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My Toyota hybrid reliably does not start after 4 weeks not driving. The 12 volt (1 year old) battery is drained too much after such a period of inactivity. I wa

My Toyota hybrid reliably does not start after 4 weeks not driving. The 12 volt (1 year old) battery is drained too much after such a period of inactivity. I was not expecting this from Toyota, pretty disappointing.

woleium 3y ago
to the fusebox with a multimeter batman!
- baking 3y ago
  Unplug the USB chargers first.
amluto 3y ago
Maybe they hired whoever designed the original Tesla Model S 12V battery management system. Or the original Tesla low-power sleep system.
- Syonyk 3y ago
  Oh man, that was a train wreck! I did some analysis of the Tesla 12V system back in 2016, and I'm amazed the batteries lasted as long as they did with how badly they abused the lead acid battery! https://www.sevarg.net/2016/10/30/tesla-model-s-12v-battery-analysis/ https://www.sevarg.net/2016/10/30/tesla-model-s-12v-battery-...
taylodl 3y ago
Welcome to the motorcycling world! Today's cars continually start the engine - that's a huge draw. If you're going to leave your car sit more than a couple weeks then you should put your battery on a tender. Motorcyclists have been doing that for decades.
- pcl 3y ago
  Why is that an issue for motorcycles?
  - Baeocystin 3y ago
    Tiny batteries have less headroom against phantom drains. Also, most motorcycles aren't daily riders, so the problem is exacerbated.
- Syonyk 3y ago
  Yeah, I (not really) joke that everything on the hill gets plugged in. It makes life a lot easier. Even with no idle draw, lead acid batteries self discharge over time. Life got way easier when I just accepted it, and now I've got a pile of 6V/12V battery tenders that go into just about everything (I have no shortage of 6V vehicles out here too). That and block heaters. The tractor and truck both appreciate them.
rwmj 3y ago
One thing I never understood is why hybrids have the 12 volt battery at all. Couldn't the entertainment system etc be powered from the 200V EV battery (after stepping it down obviously)?
- JonathonW 3y ago
  Everything on the 12V system essentially is powered from the traction battery (the big one that can power the motors), once the car is turned on. In Toyota, at least, the traction battery is completely disconnected (via a relay) when the car is off. The 12V battery is needed to power anything on the 12V system up until the car starts-- that includes the car's computer, which is what (after doing all its self-checks and whatnot) activates that relay and connects the traction battery to everything else in the car. The traction battery isn't always connected probably mostly for safety reasons (having 400-someodd volts energized across the whole car even when it doesn't need it isn't great), but that also keeps it from getting excessively drained if something in the car malfunctions. It's pretty cheap to replace a 12V lead-acid battery if it's overdischarged after you left the lights on... the big hybrid battery, not so much.
  - rwmj 3y ago
    Makes sense, thanks for the explanation.
  - sokoloff 3y ago
    Some EVs will monitor the 12V battery and periodically connect the traction battery to the DC-DC converter to maintain the 12V battery when the car is parked for an extended period of time. (On the older Smart EVs, this doesn’t have a limit, so the traction battery will kill itself trying to maintain a weak 12V battery. There’s a firmware patch for it.)
    - Stratoscope 3y ago
      My Kia EV6 does that, and when the 800V battery pack is charging the 12V battery while parked, an orange light on top of the dashboard goes on. This had me worried the first few times it happened. Then I found out it is a warning to mechanics/tow truck drivers/first responders that the high voltage system is energized.
TacticalCoder 3y ago
Happened to my wife's ex-Toyota CHR hybrid (not plug-in hybrid) after 5 weeks of vacation. I hooked a CTEK charger to it for 8 to 12 hours and all was good again. I didn't leave the car on the CTEK charger for five weeks because it was parked outside and not at our place. Otherwise CTEK chargers are really nice. Certain car brands like Porsche while sell you a "Porsche charger" for two or three times the price but it's just a CTEK charger re-branded with the Porsche logo on it. If you've got a garage with electricity, it's an option. If you don't want to let the car on the charger during 5 weeks, just connect it as soon as you come back and in a few hours the car is ready.
- jacquesm 3y ago
