# 12-Volt Battery(s) Usage-time help?

**URL:** https://discuss.bluerobotics.com/t/12-volt-battery-s-usage-time-help/7706
**Category:** General Discussion
**Created:** [July 4, 2020, 12:55am UTC](https://discuss.bluerobotics.com/t/12-volt-battery-s-usage-time-help/7706 "2020-07-04T00:55:49Z")
**Posts on this page:** 5
**Page:** 1

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### Author: ![CCinPA](https://avatars.discourse-cdn.com/v4/letter/c/a5b964/32.png) [@CCinPA](https://discuss.bluerobotics.com/u/CCinPA)
#### Post date: [July 4, 2020, 12:55am UTC](https://discuss.bluerobotics.com/t/12-volt-battery-s-usage-time-help/7706/1 "2020-07-04T00:55:49Z")

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Here is the battery (two used in-line):

> **[SP12-3.5 SigmasTek genuine SLA Battery (12V 3.5AH)](https://www.batterysharks.com/ProductDetails.asp?ProductCode=SP12-3.5_B12-3)**
>
> The genuine SigmasTek SP12-3.5 SLA battery is guaranteed to meet or exceed OEM specifications. We supply brand new, factory fresh, high quality batteries at the lowest prices.

Fully-charged / After 10-minutes of use:

 ![Two Bat1](https://us1.discourse-cdn.com/flex019/uploads/bluerobotics/original/2X/7/7a554f2be0c0b452f64b987ad37064dfd0451902.jpeg)

Is this the normal drop in voltage after 10-minutes of use?

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### Author: ![spotxuv](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.bluerobotics.com/spotxuv/32/1112_2.png) [@spotxuv](https://discuss.bluerobotics.com/u/spotxuv)
#### Post date: [July 4, 2020, 2:57am UTC](https://discuss.bluerobotics.com/t/12-volt-battery-s-usage-time-help/7706/2 "2020-07-04T02:57:20Z")

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Are the batteries new? 11.75V is not a fully charged gel-cell. And if you’ve discharged to 9.21V it is likely damaged. Also, what were the batteries hooked up to? The case of the battery says it only supports up to 1.05A, you’ll easily exceed that if this was hooked to thrusters.

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### Author: ![kklemens](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.bluerobotics.com/kklemens/32/2247_2.png) [@kklemens](https://discuss.bluerobotics.com/u/kklemens)
#### Post date: [July 4, 2020, 6:43pm UTC](https://discuss.bluerobotics.com/t/12-volt-battery-s-usage-time-help/7706/3 "2020-07-04T18:43:11Z")

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3.5Ah isn’t a very high capacity. I’d expect that to be normal if driving at T200 at full power.

As @spotxuv mentioned, its not recommended to discharge a lead acid battery below 10.5V: [Reliable Power Converters and Battery Charging Systems](https://www.progressivedyn.com/service/battery-basics/)

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### Author: ![CCinPA](https://avatars.discourse-cdn.com/v4/letter/c/a5b964/32.png) [@CCinPA](https://discuss.bluerobotics.com/u/CCinPA)
#### Post date: [July 5, 2020, 12:52am UTC](https://discuss.bluerobotics.com/t/12-volt-battery-s-usage-time-help/7706/4 "2020-07-05T00:52:19Z")

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Here’s the device the batteries are used f

 ![LT1](https://us1.discourse-cdn.com/flex019/uploads/bluerobotics/original/2X/b/b446dd696ac17462c2670504e3f9deaff5c6d94e.png) or:

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### Author: ![CCinPA](https://avatars.discourse-cdn.com/v4/letter/c/a5b964/32.png) [@CCinPA](https://discuss.bluerobotics.com/u/CCinPA)
#### Post date: [July 5, 2020, 12:56am UTC](https://discuss.bluerobotics.com/t/12-volt-battery-s-usage-time-help/7706/5 "2020-07-05T00:56:26Z")

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Yes the batteries are new. Good lead-in to why I posted this. I am replacing the batteries for the line-trimmer. But they only ran the trimmer of 10-minutes. I am trying to learn what what facts I can use to communicate with the folks I purchased the batteries.