Good Battery Capacity Tester

[Steve_S]

Well an UPDATE aka Discovery of sorts.
It seems that Will's little video did a Business Boom on the testers and getting one off eBay / Amazon that is local (Canada and then US) is danged near impossible unless you want to drop $100 ! ~NOT~ Oivey the profiteers are something.... The Ferenghi rules of acquisition I suspect.

I started poking through Ali* and even went to MakerHawk directly which can sell directly from their store, NOTA BENE ! They ONLY have the 150W model which Will used in his demo. So on further investigative furtling, I found other companies making similar testers but with subtle differences that you have to pay close attention to discover. I've located TWO companies that produce 180W units and guess what, they ARE different !

The 180W unit with cooling tower radiator. $40 USD + S&H
2 models, the 150 & 180 (150 uses the other fan system).

8 In 1 150w 180w Digital Battery Capacity Tester Voltmeter Adjustable Constant Current Electronic Load Charger Meter Indicator - Buy Digital Battery Capacity Tester,Usb Meter Indicator,External Battery Charger Product on Alibaba.com

8 In 1 150w 180w Digital Battery Capacity Tester Voltmeter Adjustable Constant Current Electronic Load Charger Meter Indicator , Find Complete Details about 8 In 1 150w 180w Digital Battery Capacity Tester Voltmeter Adjustable Constant Current Electronic Load Charger Meter Indicator,Digital...

www.alibaba.com

Similar product from another manufacturer:

12v 24v 48v Lead-acid Lithium 180w Constant Current Electronic Load 200v 20a Battery Tester Discharge Capacity Tester - Buy 180w Discharge Capacity Tester,Discharge Capacity Tester,Battery Tester Product on Alibaba.com

12v 24v 48v Lead-acid Lithium 180w Constant Current Electronic Load 200v 20a Battery Tester Discharge Capacity Tester , Find Complete Details about 12v 24v 48v Lead-acid Lithium 180w Constant Current Electronic Load 200v 20a Battery Tester Discharge Capacity Tester,180w Discharge Capacity...

www.alibaba.com

 

[MrNatural22]

I’ve been running the 150watts replacement Amazon tester at these limits. It seems to stay cooler and has been run on two different LiFePo batteries with BMSs to protect, taking about 8 hours to complete each test.
Setting lower limits I may get some longevity out of this one.
Bluetooth BMS shows more wattage than the tester?
Normal?

 

[Craig]

I would expect some differences.looks like yours are within what I would expect. It might have something to do with where the volts are being measured.

 

[MrNatural22]

@Craig thanks? I was wondering. The BMS is on the battery. And wire resistance on the connection to the tester 2' of 12g wire and xt60 connecter.

 

[Barold]

I picked one of the 180W units up off Aliexpress - Not sure due to covid and other distractions I never got around to my build - i just pulled it out of the box and it looks like it's DOA - doesn't turn on (with the AC adapter). I may try to fiddle with it but does anyone have recos for a capacity tester that has a bit higher level QC?

 

[Zil]

Fuses protect wires. Not devices. Size any fuse to the awg of the cable. Place fuse close to battery positive. These battery can make a big mess of a short.

 

[Sylwood2]

I just received the one with the pink looking fan... i have a question on these...
I set low cutoff to 11.5 and had volt meter on battery directly, I noticed the volt difference between the two was like .2-.4 volts.
Tester turned off at 11.5 but volt meter showed battery was still at 11.8. I think I was running the tester at about 10 amps.
Should I test capacity with tester at 11.5 (fla) or bump it down to like 11.2 so battery meter showes battery at 11.5?

 

[lmwilco1]

You need to run wires large enough for the load that your are drawing. If you have a .2-.4 voltage drop across the wires try using larger gauge wire. When I tested my battery I used 10g wire and did not see significant voltage drop.

 

[Hydroselator]

I ordered the one Will recommended from Ali-express. After waiting two months I eagerly opened the package to find a stupid 12,000 piece diamond puzzle of a dog - grrrr. Anyways, not wanting to wait two more months I ordered the following from Amazon and I'm pleased and wanted to share my results. The tester was $45 on Amazon but did the job. The tester is only rated to 150W so the test of my 200Ah, 24V battery required 36 hours. I used a true RMS amp meter to check the tester displayed value of 5.00 amps - the true RMS meter measured 5.01 amps. Voltage readings were also reasonably the same between the test unit and meter.

Using 8 each 200Ah Lifepo4 batteries in series and a 2020 model Daly 150amp BMS - achieved 202.1 Ah stopping test at 23.11 volts. I had the tester set on 20.8 volts and per the seller on Ali-express the BMS should not have cut out discharge unless one of the eight cells went below 2.5V (lowest was 2.826V after the test) so I need to figure out why the test unit stopped the test. The unit is well built and the cooler master fan is whisper quiet.

 

[nosys70]

the easiest way to test a battery is to put it at work in real life.
you hook it up to your inverter, install a load with a kill-o-watt meter and just check when the inverter cut.
then you read the meter and get your answer.
usually i use a halogen lamp with a variator and set the variator to reflect the load i want (peukert effect in action here).
you easily find halogen lamp from 150 to 500w.