Auris hybrid 12v battery has no power

[G Cameron]

This morning very cold and for the first time my auras hybrid wont start, dash says "12v Battery low" no heater to defrost windscreen although blower worked . After 10 mins it started. Been driving auris hybrids for 5 years and never had this before, present car is less than 2 yrs old

 

[Bob110023]

Hi. If the car is less than two years old go back to the dealer.

[eygo]

if you get anymore messages on the dash take a photo of them to show the dealership

as your car always seem to be running right when you get to them for a quick check over

[Beekeeper D]

Our hybrids have a pretty minimal 12v Battery. 

I've recently had a couple of "flat battery" events and am looking to replace mine. 

The 12v Battery doesn't do the same work it would in an 'ordinary' car. But we have a fairly ordinary Battery, just an unusually small one! 

In a petrol or diesel vehicle, the battery is selected for its ability to turn over the engine to start it. A massive but brief effort - think of it as a 100m sprint. 

In our hybrids that job is done by the massive hybrid battery pack, not the 12v. 

The work our 12v batteries do is more like a very long walk, with a brief gentle jog at the end - never a vein-bursting sprint!

But the 12v is needed to "boot up" the hybrid system and thus allow the big battery to do its work. 

A flat 12v means it doesn't 'boot' and doesn't start. 

Good news - it takes very little 12v power to "jump start" the system (so the big battery can get to work) and Toyota thoughtfully provided an easy-access connector for the purpose. Once the system is rebooted ("Ready" showing on the dash) the 12v will be charged from the big hybrid battery - so the jump start connection is only needed for a few seconds. 

Bad news - 'ordinary' 12v lead/acid batteries get damaged by going flat. So it happens more easily next time. EDITED TO ADD Because my battery is in a back corner of the car, and the rear hatch-latch turns out to need 12v to operate it, you can't easily check the battery state before you start recharging it! 

So what does our 12v battery do? 

It does a slow and steady job while the car is parked, running the alarm and (if fitted) the keyless entry system. It works the central locking and in "Accessories" mode it'll run the radio etc for just 20 minutes before nanny Toyota shuts things off to protect the poor little 12v battery! And when you try and start the car it has to reboot things - seemingly the most energy intensive part of that task has to do with (electrically) restoring hydraulic pressure to the brakes (which I gather draws about 8 amps from the battery - less one tenth of a typical starter motor peak current). 

Given that its work characteristic is so different from that of an 'ordinary' battery, it is kinda surprising that we have an 'ordinary' battery. 

Now that my 12v battery looks to be nearing the end of its life, I recalled a thread on here that referenced a Priuschat thread about using a 12v battery that should be better suited to the duty cycle in an Auris (or Prius, or Yaris) hybrid. 

The idea was to use a battery designed not for brief intensive sprints, but one designed for really long jogging sessions. Such batteries are employed in electric mowers, mobility scooters, solar power banks and computer UPS, for example. Big ones got used on forklift trucks and, back in the day, milkfloats. 

The favoured battery in the 2010 Priuschat thread was a Ritar RA12-55, which seems to be no longer available in the UK. 

In March 2018, a member of this forum fitted a Lucas battery to his Yaris hybrid, but was going to have to somehow redo the clamp to secure it. 

https://www.toyotaownersclub.com/forums/topic/175037-does-12v-auxiliary-battery-in-auris-hybrid-need-to-be-agm/?do=findComment&comment=1469349

That battery is available today, and for less than £100 should provide not just greater capacity than the standard one, but much greater usable capacity as it can be "run flat" without suffering significant damage. Charging rates, gassing, etc do not appear to be anywhere near being a problem. 

My first question therefore is "Does anyone know if the Lucas LSLC55-12 will fit the Auris (hybrid) Touring Sports, without modification to the battery mounting?"  Yes, I know that you need to add screw-in posts to the battery - no problem, £9 eBay from the UK. The height dimension (thinking clamp) looks to be the one that is closest to the standard dimension... 

Or is there an alternative mobility/leisure (deep discharge) battery that anyone has fitted simply to the Auris hybrid? (Do hatch and estate share the same battery tray?)

Secondly "Can anyone recommend a small, cheap, reliable 12v reboot jumper battery, as it seems prudent to have one, given the twee little 12v fitted as standard?" (eBay has some very cheap, very small ones - but a month or more to ship from China!)

I should share that my first no start episode was the day after I'd awkwardly lifted some shopping over from the front passenger seat as I exited the car, and may have brushed the interior light (or, old chestnut supposed to have been fixed, the hazard light switch) leaving the light on overnight. The car unlocked normally, and the dash lit up briefly before everything went off - except the Hybrid Malfunction warning light! I had a few kittens before I realised that opening the door, the interior light wasn't coming on... (my lightbulb moment!)

Just a few days after that, the car had to be left parked for 3 days, leading to a similar event (but with a blank dash). No dash messages for me, but anyway... I reckon it is time for a new 12v battery to be sourced... 

Closing thought - If Toyota had designed the start-up sequence slightly differently, this wouldn't be so dramatic a problem. 

The priority could have been to reconnect the 12v to the big battery, before asking the 12v to do any serious work (like running the pump to repressurise the hydraulics). That way, even a very flat 12v could 'start' the car - ideally with a warning being displayed. But hey, they seem to have expected the 12v battery to be in great shape. 

Maybe they did this with the 'facelift'? (The OP's car is 2 years old, so facelift, mine is the older one.) 

[Scandinavian]

Hi. My 12 Volt Battery was empty several times. When I visited certified Toyota service (Elke auto Estonia(´) they told: "there is nothing wrong in the Battery, you just need to charge it a bit more". No quaranteen change. It was 25 Ah Yuasa. I bought little bigger Toyota Prius Battery 35 Ah, Toyota brand but Korean. It needed new holder, but there is enough place. Same cables. Now it works! Toyota told that it is forbidden to put bigger, but it works now!

[TonyHSD]

Just keep using the cars and never gonna have problems with the battery. If it’s cold twice a week keep the car in ready mode for 30-40 min each time if you not able to drive lockdown or whatever reason. Good luck 👍