Using an automotive battery charger when onboard fails

Only JUNK chargers do not have a timer. Hello Kalifornistan.

The problem with smart chargers isn't only they do not fully charge a battery.

The BIG problem is they have the durability of a soap bubble. Eighty bucks spent eighty bucks wasted. Smart chargers will blow up on a trip. Then other than being short eighty dollars, where does that leave you?

A high amperage Power Max pre-wired as a charger would be the best choice. Stow it as a spare. Or use a Megawatt and that timer.

At one time I had a stack of <3-year-old Die Hard SMART chargers. And another stack of SMART chargers. The SMART part was 100% the failure. Absolute junk circuitry.

My "smart" battery charger will shut off if it sees a significant voltage drop after it goes to float made. It also throws an error code if I try to charge 400AH bank from 50% SOC. Apparently, it takes too long so the charger thinks something is wrong. Reset it enough times and you can eventually get the bank charged. Think the charger is too "smart" for use as a backup for the converter.

My smart charger records time in the bulk phase. Next it will hold absorption (14.6v) for 1.5x the bulk period. Next it limits current to 2 amps and creeps up to 16 volts for half the bulk time measured earlier. Then drops to 13.4 and will use full 20 amp rated power as needed. Minimum bulk time is 30 minutes. I think my battery is full.

opnspaces wrote:

2oldman wrote:

opnspaces wrote:
can any newer, automatic battery charger be used for to keep the coach 12 volt running? Or does a person need to look for a cheaper (possibly something from Harbor Freight) charger?

Not sure I understand. Why would you 'need' a cheaper charger?

Remember this is all theoretical. My charging system is working fine, I'm just thinking things through.

My thought is I have seen warnings on battery chargers to not use them as a power supply. I have also seen other chargers that shut off if they don't like something about the battery. So I was wondering if people have experienced a charger that would not work as a power supply because it was too smart, hence possibly necessitating the need for an older dumb charger.

There are chargers that will not 'turn on' if the battery voltage is too low. Jumper-ed to a vehicle battery should get them started.

i have a $40 "smart charger"bought off amazon i use for my boat batteries and i will periodically use it when home on my Travel trailer batteries to keep them topped off in condition instead of using onboard wfco converter. i turn off my battery disconnect switch to isolate the batteries first. been working well for me for boat batteries and TT batteries.

Remember, Your RV Charging system has FAILED and you are camping. When you get any type 12 volt charger from Walmart or any vendor, THAT charger is just supposed to charge a low/dead battery. NOT run any 12 volt loads. So, when people here talk about charge rate and Smart chargers, you are talking apples and oranges. What you want is at least a 20 to 40 amp stand alone battery charger. Remember, you are not only charging a DEAD battery, you are also in need of supplying enough amperage to run the various 12 volt appliances in the RV in conjunction with your battery. So, you want a charger that will charge the Battery and also have enough guts to supply at least 20 to 30 amps of DC power to the RV. That means you will want to install a simple Xmas light type timer on the 120 cord of the charger to turn it off at times to prevent overcharging when your RV amp loads are minimal to keep from overcharging your batteries. This is critical if you only have 1 battery. Having 2 or more it is not that critical about overcharging or boiling the batteries. So, buy a quality charger that has multiple AMP charge control. This type thing is just to get you thru the failure until you the get the RV system fixed. Doug

We used one short term when the Converter/Charger failed to charge. We were on a 6 week trip in our Class C and had about 4 other issues before the Converter stopped charging. I didn't want to be bothered with it, so I just used a 12 amp/2 amp/75 amp charger. We were at the same campground for the remainder of the trip, so I charged the battery overnight the first night on 12 amp setting until full, then kept it on 2 amps the remainder of the trip. It kept the battery charged enough. Our battery compartment was under a slide, so the charger stayed under the slide as well, safe from rain.

We ran the fridge and hot water heater on electric the whole trip, so it was really just lights and vent fans using battery. After we got home, I replaced the Converter/Charger.

-Michael

A stand alone charger charges the batteries. The batteries run the RV.

I've had the converter fail while camping. Back then, I didn't bring a stand-alone charger with me. But I did have my jump pack, which had a sealed lead acid battery inside. I only needed power for one more night, and this worked fine, though looked a little odd.



Now I carry my old Diehard (Sears) 12V automatic battery charger. I used this to keep batteries fully charged for several years in my garage.



While on another camping trip, someone with a new 5th wheel asked if I could help troubleshoot their battery issue. Dead converter. I loaned him our charger for the several days we were in the same park. Turned out he was one of the folks that reviews campgrounds for Woodalls. Gave me the latest campground guide when he returned the charger. That said, yes, a stand-alone charger will keep your camper going. Mine will only supply up to 10A continuously. But with it charging all day, with little 12V usage, any spikes at night will be supplied by the charger AND the recharged battery bank.

The jump pack lasted for years. Every few years I had to replace the internal battery. The case eventually started cracking. Finally threw it away. I now carry a DBPower lithium jump pack in each of my vehicles. https://amzn.to/2Z7FW5p

THIS

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Is an authentic battery charger forbidden to ship to Kaliforniastan

The KRAP available to consumers are props only useful in a George Lucas film. Where is Darth Vader?

Under conditions of boondocking longer than a couple of weeks a genuine charger will DOUBLE or TRIPLE battery life and give you 15 to 20 percent more stored power per charge because the batteries are charged fully.

But it requires a person to get off their dead *** once or twice during the recharging process.