainers. I have this battery on a 1.5 A Schumacher, and a NOCO G7200 sitting on the sidelines. I follow your advice and I get the results that I posted. I have a charger that effectively does not fully charge my battery in the lowest setting. No biggie for me, I swap out one for a different one.

Looks like the OP doesn't have a charger to begin with. Why do you go through all this trouble to make a point when the goal is a successful charge for the OP?

moto g(7) power ?

 

The only way to guarantee you won't ever charge at a rate above 4.2 A is to use a charger rated 4.2A or below. Even just using the 4 A Duracell I saw a little discharge from the vent one time from this battery, hence why I set it away from the wood. (Probably should put a tray now that I think about it).

moto g(7) power ?

 

Because of exactly what you posted your very self.
It is a "biggie" for most people.
And the truth is the truth.
Buying a charger with a slightly higher capacity does NOT necessarily mean that it will charge significantly faster in an identical situation.

A 4 amp smart charger is a much better choice for a person who will only have ONE......than a 1.5 one or a .75 one.
And a 6 amp SMART charger is a better choice too........because it will not force 6 amps into a battery that doesn't need it.
It just won't.

 

While that is true, it is NOT that critical.
Really it isn't.

 

The 12 V system is separate from the one that could really hurt you. Besides pulling all the stuff out of the trunk to get to it, there is no difference. I can find the torque specs if you will use a torque wrench.

moto g(7) power ?

 

Love the "others share" comment.! Would I be in there....hopefully not.
kris