See my post above yours. Basically if you use "their" charger you get the 10yr warranty but at 6 amps I'm curious how it trickles. Then there's the hybrid Tender models that you can switch between lead and Li.

 

It's the balancing risk I described.

If you leave it charging, even if it cycles on/off, then over time the cells could fall out of balance and get damaged.

If you need a charger in the first place, it means the car is draining power from the battery. If the battery is drained enough to switch the charger on every few days (or more) that can add up to a lot of small charge cycles.

 

Gotcha. It "shouldn't" have any drain with the kill switch off. But still it "sits connected" for months at a time meaning the ground is still grounded and the positive still goes to the switch. So it sounds like a pita to go out every week and measure the voltage when a brand name charger should be doing that for you. Goal, get the 5-10 years out of it. So scenarios:

Charger or no charger:
1. Motor swapping, battery sitting there as you add/remove mech/elec stuff from the car but you aren't starting/running.
2. Car complete just waiting on the next event, start it every other weekend and let it run like usual.
3. Track day - used to plugging in the AGM between sessions due to running the fans/data with the car off for minutes at a time. Then leave it plugged in overnight.

 

Does your meter have a setting to measure mA? If so, you can check the parasitic draw on the battery. If it's low enough (<1mA ideally) then you shouldn't have to worry about charging it while the kill switch is off.

Lithium batteries don't generally self-discharge very quickly.

In my experience, things like gauges or even ECUs can have weird power draws at idle, though. If those aren't behind your kill switch, they would drain the battery.

 

So.....lesson learned...again...sigh. The NEW battery I got off a friend, the Braille G30 LifePO4 I mentioned before, is officially dead after 1 evening mistake. It seems I left the kill switch on last night and the datalogger as well. SUPER small drain, but it...was enough to take it from 13.21 volts to 0.195 volts. I wasn't paying attention this morning as I was chasing other small issues on my list but when I went to do a boost leak and check the boost pressure display, click click...the f*....click clickly....oh hell no. Yes that's correct, the "BRAILLE" bastards strike....again. Not only does the G series not have a real BMS, but it does not have the "cut off" like the Antigravity brand does. Luckily, amazon can get me the ATX30 by Tuesday. So only a 500 dollar battery and a 150 dollar charger mistake. The charger was intensionally left off because as above mentioned and by Braille themselves you "shouldn't leave it on". I only left it on once a week for several hours and it never really charged because it always stayed above 13v.....until it wasn't.

So hell with all that. ATX re-start life saver, proper CTEK charger inbound. Do Not Buy Braille.

 

Ugh, thats definitely super annoying. The antigravity cuttoff has saved me a couple times now.

 

that's what i'm running now as well. got one of their new automotive series, a 51r.

 

I've been using a fairly priced Battery Tender 3.5lb battery for almost 4 years. Granted, the car doesn't do much street driving, but I've been leaving this '06 evo off the trickle charger and it hasn't ever drained it! I think it was like $160.