Replacing car battery with ebike battery

[loysius]

Hi guys,

My gf's car battery just won't hold a charge and keeps dieing on her. I looked to see how much a replacement costs and it looks to be about $108 which may or may not be ridiculous for a 12v lead acid battery. Surely I could get a much better "ebike" battery to fit in the battery space. Where we live the temperature ranges between 0 Fahrenheit to 102F and those extremes are very rare.

Here is the $108 car battery replacement. http://www.walmart.com/ip/EverStart-Maxx-Group-Size-H5-Automotive-Battery/20531541?wmlspartner=wlpa&selectedSellerId=0&adid=22222222227017563455&wl0=&wl1=g&wl2=c&wl3=80425812649&wl4=pla-177652176289&wl5=9009703&wl6=&wl7=&wl8=&wl9=pla&wl10=8175035&wl11=online&wl12=20531541&wl13=&veh=sem

What do you guys recommend? Is there a less expensive alternative? If there is one then I should just be able to ziptie the 12v battery in and solder or clamp the wires to the original car battery connectors.

Thanks,
Loysius

 

[Punx0r]

Any lithium-ion battery capable of starting a car will cost several times that of a regular lead-acid starting battery. Most (if not all) ebike batteries for sale are incapable of starting a car and are not compatible with the car's charging system.

 

[Chalo]

A good sized 130C model airplane battery would start the car, but it wouldn't get along with the car's charging system. It would need a relatively sophisticated charger to turn the voltage regulator's output into a form the battery can tolerate. That alone would cost more than a car battery.

And it might burn the car down after being exposed to the heat, vibration, and peak loads of a car battery.

 

[loysius]

A123 cells work great for replacing lead-acid. Costco is most economical for car batteries.
Answer: sell the car, ride an ebike.

lol, well thanks guys. Guess it's just time to go buy that damn Lead Acid battery then.

 

[marty]

If you haven't already, test the charging system. Here is how I do.

1. Do visual inspection of battery terminals. Should be clean and tight.
2. Charge battery all night.
3. Remove charger, wait a few minutes for battery to settle down, then measure voltage with car off. [write it down]
4. Start car and measure voltage with car running. [write it down]

Report back with those two numbers and all the wonderful auto mechanics here will tell you what to replace.

Test don't guess.

 

[999zip999]

AAA is the way to go. Find a friend that has triple A. They cometo the house and computer style test the system. Give a print out have cheapest prices and two yrs we come to you battery warranty. So no girl worries. Where you live ? Lead is good for cars. Start and drive three times a month. Yes far enough to charge battery. What car ?
Yes clean inspect all connection's, look for green stuff. All battery connections must look bright no dull coat with vasoline. Look for cph by the battery terminals as a crackhead case or hydrogen gas is leaking forming green s***.

 

[redilast]

Are you sure the battery is not holding a charge? Or maybe you have some parasitic drain?

Before you buy a battery I'd check 2 main things.

1) Check the voltage of the battery when the car is started, headlights on, fans on max. Should be in the 13.5 to 15v range. If not, you have a bad alternator most likely.

2) Check for parasitic drain. Use a multimeter set on the 10A range and remove the negative terminal from the battery. Put one meter lead to the battery and another to the - battery cable. And measure the drain. Some newer cars with alarm systems and other systems may draw more power for a few minutes then settle down, but you don't want more than a 50mA continuous drain on your battery.

Then after trying step 1 and 2, if you believe the battery is bad take it in to an auto shop and have them test it. They basically will just load test it to test the cranking amps to see if it passes or fails.

 

[loysius]

Are you sure the battery is not holding a charge? Or maybe you have some parasitic drain?

Before you buy a battery I'd check 2 main things.

1) Check the voltage of the battery when the car is started, headlights on, fans on max. Should be in the 13.5 to 15v range. If not, you have a bad alternator most likely.

2) Check for parasitic drain. Use a multimeter set on the 10A range and remove the negative terminal from the battery. Put one meter lead to the battery and another to the - battery cable. And measure the drain. Some newer cars with alarm systems and other systems may draw more power for a few minutes then settle down, but you don't want more than a 50mA continuous drain on your battery.

Then after trying step 1 and 2, if you believe the battery is bad take it in to an auto shop and have them test it. They basically will just load test it to test the cranking amps to see if it passes or fails.

Thanks I'll give this ago and see what I can find out

 

[Syonyk]

Agree that any cheap lithium battery either won't start the car or is a hazard.

"Keeps dying" either means the battery capacity is tiny at this point (if it's more than 5 years old, just replace the thing), that it's not getting charged properly (you *have* tested running voltage, right?), or that there's a serious parasitic drain somewhere. Any recent maintenance?

Test all those things. All you need is a cheap multimeter to test charging voltage and parasitic drain, and if those aren't the problem, then replace the battery. Lead acid batteries don't last forever.

That said, they're a seriously good source of cheap cranking amps. I figured at some point that my truck needs about 750A (9kW) to start, but only uses about 5WH in the process.