Having quite a collection of Lithium and Lead Acid batteries, I was curious how they were standing up after years of use. A little research on one of the best Solar/Lithium Battery YouTube channels, Will Prowse ( DIY Solar Power with Will Prowse – YouTube ) suggested a very inexpensive, easy to use, battery tester. For under $50 (2023), you can purchase it from Amazon… MakerHawk Battery Tester.
Search Amazon for “MakerHawk Battery Tester”….
I’m not going to go into the total setup of the device. Will Prowse has a good video on it and there are dozens more YouTube videos on set up.
In my case I have two Renogy 100aH lithium batteries that are 5 years old and have been in service in a Toy Hauler camping trailer 24/7 all this time. I leave them installed and connected 12 months a year. Even during New England winters with a DIY battery heating system (See my article on battery heating here: ( LITHIUM BATTERY HEATING PROJECT – RVB Precision ). These batteries have more than 70,000 miles and hundreds of cups of Keurig coffee and slices of toast through a 1500w inverter on them.
So let’s see how they have stood up.
First you need to charge the battery to 100%
I use the amazing Victron “Blue Smart IP22” 12v, 30 amp charger for this duty
Once the battery is at 100%, it is time to connect the MakerHawk tester. But first be sure to turn both knobs on the tester completely counter clock wise, to off.
Next plug in the little 9V power “wall wart” that comes with the tester.
Set the current you want the battery to discharge at with the two knobs. Top knob is course adjustment and bottom knob is fine adjustment.
I chose 10 amps for a 100 amp hour lithium battery. You can set it from under 1 amp to about 17 amps. (185 watts is maximum)
Leave it in this discharge configuration until the batteries BMS shuts the battery down. Depending on your discharge amp setting it can take 10 or more hours. (100 amp hour battery discharging at 10 amps takes 10 hours…)
Once the battery has shut down it’s a simple matter of reading the Amp Hours on the testers LCD screen. In this case, 102.34 aH……. Pretty good for a five year old battery that has been in continuous service for 5 years!
But now this battery is “dead”….Not really, but it is “asleep”…..To recharge it, it needs to be woken up. (This battery has bluetooth so we can see what condition it is in and any warnings it might throw)
This BlueTooth screen shows the battery is depleted.
Warnings! (from batteries BlueTooth)
So we need to “jump” it with another charged battery for a second or two to “wake it up”….Simply connect another charged, same voltage battery to it in parallel for a couple seconds and it will be ready to be recharged
Battery “Woken Up”
The Victron charger is connected and in a few hours it will be good as new!
(I used a “Clamp On” amp meter to verify the charge current of the tester. It was spot on!)
Hope this helps folks that want to test thier batteries.
Be sure to visit my whole web site… www.rvbprecision.com
THANKS!