Hi,
I've been reading and watching youtube clips a lot for the last two months and I have plans to build a 50S10P 18650 pack. Well, two actually but let's start with one. Now I don't want to go into details here about this pack, nor the controls I have in mind to feed the energy into the house when the sun goes down. My question here is about charging the pack.
Some numbers, first:
- Pack minimum voltage: 3V x 50 = 150V.
- Pack nominal voltage: 3,7V x 50 = 185V.
- Pack maximum voltage: 4,2 x 50 = 210V
- PV panel voltage, I have some in series: 200 - 220V, depening on the weather. Very early in the morning I have seen 193V, but that only occours for like an hour at dawn and dusk, the rest is 200V+. The current produced seems to be of very little influence (none, as far as I can see) on the voltage.
- The PV panels cansupply 9,5A current max. I never saw that (we don't have that kind of weather, here), but the manufacturer says in theory they could.
My idea is to put a large two-way contactor in line with the PV panels. With the battery pack below 200V, the contactor directs the power to the pack. The pack sends it to my controller and the controller to the DC-AC converter as need be. When the pack reaches 200V, the contactor switches and the PV panels are connected bypass the pack and controller, and are directly hooked up to the converter. As it is normally, if I wouldn't have a pack. And when the pack is discharged to below, say, 195V, the contactor is switched back. So, my whole 'charger' is a simple volt meter controlling the contactor. I cannot charge at an amperage higher than the pack can handle, as the PV panels cannot product such a current.
There is one thing I don't know, that would make or break the idea. The big question for me is; will the pack pull down the PV panel voltage? If the PV panels want to give 220V, the pack is at 150, I think the pack will pull the PV panel voltage to below 200V. But if the pack is at, say, 195V, will it still pull the PV panel voltage down to below 200V?
I will put in diodes and fuses here and there to make sure everything goes as it should, but I leave that out of the discussion, now, too.
Please let me know what you think, prefferably from experience.
Cheers,
Hugo
I've been reading and watching youtube clips a lot for the last two months and I have plans to build a 50S10P 18650 pack. Well, two actually but let's start with one. Now I don't want to go into details here about this pack, nor the controls I have in mind to feed the energy into the house when the sun goes down. My question here is about charging the pack.
Some numbers, first:
- Pack minimum voltage: 3V x 50 = 150V.
- Pack nominal voltage: 3,7V x 50 = 185V.
- Pack maximum voltage: 4,2 x 50 = 210V
- PV panel voltage, I have some in series: 200 - 220V, depening on the weather. Very early in the morning I have seen 193V, but that only occours for like an hour at dawn and dusk, the rest is 200V+. The current produced seems to be of very little influence (none, as far as I can see) on the voltage.
- The PV panels cansupply 9,5A current max. I never saw that (we don't have that kind of weather, here), but the manufacturer says in theory they could.
My idea is to put a large two-way contactor in line with the PV panels. With the battery pack below 200V, the contactor directs the power to the pack. The pack sends it to my controller and the controller to the DC-AC converter as need be. When the pack reaches 200V, the contactor switches and the PV panels are connected bypass the pack and controller, and are directly hooked up to the converter. As it is normally, if I wouldn't have a pack. And when the pack is discharged to below, say, 195V, the contactor is switched back. So, my whole 'charger' is a simple volt meter controlling the contactor. I cannot charge at an amperage higher than the pack can handle, as the PV panels cannot product such a current.
There is one thing I don't know, that would make or break the idea. The big question for me is; will the pack pull down the PV panel voltage? If the PV panels want to give 220V, the pack is at 150, I think the pack will pull the PV panel voltage to below 200V. But if the pack is at, say, 195V, will it still pull the PV panel voltage down to below 200V?
I will put in diodes and fuses here and there to make sure everything goes as it should, but I leave that out of the discussion, now, too.
Please let me know what you think, prefferably from experience.
Cheers,
Hugo