Connecting battery in parallel - advice needed

[tndl79]

We've got these cheap 12V 7Ah lead-acid batteries for alarm and gates. They perform poorly and my display keeps beeping as battery is weak. These batteries take strain for life especially at lower charges.

While getting better expensive batteries is a solution, I'm wondering if I could instead connect two or more of these cheap batteries in parallel (connecting positives together, and negatives together with a jump cable) which will retain the voltage at 7V but increases the capacity Ah.

I haven't seen much on this topic, is it because it doesn't work?

And could I even keep my old battery that is a bit run down and top it up with a new fresh one in parallel, or even two new ones?

 

[Tomtomtom]

Yes you can. But, they'll still be killed by loadshedding. It might take a bit longer, but you'll have two dead batteries to replace instead of one.

A big problem with alarms and gates is they don't have fast charge circuits. So the battery might not get fully recharged after each session and that kills it quickly, even if it's oversized.

An external charger could be a better investment than a second battery.

 

[B-1]

Yip will be perfectly fine as long as the charger can cope with the extra capacity. Its also good to have them roughly the same age.

 

[netstrider]

Alternatively you could get a 17Ah battery, assuming it fits the case. Else it will have to be in its own container.

 

[krieg]

We've got these cheap 12V 7Ah lead-acid batteries for alarm and gates. They perform poorly and my display keeps beeping as battery is weak. These batteries take strain for life especially at lower charges.

While getting better expensive batteries is a solution, I'm wondering if I could instead connect two or more of these cheap batteries in parallel (connecting positives together, and negatives together with a jump cable) which will retain the voltage at 7V but increases the capacity Ah.

I haven't seen much on this topic, is it because it doesn't work?

And could I even keep my old battery that is a bit run down and top it up with a new fresh one in parallel, or even two new ones?

Make sure your cables are exactly the same length.

 

[tndl79]

Yes you can. But, they'll still be killed by loadshedding. It might take a bit longer, but you'll have two dead batteries to replace instead of one.

A big problem with alarms and gates is they don't have fast charge circuits. So the battery might not get fully recharged after each session and that kills it quickly, even if it's oversized.

An external charger could be a better investment than a second battery.

Thanks for your explanation.. What type of charger might I use, and do you reckon I can just connect them onto the battery while it is connected to the alarm system?

 

[Tomtomtom]

Thanks for your explanation.. What type of charger might I use, and do you reckon I can just connect them onto the battery while it is connected to the alarm system?

Any car battery charger suitable for leaving in place long-term. It must float at ~13.6 V. This one should be fine:

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You almost certainly can hook it to the battery while it's still on the alarm (and this is the only way it's going to be practical), but obviously best to check with the manufacturer.

 

[soulie]

Any car battery charger suitable for leaving in place long-term. It must float at ~13.6 V. This one should be fine:

Takealot.com: Online Shopping | SA's leading online store

South Africa's leading online store. Fast, reliable delivery to your door. Many ways to pay. Shop anything you can imagine: TVs, laptops, cellphones, kitchen appliances, toys, books, beauty & more. Shop the mobile app anytime, anywhere.

www.takealot.com

You almost certainly can hook it to the battery while it's still on the alarm (and this is the only way it's going to be practical), but obviously best to check with the manufacturer.

unplug your alarm beforeyou fiddle

Thanks for your explanation.. What type of charger might I use, and do you reckon I can just connect them onto the battery while it is connected to the alarm system?

unplug your alarm before you connect the new charger to it .the alarm can run happily on one charger .if you leave the alarm charger on and connect another charger up to the same battery they gonna wrestle each other to the death .by bypassing the alarm charger you may lose some functions like power off notifications etc