Charge 12V 7A battery with EB55

What would I need to charge a 12V 7A battery directly from the EB55? Seems like should NOT be able to just take the cigarette lighter 12V out and hook it directly to the battery, but just not sure what I would need in between.

As I have personally never done this exact thing, maybe @Scott-Benson can correct me if I am wrong…

@BPS the cig port of the EB55 is regulated to 12VDC @ 10a so technically yes, you could just connect a cable from the cig port to your batteries. Something like this I imagine would work…

** I would recommend double checking polarity on the outputs first and note that this “charge” won’t be as fast as an actual battery charger. Also won’t be monitoring your 12v batteries voltage to supply any different “charging cycles”. It would be a solid 12Vx7a, so roughly 84w charge to the battery.

Well, I was also wondering since I have a charge controller, can I hook the DC output of the EB55 as the input to charge controller (connect to what says solar panel)? This is rated at 8A so I would need to use one of the lower outputs as 10A would be too much for it. I also have an AC200P that has 12v/3A outputs. I wouldn’t think the charge controller would know the difference between PV input and straight DC input.

Of course on sunny days, I will just charge the 12v battery with a 100W panel I have using the charge controller.

The item you attached looks interesting as it does show connecting directly to the batter from the power station. I will try to do a little more research on it since it has a charging light I am wondering if it has a built in controller.

As an aside, I am trying to avoid charging the battery with the AC outputs as to not use power through the inverter.

My thought is that a 7 amp current to charge a 7 amp hour battery is way too much charging current. Don’t know what the battery chemistry is but I would not want to charge it with much more than 2 amps. If it was me, I would just connect an AC powered battery charger to the AC outlet that can output a correct amperage into your battery you want to charge. The efficiency loss is not going to be large for a battery that small and you state you only need it when you can’t solar charge in the first place.

You may be able to connect direct from the EB55 to the battery but the current the battery will try to draw if low may exceed the 10 amp limit and overload the EB55. No problem if it does, you would just need to re set and try another method. In either case, a 7 amp hour battery cannot be charged at that high a rate without damage and overheating.

The battery is small.

I am assuming that I will have no trouble charging from my solar panel with the zeallife charge controller. Haven’t tried it yet but there are many videos showing this process. The batteries are for my security system and if we are out of power for a few days I want to keep it working. I bought 2 backup batteries (not here yet) and will test with solar charging once they arrive. This way I will have 3 (one is getting old though) so that I can keep them charged up and ready to go.

Worst case is that I do have a battery tender that I can run with the AC outlets on EB55 or AC200P or just plug the entire security system into the EB55 and let it charge that way.

I did send a question to Zeallife about the charge controller and if you can send just a standard DC current into it. Is there a difference between PV DC current and battery DC current? I wouldn’t think so. So as long as the Battery DC voltage plugged into the Solar Panel input does not exceed 8A and 12V logically it seems like it should work. Again, assuming there is no difference to the charge controller if the voltage comes from a solar panel or a battery.

The auto battery uses lead-acid cells that charge at 2.2 VDC per cell or 13.2 VDC for the entire battery. Applying just 12 volts from the EB55 (I have one) will not be enough unless the battery is way below 11.8 volts and will be extremely slow. I recommend using a commercial battery charger instead of the EB55.
You can use the EB55 to run any 12 volt devices.

Thanks Ray.

The battery isn’t an auto battery, it is a smaller lead-acid rechargeable for my security system. More like a motorcycle battery. I was hoping to use the charge controller I got for when I am charging through solar panel. This seems to work fine. When I hook the EB55 to the PV input on the charge controller, it recognizes the voltage, but doesn’t show any amps. Also, the solar panel icon does not show up.

Confusing to me as I don’t understand how the charge controller would know the difference between DV volts and PV volts. The charge controller has a max PV input of 50 VDC but no minimum so I wouldn’t think it is that it is only 12V.

So if there is somehow a difference between PV (putting out DC Volts) and the EB55 putting out DC, I would love to know.


As a lead acid battery you still need more than 12 volts for any current to flow for charging. And a PV system can generate more voltages but the controllers will still limit its output to just 12 volts. If you can find a model with an adjustable output then set it for 13.2 volts, or ask around for someone who can modify or build a controller to put out the 13.2 volts.

EDIT: There is another way but it adds cost. You can use a Boost Convertor which takes in a voltage and outputs a higher voltage. Since you need to charge, the current is not high, so a boost convertor can take the 12 volts from the EB55 and increase it to the needed 13.2 volts.

I did see some DC to DC chargers, but most were expensive. This setup I am looking at is kind of a worst case scenario where I don’t have any sun for few days. I have 2 new batteries and the one that is in the system now (it gets charged from the AC of the system itself). I should have at least a few days of battery power with the 3 batteries. So I did do a test yesterday of charging a battery with a Battery Tender I have which uses AC. Of course that worked fine. I was just trying to avoid going through the inverter and using more power out of the EB55. I don’t think the $100 for the DC to DC is worth it.

What you are saying seems to make sense with the controller. It is not getting enough volts to activate. It doesn’t have anything to do with where the DC is coming from.

Thanks again.

The regulated DC output from the EB55 is 13.0 volts under load.

So I did find a relatively inexpensive 300 watt model that has a 24V 3A output on it. Since the Volts are above the 13-14 range, would this charge the 12 volt battery? Since it is 3A I assume it will be a slow charge.

Not sure what you found, but you say the output is 24 volts @ 3 amps and that voltage would be too high to charge a 12 volt battery. The simplest thing you can do is buy a 2 to 3 amp automotive battery charger that has multiple battery chemistry types that can be selected to match the battery chemistry type that you have but is not specified.

I would run it through a solar charge controller. Nobody has been able to answer how one of these charge controllers knows the difference between PV DC current and Battery DC current. It seems as though a solar charge controller that can handle 24V DC from a solar panel should be able to receive 24V DC from the output of a battery system. If there is a difference and the solar charge controller would not buffer the 24V input to the appropriate output for the battery, then this won’t work.

Here is a link to the units I was referring.

I would think the charge controller would work but it seems like a whole lit of work rather than simply buying a small ac charger and simply charging your batteries with it.

I suppose. Still new to this but what I have seen is that anytime you fire up the AC the inverter eats the battery much more than just straight DC. Of course I haven’t been able to really test this process but it seems like I can get twice as much life out of a charge using DC rather than AC. My testing so far has been with my CPAP machine. If I use 12V adapter, I get twice the time then when I use the AC.

Thanks for all the input!

You will notice very little difference. The 12 volt regulated outputs consume power similar to AC. Going through all the other work arounds will consume power in the conversions.

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OK, good to know. Thanks!!