# 7 TH 12v Battery **URL:** \ **Category:** GEM Forum\ **Created:** [January 31, 2021, 12:23am UTC](https://community.electricforum.com/t/7-th-12v-battery/20736 "2021-01-31T00:23:43Z")\ **Posts on this page:** 1\ **Showing post:** 4
**Author:** ![JarJarJava](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.electricforum.com/jarjarjava/32/15158_2.png) [@JarJarJava](https://community.electricforum.com/u/JarJarJava)\ **Post date:** [January 31, 2021, 8:15am UTC](https://community.electricforum.com/t/7-th-12v-battery/20736/4 "2021-01-31T08:15:20Z")
About a year and half ago I became the first person AFAI&DK to test this out for Dave (@Inwo ). He had an old idea on sticking an extra battery between the contactor and the controller and it sounded interesting to me. As a bonus it’s also been a test of a mixed battery system as the GEM it’s installed in has 6 FLA mains and a 4s lifepo pack as the extra battery. It’s been rock solid. Seriously, it’s been flawless. I’ve put a bit shy of 4k miles on it since installing that pack. Here’s the install and testing thread: > [@LiFePo4 "7th battery" on a lead bottom GEM](https://community.electricforum.com/t/lifepo4-7th-battery-on-a-lead-bottom-gem/16591): > > This was an idea that Dave @Inwo came up with at some point in the past and I was the first ̶i̶d̶i̶o̶t̶ scientific pioneer willing to test it… … Adding an extra battery after the main contactor, so that only the high amperage terminals on the controller see the extra voltage. Translation, no voltage shunt needed for control power and that somehow changes how the controller sees things and the car performs and I’m gonna let Dave explain that part because he’s an electronics genius and I just f… --- _[View the full topic](https://community.electricforum.com/t/7-th-12v-battery/20736)._