# Car keeps losing battery power 100% while battery is fully charged **URL:** \ **Category:** Maintenance/Repairs\ **Tags:** toyota, highlander\ **Created:** [April 24, 2023, 9:56pm UTC](https://community.cartalk.com/t/car-keeps-losing-battery-power-100-while-battery-is-fully-charged/190252 "2023-04-24T21:56:30Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![dale.athy\_184955](https://avatars.discourse-cdn.com/v4/letter/d/b4bc9f/32.png) [@dale.athy\_184955](https://community.cartalk.com/u/dale.athy_184955)\ **Post date:** [April 24, 2023, 9:56pm UTC](https://community.cartalk.com/t/car-keeps-losing-battery-power-100-while-battery-is-fully-charged/190252/1 "2023-04-24T21:56:30Z")
About a month ago my highlander lost battery power and I noticed that there was a door left open. Got a jump from insurance guy who said battery was fully charged when he hooked up to give me a jump. The car started right up and I thought that was that. A few days later while we were driving the radio kept losing power though the car kept running without issue. I checked the battery to discover that the positive side terminal connector could be rotated slightly, so I tightened that up and figured all was well - until it happened again. All power gone, no dash lights on with key on & door open. Read an article on the subject here (older Cadillac I think) and took the advice to clean the battery terminal, so I took off the wires, filed down the terminal connector so that it was clean and flat. The 2 wire connections on the hot side were a bit rusty, so I put a little grease on those surfaces to make sure they’re making solid connections. Since it was rustier than I expected, I figured this must be it - until it happened again today - about a week later. I turned off the car and was back to the original complete loss of power for anything in the car. I banged around the ignition and slammed the door to see if this would bring back power, but nothing. So I’m sitting there thinking and then the power comes back on once again and everything looks fine. Fortunately we’ve not been stranded, but it’s only a matter of time I expect and sure would like to get this fixed once and for all. Thanks in advance, Dale ---
**Author:** ![texases](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/texases/32/862_2.png) [@texases](https://community.cartalk.com/u/texases)\ **Post date:** [April 24, 2023, 10:13pm UTC](https://community.cartalk.com/t/car-keeps-losing-battery-power-100-while-battery-is-fully-charged/190252/2 "2023-04-24T22:13:08Z")
Year/miles on Highlander? Battery age? ---
**Author:** ![Mustangman](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/mustangman/32/44130_2.png) [@Mustangman](https://community.cartalk.com/u/Mustangman)\ **Post date:** [April 24, 2023, 10:18pm UTC](https://community.cartalk.com/t/car-keeps-losing-battery-power-100-while-battery-is-fully-charged/190252/3 "2023-04-24T22:18:07Z")
> [@dale.athy\_184955](#): > > The 2 wire connections on the hot side were a bit rusty, so I put a little grease on those surfaces to make sure they’re making solid connections Did you clean them before you reattached and then greased them? Grease is not a conductor. More info about this car would very useful… like, Do you live where the roads are salted in the winter? How old is the car? Miles? ---
**Author:** ![dale.athy\_184955](https://avatars.discourse-cdn.com/v4/letter/d/b4bc9f/32.png) [@dale.athy\_184955](https://community.cartalk.com/u/dale.athy_184955)\ **Post date:** [April 24, 2023, 10:32pm UTC](https://community.cartalk.com/t/car-keeps-losing-battery-power-100-while-battery-is-fully-charged/190252/4 "2023-04-24T22:32:31Z")
I didn’t clean them. I thought the grease would stop the rust as it was all just light surface rust. Didn’t realize that grease wasn’t a conductor though. I thought the car info I provided came through. It is a 2005, 160K miles. I live in Arizona, so roads aren’t typically salted. ---
