Battery Tester

[Velpew]

Wondering if mounting this on my battery would give me all the info I need on the state of my battery:
https://www.amazon.com/DROK-Programmabl ... B07759SLYP

Also, I got a Yeti 1400 so I can have back up power and solar recharge capacity. I notice that it runs down faster than my teardrop (T@G Little Guy 2017) battery. I thought it would be at least equivalent if not have more juice.

Any thoughts would be appreciated - I am clueless about all things electrical.....
Andy Taylor
Brookline

[troubleScottie]

To determine the state of charge (SOC) for a battery system, one requires a device with a current shunt. There are ones available with numerous price ranges. For example, at about $20, bayite DC 6.5-100V 0-100A LCD Display Digital Current Voltage Power Energy Meter Multimeter Ammeter Voltmeter with 100A Current Shunt. This is not a recommendation. I have no idea how well it works. However, it should be possible to build/purchase an inexpensive one.

As to the Yeti 1400, from the Yeti site, the battery has 1425 Wh or about 114 AH at 12V. Assuming 80% usage before you must recharge, this is only 100AH. And that assumes that the Yeti does not have controls to stop you sooner. Using the inverter output, you will get considerably less power due to the inverter inefficiencies. Not knowing how it is constructed internally, it is possible that there is some parasitic power consumption by the inverter.

A quick look does not show anyone actually testing the capacity of the battery. If the Yeti is really 100AH Li battery, it should out perform a 100 AH SLA battery.

[MtnDon]

You only need a meter with a shunt if you are drawing large amounts of amps or are pulling the amps through long lengths of wire.

I have a stationary setup at our cabin which uses a meter on a low volt and low amp DC circuit with a max of 6 - 8 amps at any one point in time. I use a meter with no external shunt on that circuit which is similar to the meter linked to.

Then I have another meter that is located 40 feet from the battery source and the device that is connected. I use a meter with a shunt on that to avoid needing to draw power through a 40-foot wire to the meter and another 40-foot wire back. That would need too large a wire to be efficient.

Yet another meter is connected to a system that can draw 150 to 175 amps at 24 volts. That one uses a shunt that can handle the maximum current.

I hope that makes sense and helps.

All that said a such a meter is not going to give as accurate a reading on the SOC of a battery as using a hydrometer. That, of course, only works on non-sealed lead-acid batteries.

[RJ Howell]

Some of these units have built in shunts. I took a look at some of th questions asked and see it's a voltage only value meter. Not bad in it's self, yet.. the kicker. You have to know the value (voltage) for your particular battery chemistry. Each has it's own values.

Simple example of this. My lithium is done 80% drawn at 12.9v. My Lead acid is full at 12.65v. So there is no way this meter works across the spectrum of chemistry.

I have always liked these https://www.amazon.com/bayite-6-5-100V-Display-Multimeter-Voltmeter/dp/B013PKYILS/ref=sr_1_3?crid=2R4V1U03WHJ8J&dchild=1&keywords=12+volt+meter+gauge&qid=1592343734&s=automotive&sprefix=12volt+meter%2Cautomotive%2C679&sr=1-3 this one has a sperate shunt (better) others have built in (okay). Still, things you need to know.. Like what is your charged capacity? I run one on my solar panel for input and one of the battery for output. Tells me with no guessing if I'm in the plus or minus column.

I used to buy these for $8 (shipped). Guess I told too many folks about them.. LOL

[tony.latham]

I have always liked these...

I have a Bayite in my new teardrop and am quite pleased that I can check the number of watts that I've used each day. (and amps by dividing the voltage.) It's easy to reset it to zero at the start of a day or end of the trip.



There's another one that looks interesting:

https://www.amazon.com/dp/B07CTKYFTG/?coliid=I301972QUD0GSE&colid=3DIEP78B3UWPM&psc=1&ref_=lv_ov_lig_dp_it

The Drok appears to be just a fancy voltmeter.



Tony

[bdosborn]

I've tested the capacity of my LiFePo4 battery using an amp-hr meter. I've got this one on my solar generator and it seems fairly accurate.
Amp-hr meter.
I like this meter better than most as it tracks amp-hrs in and out. I can check to see that the amount used jives with the amount the charger puts in. And you don't have to worry about resetting it. I tested the amp-hrs I took out to the battery voltage by running the trailer TV, lights and fridge for a weekend, while checking the battery voltage against its acceptable low value. Its a little harder with a lead acid battery since they voltage dips more under load than with a LiFePo4. I have a low voltage battery disconnect on my battery to make sure I don't ever draw the battery down too low - you'll need to be real careful to watch the voltage drop so you don't go too low and damage it.

Here's the values I looked at on my battery test:


I knew my total amp-hrs out should be 145 amp-hrs max so I drew the battery down to that level and made sure the voltage didn't go below 12.9V. I have a Victron battery meter to track everything but this gives you an idea of what values I looked at. You really only care about two values, amp-hrs discharged and final voltage.

P.S. Checking battery SOC by voltage alone is pretty inaccurate, its much better to track amp-hrs.


Bruce

[bdosborn]

Ha! I linked to the same meter you did!

Bruce

[Tom&Shelly]

Ha! I linked to the same meter you did!

Bruce

Seems like a good idea. You and Tony have Shelly and me considering it, as we design the electrical "hub" in our galley.

Looks like it will almost fit in the space the voltmeter would take.

Thank you!

Tom