  I have a VW bus that doesn't see a lot of use and with a bit of fiddling it was easy enough to run a (fused) connector to just behind the grill with a little rubber lid to make it waterproof. That allows me to plug in a trickle charger without having to open the hood. That little trick has saved me multiple batteries already.
  - ct0 3y ago
    I can use the cigerette lighter on my tt roadster's trickle charger. Does the bus have one?
    - jacquesm 3y ago
      I could have gone that route but it would require the cable to go into the interior from the outside so that's why I hardwired it to the front. It also helps that I park it with its nose to the garage so the wire is very short and I just let it dangle down when it isn't in use.
Johnny555 3y ago
My Honda Hybrid is the same way, sometimes I go weeks between drives and if I park it for more than a couple weeks, I plug it into a 12V battery charger to keep the 12V battery topped up. But I blame the car's smart features (that use the cell modem to allow remote start, etc) rather than it being a hybrid. I suspect that the non-hybrid model would be the same.
- mulmen 3y ago
  My 1991 Honda motorcycle does this too. I can promise you that it has no smart features. It doesn’t even have a fuel pump. Lead acid batteries just don’t have long shelf lives.
  - Johnny555 3y ago
    Well I get that lead acid batteries experience self discharge, my 2003 era car will go for over a month with around 20% discharge (it'll be around 12.4V), but after 2 or 3 weeks, my 2020 Honda will be at 50% discharge (around 12.0V). I'd like to think that at some point the parasitic drain devices will shut down before they drain the battery completely, but I've never tested it beyond that point, I always plug in the charger if the car's going to be parked for more than a couple weeks. I installed a charger plug that comes out the front grill so I can plug it into the battery maintainer without even opening the hood.
    - orangepurple 3y ago
      Lead acid gel batteries hold their charge MUCH better than standard lead acid batteries. The difference is gel lead acid often self-discharge around 1% per month but standard lead acid batteries self-discharge on the order of 10% per month. I only use gel batteries on my small engine equipment like snowmobiles, motorcycles, and snowblower.
    - defrost 3y ago
      > I always plug in the charger if the car's going to be parked for more than a couple weeks. To this day, since ~1980, I disconnect the +ve battery lead if the cars not going to be used for a few days or parked up in the bush waiting for when we get back from a walk. Stops parasitic drains and Heisenbug discharges when thermal expansion during a very hot day causes a hard to track short.
mulmen 3y ago
This is true of basically every car ever. Lead acid batteries can’t maintain a charge forever. Get a battery tender if you aren’t going to drive for long periods of time. If you only drive once a month do you even need to own a car? Just rent/uber when you occasionally need a car.
- deleted 3y ago
  [deleted]
codazoda 3y ago
I hate to admit it, but Kia got this right. I own 3 Kia’s and they all have various problems, including really big problems, but this is an area they got right. On my daily driver, the Kia Niro, it has a battery button that instantly charges the 12v from the HEV battery. I’ve only needed it once, when I left a light on camping, but it was like magic.
- idontwantthis 3y ago
  What big problems have you had? I’m considering a Niro phev.
  - tonyarkles 3y ago
    Not a Niro PHEV, but they have had... a couple of serious motor issues: - https://www.kiaenginesettlement.com https://www.kiaenginesettlement.com - https://www.kiaengineclasssettlement.com https://www.kiaengineclasssettlement.com Edit: A friend of mine just got a free engine swap for her... 2012-ish Optima. It threw a CEL on the highway, had the appropriate trouble code, and bam, new engine from the dealership when she told them the code.
S201 3y ago
Is it the stock battery or after-market? Even if you bought it one year ago, when was it filled with acid? Many auto parts stores sell sealed lead-acid batteries as "new" when they've been sitting on the shelf for a year and the clock starts ticking when the acid goes in. You can get higher quality AGM batteries that will last far longer, but know they are quite expensive. Alternatively, you have a parasitic battery drain going on with your car.
shrubble 3y ago
I had something like this happen on my non-hybrid vehicle. The battery was replaced under warranty, for free since it was less than 18 months old.

woleium 3y ago

to the fusebox with a multimeter batman!

baking 3y ago
Unplug the USB chargers first.

amluto 3y ago

Maybe they hired whoever designed the original Tesla Model S 12V battery management system. Or the original Tesla low-power sleep system.

