Any ideas for improvement?
- Thread starter AF_Bob
- Start date
I'll try some different settings once I get everything up and running. I need to build 2 solar panel carts which hold 2 single 100 watt panels each. A friend and I built a portable one on wheels for him and although it's heavy (all 2X4s), it's easy to move and position. Currently, I carry 4 of them outside and lean them up against my golf cart, facing the sun. Thanks for the values you listed. I wrote them down and when my mid-point deviation starts increasing, I'll try various settings to see what balances them better. Thanks for your help.
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Rocketman, do you recommend getting one of those battery equalizers? After I try various settings and manually running the equalization to give some extra time for balancing...if that doesn't work, should I consider purchasing a battery equalizer? I just sent Li Time an email about my batteries since I noticed that they came from different lots to see what they recommend but I was curious what you thought.
I emailed Li Time about the batteries in series not exactly matching and I thought I'd share the reply with anyone in case they're using two 12V LIFEPO4 batteries in series. Li-Time said: "Our batteries are not automatically balanced, they need to be balanced manually or with an equaliser.
It is recommended that the batteries are fully charged and then connected in parallel for twelve hours to equalise the voltage, after equalisation the batteries can be connected again in series; in addition to this, it is recommended that the voltage is equalised again every six months."
Li-Time is super easy to contact and very good about responding within 24 hours. I also realized that I calculated incorrectly when I thought there was 0.7V of deviation (13.64V and 13.57). It was only .07V of deviation so I'm not gonna go crazy over getting a balancer/equalizer unless I start having close to 2% deviation.
It is recommended that the batteries are fully charged and then connected in parallel for twelve hours to equalise the voltage, after equalisation the batteries can be connected again in series; in addition to this, it is recommended that the voltage is equalised again every six months."
Li-Time is super easy to contact and very good about responding within 24 hours. I also realized that I calculated incorrectly when I thought there was 0.7V of deviation (13.64V and 13.57). It was only .07V of deviation so I'm not gonna go crazy over getting a balancer/equalizer unless I start having close to 2% deviation.
robbob2112
Doing more research, mosty harmless
I would suggest and active equalizer. There are two types, the difference being how much current it uses to balance the batteries. The active balancers can push 10amps or more. The passive version just pushes an amp or less. The difference is how fast they balance the batteries. Something like this
Thanks for the feedback. It makes sense to me when you have a bunch of 3.2V cells connected since equalizers can direct current to or from a particular cell but when you have two 12V batteries in series, it's a little tougher to grasp how an equalizer can correct a cell within a battery. I thought the battery's BMS did that so when 2 batteries are in series and 1 battery has a higher voltage, I'm assuming the equalizer forces more current into the battery that has a lower voltage. It's still amazing to me how they can make all 8 cells (in 2 batteries) get to the same level.
robbob2112
Doing more research, mosty harmless
the batteries have different internal resistances... it is a tiny variation. So the equalizer takes power from one battery and pumps it into another battery. Puting them in parallel will equalize over time, but the active balancer will shorten that time greatly. And it stays on while they are in series so no need to move connections.
Thanks for the info. At what level or percentage would you think it's necessary to get an equalizer? My variation was about 0.3% (.07V) difference between battery A and Battery B. On a system that's used frequently, I wouldn't think twice about getting one since they're pretty inexpensive. My fear (since I don't plan on using my power station regularly) is that between the SmartShunt (which draws power constantly) and the equalizer (which can probably also draw current constantly), that I would be topping it off or charging with solar a lot more than I'd want to.
robbob2112
Doing more research, mosty harmless
I am not sure... were I building the system I would probably just hook it up and let it run. It only consumes power when the batteries are out of balance, maybe a tiny bit more. If you are worried about it get a DTDP switch and wire it in through that so you can just turn it off. The problem with not leaving it connected is the batteries may drift apart while idle. Speculation on my part, but makes sense to me. You can test and see.
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