Problems with Trickle Chargers?

I recently had to change out three batteries maintained by trickle chargers. In both cases fluid was well below the top of the plates and at the end of their expected lives. Since then I was told by a parts representative not to use maintainers because of this issue. In all cases the maintainers indicated batteries where fully charged. What is your experience/knowledge/impressions?

Are they actual maintainers or just small chargers? Those battery tenders are supposed to turn on and off as needed. I'm pretty sure trickle chargers even small can overcharge a battery over an extended time.

They're the cheap trickle chargers. 

As Don mentioned, you shouldn't have any problems with a Maintainer. If its a trickle charger, you could absolutely have an overcharge problem. We sell a lot of maintainers, and I have a few myself for my vehicles and tractors. No problems. Some of those maintainers are close to 10 years old....

There are products that very actively 'maintain' the battery's state of charge with a little microprocessor.

Then there are little power transformers... simple linear supplies... that don't generate much current, but the voltage is high enough so that once the battery reaches full state, it continues pushing current at a very small rate, into the battery.

The problem is, anytime you continue pushing current into a fully charged battery, it will boil off. Typically, a newer machine (especially computer controlled new stuff) will have enough idle-draw that the presence of a maintainer equates to the amount of drain that the other stuff uses, but on an old tractor, the only discharge that occurs, is from whatever leaks through it internally, or across the dust on the top of the battery... so a tiny supply will still boil it off.

There's several ways to combat this:

1) put the tiny supply on a 24-hour mechanical wall timer... set it for 10 minutes a day. This will NOT stop it from boiling away, but it WILL cut the charge rate down enough so that it won't be as likely. Typically a battery in storage won't need but a few minutes a day to stay good.

2) Put something on the battery that uses a little current every so often. Not an easy thing to sort out, but if the battery's powering something every so often... like a low-voltage motion sensor light... it'll gently work the battery while in storage... which is a good thing.

Boiling battery notes:

1) Check water regularly. When the electrolyte level falls below the plate tops, the uncovered surfaces suffer, and don't recover well, if at all.

2) VENTILATION IS MANDATORY. Boiling batteries emit hydrogen gas. If you're boiling a battery, the area will flood with explosive gases, and you WILL find out what a battery explosion is really like... so make sure your battery storage area is ventilated. I prefer to store batteries in a rack or shelves in a room absolutely separated from living, storage and work areas, with vents to allow airflow. If you have lots of batteries to store, you might consider building a lean-to shed along the side of one building, and incorporating vents at the top of the roof edge and the floor, to allow gases to dissipate... and then use one chager, on a timer, and a series of fused clip-leads to connect all the batteries to the charger. This is what I do with my boat and motorcycle batteries, and I keep chem gloves and a faceshield right there... as well as several boxes of baking soda, my hydrometer, fire extinguisher, and distilled water all there for proper maintenance.

Get a maintainer, use it and forget it.  I've got 12 or so and use them on everything with a battery that's not used weekly.  Batteries last much longer if you use one.  I'd also stay away from the cheap one's but that's MHO.

The Schumacher XM1-5 Automatic Maintainers that I'm using from Wallyworld says on the box: 6/12v. "Auto voltage"  Bar code 0  26666 70970  5 and cost $20.94 at Waterloo, IA June 24, 2011. The ticket shows the bar code as 002666670970

Gerald J.


Edited by Gerald J. - 12 Sep 2012 at 6:26pm

If no OTHER good suggestion, one should not put 'good' and 'inexpensive' in the same specification when it comes to battery maintaining systems. Many of the wall-transformer 'maintainers', and even some of the small-plastic-box 'chargers' that have indicator lights, have no regulation or ramping. I've seen some with advertising in the package that suggest it to be a 'plug and forget "maintainer", that actually amounted to nothing more than a 14v 'wall-wart' power supply... internally consisting of about a 100mA 120:12v transformer and a bridge rectifier... and from a functional perspective, it would trickle charge a 12v battery, but when the battery reached full charge, the little wart would just keep going, because when you full-wave rectify a 12v RMS AC waveform, you get almost 17v!!

Now... there's many good products out there, but I've learned not to trust ANY battery chargers to be fully automatic 'plug-and-forget'... because I've had incidences where the automatic feature failed (lightning or power line transients, I'm guessing) and the unit just stayed in charge-mode. I've even had it happen in very, very, very expensive marine inverter/charger/maintainer units... fortunately, it was figured out before something really bad happened.

SO... this is the reason why a mechanical lamp-timer is my recommendation for ALL devices... it's belt-and-suspenders. I even use them on my conventional battery chargers. I haven't seen one in a Lowe's or Home Depot stor in a while, but back when it was really popular to have heat lamps in bathroom ceilings, you could buy a twist-knob timer that you could turn on for what... mebbie up to 20 minutes, or an hour. At our old place, I had a large-capacity charger on my house batteries (two 8D's) that had a twist-timer that I could kick on for about an hour-and-a-half, and it sure did help my peace-of-mind to know that if I walked away from the house, that big honker would NOT run unrestrained for long.

As for getting a 6v maintainer, it would not be difficult to make either an external regulation circuit, or install or adjust some internal components to knock the reference voltage on a 12v unit to 6v, however, you couldn't access the internal control wiring on most that I've seen in stores. It's not a difficult thing to build if you're adept at electronics, but I'd recommend a commercially-built unit over home-made to anyone who wasn't an experienced electronics buff.

Now one other thing... there's some 'maintainers' out there that exhibit the tendancy to DRAW current from the battery anytime they're not actually charging. I experienced this with a small Schumacher charger, as well as some Harbor Freight units... and it doesn't surprise me... in order for a REAL maintainer to actively monitor the battery it's charging, it needs to automatically STOP charging for a while, let the battery stabilize, and then MEASURE the battery's voltage, and decide to kick on again. When it decides NOT to kick on, it has to go back to monitoring voltage. Well, monitoring voltage means it'll be flowing a little bit'a current. (some much more than others, apparently)... and of course, if you disconnect the AC power to the maintainer, you may find that it runs the darned battery flat-dead. I never bothered messing with mine to rectify the situation... I just switched to a simpler charger and the wall-timer.

Edited by DaveKamp - 13 Sep 2012 at 12:11am

I checked and my chargers are Schumacher XM1-5 Automatic Maintainers. The batteries that went dry were at the end of their life and had at least one bad cell. I'm thinking as the cells go bad the maintainers continue to pump in charge and evaporates out the water. When I checked the "good" batteries under continuous charger-maintainer connection fluid levels  are fine. 

Well, I went and got the Schumacher XM1-5 maintainer from Walmart for $19.97 plus tax.  It sure looks to be a nice one.  Much better than the 12 volt ones I have previously bought from Harbor Freight.  It has a nice feature.  You can connect ring terminals  permanently to the battery leaving an end to snap into the cable running from the maintainer.  It says, if the battery is fully charged, this will not be charging more.  Will hook it up tomorrow and see how it works.  Thanks for all of the advice.  Dave