Syonyk 3y ago
Oh man, that was a train wreck! I did some analysis of the Tesla 12V system back in 2016, and I'm amazed the batteries lasted as long as they did with how badly they abused the lead acid battery! https://www.sevarg.net/2016/10/30/tesla-model-s-12v-battery-analysis/ https://www.sevarg.net/2016/10/30/tesla-model-s-12v-battery-...

taylodl 3y ago

Welcome to the motorcycling world! Today's cars continually start the engine - that's a huge draw. If you're going to leave your car sit more than a couple weeks then you should put your battery on a tender. Motorcyclists have been doing that for decades.

pcl 3y ago
Why is that an issue for motorcycles?
- Baeocystin 3y ago
  Tiny batteries have less headroom against phantom drains. Also, most motorcycles aren't daily riders, so the problem is exacerbated.
Syonyk 3y ago
Yeah, I (not really) joke that everything on the hill gets plugged in. It makes life a lot easier. Even with no idle draw, lead acid batteries self discharge over time. Life got way easier when I just accepted it, and now I've got a pile of 6V/12V battery tenders that go into just about everything (I have no shortage of 6V vehicles out here too). That and block heaters. The tractor and truck both appreciate them.

rwmj 3y ago

One thing I never understood is why hybrids have the 12 volt battery at all. Couldn't the entertainment system etc be powered from the 200V EV battery (after stepping it down obviously)?

JonathonW 3y ago
Everything on the 12V system essentially is powered from the traction battery (the big one that can power the motors), once the car is turned on. In Toyota, at least, the traction battery is completely disconnected (via a relay) when the car is off. The 12V battery is needed to power anything on the 12V system up until the car starts-- that includes the car's computer, which is what (after doing all its self-checks and whatnot) activates that relay and connects the traction battery to everything else in the car. The traction battery isn't always connected probably mostly for safety reasons (having 400-someodd volts energized across the whole car even when it doesn't need it isn't great), but that also keeps it from getting excessively drained if something in the car malfunctions. It's pretty cheap to replace a 12V lead-acid battery if it's overdischarged after you left the lights on... the big hybrid battery, not so much.
- rwmj 3y ago
  Makes sense, thanks for the explanation.
- sokoloff 3y ago
  Some EVs will monitor the 12V battery and periodically connect the traction battery to the DC-DC converter to maintain the 12V battery when the car is parked for an extended period of time. (On the older Smart EVs, this doesn’t have a limit, so the traction battery will kill itself trying to maintain a weak 12V battery. There’s a firmware patch for it.)
  - Stratoscope 3y ago
    My Kia EV6 does that, and when the 800V battery pack is charging the 12V battery while parked, an orange light on top of the dashboard goes on. This had me worried the first few times it happened. Then I found out it is a warning to mechanics/tow truck drivers/first responders that the high voltage system is energized.

TacticalCoder 3y ago

Happened to my wife's ex-Toyota CHR hybrid (not plug-in hybrid) after 5 weeks of vacation. I hooked a CTEK charger to it for 8 to 12 hours and all was good again. I didn't leave the car on the CTEK charger for five weeks because it was parked outside and not at our place. Otherwise CTEK chargers are really nice. Certain car brands like Porsche while sell you a "Porsche charger" for two or three times the price but it's just a CTEK charger re-branded with the Porsche logo on it. If you've got a garage with electricity, it's an option. If you don't want to let the car on the charger during 5 weeks, just connect it as soon as you come back and in a few hours the car is ready.

jacquesm 3y ago
I have a VW bus that doesn't see a lot of use and with a bit of fiddling it was easy enough to run a (fused) connector to just behind the grill with a little rubber lid to make it waterproof. That allows me to plug in a trickle charger without having to open the hood. That little trick has saved me multiple batteries already.
- ct0 3y ago
  I can use the cigerette lighter on my tt roadster's trickle charger. Does the bus have one?
  - jacquesm 3y ago
    I could have gone that route but it would require the cable to go into the interior from the outside so that's why I hardwired it to the front. It also helps that I park it with its nose to the garage so the wire is very short and I just let it dangle down when it isn't in use.

