Need some help with a battery box

[msacco]

Hello, I recently bought a 12v deep cycle battery 75 AH and I made a battery box following these tutorials:

and

(no need to watch it ofc, just to understand the basic idea). Here is the outcome:
asd - https://Upload the image directly to the thread.com/a/crgzYlJ

I know the pictures quality is not really good, but hopefully it will be good enough.

The problem I encounter is that if for example I power the second switch which turns on led lights, the voltage that is then going to the rest of the switches is getting lower, for example:

I turn on the first switch(turns on voltmeter and gives power to the rest of the switches), the voltmeter reads 12.5v, then I turn on the second switch, and the voltage is dropping to 12.4v, the third switch is used to power my telescope, which takes pretty high current, so whenever I use it the voltage drops even further to around 12.2v or even 12.0v.

Now I obviously understand that voltage drops will happen, but not that much. I have another voltmeter connected directly to the battery, and the voltage will drop from like 12.5v to 12.48v or even slightly lower, but not more than that(thats the way it should be ofc).

I have tested the wires, and it doesn't seem like there's any loose connector or something similar, when using my multimeter the voltage transferred to the rest of the components are as should when everything is turned off, only when I power something the voltage that is transferred to the rest of the system is getting very low.

I'm currently using 16 gauge cables for all the components, and 14 gauge cables from the battery to the system.

Any ideas? I'm not really sure what I can do about it. Thanks!

 

[Strima]

Use a bigger battery. Your voltage is proportional to the load you place upon it, the grater the load the lower the voltage will get.

As soon as you remove the loads the voltage will tend to recover quite quickly but will never return to it's last charge level until you physically recharge it.

What is the combined load of all your equipment in watts?

What is the AH rating of the battery?

 

[msacco]

Use a bigger battery. Your voltage is proportional to the load you place upon it, the grater the load the lower the voltage will get.

As soon as you remove the loads the voltage will tend to recover quite quickly but will never return to it's last charge level until you physically recharge it.

What is the combined load of all your equipment in watts?

What is the AH rating of the battery?

I stated that in my post, the voltage will always drop, but not as much as it is the way it is wired, the actual battery voltage is barely dropping, but the voltage that is transferred to the other components are dropping.

I don't really know what is the combined load, my telescope current is determined by how fast I move it, so its not a fixed current.

And the battery is brand new AGM deep cycle battery 75 AH.

 

[telectrix]

you will see the volt drop at the point of utilisation, due to the resistance of the cable from the battery. this is normal.

 

[msacco]

you will see the volt drop at the point of utilisation, due to the resistance of the cable from the battery. this is normal.

Did you read my post? :\

 

[SparkyChick]

Did you read my post? :\

I did and I agree with @telectrix .

You will notice a slight dip in voltage at the battery terminals, but you will notice significant drops the further away from the battery you get due to the resistance of the cables.

Voltage drop in cables is proportional to the current flowing in them (Ohms law).

 

[msacco]

I did and I agree with @telectrix .

You will notice a slight dip in voltage at the battery terminals, but you will notice significant drops the further away from the battery you get due to the resistance of the cables.

Voltage drop in cables is proportional to the current flowing in them (Ohms law).

I understand the situation, what I need is advices on how to fix it, what would you recommend me doing? replacing to lower gauge cables? rewiring in a different way? What would you do in this situation? Thanks.

 

[SparkyChick]

Probably use bigger cables and adopt an approach similar to that of a car where big loads are connected directly to a fuse off the battery rather than some daisy chained setup.

 

[msacco]

Probably use bigger cables and adopt an approach similar to that of a car where big loads are connected directly to a fuse off the battery rather than some daisy chained setup.

I'll think how to rewire it that way, thanks

 

[Silly Sausage]

I did and I agree with @telectrix .

You will notice a slight dip in voltage at the battery terminals, but you will notice significant drops the further away from the battery you get due to the resistance of the cables.

Voltage drop in cables is proportional to the current flowing in them (Ohms law).

You'll also get a voltage drop across the battery terminals, under load, due to its internal resistance.

 

[msacco]

You'll also get a voltage drop across the battery terminals, under load, due to its internal resistance.

When wiring the 12v cable I'm using directly from the battery to the switch that powers the cable to the telescope it works just fine, and when I'm using my telescope there's nothing else that should be powered up as well, maybe some phone charging or something else, but even then I think that the resistance will be much less than the current resistance, and I don't think I need to wire anything else directly to the battery, so hopefully it will work fine