Harbor Freight cheap charger quesiton!!

[chuckycheese]

I bought one of the cheap battery chargers (on sale) and am wondering...how do they work? From the directions, it looks like it maintains your battery without overloading it but it makes no mention of a shut-off or anything like that. How high should it take the voltage before it gets no higher?

I have a great Battery Tender and understand that it regulates the voltage and does what is necessary in order to keep the voltage 'in check'. The HF charger information looks as though it just offers a very slight charge constantly. Is this a good idea and how high will the voltage go? Also, when I put it on the battery, without the charger being plugged in, the light on the charger came on....does this mean that my battery was powering the charger light and that the electricity can flow both ways???

Thanks to you electrical experts!!\\/

[Steve]

Is this the one you got?

According to the description, it should be a "plug it in and forget it" device. I don't have one of them yet, but I have considered it. 8-[


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[80-81, GS 1100]

I was at Pasco the other day and the guy there was trieing to sell
me a battery tender. He explained to me that the tender works so
well because it will charge the battery up then slowly discharge it a little.
This, he said is better for the battery than a constant charge. Charge, discharge and charge again. I have a Battery tender on my best bike,
the others I will charge one week and unplug the next over the winter.
I also run the engines once a week.

[tconroy]

I bought a shumaker 1.5 amp float charger. Just plug it in and forget it.Also has led light for charging,charge and trouble.Comes with a pig tail that you can attach permanently to your battery post so you can just plug that in instead of using the small battery clamps.38 bucks at advanced auto.

[chuckycheese]

Is this the one you got?

According to the description, it should be a "plug it in and forget it" device. I don't have one of them yet, but I have considered it. 8-[


.

Yes, Steve, that is exactly the one I bought. I have a real "Battery Tender" (which is great) but read that a bunch of guys on the site were using this...and I figured it would be a good one to use on one of my other batteries. I'm wondering if they're trustworthy???

The thing I wonder most about is that the Battery Tenders will stop sending current to the battery when it's fully charged. According to the directions on this cheap model (as I understood it) it sends a constant, very low current. What do you think? Can this be a good thing?

[physics-teacher]

I bought a couple of these incredibly inexpensive devices and have been testing them. They put out a constant 12.87 volts. If your battery falls below this via self-discharge (and all batteries do this) it will juice it at the rate of about 0.25 amps (250 ma) until your battery matches its voltage of 12.87. When there is no potential difference, no current flows. Simple, huh? A healthy battery feels nothing, but as soon as it slips a little bit the charging device gooses it back up to snuff. Mine have worked OK for a few weeks, anyway. The ninety day warranty is frightening, but how much are you out?

[bwringer]

I grabbed one of the HF cheepies for $5, and it pretty much works as described -- a constant, low-amperage 13-ish volts (mine reads 13.2V).

I wouldn't leave it hooked up to a motorcycle battery for months on end, but I figure it's better than nothing for a couple of days every week or so.

I do have a couple of the small Schumacher battery maintainers which can be left connected indefinitely, so I normally use those. I lost one somewhere, so I've been using the HF El Cheapo off and on as described on my VX800 battery.

I've also used the charger on a small 12V SLA battery from a failed UPS. The battery is still good, so I use it for testing light bulbs and such.

[bakalorz]

Bleah ... QC must be bad ... mine reads about 12.7, which is a hair too low. I'd be happy between 13.00 and 13.20
That should be a float voltage thats safe forever.

Are yours the model 42292 ones too?

The box on those says 12.5 which is way too low.

I had mine apart, and will probably try to figure out how to adjust it up and down. (for $6 I don't really care too much if I kill it)

BTW, the box says for flooded and gel cell batteries. I suspect the voltage is definately too low for an Absorbed Glass Mat (AGM ... $$$) battery

[chuckycheese]

Thanks!

Thanks, guys! That's just what I needed to know!:-D

[DaveDanger]

I'm particular to a charger (trickle or otherwise) that puts out a steady 13.25 to 13.75 at all times. That being said... I'm not going to toss a "battery tender" type charger if it only charges at 12.5 or so. I figure in the long run, ANY amount of charge going into a battery is better than it sitting and slowly discharging.
I'm slightly embarrassed to admit it, but while in high school, I worked in the garage at the local Montgomery Wards (not the highest of recommandations for quality wrenching) and I was "trained" to become the electrical systems specialist (WhooHoo!). One of the things I specifically remember is that lead-acid batteries do develop "charge memory". If the battery is constantly kept at a steady charged state without discharging for long periods of time, it will develop a memory for taking a light charge and no more. It will reach a point that even when it is fully discharged, it won't take a good charge afterwards. It is much better to discharge it occasionally, and recharge again afterwards. The cycling up and down keeps the lead plates healthy and capable of current output for the longest period of time. (full battery life).
The sulphuric acid (electrolyte) floods the lead plates and the discharge/charge process causes the sulphate ions to transfer into and out of the lead plates depending on the current flow. Sitting in either a fully charged or fully discharged state for long periods of time tends to permanently "clog" the pores of the lead plates, drastically reducing the transfer of the sulphate ions.

