Whats your recommended 12v auto battery charger?

[TWIH]

Hi all,

Since I’m not “sold” on my craptastic HF Centek 10/2 battery charger (as far as it’s quality level) I thought I’d poll you all to see what you use or would like to have.

I’m not pleased that I cannot find any documentation/information on the stages and voltages, as well as the way the microprocessor (if it even has them) works. I can’t even tell you anything about how it determines the battery SOC etc. In short, it’s just hope that the dumb thing puts anything much of a charge into the (starting) battery.  

I also realize that the 10 amp is seriously underpowered for a dual golf cart house setup, as even a 10% of capacity charge rate would call for about a 21+ amp unit. On 2 amp it could take days to do anything...

So anyone have ideas?  I have read about SW not being happy with the voltage swings out of his Schumacher, and I am aware that at the price point that most of these big box store 12v units are at, a buyer won’t get much quality.

Thanks

[B and C]

I still have my (now probably) antique 2-10-30 amp Schumacher from around the '70's. I hardly ever use it anymore. I only ever used it when a battery was about dead to get the car started and then got a new battery. Voltages it puts out? Not a clue. I use it to charge at 10 amps and when it drops to around 2 amps, I call it good enough. It is old enough that it has an analog meter on it. I haven't seen one with an actual meter on it in ages. I don't think I would ever use one of these dumb chargers on house batteries except in an emergency.

Edit to add: For house batteries I have a progressive dynamics charger. Not cheap but worth it.

[sternwake]

Every charger should have a wattmeter, or some similar sort of ammeter, to measure not only voltage, to watch it rise as the battery charges, but how many amps are flowing to raising that voltage. A neighbors 12 amp old school looking metal cased Schumacher I measured maxing out at 4 amps, while it was declaring 10+ were flowing

This is the only 'watts up' clone I can say is worthy, except for the KWH figure:

https://www.ebay.com/itm/200-Amp-Watt-Me...2024!US!-1

Know what your charging source is doing.
Not knowing how many amps are flowing at a certain voltage is like saying I need to get from A to B, but no idea how far apart A is from B, nor how fast I will travel from A to B, and only a slight idea that B is over that way somewhere, just lemme know when I am withing 50 miles or so, and flash the green light, and don;t forget to tell me I am attractive.

When charging....How many of those amps are charging the battery, and how many amps are powering loads?

Regular garage style 'smart' chargers do not expect any load to be on the battery. if they notice that suddenly it takes 12 amps to maintain 14.7 rather than the 9 it was providing a few seconds earlier, they can freak out and shut off, and give no obvious alerting indication that they have done so.

Likewise if a load is shut off and suddenly 3 amps are required to maintain 13.2v in float, when a minute before 8 amps were required, they can freak out and shut off.

If they do not shut off quickly, they might not respond instantly to the different amount of amperage required to maintain a voltage setpoint, the voltage can swing wildly in either direction, and perhaps when it shoots to mid 16's for a while, then it shuts off.

A RV converter like the progressive dynamics has an automatic 3 stage, but a button one can push or push and hold to force the charger into any one of the three voltage stages. It does not get confused and shut off if one applues 40 amps of load and shuts it off than back on, it just provides all it can, or as much as required to seek or maintain that voltage 'stage'

The PD9245 is a great size for a pair of GC-2 golf cart batteries, and PD sells a PD9245 -14.8v version which will charge a bit faster. One can also get the 60 or 70 (pd9260 or pd9270) amp version and power them on a regular 15 amp household circuit. PDs with more amps than this need a 20 amp household circuit and if one is using a generator to power the converter its rating is a big factor in just how big a charger/converter can be used


As far as a good enough, or the best offerings of the sub 75$ garage chargers marketed to the general nimrod automotive market, I have NO recommendations. They all suck, none were ever intended to fully charge hard working regularly deep cycling batteries . They are primarily to get a battery 'good enough' to be able to start the engine. They are designed to NEVER overcharge. Deep cycling batteries require more time held at safe absorption voltages, as reaching true full charge is the only way to keep them from prematurely losing capacity each and every cycle until they are nearly useless.

