Battery capacity tester

[Simonbr]

I recently received a battery i purchased, 24v 300Ah, and I wanted to test it to make sure everything is working correctly and it actually has the capacity it’s supposed to have. I`ve been looking through the forum as well as online for a capacity tester for the entire battery (not individual cells) and it doesn’t seem like there is anything that is made for higher amperage, everything I find is for lower amperage, I don’t want to spend 24 hours . Does anyone know of any higher amp tester that works for a 24v battery?

The ones I found and looked at;

DL24EW
seems to allow to go up to 600w with 3 expansion boards - 600w/24v = 25A

CBA A2 500W
seems like a nice setup, a little costly but I’m planning on getting more batteries and having a good tool never hurts

option 3
build my own using a smaller 600w 24v inverter and a shunt (haven’t picked it out yet) would say it might cost me $150 range after all cables, shunt, inverter, etc.

Any thoughts or other suggestions?

 

[Andrewr05]

I don't know how accurate it is, but I'd just wire it up to a shunt, then to an inverter and then run a high wattage heater until it shuts off.

Then your shunt should tell you how many Amp hours you drew. That's what I do.

Edit:
Sorry, I didn't read your thread completely.

I would say your third option is the most cost effective because you can just use the components you were already going to use, no need to get other products to do the same thing.

 

[Mattb4]

It might take longer to use a lower amperage tester but you can just walk away from it and come back when it is done. I use a 150w tester and thought it took me ~14 hours to test my 105ah 24 volt battery it was no big deal. Set it going one day and the next morning it was done and I read out the results.

 

[Simonbr]

I don't know how accurate it is, but I'd just wire it up to a shunt, then to an inverter and then run a high wattage heater until it shuts off.

Then your shunt should tell you how many Amp hours you drew. That's what I do.

Edit:
Sorry, I didn't read your thread completely.

I would say your third option is the most cost effective because you can just use the components you were already going to use, no need to get other products to do the same thing.

I would use the inverter and shunt I currently have but all of it is at my camp which is not accessible during winter. I ordered myself a cheap 24v inverter and shunt.

https://www.amazon.ca/gp/product/B08TR3JZ4W/ref=ox_sc_act_title_1?smid=A505H0U4TGVUQ&th=1

https://www.amazon.ca/gp/product/B0CBWLLB4X/ref=ox_sc_act_title_2?smid=A7ZYR8NF7E3HZ&psc=1

 

[Simonbr]

It might take longer to use a lower amperage tester but you can just walk away from it and come back when it is done. I use a 150w tester and thought it took me ~14 hours to test my 105ah 24 volt battery it was no big deal. Set it going one day and the next morning it was done and I read out the results.

I'm not too keen on leaving this run overnight, do you think it would matter if I run it all day, stop it at night and resume in the morning? Im also thinking on getting the one that has multiple boards so it can go up to 600w.

 

[Mattb4]

I'm not too keen on leaving this run overnight, ...

The capacity tester shuts itself off at the low battery voltage you set. If you are concerned that it might halt and catch fire you could place it and the battery in a place that is not combustible such as a concrete floor or metal work table. I don't know how it would work to stop the test and than resume later. Not sure if it is even possible other than recording the reading at the point you stop and than adding it to the next run.

Ideally you will get a more accurate ah reading if you do not try a real large load doing testing. For a 300ah 24DC battery and a 20 hour load test this works out to 15a or 360watts. Large loads for a quicker test lead to battery voltage slump which can cause your tester to shut down leaving a fair amount of reserve.

 

[MisterSandals]

Ideally you will get a more accurate ah reading if you do not try a real large load doing testing.

This is interesting in that I see “more accurate” as possibly meaning 2 different things:
1) as stated, more accurate when compared to how batteries are normally tested and rated

2) if testing split up and more uneven, it will be more like day to day usage (for me anyway) and be more accurate in what you can expect it to deliver under YOUR conditions.

I guess it depends on what you are expecting to gain from testing.

and I wanted to test it to make sure everything is working correctly

Either method should satisfy this curiosity.

 

[Simonbr]

Thanks guys I'll update this thread to give information to whoever is interested.

 

[Mattb4]

Thanks guys I'll update this thread to give information to whoever is interested.

I am curious about your battery brand and where you obtained it.