I am designing my own starter battery maintainer circuit from scratch. It will work with lead acid leisure batteries only and not need any configuration switches. I'll post again when I have a working prototype.
[Guide] Battery Maintainer (for Starter battery) -- How I Done It --
- Thread starter Dellmassive
- Start date
Prototype circuit working as designed, but I will uprate diode current to have a bit more margin. Also, I think I can make a version for lithium batteries by changing 2 components. Need to order aforementioned components...
![20241029_215447[1].jpg](https://www.t6forum.com/data/attachments/263/263107-3da7c282339a01b030386a327bdc6752.jpg "20241029_215447[1].jpg")
I had failed to consider battery voltage during cranking (duh - that's why it's called a starter battery), so design change implemented and new PCBs ordered.
Hi, how can I charge through the cut lighter please? What do I need to get. My t6.1 starter battery keeps going flat as I don’t use it every day, only about 4 tine a week
How far are you driving? If you are driving 4 times a week for a reasonable distance/time and still getting a flat battery then there is something wrong with either:
As an aside if you have a factory leisure system and a recent T6.1 then none of the 12v sockets go to the starter battery anymore.
- Your battery - how old is it?
- Your charging system
- Your leisure system charging when it shouldn't (I think you mentioned you had one in another thread)
As an aside if you have a factory leisure system and a recent T6.1 then none of the 12v sockets go to the starter battery anymore.
Ok so it took a few iterations until I had a design that worked to my satisfaction on bench test, so this one will be going in my van for long term test. Meanwhile I'll make a version for use with lithium batteries. If that also works satisfactorily I'll offer it up for testing.
In the unlikely event of anyone actually being interested, I post some measurements of my final design of a starter battery charge maintainer, charging a partially discharged starter battery.
First, when the output of the leisure battery charger is constrained by low power from the solar panel, the charge current into the starter battery is a steady value depending on the available solar power and the state of charge of the starter battery. In this test (above) it was 1.0A
Most of the time the charge current will be a lot less than this as there should be very little load current on the starter battery when the ignition is off, but we need to consider all other possible conditions.
If there is sufficient solar power and the leisure battery charger is in float charge mode (13.6V), the charge current to the starter battery becomes pulse frequency modulated. The "on" pulse is always 2.5s but the time between pulses varies. In this test (above), the "on" pulse current was 2.3A but the average current over a 4s period is 1.4A
As the charge in the battery increases, the "on" current will decrease and the "off" time will increase to more than a minute.
Finally, if there is sufficient solar power and the leisure battery charger is in absorption charge mode (14.6V), the "on" charge current to the starter battery will increase but the "off" time increases to compensate, in this test the "on" current was 4.5A but the average charge current is 1.6A over a 7s period
First, when the output of the leisure battery charger is constrained by low power from the solar panel, the charge current into the starter battery is a steady value depending on the available solar power and the state of charge of the starter battery. In this test (above) it was 1.0A
Most of the time the charge current will be a lot less than this as there should be very little load current on the starter battery when the ignition is off, but we need to consider all other possible conditions.
If there is sufficient solar power and the leisure battery charger is in float charge mode (13.6V), the charge current to the starter battery becomes pulse frequency modulated. The "on" pulse is always 2.5s but the time between pulses varies. In this test (above), the "on" pulse current was 2.3A but the average current over a 4s period is 1.4A
As the charge in the battery increases, the "on" current will decrease and the "off" time will increase to more than a minute.
Finally, if there is sufficient solar power and the leisure battery charger is in absorption charge mode (14.6V), the "on" charge current to the starter battery will increase but the "off" time increases to compensate, in this test the "on" current was 4.5A but the average charge current is 1.6A over a 7s period
Similar threads
