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Piwoslaw 12-30-18 07:58 AM

What to do with a lead-acid car battery?
I recently bought a new car, but it came with a cheap, undersized battery. For the engine Start-Stop function to work, I had to get a larger AGM battery. Now I have the old one as a spare.

What can I use a 12V, 510A, 62Ah lead-acid battery for?
  • I could keep it in the car, wired parallel, and delete the alternator, but the alternator doubles as a starter. And the ECU already turns off the alt field when the battery is topped off.
  • I would love to use it to catch solar or wind, but our house is shaded year-round under tall trees.
  • I could charge it at off-peak hours and power the house at peak hours, but our utility does not offer such a tariff, only flat rate.
  • I could just leave it in the garage, topping it off every weekend with a trickle charger, and use it for testing random electronics projects, but that seems like a waste of a nearly new battery.
Any other ideas?

EDIT: One more idea would be some kind of e-assist project for a bicycle or bike trailer.

Daox 01-01-19 05:21 PM

Unfortunately, a starting battery isn't really all that useful. You can't deeply discharge it without significantly reducing the life of the battery.

stevehull 01-02-19 05:37 AM

I use batteries like this for my electronic work. I do fuse it, but what you have is a virtually unlimited current source at a voltage that never changes.

For + - ground supply, I hook up two batteries in series and now have a ground in the middle with a + and - 12 volt supply. FAR better than commercial power supplies - and the price is right.

Some solid state stuff, especially analog, wants a very stable power supply. Bread boarding and prototype with the above configuration makes it a LOT easier as I don't have to be concerned with the stability and cleanliness of the power (no spikes, no high frequency "fuzz" - just pure DC at it's best.


Happy new year!

NiHaoMike 01-02-19 07:01 PM

Find a used UPS that takes a single 12V battery and just connect it.
Upgrade your UPS! (with some car batteries...)

pinballlooking 01-02-19 08:08 PM


Originally Posted by NiHaoMike (Post 60407)
Find a used UPS that takes a single 12V battery and just connect it.
Upgrade your UPS! (with some car batteries...)

I really like this idea a have a jetski AMG battery that would be great for this. I also have a UPS that has a bad battery. It is 12 volts so I think the two should work together.

randen 01-05-19 01:29 PM

A starting battery is just that. Was designed and tailored for just that. Put it on a buy and sell and use the money for other things. There are other things at play here that will render the battery useless to anyone and affecting its value to someone that needs a proper starting battery

It seems a lack of a quick discharge followed by a complete charge is not unlike exercise to extend the life. Sitting around and self discharging with the odd recharge is highly detrimental to a reasonable battery longevity


PS an investment in lithium with a battery management system is absolutely golden for any energy necessary experiment or toy. Lead acid is an absolute waste of time!!! Like screwing around with a film camera!!

oil pan 4 01-06-19 01:19 AM

Keep it as a spare.

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