Has anyone considered a lightweight 12v battery?

[doverosx]

Sounds like the lightweight battery is good for racing season and swapping to a typical sized battery in the winter for those that daily their race cars is the way to go.

[sportfan]

I used to swap out my AntiGravity battery every fall for the lead acid one but, this year I didn't. We get pretty cold winters here in Oklahoma but, the car stays in a heated garage and with the battery inside the car in an sealed ammo bow it can't get very cold. I didn't have any problems starting it .

[USA_EV]

Based on this thread and because it sounded like a fun experiment when the 12V in our 2015 died last winter we replaced it with a 12AH AGM battery. Our car is plugged into 120V essentially all the time. In the winter after around 4 days without driving, but still plugged in, this battery would be dead (integrated LCD volt meter wouldn't even come on). Now, all summer it has not gone flat once. Coming into winter again so we'll see how it goes.

Post-winter #2 report: Had same experience this winter. Just had to open the door every couple of days to wake the car up and it would "charge" for about 15 minutes keeping the 12V topped up. Not a big deal.

[ElectricTireShredder]

Just to clarify:

- The top two posts on this page are from gas cars with MUCH higher starting load.

- Opening the door while parked will only charge the 12V if the HV drive battery is charging. If it's not plugged in you'd need to turn the key 1 click for about 15 minutes every couple of days to charge the 12V from the HV drive battery.


Apparently cold makes a pretty big difference. At only 6Ah, my 12V is HALF that size. But it's fine even though I frequently leave it parked unplugged for 5 days. My underground garage is unheated, but very mild here in coastal southern CA.

[deftoner]

There is so little information about the 500e. but from the open source data of the leaf and some of the bolt and tesla, most EVs actively heat the battery pack even if they are not charging, but at different temperatures.

The leaf will heat the battery pack to avoid to going bellow -4 F. Tesla does not share the number (provably change model to model) but it clarifies that the battery level could be lower next day because of the temperature and because of actively warming or cooling when the car is parked.

I dont even know if the 500e uses the same cooling system with a resistor or heating pads like the tesla. But in the dissembled battery pack that I saw, didnt had any wiring or visible heating pads. During the cooling process, even when charging, the main fan and the pump works on the 12v battery, that is not being charged during that process... :/

[ElectricTireShredder]

Correction: A 500e 12v battery is being charged whenever the car is charging, as shown by a quick check with a voltmeter. Before plugging in, the battery is below 14V. After plugging in, it it's over 14V.

Same goes for whenever the HV's isolating contactors are held closed, such as when the key is turned one click, or 2 clicks. So if a 500e activated its battery heater when unplugged, it should actually CHARGE the 12V battery, not drain it.

The 500e battery heater is powered by the HV pack, as shown in the published 500e wiring diagrams: Pg 45 (pdf pg 53), & Pg 52 (pdf pg 60). Click here

[shay2nak]

Has anyone used this battery from Road Race? How many days can you let the car sit locked until the battery dies?
My other cars - one lasts 12 days and the other 6 weeks.

https://roadracemotorsports.com/stor...0121g79j1gna84

[ElectricTireShredder]

That link won't work for me, but it's easy math:


In warm weather a lead-acid 12V lasts about 1.5 days per Ah, & still start a 500e reliably. Nearly 2 days per Ah if you lock it with the key so the alarm isn't armed.

For example, my current 6Ah battery lasts about 9 days (6 x 1.5) with the alarm on, & about 11.5 with the alarm off (just shy of 6 x 2).


Lithium-ion (Lithium Iron Phosphate, or LiFePO4) SHOULD last about 25% longer but I haven't actually done that test like I did for 3Ah & 6Ah lead acid.


For cold weather, it's best to at least double the battery capacity.