Johnny555 3y ago

My Honda Hybrid is the same way, sometimes I go weeks between drives and if I park it for more than a couple weeks, I plug it into a 12V battery charger to keep the 12V battery topped up. But I blame the car's smart features (that use the cell modem to allow remote start, etc) rather than it being a hybrid. I suspect that the non-hybrid model would be the same.

mulmen 3y ago
My 1991 Honda motorcycle does this too. I can promise you that it has no smart features. It doesn’t even have a fuel pump. Lead acid batteries just don’t have long shelf lives.
- Johnny555 3y ago
  Well I get that lead acid batteries experience self discharge, my 2003 era car will go for over a month with around 20% discharge (it'll be around 12.4V), but after 2 or 3 weeks, my 2020 Honda will be at 50% discharge (around 12.0V). I'd like to think that at some point the parasitic drain devices will shut down before they drain the battery completely, but I've never tested it beyond that point, I always plug in the charger if the car's going to be parked for more than a couple weeks. I installed a charger plug that comes out the front grill so I can plug it into the battery maintainer without even opening the hood.
  - orangepurple 3y ago
    Lead acid gel batteries hold their charge MUCH better than standard lead acid batteries. The difference is gel lead acid often self-discharge around 1% per month but standard lead acid batteries self-discharge on the order of 10% per month. I only use gel batteries on my small engine equipment like snowmobiles, motorcycles, and snowblower.
  - defrost 3y ago
    > I always plug in the charger if the car's going to be parked for more than a couple weeks. To this day, since ~1980, I disconnect the +ve battery lead if the cars not going to be used for a few days or parked up in the bush waiting for when we get back from a walk. Stops parasitic drains and Heisenbug discharges when thermal expansion during a very hot day causes a hard to track short.

mulmen 3y ago

This is true of basically every car ever. Lead acid batteries can’t maintain a charge forever. Get a battery tender if you aren’t going to drive for long periods of time. If you only drive once a month do you even need to own a car? Just rent/uber when you occasionally need a car.

deleted 3y ago
[deleted]

codazoda 3y ago

I hate to admit it, but Kia got this right. I own 3 Kia’s and they all have various problems, including really big problems, but this is an area they got right. On my daily driver, the Kia Niro, it has a battery button that instantly charges the 12v from the HEV battery. I’ve only needed it once, when I left a light on camping, but it was like magic.

idontwantthis 3y ago
What big problems have you had? I’m considering a Niro phev.
- tonyarkles 3y ago
  Not a Niro PHEV, but they have had... a couple of serious motor issues: - https://www.kiaenginesettlement.com https://www.kiaenginesettlement.com - https://www.kiaengineclasssettlement.com https://www.kiaengineclasssettlement.com Edit: A friend of mine just got a free engine swap for her... 2012-ish Optima. It threw a CEL on the highway, had the appropriate trouble code, and bam, new engine from the dealership when she told them the code.

S201 3y ago

Is it the stock battery or after-market? Even if you bought it one year ago, when was it filled with acid? Many auto parts stores sell sealed lead-acid batteries as "new" when they've been sitting on the shelf for a year and the clock starts ticking when the acid goes in. You can get higher quality AGM batteries that will last far longer, but know they are quite expensive. Alternatively, you have a parasitic battery drain going on with your car.

shrubble 3y ago

I had something like this happen on my non-hybrid vehicle. The battery was replaced under warranty, for free since it was less than 18 months old.