**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\ **Post date:** [April 24, 2023, 10:35pm UTC](https://community.cartalk.com/t/car-keeps-losing-battery-power-100-while-battery-is-fully-charged/190252/5 "2023-04-24T22:35:39Z")
If the battery is over 5 years old, have it tested. Tester ---
**Author:** ![Mustangman](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/mustangman/32/44130_2.png) [@Mustangman](https://community.cartalk.com/u/Mustangman)\ **Post date:** [April 24, 2023, 10:39pm UTC](https://community.cartalk.com/t/car-keeps-losing-battery-power-100-while-battery-is-fully-charged/190252/6 "2023-04-24T22:39:54Z")
It may be AZ but there is still the possibility of corrosion. You clean, wire brush, reattach and THEN grease the joint. Have your battery tested. Have the resistance of your battery plus and grounds tested, too. ---
**Author:** ![dale.athy\_184955](https://avatars.discourse-cdn.com/v4/letter/d/b4bc9f/32.png) [@dale.athy\_184955](https://community.cartalk.com/u/dale.athy_184955)\ **Post date:** [April 24, 2023, 10:40pm UTC](https://community.cartalk.com/t/car-keeps-losing-battery-power-100-while-battery-is-fully-charged/190252/7 "2023-04-24T22:40:25Z")
It’s a 2005, 160K miles. 4 year battery purchased in July 2019. ---
**Author:** ![dale.athy\_184955](https://avatars.discourse-cdn.com/v4/letter/d/b4bc9f/32.png) [@dale.athy\_184955](https://community.cartalk.com/u/dale.athy_184955)\ **Post date:** [April 24, 2023, 10:41pm UTC](https://community.cartalk.com/t/car-keeps-losing-battery-power-100-while-battery-is-fully-charged/190252/8 "2023-04-24T22:41:34Z")
It’s not qute 4 years old - July 2019. ---
**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\ **Post date:** [April 24, 2023, 10:42pm UTC](https://community.cartalk.com/t/car-keeps-losing-battery-power-100-while-battery-is-fully-charged/190252/9 "2023-04-24T22:42:26Z")
> [@dale.athy\_184955](#): > > 4 year battery purchased in July 2019. Still have the battery tested. Heat kills batteries. Tester ---
**Author:** ![dale.athy\_184955](https://avatars.discourse-cdn.com/v4/letter/d/b4bc9f/32.png) [@dale.athy\_184955](https://community.cartalk.com/u/dale.athy_184955)\ **Post date:** [April 24, 2023, 10:48pm UTC](https://community.cartalk.com/t/car-keeps-losing-battery-power-100-while-battery-is-fully-charged/190252/10 "2023-04-24T22:48:10Z")
Thanks for the procedure. Do you know if Napa or another regular parts type store will test the battery & grounds as you suggest, or would I need to go to a mechanic for that? ---
**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\ **Post date:** [April 24, 2023, 10:49pm UTC](https://community.cartalk.com/t/car-keeps-losing-battery-power-100-while-battery-is-fully-charged/190252/11 "2023-04-24T22:49:30Z")
Some parts stores will test the battery for free. Tester ---
**Author:** ![dale.athy\_184955](https://avatars.discourse-cdn.com/v4/letter/d/b4bc9f/32.png) [@dale.athy\_184955](https://community.cartalk.com/u/dale.athy_184955)\ **Post date:** [April 24, 2023, 10:50pm UTC](https://community.cartalk.com/t/car-keeps-losing-battery-power-100-while-battery-is-fully-charged/190252/12 "2023-04-24T22:50:01Z")
Thank you. Do you think Napa or regular parts store will suffice to do the testing? ---
**Author:** ![dale.athy\_184955](https://avatars.discourse-cdn.com/v4/letter/d/b4bc9f/32.png) [@dale.athy\_184955](https://community.cartalk.com/u/dale.athy_184955)\ **Post date:** [April 24, 2023, 10:51pm UTC](https://community.cartalk.com/t/car-keeps-losing-battery-power-100-while-battery-is-fully-charged/190252/13 "2023-04-24T22:51:02Z")
Okay, I’ll get the battery tested. Thank you. ---
