Battery maintainer install directly to 12V battery

Just need to point out that, even though the more recent question was posted in a thread about battery maintainers, that poster doesn't actually need one. They live in southern California and they don't own a Prime/PHV. Giving them advice on how to permanently install a battery maintainer doesn't really help them. As long as they don't sit in the driveway listening to music in ACC or POWER ON mode, they aren't going to have any problems.

 

LoL; Always route the power cord pass or over your driver's side mirror, flip the sun visor down, or a large sign on your steering wheel. That's how I make sure I don't drag a plug.
If you want to get really fancy; you can use a relay to disable the brake switch. That way you can't start the car when your plugged in. The PHEV won't start with the charge door open, so you can wire-in there, without disturbing the brake switch wiring.

There are many ways to prevent you from dragging a plug. You just need to figure one out and stick with it. Over time it'll become routine, especially as we get older and forgetful.

Hope this helps....

 

Don’t attach jumper cables or a battery maintainer directly to your battery. she the points under your hood. And it’s best to never use jumper cables and use a jump pack (battery) instead.

 

I have connected a pigtail quick connector directly to the 12V battery in the back, and did charge the 12V battery fully two days ago with a CTEK charger. Should I have not done this? Why? You have me worried.....

I do also plan to connect a pigtail quick connector under the hood for my CTEK charger based on the pics and instructions earlier in this thread.

 

I haven't used a jump pack in over a year, but I still carry one. My precautions seem to have prevented having a dead battery so far. I have a bypass switch on my auxiliary battery, but if I ever need it, I won't be able to access the rear hatch to use it. Maybe what I need is a remote switch from the front seat. I know there is a manual pull handle somewhere, but I'm a long way past being able to crawl back there to access it.

I have an idea for another mod; I am able to order a remote switch, capable of handling 40 amps which I can use to bypass the battery isolator. They are less than $3 on Aliexpress, so I ordered two different models. The exact same thing on Amazon sells for over $30. They have 2 channels, A and B, so perhaps I can wire one to bypass the aux battery, and the other one for the rear hatch release. This way, when the battery is dead, I can activate a boost from the aux battery. I have a 30 amp breaker already in the bypass switch circuit. I can either replace the toggle switch or run this relay in parallel with it. I think I'll leave the toggle switch as a backup.

 

Nothing broke, so nothing to worry about.

My BMW has similar rigmarole attached to the battery. Its purpose is to detect phantom power draws and to shut off systems when the car is powered off to ensure that the battery doesn’t die. It’s because cars are full of systems that keep running when the car’s off, like remote start, keyless entry, etc.

So it’s best not to use another car to jumpstart, because of voltage spikes, and it’s best to attach the battery tender up front from now on.

 

It is OK to jump-start from another car.

You can connect the battery maintainer wherever you want. It makes no difference.

 

What is your basis for that determination?

 

A battery maintainer can be connected to any battery, any time. It simply monitors battery voltage periodically, and if the battery can take a charge, it delivers one. This differs from a trickle charger, which applies a small current to the battery constantly.

I have ordered a voltage/current logger to see when the battery is charging while sitting idle. This can give a clue about parasitic drain.

 

Sorry, need to chime in here.
Stay away from those charger/maintainer that claim to desulfate batteries. It does so by sending high energy pulses, that may damage your electrical system. Power supply capacitor are suppose to filter that out, but on an old tired dried out one - good luck.....
Some of those units instructs you to remove or disconnect the battery from the car; but who reads instructions.

Just something to think about, sometimes all you need is some good clean DC current.....

 

On the Noco Genius, it is safe to charge the battery in the car in the normal flooded-cell or AGM modes. However, yes, if you decide to use the repair mode, you need to disconnect the battery from the car as instructed in the manual since the voltages could be too high and damaging.

 

My Gen 3 manual says this:



Which I've never done.

 

But are you using an old school battery charger or one of those high frequency pulse battery desulfator / refurbisher?
As stated earlier, you can probably get away with it - until you don't and fry something. The simplest thing to do is, turn-off and don't use that option or disconnect one of your cables. It's your car and you can do whatever you want to it.
I know a lot of people, professionals included, who jump start a car by connecting battery terminal to battery terminal - NOT to engine block or other ground point. They can get away with that, but what happens in that 1 in 1000 chance that the battery explodes in their face? Not worth it to me, I prefer to do it the correct way - but that's just me....

PS, the Toyota manual states that so they don't get sued in that 1 in 1000 chance.

 

You can turn off the battery maintainer before you remove the wires, which eliminates any spark hazard, the latter of which is the reason for the note in the owner’s manual.

 

A word of warning during these hot summer days. Many battery chargers are not temperature compensated (neither of mine is) and the hotter it gets the lower the optimal charge and float voltages become. See 2nd table here:

Gel batteries,VRLA Batteries,flooded batteries,AGM batteries

So if the car is in a 70F garage and has come to thermal equilibrium no problems, charge away. If it is sitting in the driveway on a 100F day though charging it with one of these devices could result in a seriously overcharged and possibly dead battery.

Use a temperature compensating charger will fix this. Maybe. The problem for cars with the battery not under the hood is that the easiest place to attach the charger is at a jump point under the hood, but the battery is at the other end of the car. Most, maybe all, BatteryMinder products have temperature compensation, and the probe sticks out just a couple of inches. Unless the rear deck comes out and it sits right next to the 12V battery it will temperature compensate, but not with the temperature at the battery. It is possible for either end to be hottest, depending on the sun mostly, but also on whether or not the windows, hatch, or hood are open. For instance I have measured a 10F degree difference between the temperature of the interior on our 2007 and the temperature of the battery. The windows were down partially, , hatch closed, hatch area fully assembled and security cover extended, car parked facing west in the afternoon, then rapidly access the battery and measure its temperature, which was lower than the interior. Permanently connecting wires to the battery is not difficult, but surprisingly extending a temperature probe to it is. BatteryMinder sells, as far as I can tell, just one product with the temperature probe on a long cable, and it is intended for aviation use and quite expensive.

 

Disconnecting the neg cable means the car has to complete the ready modes for emissions controls. The cat monitor seems to take a long time and needs a highway run to get the cat hot enough. Until then, the car isn’t running optimally.

 

After more searching I found this 6 ft cable with a temperature sensor on it is also sold separately:

BatteryMINDer® Accessory: ABS-248: At the Battery Temperature Sensor

The link has a list of models it can work with. Also in the manual for their 12248 charger

https://www.batterystuff.com/files/12248.pdf

they say:

with a picture of ABS-248 - which differs from the one in the link above in that it is all of one piece, whereas the current variant has a plug at some distance from the loop, perhaps a foot out? I do wonder why the circuit would be fussy about the length of this extension when for all the same chargers they also sell a stubby variant that is only a few inches long (which is what they come with by default except the one model mentioned a couple of posts up):

BatteryMINDer® Accessory: ATS-1: Ambient Temperature Sensor

 

I recall a mechanic telling me he had had a battery explode during a jump despite the cables being placed properly. He didn't know why it had happened. I don't recall his exact words but it was along the lines of "I put the clamps on stood up and stepped back and had my co-worker try to start it. When he turned the key the battery blew up. Luckily I had big sunglasses on since parts of it hit me in the face." Seems like an even rarer sort of problem than a spark setting off a battery when attaching the cables.