Hello everyone I just bought a GoodWe hybrid inverter GW20K-ET, unfortunately it only has one battery connection. On this connection the hybrid inverter can charge/discharge the battery with 50A. GoodWe offers Lynx F Plus+ batteries that can be connected in parallel. This battery can be charged/discharged with a maximum current of 25A. The question is: if you connect two of these batteries in parallel, can you charge and discharge them with a total of 50A, or only with 25A? Does anyone have any information here? Thanks for any insights! Chrisgraham
Well, theoretically, in a parallel circuit of two legs of equal resistance in each leg, the current to each leg of that circuit is 1/2 the total input current.
Altoidfishfins is correct. Probably need to ask the seller but I would bet that is why the extra batteries state "battery can be charged/discharged with a maximum current of 25A." The increase batteries give you more current - meaning - more power (wattage) but doesn't change the recharging circuitry. This would be my bet but ask the seller.
The charger specs are 50 amps, so 2 batteries should be fine. But I have not dealt with an inverter using 200-800 volts DC...make sure you get some HV gloves and other appropriate safety gear. ETA: You do realize this is a 3 phase 400 volt inverter, right?
It is interesting, you have two operations, charging and discharging and a lot of it depends on the type of batteries. What is safe for lead acid can be deadly for LiPo. Problem is the internal resistance of the batteries. You can buy batteries with cells in parallel. but the factory matches them up so they are close or so they say. Don't know how the internal resistance would be changed, state of charge, capacity of the battery, age or number of discharge cycles, temp, but a lot of factors could take place. If you bought a set that were matched, ran them in parallel, charged them in parallel, etc. then they should work well. If not you could charge one with most of the current. A guy who is into drones, really wrings out a battery, has a good discussion on the internal resistance and charging. In particular, balancing the charge in each cell. Parallel vs. Series Charging A wonderful gentleman from the Netherlands contacted me recently asking about parallel charging versus series charging. He wanted to know how best to charge six of his single-cell LiPo batteries at the same time. Parallel charging adapters are readily available, so that must be the best way, right? Absolutely not! Parallel charging can be very dangerous. Even experts from well-known battery manufacturers "consider parallel pack charging to be highly dangerous and should not be attempted even by experienced users". The problem with parallel charging (or even using your batteries in parallel) is that, when hooking up batteries in parallel, you are doubling the capacity of the batteries while, and this is important, maintaining the voltage of one of the individual batteries. What this means is that your charger, which normally monitors the battery while charging to prevent overcharging, cannot see all of the individual batteries' voltages - it can only see one. Another problem with parallel charging is the inequality of the batteries. If the two batteries (and the cells contained therein) were from the exact same production lot, had the exact same chemical composition and age and charge history and everything else - in other words, if they were completely identical - parallel charging would be okay. But a consumer (that's you) will never be able to replicate those conditions, or even come close. The more those parameters differ, and considering the questionable balance charging techniques that many battery chargers use, the higher the chance of over charging and thermal runaway (more on that in the next section). But what about batteries that are built in parallel? Doesn't the fact that batteries are sometime constructed in parallel mean that parallel charging is safe? Like I said before, if you can match all those parameters to be identical, parallel charging is okay. At the factory where they make the packs, manufacturers are constantly monitoring and testing the materials that make up the cells. Each cell is labelled with a UPC code that contains the entire chemical makeup and history for that cell. When a manufacturer assembles a battery, a computer scans and sorts the cells into compatible matches. Only then is it safe to parallel charge these cells. However, when you charge a LiPo battery at home, even if it is already constructed in parallel, you don't need any fancy parallel charging boards - the work is already done for you, and you simply need to charge it as you would a normal battery. Don't know about discharge in parallel, but wouldn't just hook it up with out asking either. Please, please, don't use parallel charging cords. There is no safe way to use these. Parallel charging simply tempts fate. You will be able to find thousands of successful attempts to parallel charge batteries around the web. These are simply people that have not yet managed to burn their home down. Every battery expert I have talked to agrees on this. Series charging is the safer of the two methods (meaning it's no less dangerous than straight-up normal charging) IF you set up your charger the right way. If you want to charge six single-cell LiPo batteries — that are all the same capacity — you can wire them up in series, set up your charger as if it were a six-cell LiPo, and balance charge your LiPos. The act of balance charging them is essentially making the charger individually charge each cell, making sure they are all kept at safe levels. If you only have a single-port charger, series charging is the only safe way to charge multiple batteries at the same time, but wiring them up properly is pretty complex and not something a beginner should attempt. And the absolute best way to charge multiple batteries at the same time is to have a multi-port charger, like the Dynamite Prophet Sport Quad mentioned above. If you find yourself needing to charge many batteries at once, do the smart thing and purchase a charger (or chargers) that will fit your needs. An Expert's Guide to Understanding LiPo Batteries — Roger's Hobby Center
The batteries mentioned in the OP have communication between the BMS's, so there should not be an issue with parallel connection, charging or discharging. For other battery types, @duane 's post above is spot on. A lot can go wrong if things aren't "just right."
Agreed , Im solar for years and 7 systems now , all different . Battery's and connection checking is the most labour.
I have already solved the problem.Thank u all. Yes, I have consulted with the seller, although the resolution time was relatively long. But the result is good. Thanks Survivalmonkey forum.
