That's an interesting graphic. BUT.....it no doubt applies ONLY to conventional wet cell types of batteries. AGM types should approach twice those expected service lives, in a vehicle that is used regularly. I think all Prius OEM batteries are AGM.
Twice that amount doesn't seem plausible given the amount of issues people seem to have with the battery after 5 years. I live in the dark blue area- I can't see the battery lasting 9 years. Btw does mileage play into it at all?
Low miles is detrimental: a car that sits a lot. There's constant low-level drain on the battery, typical for any modern car. Ours is on life support most of the time, since it'll sit 2~3 days at a time. I just hook up my smart charger, let it run it's charge cycle, leave it on till the car's next use. The charger reverts to trickle charge mode once done with it's charge cycle.
I said "approach". Some do indeed last that long. Oddly enough, a vehicle with VERY low mileage is harder on the 12 V than one with high miles.
Anecdotal evidence over the years has shown the same to be true of NiMH and LiOn chemistries. Another rule of thumb I personally got from a battery engineer who works on PHEV's: if you're comfortable, the battery is too.
The same what ? The expected life span for an AGM battery is unquestionably longer than a conventional wet cell. Which of those are you comparing the other two technologies to ??
Temperature affects battery lifespan of all current automotive battery chemistries. IOW, the chart is a good (enough) general-rule-of-thumb for those too.
Is there a trickle smart charger that works portably or does it need a outlet? I park my car on the street in the city.
I'd look into small, plug-in solar panel chargers used by RV, boaters, etc who also need to keep seldom used batteries healthy.
Well except in order to work, it HAS to be out in the open......in the day time. It may have a tendency to "walk away" if left unattended. Why do you think you need a maintenance charger ? Most people don't.
it easy enough to check who the OP is – it is at the top of each page: Aux Battery Prophylactic Replacement? Discussion in 'Gen 2 Prius Main Forum' started by Bluesman78, Mar 17, 2017.
I can't open the link (I'm outside of the US), but if it can supply 20 amperes for half a minute (plus whatever the 12V battery is sucking up...), it should get the computer and the high voltage relays working and from then on, the 200=>12V inverter should be supplying 14V for the entire car. Yes, something can be screwed up, yet it is beyond me how people manage this. If you make the same mistake on any other car you may see fireworks and hundreds and hundreds of amperes running through your startercables letting them curl up as well. Supposedly peope manage to attach the red and black startercable the wrong way around. There is a red clip/cover under the fusecompartment in the engine bay (see pic from here). On the bolt that is under it, you put the PLUS startercable that also attaches to the red-PLUS terminal on the donor battery. How can anyone mess this up??? And the black cable goes from the chassis of the donorcar, preferable on the bolt where the groundwire from the battery is attached, to a bolt on the chassis of the Prius. Once again, how can anyone mess this up? When attaching the black startercable, you may see sparks. And since batteries can gas hydrogen, it was iirc once decided that it is best to let these sparks happen at some distance from the battery. I think it is far fetched, but reasonably simple to just take the extra precaution.