AC charger

[FilterGuy]

I have no problem to let the charger in place at target voltage IF the BMS can disconnect the battery from charger in case of overvoltage

The problem is that even when the BMS is working correctly, the cells will be held at the target voltage and never be allowed to go to their resting voltage. It is probably not a big deal for several hours or even over night, but holding them at the high voltage will tend to lower their lifespan.

 

[BlackWaterPark]

Thanks for report on the Genetry. I keep forgetting it's out there but need to remember it. So you've asked it to charge a battery that was so low it's BMS's had engaged the LVD? I'm may be not using the right term. I've had to restart a few LiFEP04's batteries using a power supply because they we're so discharged the inverters refused to turn on.

Well, sort of. I set the lvd to a somewhat higher voltage than the batteries bms, too avoid the batteries ever going to sleep mode from extreme depletion. I have however ran them to that point, and had the inverter failsafe come on, which whistles really loudly to let you know your at your lvd setpoint. Plus, the latching power button is pretty clever, as it lights up in 5 different colors which can be either solid or blinking to give you an at-a-glance status report on what's happening and how the inverter is currently functioning. If your battery's go to sleep, you can wake them by manually engaging the charge mode, or if i just flip my breaker to the genset while it's running, I have it programed in the inverter so that it auto switches to charger mode the moment it detects any current in the AC input side. The inverter itself has an internal (5v i think?) backup so the display can run and be programed even if the batteries are so low as to be dead. Sid put a LOT of thought into this thing.

 

[BlackWaterPark]

I'm not charging a golf cart.

Downloaded all the files for the Lester chargers, couldn't find any documentation for the setpoints. Hell, I couldnt even find the price or even the ordering form or a link to vendors (if they don't sell direct, which... who knows?). Confusing website anyway. But, whatever else, a 48v charger that tops out at ">12a" on the ac input side is, in my opinion, not very suitable for trying to charge up a typical residential off grid bank, or larger grid connected backup unless your plan is to basically trickle charge with grid power to restore backup use power. My system is 300ah at 48v nominal, and that's not even really a big system at all. I'd want at least 3 of these things working together, if not 4.

 

[FilterGuy]

I'm not charging a golf cart.

No, but the Lester can charge any LiFePO4 battery.

 

[FilterGuy]

Downloaded all the files for the Lester chargers, couldn't find any documentation for the setpoints.

Yes, That is frustrating.

I couldnt even find the price or even the ordering form or a link to vendors

A simple google search brought this up: https://www.amazon.com/Lester-Summit-II-Battery-Charger/dp/B07N1WHXS6/
It is common (But often frustrating) for manufacturers to not have "Where to buy" info on their site. The reason for this is that they don't want to piss off any of their distributors by not listing them while they do list the competitors. It is simpler to not list the distributers than keeping the site up to date.

a 48v charger that tops out at ">12a" on the ac input side is, in my opinion, not very suitable

According to the datasheet, the charge current is 22A for a 48V system.



For a 300Ah system, it would take 300Ah/22A=13.6Hr to charge from zero to full. In the original post @MaximusAnonus stated a requirement for 30A so this may not be sufficient. However, this could be fine for other applications. Even if I am trying to arbitrage between peak power price and non-peak power price, this may be sufficient.

 

[BlackWaterPark]

Yes, That is frustrating.


A simple google search brought this up: https://www.amazon.com/Lester-Summit-II-Battery-Charger/dp/B07N1WHXS6/
It is common (But often frustrating) for manufacturers to not have "Where to buy" info on their site. The reason for this is that they don't want to piss off any of their distributors by not listing them while they do list the competitors. It is simpler to not list the distributers than keeping the site up to date.


According to the datasheet, the charge current is 22A for a 48V system.

View attachment 117960

For a 300Ah system, it would take 300Ah/22A=13.6Hr to charge from zero to full. In the original post @MaximusAnonus stated a requirement for 30A so this may not be sufficient. However, this could be fine for other applications. Even if I am trying to arbitrage between peak power price and non-peak power price, this may be sufficient.

The quoted amperage limitation was for the ac input side. For a grid tied backup power situation, it's fine for smaller banks I'm sure.
I do get why some companies do elect not to list prices or vendors, but i prefer when they at least list their MSRPs and their list of verified and trusted resellers. Personally, I'll opt for those companies that prioritize their end user customer base over their vendors interests any day of the week.

 

[MaximusAnonus]

No, but the Lester can charge any LiFePO4 battery.

The Lester is also 2 or 3 times the price of the MW SE-1500-48.

 

[MaximusAnonus]

I used Meanwell power supply in the past with great success. I used RSP-1000 and RSP-2000 few years ago. Most continuous current power supply will do perfect job to charge lithium.
Interesting fact, I used a RSP-500-12 as DC-DC converter as those unit can take AC or DC input.

Oh, also noted those power supply can output 125% current continuously. So a 21A power supply is in fact a 26A

I can get 3 of those genuine Mean Well RSP-2400-48 power supplies for around 1000USD from a local distributor with warranty and everything.
Can someone confirm that my plan of setting these to 53V (they can be set anywhere between 43V-56V but I won't be charging to full so 53V on an 16S battery bank is ok) and then using Home Assistant and a smart relay to turn them on during times of low light/low electricity prices (here it's usually every early saturday morning and every early sunday morning) to charge the battery bank will work?
I personally don't see a reason why it shouldn't. But I've never done anything like this.

 

[timselectric]

Yes, that would work. As long as you have a BMS to protect the battery in case something goes wrong.

 

[FilterGuy]

I can get 3 of those genuine Mean Well RSP-2400-48 power supplies for around 1000USD from a local distributor with warranty and everything.
Can someone confirm that my plan of setting these to 53V (they can be set anywhere between 43V-56V but I won't be charging to full so 53V on an 16S battery bank is ok) and then using Home Assistant and a smart relay to turn them on during times of low light/low electricity prices (here it's usually every early saturday morning and every early sunday morning) to charge the battery bank will work?
I personally don't see a reason why it shouldn't. But I've never done anything like this.

Yes, they will work in a set-up like you describe because:

1) They will not be continuously on
2) You are only charging to 53V

I make these distinctions because these are power supplies, not multi-stage chargers. As such these will charge to the target voltage and then hold the battery at that voltage. Keeping the voltage at a high charge voltage for an extended time will degrade them.

You describe a scenario where the units will only be on at select and reasonably short times so this is not an issue. Furthermore, the target 53V voltage you are planning to use is not very high. In fact, it is more like the float voltage that many systems are set to. (53V is not going to put a full charge on the batteries)

 

[MaximusAnonus]

On my old system I used to simply shut the solar off during winter nights but on my new (almost 40kWp) array with the big battery pack (over 80kWh) I bet I can get close to 24/7/365 running solely on solar and when it gets dark and I get to the "only 5 hours of daylight and a shitty daylight at that" territory in December-January I can simply top up during the night when electricity is like 10c/kWh opposed to my normal rate of 50c/kWh.

But it helps me sleep at night when I discuss these setups with someone else. As again I've never done anything similar. And while some ideas sound good on paper they might suck in reality.