Battery Maintainer Question??

[rainjer]

I installed a Harbor Freight 12 Volt Onboard Battery and Alternator Load Tester and 1.5 Amp Three Stage Onboard Battery Charger/Maintainer in my teardrop. I also have a kill switch for the battery.

http://www.harborfreight.com/cpi/ctaf/d ... mber=65928
http://www.harborfreight.com/cpi/ctaf/d ... mber=99857

Does the 1.5 Amp Three Stage Onboard Battery Charger/Maintainer draw power if it is not plugged into shore power?

The reason I ask is when unplugged the charger and moved my trailer last week I had a full charge on the battery according to the battery tester. Today in is showing in the red/low yellow. (the battery box also has a tester and I get the same results. When I check it with a volt meter I get 12.4 volts. I know I don't have any other drain because the kill switch key was not in the socket.

What should the volt meter read if the battery is fully charged?

Jeremy

[RonS]

Fully charged would be 12.6V 12.4 doesn't sound too far off for sitting for a week. Many batteries will self-discharge slightly.

[Shadow Catcher]

Wet Standard at rest 100% is 12.65 75% is 12.45
Wet maintenance free or AGM at rest is 100% 12.80 75% 12.60

I have one of the HF three stage maintainers and I feel there may well be a drain when unplugged.

[Arne]

any good ones will have diodes in them to prevent back flow....

battery tenders do have this one way diode. my battery tender is hooked up permanently to the battery. when I plug in shore power it starts to charge the battery.... no shore power, no back flow.

[rainjer]

Well I did a test. I charged the battery back up and disconnected the battery maintainer. I have checked the battery every day. It is holding at 12.8 volts. That makes me believe that the Harbor freight maintainer allows back flow of current...It looks like I will need to put some sort of quick connect or switch on it to prevent it when it is not on shore power.


Jeremy

[Justin & Katy]

any good ones will have diodes in them to prevent back flow....

battery tenders do have this one way diode. my battery tender is hooked up permanently to the battery. when I plug in shore power it starts to charge the battery.... no shore power, no back flow.

What kind of tender do you have?

[Arne]

I have a 'battery tender junior'... puts out .75 amps when needed. When not needed it has no back flow of current from the battery.. it incorporates a one way diode for current flow.

[Justin & Katy]

i was just looking at those. Are you completely satified with it? Does it take a long time to bring a battery back up?

[Carter]

I have a Battery Tender Junior that has been in use with the same marine battery since 2004. I am completely satisfied. They are a "trickle" charger and only rated at 750ma compared to even low end conventional charger that is 6 amps or up. It takes awhile if the battery is down. I use only that and recharging from the tow vehicle when on the road. I credit the long life of the marine battery to the low charge rates but I'm just guessing.

[Arne]

how long it takes depends on how much you draw.. .75 amps is not much. I only run my fantastic fan and interior lights and have no problem. If you run a string of decorative lights for hours at night, I'm not sure....