New system lasting less than an hour.

[Beavo]

So just a quick update and question.
Installed some of the new stuff today.

Not too keen on those busbars being so close together but I'll make another board soon.

My question is about fuses. Is there a specific type or size that I need to be looking at for the fuses from the battery and charge controller?

Thanks for all the input.
Cheers

 

[740GLE]

Some feel every wire/component should be fused.

I’d toss an ANL or Mega or MRBF on each battery.

 

[NBs]

Hi, when you first connected the batteries in parallel, did you charge both batteries to full and check that they were at the same V with a max difference of 0.1V when the batteries were sitting in for 1 day before connecting them in parallel.

You said you didn't have a suitable charger, so I thought you had skipped this exact step to balance the batteries before connecting them in parallel.

 

[Neil H]

What is the black cable ?

 

[Primal1]

Hi, when you first connected the batteries in parallel, did you charge both batteries to full and check that they were at the same V with a max difference of 0.1V when the batteries were sitting in for 1 day before connecting them in parallel.

You said you didn't have a suitable charger, so I thought you had skipped this exact step to balance the batteries before connecting them in parallel.

I did not know about this step, I am awaiting 2 LiFePO4 batteries to wire in parallel. Is this a necessary step? Is there a thread to school a noob on this?

 

[NBs]

I did not know about this step, I am awaiting 2 LiFePO4 batteries to wire in parallel. Is this a necessary step? Is there a thread to school a noob on this?

 

[NBs]

This information can be found in the instructions for use of the Eco Worthy lifepo on page 6 , in addition they recommend doing a balancing every 2-3 months or so, breaking the chest connection and fully charging the batteries one at a time. If you didn't do this, your batteries can't give out full capacity because you didn't balance the V before connecting. As far as I know, the batteries will not be damaged, but they just won't charge fully when they are paralleled.

 

[Primal1]

This information can be found in the instructions for use of the Eco Worthy lifepo on page 6 , in addition they recommend doing a balancing every 2-3 months or so, breaking the chest connection and fully charging the batteries one at a time. If you didn't do this, your batteries can't give out full capacity because you didn't balance the V before connecting. As far as I know, the batteries will not be damaged, but they just won't charge fully when they are paralleled.

Wow.. Okay thank you. I don't know how I got the idea LiFePO4 was going to be an upgrade to lead acid and make my life easier. I only added.water once every 6 months and it took a few minutes. This is going to take hours to days every few months. Lesson learned on research.

 

[740GLE]

Wow.. Okay thank you. I don't know how I got the idea LiFePO4 was going to be an upgrade to lead acid and make my life easier. I only added.water once every 6 months and it took a few minutes. This is going to take hours to days every few months. Lesson learned on research.

It is easier if you’re batteries are your native system voltage, if you combine 12v of the shelf batteries to make 24 or 48 volt systems there’s a couple more hoops to jump through.

Remember you’ll never have to “water” your lithium batteries so that in itself is a huge win.

 

[Primal1]

It is easier if you’re batteries are your native system voltage, if you combine 12v of the shelf batteries to make 24 or 48 volt systems there’s a couple more hoops to jump through.

Remember you’ll never have to “water” your lithium batteries so that in itself is a huge win.

I'm wiring 2 12v in parallel same as the OP and if I have to pull them out and balance them 4 times a year that's going to mean I am losing between 8 and 12 days per year to maintenance. Unacceptable when watering didn't take an hour a year. My wife wants me to return them and buy another set of lead acid.

 

[Mattb4]

I'm wiring 2 12v in parallel same as the OP and if I have to pull them out and balance them 4 times a year that's going to mean I am losing between 8 and 12 days per year to maintenance. Unacceptable when watering didn't take an hour a year. My wife wants me to return them and buy another set of lead acid.

Not the same. The OP is series connecting. You should likely never need to disconnect batteries in parallel.

 

[Hedges]

Batteries in parallel don't get imbalanced. Except to the extent one gets more of the charge current and more of the discharge current if resistance imbalanced.

A pair of batteries should be wired in parallel, and system connected to the battery bank diagonally. (or equal length wires to busbar etc.)

A single 12V lithium battery can have its 4 cells get imbalanced. Holding at a charge voltage high enough for BMS to balance could fix that.

If removing paralleled batteries to rebalance helps, whatever is used to charge them may be a higher voltage, or holds that higher voltage.

You should be able to get it to work by connecting wires symmetrically, and configuring charge controller for the right voltages and time.

Not the same. The OP is series connecting. You should likely never need to disconnect batteries in parallel.

For OP, how about a balancer of the type intended for two 12V lead-acid batteries?

