On-board Battery Charger
 

As many of you FAS-ers have experienced, my alternator isn't running enough to keep my battery charged. I bought a chager at Harbor Freight, but I don't have the discipline to drag it out every night. My plan is to keep the charger on-board in the engine bay, and have a dedicated length of extension cord that I can simply plug into the nearest exterior outlet when I park in the driveway.

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The unit has some stand-offs to keep the fan clear for adequate airflow. Since the fan side of the unit will be facing the inside of the engine bay, I wanted to remove the stand-offs.

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Stand-offs coming off.

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Relocated indicator lights to be visible from fan-side as they would otherwise be covered when the unit was mounted.

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handle removed, lights relocated, stand-offs removed. I'm going to just let it do it's job normally for tonight, and tomorrow find a good spot for it.

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sounds like a solar battery charger would be another good option for you if this does not work

I also have an onboard charger. It was recommended to me by the distributor (who knows his stuff) to not put the charger in the engine bay due to heat.

I had considered that, and figured that since most of the actual operation of the charger would occur at night w/ the engine off it might be ok.

BUT...the engine bay idea didn't work out anyway (I should have expected as much with an econobox). I mounted it right in front of the driver's side front tire, in the bumper cavity where cold air intakes are usually designed to run. I was shocked by how clean it was in there. I think I introduced the first dirt that area had seen in its 7+ years.

Maybe I've misunderstood the instructions, but it seems when I kill 120V power to the unit, under charging mode, it will stay in charging mode, with the cooling fan running, until I remove the 12V clamps. However, if I just attach the 12V clamps to the unpowered unit, just the trickle charge light will come on. I guess I'll just install an in-car switch to kill the 12V side..?

what you need to do is find an older charger that is nothing more than a 120 volt to 12 volt transformer and a full wave bridge rectifier, and not all of the other "sensing" junk, if you want to keep it hooked up all the time to the 12 volt system. Yard sales, junk yards, flea markets are a good place to look for the "old school" type of chargers.

Well, I guess I'm too naive to let go of all the sensing junk. I'm a gear-head not a sparky.

The sensing 'junk' keeps your battery alive longer. Not really junk IMO.

Mine does not have any sensing stuff on it - basic. It is, however, only a 15 watt unit. Running all night long is just right to top off the battery but not to overcharge it.

I have mine on board. It's on the side, between the air intake and the fender. The intake box separates it from the main engine compartment. Also, it only cost me $7, so I can replace it if it fails from the heat.

Quick, dirty, works. If you want the elegant solution, Daox has that covered.

Get a relay with a 120V coil, then have it connect the charger only when AC power is connected.

What you want is a charger that is designed to stay hooked up to the battery, they tend to cost a little more because they also tend to be in a sealed weather tight box but they are pretty common for trolling motor batteries, motorcycles that sit over winter or hot rods that tend to sit for months at a time.

Actually just use the charger, a small amount of hassle is no biggy, a switch will be fine or you can install a sufficiently rated 20v diode such as a 10amp unit and a 1kohm resistor such that current can flow out of the charger but not really into it.

Good Luck
Ryan

As usual during the colder part of the year, I'm looking for an on-board battery charger. I'd like to ask what you think about pulse vs. transformer chargers? Does anyone have an opinion about which makers are better/worse, for example Yato and CTEK?

I'll most likely use it for 2 hours at a time while the engine heater is on, so what amperage is better - 4A or 1A? I already have a 1.5W solar trickle charger and haven't had problems with the battery yet, but it is 6 years old so I should start giving it more TLC, especially since the car is parked outside.

And can I use a charger designed for smaller batteries (<36Ah)?

6 years old? 2 years is what I was told by an auto electrician as 'good' - I do know much more is possible, having only this year replaced an 8 year old battery, and knowing the last battery in the Sonata was 4 years old+!

As for chargers, any charger that charges 12V batteries will be fine, it's the rate of charge that matters and whether it's smart enough to stop.

If you keep charging, and charging, and charging past the battery capacity, you'll be doing a lot of damage to the battery. If you use too small of a charger, you won't do much at all to help the battery.

What is status on SR Motor project?
Haven't seen anything for a long time. Thought this would be the way to go, as the SR is rated most stable.
Not trying to look pushy, just curious.

Ray

My best battery was a pair of fleet farm 1100anp specials in the old 82 diesel suburban, it took 10 years before they started getting too weak for the rig. Odd part was the $38 fleet farm special desert dog tires on that truck started to fail at roughly the same time (tread fell off)
I still have one battery oddly in my subaru, its 20 years old now but puts out the 30amps needed to crank the subaru but not much else.

My father still has the one desert dog tire on his old wood trailer, it too is 20 years old, still seems fine on his rarely used trailer.

I think luck combined with the way the batteries are charged/ discharged explains all this.