The Once And For All On Batteries...

[Ronmar]

Now im already using a controller from solar to house batteries so go in behind my other controller and ad this dc/dc thing or just run a piece of #10 from my controller to the 3rd 6tl instead of the 2/0 i have down there now ! or your saying tap in the line coming from panels before it gets to solar controller then onto the 3rd 6tl

Tap into the line between the panel and the house controller. You want raw DC to feed the small controller to the 3rd battery the same as it feeds the house system. Dc to dc converters work best when there is a voltage difference so you dont want to use the output of the house converter which is basically the same voltage as you want to feed the 3rd…

the whole point of the added dc-dc controller is to NOT add a different sized battery to the house bank which will effect the way BOTH charge(and not in a good way)…

You can temporarily tie the 3rd into either the house bank or the service system to use that energy in those systems, but for longest life you want the 3 different sized systems to charge independently of each other on their own controllers…

 

[chucky]

Tap into the line between the panel and the house controller. You want raw DC to feed the small controller to the 3rd battery the same as it feeds the house system. Dc to dc converters work best when there is a voltage difference so you dont want to use the output of the house converter which is basically the same voltage as you want to feed the 3rd…

the whole point of the added dc-dc controller is to NOT add a different sized battery to the house bank which will effect the way BOTH charge(and not in a good way)…

You can temporarily tie the 3rd into either the house bank or the service system to use that energy in those systems, but for longest life you want the 3 different sized systems to charge independently of each other on their own controllers…

Thank you this all makes sence to me now ! about time! now im going to draw a picture of the batteries just like my other drawings but today i drew this picture and this fella tells me if i tie that 3rd 6tl in the way ive drawn the picture thats going to make 36volts

 

[chucky]

The curly q wire he says will make that top battery 36v is that right?

 

[Ronmar]

Thank you this all makes sence to me now ! about time! now im going to draw a picture of the batteries just like my other drawings but today i drew this picture and this fella tells me if i tie that 3rd 6tl in the way ive drawn the picture thats going to make 36voltsView attachment 854516

I think he mis-understood your drawing, the connection points look OK for adding the 3rd in parallel with the 0-12v service battery. Maybe he thinks those lines are connected instead of just drawn over each other…

batteries often mess people up, particularly series and parallel. Everything here is referenced to ground. The top right battery is the 0-12v service battery. It connects to ground on - side and the +terminal connects to the - terminal on the 12-24v battery(top left) Connecting the 3rd battery to ground and tothe same point where the other 2 meet will simply put it in parallel with the 0-12. Batteries in parallel double current capacity but the voltage stays the same. batteries in series double voltage but the current capacity stays the same…

he probably has that info backwards in his head and thinks the two batts in parallel will deliver 24v… they wont…

like I said batts mess people up

 

[chucky]

I think he mis-understood your drawing, the connection points liik OK for adding the 3rd in parallel with the 0-12v service battery. Maybe he thinks those lines are connected instead of just drawn over each other…

OK great because this is the only cable i havnt done yet but in my mind it seemed rite and like i said before im putting a heavy on/off switch in line on that short jumper to just have the option ! I think this layout will be a better all round than 4 good truck 6tl (i think) lol

 

[Ronmar]

Here is a quick test before you arc weld something, if you are ever in doubt as to what is going to happen when you connect that last wire/complete the circuit.

Connect a volt meter in place of the last wire you are going to connect in the circuit. You must have a difference in potential(voltage, pressure) in order to have flow.

No voltage, no potential. But if you do measure a voltage, you need to find out why. It may be normal, but you still need to figure out why.

As an example, say you are connecting two batteries in parallel, one is at 100% and the other is at 50% state of charge. The full batt will be around 12.75V while the half charged batt will be around 12.1V. If I connect the - terminals together and put a volt meter across the + terminals, the meter should see the 0.65V difference in potential between the batteries. If I connected the two terminals, current would flow, and the full batt would try and charge the weak batt till they equalized.

Now say I screw up and instead of connecting the two - terminals together, I connect a + and a - terminal together without noticing it. If I put a volt meter across the remaining two terminals where the last wire goes, I am going to see 24.85V and go holy crap, what the heck is going on here.

Now if I had just thrown that last wire on before checking, bad things would have probably happened as high current connections made by mistake tend to weld themselves in place…

Batteries are some of the most dangerous things you are ever going to work with, so a little caution and testing before you close the circuit is not a bad thing…

 

[Mullaney]

Here is a quick test before you arc weld something, if you are ever in doubt as to what is going to happen when you connect that last wire/complete the circuit.

Connect a volt meter in place of the last wire you are going to connect in the circuit. You must have a difference in potential(voltage, pressure) in order to have flow.

No voltage, no potential. But if you do measure a voltage, you need to find out why. It may be normal, but you still need to figure out why.

As an example, say you are connecting two batteries in parallel, one is at 100% and the other is at 50% state of charge. The full batt will be around 12.75V while the half charged batt will be around 12.1V. If I connect the - terminals together and put a volt meter across the + terminals, the meter should see the 0.65V difference in potential between the batteries. If I connected the two terminals, current would flow, and the full batt would try and charge the weak batt till they equalized.

Now say I screw up and instead of connecting the two - terminals together, I connect a + and a - terminal together without noticing it. If I put a volt meter across the remaining two terminals where the last wire goes, I am going to see 24.85V and go holy crap, what the heck is going on here.

Now if I had just thrown that last wire on before checking, bad things would have probably happened as high current connections made by mistake tend to weld themselves in place…

Batteries are some of the most dangerous things you are ever going to work with, so a little caution and testing before you close the circuit is not a bad thing…

.
Wow!
Nice easy way to test a questionable connection Ronmar !

 

[chucky]

Here is a quick test before you arc weld something, if you are ever in doubt as to what is going to happen when you connect that last wire/complete the circuit.

Connect a volt meter in place of the last wire you are going to connect in the circuit. You must have a difference in potential(voltage, pressure) in order to have flow.

No voltage, no potential. But if you do measure a voltage, you need to find out why. It may be normal, but you still need to figure out why.

As an example, say you are connecting two batteries in parallel, one is at 100% and the other is at 50% state of charge. The full batt will be around 12.75V while the half charged batt will be around 12.1V. If I connect the - terminals together and put a volt meter across the + terminals, the meter should see the 0.65V difference in potential between the batteries. If I connected the two terminals, current would flow, and the full batt would try and charge the weak batt till they equalized.

Now say I screw up and instead of connecting the two - terminals together, I connect a + and a - terminal together without noticing it. If I put a volt meter across the remaining two terminals where the last wire goes, I am going to see 24.85V and go holy crap, what the heck is going on here.

Now if I had just thrown that last wire on before checking, bad things would have probably happened as high current connections made by mistake tend to weld themselves in place…

Batteries are some of the most dangerous things you are ever going to work with, so a little caution and testing before you close the circuit is not a bad thing…

THANKS SO MUCH!