SLA 7Ah small solar system

[ElectronicPR]

I have more than 100 12V@7Ah Sealed Lead Acid batteries that I will like to use to build a small solar system to use it as a backup when power is lost for critical loads such as refrigerator and illumination.

Since I got those batteries for pennies, i would like to configure them so when they go bad I just replace them with a bigger battery that has the same capacity.

Just as an example:

Configured at 24V (2 in series 14 in parallel) in theory i will have a battery of (12Vx2)@(7AhX14) 24V@98Ah

Then if i do that 4 times my system will have a total of 24V@392Ah
that can be replaced with eight 12V batteries that have the same 98Ah

Has anyone done something similar?

The thing is that I have the batteries sitting there and i want to do something with them.

[SunEagle]

I have more than 100 12V@7Ah Sealed Lead Acid batteries that I will like to use to build a small solar system to use it as a backup when power is lost for critical loads such as refrigerator and illumination.

Since I got those batteries for pennies, i would like to configure them so when they go bad I just replace them with a bigger battery that has the same capacity.

Just as an example:

Configured at 24V (2 in series 14 in parallel) in theory i will have a battery of (12Vx2)@(7AhX14) 24V@98Ah

Then if i do that 4 times my system will have a total of 24V@392Ah
that can be replaced with eight 12V batteries that have the same 98Ah

Has anyone done something similar?

The thing is that I have the batteries sitting there and i want to do something with them.

I would either sell them or give them away.

Building a battery system by wiring 14 sets in parallel will just about destroy them when they are being charged. For that matter even 4 strings of 2 in parallel will turn them to toast in short order.

The terminals on those batteries are designed for low amps. Creating a large battery system will generate higher amps and can cause those terminals to melt. IMO sell or give 94 of them away. Then you can experiment with the last 6.

[PNjunction]

The terminals on those batteries are designed for low amps. Creating a large battery system will generate higher amps and can cause those terminals to melt. IMO sell or give 94 of them away. Then you can experiment with the last 6.

Even if the batteries were pristine straight from the Yuasa factory, it is an insanely bad idea from a balance standpoint, not to mention dangerous - even with these small cells. Somehow I doubt they are pristine, but pulls from another source like a ups, old stock etc.

In the real world, those terminals WILL melt, or at least the internal bus-bars will fuse open. If any of the batteries are overcharged and gassing, and the fuse action takes place internally and sparks doing so, welcome to combustion.

Suneagle is spot on. Save 6 of those max showing the highest ocv for goofing around SAFELY. Better yet, junk them ALL, and get a larger single battery for your 12v experimentation.

If you absolutely MUST play around with them, vet their performance *individually* with a decent charger. In your case a Tecmate-Optimate "5" would be ideal as it provides test results much more extensive than just a simple "done charging" led.

[Sunking]

They make nice small boat anchors. Otherwise completely useless.