[Steve]

I was aware of the 'memory effect' on Ni-Cad batteries, I did not know that lead-acid batteries were also affected.

It sounds like the effects were a bit different, though. If Ni-Cads were partially discharged to about the same point repeatedly, they would develop a memory and work well to that point, but if asked to go a bit farther, they said [-X.

This problem was especially bad for maintenance or security personnel who use radios for an 8-hour shift.
The one day they need to work an hour or so of overtime, the radio battery would fall flat on its face.


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[bakalorz]

I'm particular to a charger (trickle or otherwise) that puts out a steady 13.25 to 13.75 at all times. That being said... I'm not going to toss a "battery tender" type charger if it only charges at 12.5 or so. I figure in the long run, ANY amount of charge going into a battery is better than it sitting and slowly discharging.

I would consider 12.5 damagingly too low. Don't forget that this is a charger that is not diode isolated from the battery. So if the battery is fully charged (Rest voltage 12.8 to 12.9 volts) and the charger is at 12.5, then the charger will actually DISCHARGE the battery.
I would say the bare minimum fairly safe voltage is about 12.8 or 12.9
I would much rather see 13 to 13.2 for long term float charging, and higher for other charge modes.

If the charger is diode isolated, then sure, even 12.5 volts won't really hurt, but it probably won't help much either unless the battery is already so low that its being damaged. In that case the 12.5 volt charger won't prevent damage, it will only keep the damage to moderate damage instead of severe damage ... whoo hoo.

All that is kind of moot though, since it appears that these chargers are about 12.8 or above...

I'm slightly embarrassed to admit it, but while in high school, I worked in the garage at the local Montgomery Wards (not the highest of recommandations for quality wrenching) and I was "trained" to become the electrical systems specialist (WhooHoo!). One of the things I specifically remember is that lead-acid batteries do develop "charge memory". If the battery is constantly kept at a steady charged state without discharging for long periods of time, it will develop a memory for taking a light charge and no more. It will reach a point that even when it is fully discharged, it won't take a good charge afterwards. It is much better to discharge it occasionally, and recharge again afterwards. The cycling up and down keeps the lead plates healthy and capable of current output for the longest period of time. (full battery life).
The sulphuric acid (electrolyte) floods the lead plates and the discharge/charge process causes the sulphate ions to transfer into and out of the lead plates depending on the current flow. Sitting in either a fully charged or fully discharged state for long periods of time tends to permanently "clog" the pores of the lead plates, drastically reducing the transfer of the sulphate ions.

Regarding float charging the battery being bad: I have NEVER heard of anything like that. Everything I have ever read about lead acid batteries from both battery manufacturers and charger manufacturers says to store by either float charging, or leaving unconnected and periodically topping up.
The details of the required voltages and how often to top up vary somewhat depending on many factors, but the overall general recommendations are ALWAYS the same.

The only thing I can imagine is that the person who taught you was really mangling the idea of something called "electrolyte stratification". This can happen for both batteries being stored open circuit, and for batteries being float charged. Although it can happen to automobile and motorcycle batteries, it is mainly a problem for physically very large batteries (like on WWII submarines, or off grid power systems)
If a battery sits for a long time, the electrolyte will form regions of different specific gravity at different heights in the battery. Just like a layer of oil will float on top of a layer of water, some of the lighter electrolyte seperates out, and will float on top of the heavier electrolyte. One of the two regions (I forget which) corresponds to discharged electrolyte. Where that electrolyte contacts the plates the plates will sulfate, just as if the battery was discharged, even though the battery as a whole is still fully charged.

The cure is to periodically charge the battery at a high rate, and make it gas (bubble). The gassing mixes the electrolyte thoroughly, so that regions of different density don't get a chance to form and then seperate. But discharging is NOT required to prevent it. And for batteries that are not specifically made for deep cycling, any significant discharge WILL reduce the life of the battery.