Anyway, no need to disconnect, could just connect a load to whichever battery is high and bleed off to match. Somebody could design a circuit to do that automatically. A "passive balancer".

 

[Primal1]

Batteries in parallel don't get imbalanced. Except to the extent one gets more of the charge current and more of the discharge current if resistance imbalanced.

A pair of batteries should be wired in parallel, and system connected to the battery bank diagonally. (or equal length wires to busbar etc.)

A single 12V lithium battery can have its 4 cells get imbalanced. Holding at a charge voltage high enough for BMS to balance could fix that.

If removing paralleled batteries to rebalance helps, whatever is used to charge them may be a higher voltage, or holds that higher voltage.

You should be able to get it to work by connecting wires symmetrically, and configuring charge controller for the right voltages and time.



For OP, how about a balancer of the type intended for two 12V lead-acid batteries?

Anyway, no need to disconnect, could just connect a load to whichever battery is high and bleed off to match. Somebody could design a circuit to do that automatically. A "passive balancer".

OK cool a big thank you to you and Mattb4 both.

I will keep them and give it a shot, being offgrid with no possible shore power made the disconnect and charge concept extremely unappealing.

By diagonal wiring I assume you mean connect the positive lead to the Inverter to the positive battery post on one battery and the negative lead to tbe other batteries negative post? If so that was my plan for the Inverter and the incoming leads from the charge controller.

 

[Hedges]

Yes, and there are similar schemes for any number of batteries that is a power of 2.
For other numbers, busbar and equal length cables.

I haven't dealt with these lithium batteries yet, but voltage settings of SCC vs. BMS and time to allow balancing should help. Maybe you should start out with conservative lower charge voltage and observe how it behaves (can you read cell voltages from BMS?) before pushing things. To avoid tripping offline and having your much better half say, "I told you so."

 

[Alarchist]

I the the OP needs a 'battery equaliser' also sometimes called a balancer.

There's loads on eBay, something like this:

eBay Battery equaliser

 

[740GLE]

I'm wiring 2 12v in parallel same as the OP and if I have to pull them out and balance them 4 times a year that's going to mean I am losing between 8 and 12 days per year to maintenance. Unacceptable when watering didn't take an hour a year. My wife wants me to return them and buy another set of lead acid.

I’m sure that 4 times a year is a cover your butt type resonse for worse case scenario.

You can always pick up a victron batter balancer and it shuffles charge between two 12v batteries and you’ll never have to touch it again.

 

[Primal1]

I’m sure that 4 times a year is a cover your butt type resonse for worse case scenario.

You can always pick up a victron batter balancer and it shuffles charge between two 12v batteries and you’ll never have to touch it again.

I am so confused. I thought the battery balancer was for series connected batteries and didn't work or was unnecessary on 2 batteries in parallel. If it works on parallel batteries it's worth it for the piece of mind.

 

[740GLE]

I am so confused. I thought the battery balancer was for series connected batteries and didn't work or was unnecessary on 2 batteries in parallel. If it works on parallel batteries it's worth it for the piece of mind.

whoops, I’m sorry I miss read your post.

If your system is all in parallel, just verify proper wiring for current sharing and also make sure you hit 100% charge routinely, otherwise you may lose a few AH.

 

[Andrewr05]

Ya'll are scaring this guy off.

I'm sure millions of people out there don't run a balancer and their systems run fine.
Should they occasionally check to see if their isn't an incredible imbalance between their batteries?
Probably yeah.

Is their system going to explode if they don't?
No.
Will it straight up not work?
No.

Could it possibly have reduced capacity?
Yes.

You guys have him panicking and his wife telling him to return everything and if he can't then potentially they're losing hundreds of dollars on having to sell them off private sale.

 

[BenQ]

Thanks for reply.

1. I've never touched any of the settings so it's how it came out of the box.
There's no mention of lithium batteries in the instructions though.

2. I'm not sure how I'd tell what mode it's in.
The icons on the screen never seen to change much, other than showing it charging it not.

3. Rover? I assume you mean Epever.
I can plug a laptop into it and it shows more information. I've only ever done that once though and was too terrified to change anything.

Cheers

This could have damaged your batteries. Many solar charge controllers SCC are preset to lead acid batteries which is probably why it worked well for those when you had them. Best case scenario is your scc tried to bulk charge and equalize your LiFePo4 batteries and caused them to shut themselves off at some point instead of charging. Then when they woke back up you drained them and they never got charged to 100% ever again. Luckily since the BMS most likely did it’s job all you have to do is find the user defined settings for your SCC and turn off the equalizing mode and lock in the charging voltage at 14 volts or so. Then give them a few days to recharge.