Battery health %- when to replace?

[Nukeman7]

See Post #9 in this recent BITOG battery thread if you are a Sam's Club member. Better price than the EverStart MAXX (exact same battery if the MAXX battery serial no. starts with "EP") at WalMart with an identical warranty. The sale ends tomorrow.

 

[Patrick0525]

If you haven't already show your daughter how to change her tire with only the tools included with vehicle or if you get a longer breaker bar etc that will always stay with it.

At a bare minimum u should equip ur daughter’s
Mazda with a pinch weld adapter so the uncouth Gorillas at road side assistance doesn’t flatten or damage the rocket panel. Makes me sleep a whole lot better at night.

Pinch weld adapter plate

 

[SC Maintenance]

What is the resistance value? What is the CA value, and what is it rated at.

The % health is a bit misleading. Its just a divisor from the CA / rated and measured at a temperature that is not probably correct. I had a 24F from Walmart (the $50 specials when they had them) that was only 80% when brand new.

If it was low resistance, like 5 milliohms, I would keep it. If its quite a bit higher than that, I would replace.

 

[Sequoiasoon]

Even the best jump pack won't start a battery that fails as a short, and sometimes old batteries fail suddenly as a short. My sister has a 1000 Amp Gooloo jump pack and I remind her to charge it every 3 months. It was fully charged and only a year old and it could not start her 2019 CR-V when the 51R battery failed as a short. Her husband connected it up properly and his attempts dropped the charge of that jump pack from 100 % to 71%.

I put a new MAXX 51R in it.

BTW, I had previously disconnected the ground wire and scraped away the paint where it mounts with a 1/8 inch flat blade screwdriver and also scraped clean the lug and clean the battery connections and coated all connections with a lite coat of Corosion X Aviation grade electric contact cleaner, and added the green and red battery corosion preventing pads, and put it all back together.


Put that money towards a Walmart MAXX, and forget about it for 3 years.

Maybe I'm in the minor percentage but in over 45 years of working on vehicles I have not come across any batteries that failed as a short that I recall. Declining percentage getting too weak, many. Lights left on killing them, many. Over 99% able to jump start except when the jump pack was low on charge.

Just because it's my vehicle, my ~60% battery in fall lasted through 2 winters until I changed it. For me it was a combo of lazy, no change in cranking speed, Jump pack and jumper cables in trunk. I also back in driveway all the time and have a slight downhill on the driveway. My '17 Accord is a 6MT so 2nd gear, let it roll a bit, let clutch out. My son and daughter did that just as practice a couple times in it. Their cars unfortunately automatic so no option for that.