AMP Question
- Thread starter niles2012
- Start date
Bud Martin
Solar Wizard
- Joined
- Aug 27, 2020
- Messages
- 4,844
60A is the DC battery charging current.
For simplicity, so if it is 12VDC system then the power will be 12VDC * 60A = 720W of power which means the AC side of the charger the current will be 720W/120VAC = 6A pull from the AC outlet, but the actual will be higher due to conversion loss so more likely to be around 7A or so.
Does the battery spec show that it can be charged at 60A (the BMS is the limiting factor)?
Thank you very much for your fast response. I’m putting things together now. I’m getting an Overkill 120 BMS and a kit of 4 units of cells from Battery Hookup to start a 100ah battery build. I’m doing everything from Wills videos and this forum.
Bud Martin
Solar Wizard
- Joined
- Aug 27, 2020
- Messages
- 4,844
If you have Kill-A-Watt then you can see how much power the charger uses while it is charging the battery, it is a really good tool to have.
Great, that’s something I didn’t think of. I’m tempted to try a bigger project but I’m slightly afraid of getting hurt or starting a fire. A watt meter to start measuring things and buying quality components for a 100ah battery seems like something that can all be used in the future. Does that sound right? And I have a small multi meter now. Is that sufficient to test for function or a problem?
Bud Martin
Solar Wizard
- Joined
- Aug 27, 2020
- Messages
- 4,844
The Kill-A-Watt is also good the measure the power usage of the load for period of time so you can figure how much power the load really uses and then you can use that data to find out how long the system will run based on load consumption (the conversion loss will have to be factor in), with the data you can also use it help you figure out what power waste you can reduce or eliminated.
Cajunwolf
Solar Enthusiast
Kill-A-Watt also makes an 8-outlet power strip with memory functions. I find it helpful to get the wh/amps/pf, etc, usage of several items at once.
Steve_S
Offgrid Cabineer, N.E. Ontario, Canada
Just an EXAMPLE...
I run with LiFePO4 (LFP) Batteries which are 99% Efficient compared to Lead Batteries @ 88%.
A "Typical" 100AH LFP Battery can take up to 50A (0.5 C-Rate) for two hours to charge.
I have a Separate Charging system aside from the Solar & Other gear. Now I do have a fairly large battery bank at 1190AH but I use the separate charger @ 75A. To Charge my 24 Volt Battery Bank @ 75A, the Charger (94% Efficient, most are NOT) pulls 120VAC/23A.
Some quick numbers to put things into place.
NB, We suggest never exceeding 250A Draw from a Battery Bank. If you start reaching that level of draw, consider a Higher Voltage (drops Amps pulled) or using Paralleled systems.
12V/100AH = 1,280Wh/1.2kWh 4x100AH cells -4S BMS
24V/100AH = 2,560Wh/2.5kWh 8x100AH cells -8S BMS
48V/100AH = 5,120Wh/5.12kWh 16x100AH cells -16S BMS
We suggest typically to NOT exceed 250A Draw from a battery bank. Stacked Inverters extend that.
12V@250A=3000W (25A@120V, 12.5A@240V),
24V@250A=6000W (50A@120V, 25A@240V),
48V@250A=12,000W (100A@120V, 50A@240V).
(Uncorrected for inefficiencies) Excluding Surge Capacity Handling (High Frequency = X2, Low Frequency = X3)
Value Grade Inverters can be 82-88% Efficient. Tier-2 can be up to 92% while Tier-1 (Premium) can be up to 96% Efficient.
I run with LiFePO4 (LFP) Batteries which are 99% Efficient compared to Lead Batteries @ 88%.
A "Typical" 100AH LFP Battery can take up to 50A (0.5 C-Rate) for two hours to charge.
I have a Separate Charging system aside from the Solar & Other gear. Now I do have a fairly large battery bank at 1190AH but I use the separate charger @ 75A. To Charge my 24 Volt Battery Bank @ 75A, the Charger (94% Efficient, most are NOT) pulls 120VAC/23A.
Some quick numbers to put things into place.
NB, We suggest never exceeding 250A Draw from a Battery Bank. If you start reaching that level of draw, consider a Higher Voltage (drops Amps pulled) or using Paralleled systems.
12V/100AH = 1,280Wh/1.2kWh 4x100AH cells -4S BMS
24V/100AH = 2,560Wh/2.5kWh 8x100AH cells -8S BMS
48V/100AH = 5,120Wh/5.12kWh 16x100AH cells -16S BMS
We suggest typically to NOT exceed 250A Draw from a battery bank. Stacked Inverters extend that.
12V@250A=3000W (25A@120V, 12.5A@240V),
24V@250A=6000W (50A@120V, 25A@240V),
48V@250A=12,000W (100A@120V, 50A@240V).
(Uncorrected for inefficiencies) Excluding Surge Capacity Handling (High Frequency = X2, Low Frequency = X3)
Value Grade Inverters can be 82-88% Efficient. Tier-2 can be up to 92% while Tier-1 (Premium) can be up to 96% Efficient.
Cajunwolf
Solar Enthusiast
That's the one!
While looking for a 12v 60 amp or higher charger I see the Inverter Store has a combination charger/inverter. I haven’t ordered an inverter yet. I’m going through Wills book and these posts and so far haven’t seen anything good or bad about them. Is there a reason?
I haven’t found much on putting together a 12v 100ah battery from 4 of the packs of small cells spot welded together. For $220 plus shipping I was thinking it’s the way to go. But as I read and watch pretty smart guys building a budget battery not many use the small cells. Is there a inherently negative side to this? And should I be posting on the Beginners?
Ampster
Renewable Energy Hobbyist
I drive two Teslas that use small cells, so I do not believe there is anything inherently wrong with that. There are plenty of people that have developed skills to do that to scale. It could be a learning experience for you. However most small cells are a more volatile chemistry and that is the biggest negative. There are some LFP cells that come in small formats and that might e a safer place to start. Twelve years ago I built some ebikes using Headway Lithium cells. I naively abused them and the worst thing that happened is they vented and the room smelled like Ether.
My research so far shows the small cells to be more robust, and have fewer issues, especially in a mobile situation than thin aluminum square cells…
No compression, no orientation preference, and easier to fit in a wider variety of packaging shapes.
They often are heavier than the square cells though.
