Hacker News

points by hbarka 1 day ago | 0 comments

I switched the 12v lead-acid batteries on my EV to the 12v Lithium from OHMMU. Best upgrade I've done. I recently saw that they now offer 12V Sodium, and their warranty now went up to 3 years on the sodium, from 1 year. They have new data on its robustness.

[–] dearsiary7 1 day ago

Why? What do you notice? I was told the 12v fail in a few years and it will be swapped out at the 3rd year service and every few years there after for about $100. I will probably never see it as it three big bolts under the passenger seats that I have no interest spending my Saturday removing. What does this upgrade get you?

Byd dolphin, Thailand prices for above

[–] imoverclocked 1 day ago

I did this with a Polaris Ranger EV that had 8x12v Lead Acid in a 2x4 configuration that produces 48V. Instead of going with more 12V batteries, I switched to two 48v BigBattery LiFePO4. In doing so, I dropped the weight by about 600-700 lbs. I use it in very hilly terrain so that weight makes a huge difference to me.

Additionally, the original batteries were not sealed and required maintenance. Each battery has two ports which need to be filled individually. On top of those ports are supports/braces and wires in an already inconvenient space.

I'm so happy to not have to deal with refilling those batteries anymore. That alone made the conversion worth it to me. Also, lead-acid doesn't necessarily last longer. The new (LiFePO4) batteries have lasted about as long already and (knock on wood) seem to be doing fine. Maybe it's because I don't have to top them off with distilled water?

[–] hbarka 1 day ago

I couldn’t believe how light those 12V lithiums were. Same form factor as the lead and I could pick it up with one hand easily.

[–] imoverclocked 1 day ago

Yeah, such a big difference. I had a similar choice with a skid steer and the lithium version adds weight into the rear of the machine in order to stay useful.

[–] AnthonBerg 1 day ago

Yep!

Tossed the lead-acid battery in my DR-Z400S motorbike, put a LiFePO4 in. The weight and mass placement difference was so significant that I had to re-set the suspension sag.

My DR-Z400S dual-sport motorcycle is like… 140kg?, kind of tall and narrow for a motorbike. The lead-acid battery is placed sort of high on a sort of fulcrumy point over the rear suspension. It's a very real difference. Didn't expect this dramatic a difference.

[–] saidinesh5 1 day ago

My guess: With all the telemetry and processing that continues to happen in modern cars, if you leave an EV parked for a longer time, the 12V battery will be discharged faster.

So having higher capacity 12V at the same size and only slightly more expensive might help?

[–] hbarka 1 day ago

My reading is avg at 13.8V. The battery also has Bluetooth which allows me to monitor cell health and discharge.

[–] hbarka 1 day ago

> three big bolts under the passenger seats that I have no interest spending my Saturday removing.

I’m not familiar with BYD but yes you need some mechanical aptitude to change the 12v battery yourself.

Premature failure of 12V lead-acid batteries remains a persistent complaint among EV owners and is a recurring frustration. Just go to any EV forum. The traction battery will not top it off either when parked for extended periods.

Lithium batteries generally tolerate periods of inactivity better than lead-acid batteries. The OHMMU batteries are also “smart enabled”, see their website.