Parallel battery

[thehippie]

I have solar 160W with 300W inverter.


How do you parallel two deep cycle battery? Is it the same way without solar?


I checked online I
Haven’t seen any parallel with solar power


Thanks

[K3WE]

Matt_Colie wrote:
I may never know what actually causes lead/acid batteries to explode.

One cause is that batteries can make hydrogen gas and electricity can make sparks.

Not sure, but I also wonder if 'explosion' doesn't also include a simple popping of the cell covers and a little acid spray.

Should you wear safety goggles when working with your batteries- probably. Should we outlaw batteries...no.

And, you're also supposed to tape over the electrodes on 9v batteries when you dispose of them! If they encounter aluminum foil wrong, you can burn your house down.

[Matt_Colie]

I may never know what actually causes lead/acid batteries to explode.

In so many years of tending these things, I have seen a single battery explode when a failure caused a massive discharge.

All of the other explosions I have seen were two batteries close strapped together. A vast majority of these were when a new battery was added to the bank, and it was a tossup whether the new or the old when up. Owners always hoped it was new, because at lease that had some warranty to use. The chances of a battery explosion go way down as they are separated as in diesel pickups, but I have seen two there also.

Matt

[wa8yxm]

azrving wrote:



Why should two 12s explode?

If I had to guess I'd say he had a bad experience.

Any battery can "Explode" if it is charged or discharged too fast.
If a battery develops a shorted cell and tt is in parallel with another battery the remaining cells may charge way too fast.

Of course it does not matter if it's a 12 volt or two pair of six volt (By teh way there are only 12 volt batteries in RV.s the six volt PAIR makes one BIG 12 volt)

I do however support the comments made about the difference between teh MARINE/deep cyle (Minimum SOC 75-80%) and TRUE DEEP CYCLE (50%) batteries. and that's the difference folks
For teh same number of amp hours. yo ucan use TRWICE the power.

[pianotuna]

Grit Dog,

If hydrogen is being produced when one jar has a short and a spark occurs the battery can explode.

K3WE, failure rates go up with cell count--my first bank had 42 cells. If I could have afforded 800 amp-hour two volt cells that would have dropped to only 6 cells.

[K3WE]

I think Matt is factually correct, but overstating that parallel connections are a significant hazard that causes explosions.

Stuff breaks AND batteries SOMETIMES explode (independently).

And a fact-if you have TWO batteries, the chances of one failing is doubled.

And I get his point that the second battery can contribute power to a problem in the good battery.

Conversely RVing half the miles will half the risk of you getting into a crash, and having zero batteries eliminates any risk of any battery explosion as well as eliminating all the great 12V lighting and heat and water pumps...

There is an extra risk for connecting batteries- but risk : benefit is everywhere and parallel batteries (or series batteries for that matter) have benefits AND risks.

PS: A semi analogous fun read is 787 lithium batteries: a case with numerous connected batteries, a quirky chemistry, and the effectiveness of safety back ups.

[Grit_dog]

Matt, since you have actual experience with this, maybe you could share what causes the battery explosions?
Because there are literally millions of 12V batteries hooked in parallel next to each other, doing their job as we speak. I have 3 sets of batteries this way. They don’t just explode for no good reason.
Overcharging? The outcome is the same regardless single or multiple.

[Matt_Colie]

Matt_Colie wrote:

If you are going to strap 2 or more 12V batteries in parallel, be sure to keep a box of baking soda on hand to neutralize the acid that will be around after one of the two explodes.

Matt

azrving wrote:

Why should two 12s explode?

They don't have to explode, but if one battery does has a problem, the other is available to pour all of its power into the failed jar and something just has to give.

ScottG wrote:

There are several million diesel trucks running around that suggest otherwise.

They explode in trucks too.
But the diesel pickups have them on opposite sides of the engine box and they are not short-strapped together. This provides enough system resistance so the bad jar will just over heat and boil.

I ran a boat maintenance business until the depression shut us down, I used to get about a dozen calls a season to clean up and do the required repairs after one one of these. I liked them because they were simple, no diagnostic to do and lots of money from the insurance companies.

Matt

[Grit_dog]

azrving wrote:

Matt_Colie wrote:
Any Marine/multipurpose battery is not a real deep cycle battery and will be damaged by even a single deep discharge. That is an unfortunate fact that is a result of being able to provide current for cranking an engine.

If you are going to strap 2 or more 12V batteries in parallel, be sure to keep a box of baking soda on hand to neutralize the acid that will be around after one of the two explodes.

Matt

Why should two 12s explode?

Just more rvnet “wisdom.”

[azrving]

Hippie
Ok so you have dual purpose. Connect them like the left side pic with the black batteries. It's the same as the pic that piano posted. That configuration will keep both batteries discharging and charging equally.

[ScottG]

azrving wrote:

Matt_Colie wrote:
Any Marine/multipurpose battery is not a real deep cycle battery and will be damaged by even a single deep discharge. That is an unfortunate fact that is a result of being able to provide current for cranking an engine.

If you are going to strap 2 or more 12V batteries in parallel, be sure to keep a box of baking soda on hand to neutralize the acid that will be around after one of the two explodes.

Matt

Why should two 12s explode?

There are several million diesel trucks running around that suggest otherwise.

[thehippie]

azrving wrote:
We are assuming that you are talking about TWO 12 volt batteries. People call dual purpose batteries and GC2 6 volts deep cycle so we need to know what you have. Since you said parallel our best assumption is 12 volt batteries but you did say DEEP so people could also think 6 volt. Do you have 12 volt or 6 volt batteries?





Solar and inverter dont matter. As Grit said, BUT be sure to connect system positive and negative in a balanced manner. Don't connect the rigs positive and negative to one battery, you want the positive to one battery and you want the negative over to the other side of the other battery.

Your solar is then going to charge both batteries the same way any other charger would be interacting with the batteries.

This pic is from the website "12 volt side of life". IF your batteries are 12 volt batteries they would look like the black ones on the left. They are showing you how to do basic wiring of both 12 volt and 6 volt batteries. If you have TRUE deep cycle 6 volts then you are actually asking about a series connection like the red batteries on the right.

12 volts deep cycle. I have interstate group 24

[thehippie]

Z

[pianotuna]

This is what is balanced and best for twin twelve volt batteries.



As it often doesn't cost a dime more to do this, I think it is worth the trouble.

If you wish to understand the "why" surf here:

correctly interconnecting multiple twelve volt batteries

Others may say it doesn't matter--but unless there is a compelling reason to not optimize charging and discharging why not do it the best possible way?

[azrving]

Matt_Colie wrote:
Any Marine/multipurpose battery is not a real deep cycle battery and will be damaged by even a single deep discharge. That is an unfortunate fact that is a result of being able to provide current for cranking an engine.

If you are going to strap 2 or more 12V batteries in parallel, be sure to keep a box of baking soda on hand to neutralize the acid that will be around after one of the two explodes.

Matt

Why should two 12s explode?