Hi, I recently bought an open box growatt 24v and had plans to put 2 12v batteries in series. I have become too scared to do this as I don't want to damage the BMSs. However, I need to test it. I hooked up AC to it and nothing happened. After reading a bit, I found that there needs to be a battery input. Can I use a battery charger that outputs 24v to simulate a battery? Barring this, I don't have any way of testing it. Kind of a noob! Thanks!
Growatt 24v- can I use a 24v battery charger to simulate battery?
- Thread starter gilcontr
- Start date
sunshine_eggo
Happy Breffast!
In most cases, no. A charger needs to see a battery voltage to respond to it.
If you have a 24V power supply that outputs a voltage acceptable to the inverter and sufficient current, yes.
If you can measure a voltage on your charger with the leads disconnect, maybe.
If you have a 24V power supply that outputs a voltage acceptable to the inverter and sufficient current, yes.
If you can measure a voltage on your charger with the leads disconnect, maybe.
They are some 280ah 12v builds with 150a JBD BMSs. They are a year apart so I don't think I can pull them apart to make a 24v battery
8ve been hoping of selling them and just getting a smaller eg4 24v, but noone is buying them. Basically new, too.
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sunshine_eggo
Happy Breffast!
They are some 280ah 12v builds with 150a JBD BMSs. They are a year apart so I don't think I can pull them apart to make a 24v battery
Shit yes you can!
Charge them to 14.4V in parallel for two hours.
confirm all cell voltages are above 3.45V
Wire for 24V
Use a #2 pencil with both ends sharpened as a pre-charge resistor before connecting the battery.
Do you mean using a 24v BMS and rewire all the cells? They are all EVE280 grade a, but the ones older ones (with almost 300ah capacity) are physically smaller than the newer ones (about 286ah). That, and I've always heard that you need to buy them in a similar batch to have batteries that are close in internal resistance.
Or do you just mean put them in series and send it?
Thanks!
sunshine_eggo
Happy Breffast!
This. Make sure both batteries are fully charged first and then put them in series. When you connect 24V, you really need a pre-charge resistor to prevent triggering BMS short circuit protection.
Best practice as recommended is to replace both BMS with a single 8S, but for test purposes, I wouldn't hesitate to run whatcha brung.
Got it! Thanks!!!
So I ended up plugging a desktop charger running 25v / 2 amps and it started right up. Whirring fans and all. And the readout made it look like it was inverting so that's good! Now, to figure out what to do with the batteries. Thank you all!!!
sunshine_eggo
Happy Breffast!
Yes, but I mean on a permanent basis. You're still saying run them in series?
sunshine_eggo
Happy Breffast!
Whelp...
Since they are different size and vintage, I would be inclined to initially keep them separate and evaluate their performance.
If you decide to make it permanent, you can still keep them grouped as 4S of each type, but remove the 4S BMS from each and use an 8S BMS.
Got it. Thanks!
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