Is there anyway to check/workout/confirm a batteries capacity?

Some sort of load test?

I am going to order cheap batteries from Aliexpress as soon as Januworry is over. Any advice would be appreciated. 

At the moment, I am just trying to keep the WiFi and a couple of 12v LEDs up. 

6 minutes ago, McGuywer said:

At the moment, I am just trying to keep the WiFi and a couple of 12v LEDs up. 

Depending on the type of battery and capacity the test load will vary. If you know the actual load you can use thar size dump load while testing Ah. 

Just now, Scorp007 said:

Depending on the type of battery and capacity the test load will vary. If you know the actual load you can use thar size dump load while testing Ah. 

Please type slowly. 😝

 

I am looking at a “100ah lithium” battery for R900. The flags are there but I a bit stuck. 
How do I confirm that it is 100ah. It is rated at 12v

https://m.aliexpress.com/item/1005005152516424.html?spm=a2g0n.shopcart.0.0.7b8d38daLidXcs&mp=1&gatewayAdapt=Pc2Msite
 

Charge it fully. Discharge it with a constant load and down to a specified voltage. You should be able to calculate usable capacity with duration and current.

1 hour ago, McGuywer said:

Please type slowly. 😝

 

I am looking at a “100ah lithium” battery for R900. The flags are there but I a bit stuck. 
How do I confirm that it is 100ah. It is rated at 12v

Get 2 car single headlamp bulbs of 55W or use a single dual filament. This gives about 9A load. A 100Ah should thus run for about 11 hrs. It gives a good estimate. Then using say 4 the time should be about 4.5hrs. 

Where are you based? PM me if in Gauteng. 

Also, not to throw in a curve ball, but what if I put this in my gate motor? 

At the moment, the 12v7ah is just not making it. Our gate is constantly on manual, replaced the battery about 3 months ago. 

Will need to replace sometime again. 

I know if I put a Lithium in, I need to check the voltages, so possibly changing the power supply as well.

A lithium battery for the gate motor can work. If you go to big, you could burn out the charging circuit. But probably the combination of draining the lead acid too much and not charging it fully is what kills the lead acids. Make sure the lithium battery can handle the voltage supplied by the gate motor circuit and that it shuts down when drained.

13 minutes ago, McGuywer said:

Also, not to throw in a curve ball, but what if I put this in my gate motor? 

At the moment, the 12v7ah is just not making it. Our gate is constantly on manual, replaced the battery about 3 months ago. 

Will need to replace sometime again. 

I know if I put a Lithium in, I need to check the voltages, so possibly changing the power supply as well.

Gate motor will take too long and you still have to measure how many times the gate worked. 100Ah too big for charger as said by Frivan. 

1 hour ago, McGuywer said:

https://m.aliexpress.com/item/1005005152516424.html?spm=a2g0n.shopcart.0.0.7b8d38daLidXcs&mp=1&gatewayAdapt=Pc2Msite
 

There is something very suspicious with the batteries from this link. They list 48V 100Ah battery for R637 and promise free shipping to South Africa. Way too good to be true!

I am just thinking, if I can prove they are not supplying what the advertise, surely I can get my money back?

 

I have ordered three times from Aliexpress, two was without issues (took long though) and another never arrived. Got a full refund.

3 minutes ago, McGuywer said:

I am just thinking, if I can prove they are not supplying what the advertise, surely I can get my money back?

 

I have ordered three times from Aliexpress, two was without issues (took long though) and another never arrived. Got a full refund.

And if they ask you to ship it back for inspection, how much shipping 40kg battery to China would cost you?

I use this tester and it works very well. Charge-Discharge Monitor, DROK 0-90V 100A DC Ammeter Voltmeter, Battery Capacity Amp-Hour Watt-Hour Power Time Multimeter, LCD Display Digital Voltage Current AH WH Watt Meter Tester with Hall Sensor: Amazon.com: Tools & Home Improvement

This is example of a 100Ah lead acid battery test result. Battery life 8 months. Test started after charging battery to 14.0V. Tested at approx C/20 rate (the rate that most battery manufacturers use) and cut-off voltage = 10.5V. This battery was in a 24V system and my guess is that the 2x 12V batteries went out of balance and with the higher stages of load shedding (greater DOD) the batteries were killed quickly. You can see in the test the battery only measured 19.3AH.

 I googled for the availabilty of the unit in SA and found it here -  DC Ammeter, DROK Digital DC Multimeter 0-90V 100A Voltmeter Ammeter 12 – Reliable Store but note that I did not buy my unit from them.

Edited January 24, 20233 yr by GreenMan

8 hours ago, PowerUser said:

And if they ask you to ship it back for inspection, how much shipping 40kg battery to China would cost you?

Shipping a 80v surgearrester from China by DHL is 100 Dollars 

Use a shunt. Cheap and very accurate. 

10 hours ago, PowerUser said:

There is something very suspicious with the batteries from this link. They list 48V 100Ah battery for R637 and promise free shipping to South Africa. Way too good to be true!

I had this before from aliexpress. They realised their fault never shipped and refund eventually came. 

12 hours ago, McGuywer said:

https://m.aliexpress.com/item/1005005152516424.html?spm=a2g0n.shopcart.0.0.7b8d38daLidXcs&mp=1&gatewayAdapt=Pc2Msite
 

Do not order. 

You can get drop in 12v7ah lithium batteries for alarms and gate motors for R600. 

Just don't use it for 24v garage doors. As soon as the 2 batteries are unbalanced the door stops working. 

Never go too cheap. Too expensive is OK. But too cheap will just cost you more in the end. Pay that 25% extra and get middle of the range for your sanity and everyone else's. 

1 minute ago, sunset1 said:

Never go too cheap. Too expensive is OK. But too cheap will just cost you more in the end. Pay that 25% extra and get middle of the range for your sanity and everyone else's. 

This!

One thing I see from several recent discussions of batteries is that batteries are not just batteries. It's easy to  think they're just cells that all come out of the same factory anyway, and a BMS (and they all do the same thing). But that's not really the case. Discussion after discussion here suggests that batteries aren't all the same, that some brands are demonstrably better, and that it is possible to not get what you pay for.

My own experience is that changing from one local brand of 10kwh battery to another has noticably improved the performance of my system.

Batteries are not all equal. As with so many things, batteries are built down to a price, and good batteries are built to a specification.

 

I would be happy to help. Send me a cell I have a battery tester that i use for battery building. It will analyze with a load charge and discharge. it will give you an electronic report for the entire cycle. It will include ah counted in and out. If you in the Gauteng area give me a shout. 

This is the machine i use.