Any charging source applied to any under charged battery is better than no charging source, but hoping and praying the marketers are not lying greedy douchebags and clueless as to how a battery charges, is lunacy.

And there is plenty of that on Automotive forums, Halfwitted nimrods parrotting incorrect uninformed opinions or basically saying ' I am clueless, but I have one, and therefore its great, and therefore you should have one too!'

Not one of the NImrods posting as authorities on Automotive style forums, has any ability to determine the efficacy of their
7 stage ultra platinum, fellate you afterwards, smartcharger, but they'll tell you just how awesome it is, and just how pleasing that green light is.

If you are going to actually deep cycle lea d acid batteries, and want them to last, save up for a real charging source. The PDs are not perfect, nor housed in a sexy pleasing with buttons and pleasing flashing lights, but they will do a MUCH MUCH better job at retaining the capacity of the deep cycling batteries than anything off the shelf in walmart, target, or any auto parts store

[Roadtripp]

The late proprietor of Bill Cloud EV suggested using inexpensive Souer 10 amp chargers. Individual chargers on each battery in the string. I tried it briefly when I had a electric pickup with a 12 battery string at 144 volts. It seemed to work well for the AGM type I was using then. They have a digital volt and amp indicator. Not sure the accuracy? They might suck for a true deep cycle flooded lead acid battery. 
  I ran into a guy with a 72 volt electric Lithium motorcycle who is doing the same strategy with the same chargers . 
 https://www.ebay.com/itm/12V-10A-Smart-Fast-Lead-acid-Battery-Charger-For-Car-Motorcycle-LCD-110V-240V/323903074556?_trkparms=aid%3D555018%26algo%3DPL.SIM%26ao%3D1%26asc%3D61112%26meid%3D23e0defa4da34f18891a0221ea1a32b2%26pid%3D100005%26rk%3D4%26rkt%3D12%26mehot%3Dag%26sd%3D322343487574%26itm%3D323903074556%26pmt%3D1%26noa%3D0%26pg%3D2047675&_trksid=p2047675.c100005.m1851
 Cloud was a Boeing engineer and won races with his EV creations so I paid heed to what he said. Four of them on 2 deep cycle batteries might work. That’s 40 amps. But I’d prefer a power supply type Charger like Sterwake mentions. I have a Todd Engineering 75 amp charger/power supply that kicks some juice out. The Iota chargers have a decent reputation.

[TWIH]

Basically, since I would rarely (except when visiting relatives) be able to use ac power, all I am looking for is a lower cost (re. automotive type) that doesn’t take up a lot of space that could be plugged in while staying at said relatives place for 24-48 hours.

I realize that this is not what SW said however, like he mentioned, ‘Any charge source applied to any under charged battery is better than no charging source...” and thats exactly the situation I may find myself in.

Now for those with recurring access to grid power, yes the PD chargers would be “the bomb” but I won’t have but perhaps 1x a month, if even that as my circle of acquaintances with ac that I could plug into is, well, limited to say the least...

If anyone else uses or has with them an automotive type charger of any decent amperage I’d be glad to hear what you think. If I ever can get to the 2 golf carts then I will likely need something stronger than what I have for the occasional recharging duty.

Thanks again SW, your advice is always well received, even if not being followed at the present.

[Gr8ful]

I have 4 roll arounds, a staraight 10 amp non taperig small one, a few 2-10-50 small ones but my 2 small favorites is on that does 6-72 volts & know what voltage & type of battery it is. I bought a 6000# cap forklift with a 4000# like new battery & used it in the winter as a float charger. We had planned on doing solar but even with a 50%+ a 30% tax credit the payback just wasn't there. The other was new when I bought it at a yard sale as the owner didn't understand it showed level of charge not charge rate & is very accurate for the $1 I paid. I have a AC to DC power supppy that adjust from 0-30 volts & you can also adjust the amps. It's not automatic but that why I wanted it. I've watched several you tubes where you can replace a fuse with diode & add 1 amp to the top charge rate.

[tx2sturgis]

For your intended use, I recommend this Schumacher unit....I have the older version of it (SC-1200) and its been working for more than 10 years in occasional to frequent use.

https://www.amazon.com/Schumacher-SC1393...V9RP9?th=1

This is NOT a battery maintainer in the typical sense, it does not start and stop charging at the 12A rate. You plug it in, hook up the clamps, and select the type of battery and the charge rate you want.

