Air pumps for better battery charging



  • john pjohn p Solar Expert Posts: 814 ✭✭✭
    Re: Air pumps for better battery charging

    Stephendy as I said when testing with air you do get benefits and the tall ones seen to benefit a bit more than the short ones . but the benefits get lost a bit if used on a solar system as I found to get best results the pump has to be running all the time, this uses up a fair amount of battery power, Now if used on any type of vehicle then the extra amount needed from the engine /alternator is not significant.
    But yes you will get longer battery life from them using air .
    For many of us with small systems the extra panel power needed and possibly an extra battery is not worth the expense to make the batteries last longer,, but in some cases it maybe.
    I just gave the figures and left it to others to decide what is best for them
  • stephendvstephendv Solar Expert Posts: 1,571 ✭✭
    Re: Air pumps for better battery charging

    Hey John,

    There are a few factors to my specific installation which makes the air system attractive, mainly because I've oversized the battery with respect to the PV, but also a number of others:
    - I've got tall cells, about 80cm high
    - For most of the year, the battery will only ever do very light cycling, maybe 10% daily. (Usage will increase in a few years time)
    - I only plan to install 2.6kW of PV, which will give me a peak charge current of 4.5% of the C20 rate. So I'm scraping on the low end of the charge current.
    - I spent a lot on a quality battery bank that should last 15+ years

    Given the above, the batteries are prime candidates for stratification unless I EQ more often, which I'd like to avoid as much as possible. So the air system starts to seem worth the effort and money (think it's about 200 Euros), to protect my much bigger investment in the battery bank ;)
  • john pjohn p Solar Expert Posts: 814 ✭✭✭
    Re: Air pumps for better battery charging

    Stephhendy yes your batteries will benefit from doing this, and certainly help make them last longer,
    I do have some worries your system , You said you only be charging at 4.5%% that is certainly on the low side , So this makes me ask this. how you going to equalize charge them ?/ that is still going to be needed.
    I cant see your solar system being able to provide enough equalize charge for long enough after they have been recharged for the day after using 10% /
    Really an equalize charge needs to be for about 2 hours 3 even better. This is a never ending problem in just about every solar panel powered system, having a system with enough reserve panel power to do that.And its one of the main problems of short battery life using std lead acid batteries,

    On another note are you going to be the one to drill the holes and insert the tubes. or are they already fitted with the tubing?
    How many cells do you have?
    Are they supplying the pump? or they specified a pump? or that something you still have to think about?
    AT 30 in high there is a fair bit of water pressure you are going to have to overcome.
  • stephendvstephendv Solar Expert Posts: 1,571 ✭✭
    Re: Air pumps for better battery charging

    I have a dirty diesel gen which I need to exercise once a month anyway, so if I do that for 2 hours or so in the early hours of the morning when starting an EQ, the solar should be able to take over the rest of the charge.

    Still waiting for the distributor to get to me about installation process, but as I understand it, everything should arrive in a kit, pump + tubes + connectors. The holes in the bat is a good question as I don't remember seeing anything predrilled... that may just be a deal breaker for me, as I will not be drilling holes in them myself! No way!

    I noticed in the Sunny Island inverter menus that one of the relays can be assigned for "electrolyte circulation system", so I could hook this up to control the pump :D

    Battery is 48V, 700Ah C5.
  • john pjohn p Solar Expert Posts: 814 ✭✭✭
    Re: Air pumps for better battery charging

    Stephendy If the batteries do not come predrilled then you will need to get in writing that they are going to honour any warranty claims, As they could easily claim you damaged the batteries by drillling holes in them. And as you said they are expensive you dont want that hanging over your head.
    another thing I found it impossible to air a cell evenly with only one tube they need 2 per cell. as remember they are stationary not moving about like in a vehicle (forklift etc)
    The batteries I did the experiments on were sent to a hazardous waste disposal depot as having holes in them for obvious reasons makes then a hazard if one was knocked over. I suggest you make some protection for them so under no circumstance could one be knocked over. its up to you.
  • JethroJethro Registered Users Posts: 1
    edited March 2019 #67

    Hi John @john p , It has been a few years so hopefully you are still on the forum. I read your injection specs and results with great interest and thanks.

    My one question is: where did you put the two air injections tubes in each cell? The commercial systems use a single tucked in one corner from what i have seen, but you state clearly two were needed for uniform circulation!?

    Does anyone else know where John put his two injector tubes to achieve circulation uniformity?

    I want to fit my new 48V bank of RV batteries with air injection to compare life with my existing set of identical batteries to check out air lift circulation for myself (and maybe get a life extension to offset the effort). They are stationary (float charging from the mains) most of the time.

    TIA, Jethro

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