Need to add 24VDC pump to 12VDC solar/battery system?

adambeazley

Hello, I'm hoping to get a little help with the wiring in order to add a 24VDC water pump to my solar system. I currently have 3 12VDC solar panels running to a 500W 12VDC charge controller which is then wired to a single 12VDC battery. Now I realize if I want to pull 24VDC I will need to add a second battery in series to pull from, but what is confusing me, is once I wire them in series to pull 24V for the water pump, how does that affect the 12V charge controller? Will I need to utilize an equalizer in order to take care of the charging? or is there another way? Or is what I am trying to do just not possible.

PS I have been using a 12VDC water pump, but it sucks and Im changing to a much better one and the ones that I like, that really last are in 24Vdc.  Thanks for the help.

Mountain Don

Look for a 12 to 24 VDC converter. Select one that can handle the amperage you need to handle.    

OR redo the entire system to be 24 volt based. 

zoneblue

You have three choices, in order or preference.

a) reconfigure your system voltage to 24V (just one of the many reasons to do so)
b) use a DC-DC boost converter
c) use an inverter and AC pump

c is probably out because you use and like the DC pumps for a reason.
b the dc to dc boost converter would need to be big enough to cope with the start surge.
a will possibly mean a new charge controller, another battery, and an even number of panels. For PWM run 2 strings of 2 x 17Vmp panels into a 24V battery.

BTW im not aware that theres any difference in the quality of 12 and 24V pumps, at least in the shurflo 2088/4008 line. Ive used several without issues. They are sweet pumps and the 4008 are even quieter than the 2088 series.

adambeazley

wow thank you for the quick responses. While I was planning on adding a 4th panel to the system and a second battery, i would wire the whole thing in 24v, but my charge controller is only rated for 12v panels, so I guess that is out of the question. I also have other devises on the 12v, so it sounds like the step up converter is going to be my best bet. I think I can  run the 12VDC through the step-up converter and then to my 12v/24v timer which alternates between two different pumps. The shurflo's don't have near the GPH that I need, I've been looking at the Jebao DCT-4000 because the ones Ive been using (harbor freight lol) are lasting on average 40 days and I'm tired of changing them out and the manager of the store is getting mad at me because Ive returned about 30 of them thusfar.

Again thanks for all of the quick replies, this forum is amazing!

BB.

One of things you want almost never do is have a 24 volt battery bank and connect some 12 volt loads across 1/2 the battery bank...

It will cause the battery to be "unbalanced". It would be better to convert everything to 24 volts (loads, charge controller, solar array, etc.)--And if you need 12 volts, get a 24 to 12 VDC converter.

-Bill

zoneblue

+1 for bills solution. Happiness there to leads.

>I've been looking at the Jebao DCT-4000 because the ones Ive been using (harbor freight lol) are lasting on average 40 days and I'm tired of changing them

Those are odd looking pumps, looking rather like a toy. I have found with experience that pumps are like inverters. Pay peanuts = get monkeys. If you need lots of flow, then youre into the grundfos league $1500+. They make a pump that runs on solar direct, and has a soft start. But you can also parallel diaphragm pumps reasonably effectively to get (almost) twice the flow.

adambeazley

Thanks Bill and thanks Zoneblue, The grunfos are way overkill for my situation. Im simply moving water 3-4 feet from an aquaponic fish tank to some grow beds. The Jebao is a huge step up from the $10 pump Ive been using, the Jebao has a soft start and some automatic sensors which shut it down if the impeller gets stuck on something or it doesnt sense any water. They are very nice aquarium pumps.. The ones your talking about are beasts for my system. Also I need pumps that don't draw more than 8 amps. For now I will just get the 24Vdc pumps and a 12v to 24v step-up converter. as time goes on and my 12v bubbler dies, Ill see if I can find a 24V bubbler and then convert the whole system to 24V to make everything more efficient.