When the charge cycle is completed, it stops charging...

Simple solution for this situation.

[Roadtripp]

Have you checked Craigslist, Offer up, or Let Go for a quality used Charger?  Ive noticed the prices on Facebook Marketplace are very low sometimes.

[sternwake]

I have the schumacher sc2500a. They only offered it for a year or 2 around 2007. 2/12/25 amps regular/deepcycle and AGM are the options.

it still works, and I still use it, but it is insane. it will goto 16.4+ volts and pushing a battery upto a bubbling stinky sulfuric acid spewing nightmare at 14 or upto 29 amps.
Other times I can't get it to charge a battery well less than fully charged it'll just keep dropping to float in less than a minute, even if I load battery to cut voltage and try a lower amp setting.

My Schumacher's worthless display has failed. the voltage was always 0.2v off and the % screen was a complete joke even when it worked. The button's lights don't light up anymore but I click one button 3 times for AGm and the other button once twice or 3 times for 2/12/25 amps and verify amp poutput with a wattmeter on the output. Mine does have a fair amount of use on it, but I do not trust it on a battery I care about due to that 16.4v tendency.

The original fan on mine failed, I replaced it with a higher CFM larger fan and drilled some more inlet holes on the opposite end.

Did they update the charge algorithm since? I have no idea. Many similar looking Schumachers also goto way too high a voltage like the video below from 2011.



The DC power supply linked below has adjustable voltage. and can likely do a solid 30 amps, perhaps more. One needs to provide their own DC cabling and perhaps AC too. Set it to 120VAC, plug it in, adjustDC voltage unloaded to 14.4 or 14.8v then hook it to the depleted battery and run it until the hydrometer says full, or the amps taper to 0.5% of capacity on AGMs or 1 to 2% for flooded.

https://www.amazon.com/MegaWatt%C2%AE-S-...B00LIBRKQM

http://www.megawattpowersupplies.com/

A spring wound timer and this 'Megawatt' will be able to outperform every automatic consumer grade garage charger, as it is actually capable of fully charging a battery, no matter how long it takes and getting a garage charger of more than 20 amps is difficult and pricey.

Put a Ammeter and voltmeter on the output and you're laughing. But its not totally automatic and will not fellate you either while the battery charges. It should likely receive extra ventilation is run flat out charging a big bank of depleted batteries

https://www.amazon.com/s?k=gt+power+wattmeter&ref=nb_sb_noss

Note there are many similar looking power supplies that have adjustable voltage,. on amazon and ebay, in the correct range for charging 12v batteries. Many of them have no protections against overload, even though they will claim so. If the battery is well depleted, and this is set to 14.8v then hooked to the battery, it will likely output well more than its maximum rating and make weird noises, until it releases the magic smoke.

I had one, and I had to use the voltage dial in order to keep it from making funny noises, start low and keep raising it as the battery charged to keep it over 30 amps but under 36 where it started making funny noises.. When I got sick of twiddling the voltage pot I set it to 14.7v and let her rip. 17 minutes later the magic smoke escaped and i ordered the meanwell rsp-500-15. 40 amps at any voltage from 13.12 to 19.23. I modified it with a better voltage pot because of course I did, and more fans because of course I did, and more heatsinks, because the casing is used as a heatsink and adding more heat dissipation is relatively simple and makes too much sense.

I'm actually installing a different Ammeter/voltmeter/Ah counter and the Ideal Diode on the output at the moment. No spring wound timer though. I think it is easy enough to watch the ammeter and turn down voltage when its full, or just set it to float voltage while I goto sleep and blast it to 14.7 come morning, see how many amps it takes to do so..

[rvpopeye]

I have a Stanley 15a /40a engine start charger. I bought at Wallys a few years ago..~$50
Surprisingly , it outputs 14.7 through entire cycle till floating kicks in around 3a.
Seems to self limit to 15.4a if batt is very depleted.
(Checked with external Fluke digital meter)

Not bragging , but reporting what it is...