**Author:** ![Mustangman](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/mustangman/32/44130_2.png) [@Mustangman](https://community.cartalk.com/u/Mustangman)\ **Post date:** [April 24, 2023, 10:56pm UTC](https://community.cartalk.com/t/car-keeps-losing-battery-power-100-while-battery-is-fully-charged/190252/14 "2023-04-24T22:56:49Z")
> [@dale.athy\_184955](#): > > parts type store will test the battery & grounds as you suggest, or would I need to go to a mechanic for that? Mechanic for that. Parts store employees are not mechanics, they are salespeople. ---
**Author:** ![dale.athy\_184955](https://avatars.discourse-cdn.com/v4/letter/d/b4bc9f/32.png) [@dale.athy\_184955](https://community.cartalk.com/u/dale.athy_184955)\ **Post date:** [April 24, 2023, 11:09pm UTC](https://community.cartalk.com/t/car-keeps-losing-battery-power-100-while-battery-is-fully-charged/190252/15 "2023-04-24T23:09:18Z")
Thank you. ---
**Author:** ![dale.athy\_184955](https://avatars.discourse-cdn.com/v4/letter/d/b4bc9f/32.png) [@dale.athy\_184955](https://community.cartalk.com/u/dale.athy_184955)\ **Post date:** [April 24, 2023, 11:47pm UTC](https://community.cartalk.com/t/car-keeps-losing-battery-power-100-while-battery-is-fully-charged/190252/16 "2023-04-24T23:47:35Z")
Do you think a batter tester like the one below would properly test as needed? > **[Amazon.com: TOPDON AB101 Car Battery Tester 12V Car Battery Load Tester on...](https://www.amazon.com/TT-TOPDON-AB101-Automotive-System%EF%BC%8CCharging/dp/B07DDDDSK9)** > > Buy TOPDON AB101 Car Battery Tester 12V Car Battery Load Tester on Cranking Charging Systems, 100-2000 CCA Automotive Alternator Analyzer for Cars/SUVs/Light Trucks with Flooded AGM Gel Types: Battery Testers - Amazon.com ✓ FREE DELIVERY possible on... ---
**Author:** ![VOLVO-V70](https://avatars.discourse-cdn.com/v4/letter/v/8e8cbc/32.png) [@VOLVO-V70](https://community.cartalk.com/u/VOLVO-V70)\ **Post date:** [April 24, 2023, 11:50pm UTC](https://community.cartalk.com/t/car-keeps-losing-battery-power-100-while-battery-is-fully-charged/190252/17 "2023-04-24T23:50:45Z")
Why buy something when most Autozone stores will test your battery for free . And if you need one thier prices are in line with most places and they might install it for free. ---
**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\ **Post date:** [April 24, 2023, 11:53pm UTC](https://community.cartalk.com/t/car-keeps-losing-battery-power-100-while-battery-is-fully-charged/190252/18 "2023-04-24T23:53:30Z")
That’s a conductance battery tester. Conductance testing is the latest technology in battery testing. Tester ---
**Author:** ![dale.athy\_184955](https://avatars.discourse-cdn.com/v4/letter/d/b4bc9f/32.png) [@dale.athy\_184955](https://community.cartalk.com/u/dale.athy_184955)\ **Post date:** [April 24, 2023, 11:53pm UTC](https://community.cartalk.com/t/car-keeps-losing-battery-power-100-while-battery-is-fully-charged/190252/19 "2023-04-24T23:53:37Z")
Thanks I’ll check it out. ---
**Author:** ![George\_San\_Jose1](https://avatars.discourse-cdn.com/v4/letter/g/e5b9ba/32.png) [@George\_San\_Jose1](https://community.cartalk.com/u/George_San_Jose1)\ **Post date:** [April 25, 2023, 12:24am UTC](https://community.cartalk.com/t/car-keeps-losing-battery-power-100-while-battery-is-fully-charged/190252/20 "2023-04-25T00:24:17Z")
Arizona-car, battery close to 4 years old, hmmmm … I"m guessing you have two problems. Battery starting to go on the fritz, and imperfect wiring harness connections at the battery. If you know how to work a volt meter, a simple test, before first start of the day the battery should measure about 12.6 volts, then immediately after starting the engine, 13.5 - 15.5 volts. Probe the battery posts, then compare to probing at the connectors. Shouldn’t be much difference between the two [Next page](https://community.cartalk.com/t/car-keeps-losing-battery-power-100-while-battery-is-fully-charged/190252.md?page=2)