Battery maintainer

[Bad Wolf]

After all of the power outages last fall I decided to add an automatic backup system. I have two new deep discharge batteries, a 600 watt Xantrex pure sine wave inverter, and a switching relay also by Xantrex that automatically switches to the inverter if the house power goes out. I've tested this out and it will run my system (TARM EXCEL 2000 and 1 to 5 circ pumps) for 6- 8 hours easily.
The only fly in the ointment is that you have to leave the inverter on all the time. When there is no load it only draws <600 ma but over a few weeks that would still draw down the batteries.

While at W-Mart this morning I saw they had a battery maintainer by Schumacher for $19 and a "AAA Battery Tender Junior" for $29. Both claim to switch over to float mode once full charge is achieved and to keep the batteries at full charge.
Anyone have experience with either of these?

Also is there any down side to leaving a maintainer on the batteries for months at a time?
In reality I probably would only set it up in the winter or when severe weather is predicted.

Thanks
Greg H

 

[Jags]

While at W-Mart this morning I saw they had a battery maintainer by Schumacher for $19 and a "AAA Battery Tender Junior" for $29. Both claim to switch over to float mode once full charge is achieved and to keep the batteries at full charge.
Anyone have experience with either of these?

With those two models specifically, no. But I do use charger/maintainers (3 of them) for my fishing boat. I have found that the quality of the unit will be the deciding factor. I had a less expensive charger/maintainer (all of these float charge as well) that cooked a very expensive deep cycle. Pitched it and got a good unit. No problem after that.

 

[begreen]

What make and model did you pitch and what replaced it?

 

[Jags]

What make and model did you pitch and what replaced it?

These are bigger units. The one that went to the dumpster was a minn-kota brand. It was replaced with an older version of this:
http://www.basspro.com/Pro-Charging...Onboard-Battery-Chargers/product/46091/104360

 

[semipro]

I have the schumacher and use it on my tractor and riding mowers. It has worked as advertised for about 3 years now.

 

[DAKSY]

I have the Battery Tender Jr. Santa gave it to me in the winter of 05 for my Sportster. I've used it every winter since.
2 more on the Sporty, 3 on the Cross Bones & last winter on the Ultra. Never had an issue with any of their batteries...

 

[nate379]

I have these on several of my vehicles and also the garden tractor. http://www.amazon.com/Battery-Tender-800-Waterproof-Charger/dp/B000CITKCE

I mounted the charger in the engine bay. In the winter I plug it into the junction block that also the block heater is plugged into. No worries about no starts when it's -30* outside.

I lost 2 near new orbitbal batteries this year in my truck. Got into a fender bender and the body shop let it sit for a couple months (yes... months) in -30* temps. Batteries froze.

 

[BrotherBart]

I tried the float chargers from Harbor Freight on my two banks of 12 volt parallel batteries. Been trying them out for four years and the batteries and the float chargers are still going strong.

Seven bucks on sale often.

 

[MasterMech]

You spent serious cash on both your batteries, inverter, and your boiler system. Don't cheap out on the charger.

I have and recomend one of these. Mine is a US3300. Best I have found by FAR.

http://smartercharger.com/battery-chargers/

 

[kettensäge]

I tried the float chargers from Harbor Freight on my two banks of 12 volt parallel batteries. Been trying them out for four years and the batteries and the float chargers are still going strong.

Seven bucks on sale often.

I had 2 of those as well for several years, and liked them a lot, no problems. 2 weeks ago went to get my ATV running so I could drag the logsplitter around. Found the transformer that is part of the charger was stuck to the seat of the ATV. Pulled it off the seat and found it was partially melted. Battery was cooked nearly dry.
I was able to save the battery with a refill of acid and a trickle charge with my 2/10/30 charger. I watch the other charger and battery it's connected to like a hawk.
I don't want to think of what could have happened.



Bought a Schumaker standard charger once. Didn't work at all, kept cycling on and off, wouldn't charge. I used Schumaker in the past with good results but obviously this one was defective from the start. Returned it, got a refund (AutoZone) and bought a Vector at Lowes. It does wet-gel and AGM batterys, tests alternator output, equalizes cells and desulphonates. Very nice for about $80 bucks back then. Will also do a 80 amp quick start.


http://www.livingdirect.com/Vector-2/10/30-A-12-Volt-Charger-VEC1097A/VEC1097A,default,pd.html

 

[Bad Wolf]

Thanks to all for the advice. I'll try to get a decent charger when the time comes.

I found something interesting. I'm using my existing Schmacher Marine charger which is 15 amp, settings for reg, AGM and gel and settings for maintenance, slow and fast charge.
When I have the batteries ganged together the charger takes forever to shut down. It will reach 100% but then take hours to switch over to float (I assume). If I separate them the first battery will reach max and shut down in minutes. The second battery takes longer. The first one is a brand new Marine deep discharge (Walmart) the second one is a Max Marine deep discharge (also Walmart) I meant to get the exact same one but messed up. Not sure what the difference is they are both 845 CCA, the Max is 125AH reserve and the regular is 122AH.
I can take it back and get the exact same one if it makes a difference.
Or is this just the difference in age (8 months) and usage. I used the older one through 5-6 cycles.

 

[Jags]

If you charge them as a "bank", they should be matched as close as possible for longevity. Its not like your specs are out of whack, just say'in. I actually use "Matched sets" in my big UPS for this reason.

 

[semipro]

Batteries may have different internal resistances depending upon the condition of the plates inside. If batteries differ too much, one can actually tend to drain the other(s). As Jags said, they need to be matched closely (or isolated when not charging or discharging, but that's tough to do).

 

[Dune]

You could readily isolate them for independent charging using a marine battery switch. Not to say that a matched pair isn't superior.

 

[Bad Wolf]

Update:
I took the battery back and got the identical one to the one I already had. After a cycle or two the charger will now charge the two batteries together and shut off.

However when I connect the inverter and turn it on it will sit quietly for 10 or 12 hours drawing its 600 mA until it drops low enough and then the charger will come on but not shut off again. I've tried at the low maintenance level and at the mid charge level and it’s the same. I can only think that with the inverter on, the charger is never seeing that 100% full charge it needs to shut off. If I disconnect or shut off the inverter the charger will shut off within a minute.

So I don't quite have the fully automatic charge and switchover system I thought.
I don't really need the 24/7/365 coverage anyway. I can keep the batteries charged with the inverter off and if I see a storm coming I can turn it on for a day or two just in case. Worst case I have to get up, push the "on" switch, and I'm good for 8-12 hours before I have to start a generator.