12 volt hack for Gen 1- Gen 3

My mechanic just informed me of this trick the other day: "might need a battery, cheapest way is just to replace the terminals then any battery will fit"...Never done it but Walmart sells batteries for $50 and Toyota wants $180-$220 so may consider..

 

Awesome diy idea. Thanks!

 

What's the amp-hour rating of that battery you bought?

 

I just make up a 4 cell battery from used LFP cells (lithium ferrous phosphate) I have or pick up cheap on EvilBay where the batteries have been replaced in delivery scooter or similar. If you can find 40Ah or 50Ah cells, they fit in the spot real easy, the 90Ah cells are a bit of a squeeze but they do drop in. You can use Duct tape to hold the 4 cells together or if you have the facilities you can fabricate 3mm thick aluminium end plates and use stainless packing strap to fabricate 6 straps (3 per side) , drill a hole in each end of the strap, bend the ends and fit screws into the aluminium plate. Often the batteries will have these plates and straps already fitted, you just need to find 4 good cells and link them in series to build a 12v battery.
The original negative terminal will clamp around the negative terminal bolt and the positive terminal is bolted on to a round terminal already, so just bolt that terminal under the positive terminal bolt on the battery. Once you fit a lithium battery in place of the lead acid battery, all your 12v battery issues will become a thing of the past. Even if you leave a drop not properly closed and the interior light flattens the battery, it will charge up again and work just fine, unlike the lead acid battery that seems to die if it gets flattened

T1 Terry

 

There is a reason the Toyota battery is so expensive. For one thing, it's a great battery and lasts an extremely long time. The second thing is that it is simply dangerous to use anything other than a vented AGM. Using anything else can result in battery acid splashed around the passenger compartment in an accident. An unvented battery can produce hydrogen sulfide in the passenger compartment even under fairly normal conditions, which is poisonous. Vented AGM batteries are just expensive, unless you get a mobility battery for an electric wheelchair.

 

Lol... The lack of a vented battery has never been shown in real life to be a problem, even in a car accident... Besides, just tonight on here I replied to a private message from a guy with a 2010 worried his hybrid battery pack didn't have vent tubing. Had to explain that Toyota decided it was no longer necessary starting in 2010. So if that's their opinion on a 220v battery, what does that say about legacy venting systems on their 12v batteries?

 

The issue with comparing to the high voltage battery is there are two key differences: the battery doesn't produce hydrogen sulfide when overcharged and doesn't have liquid acid that can fly around. Yes, it has its own challenges and ways to deal with them, but there is actually less danger with a massive nickel metal-hydride battery in the passenger compartment than a liquid lead-acid unvented battery. The concern with the HV battery has more to do with the amount of power stored than any chemistry effects. The 12V battery can literally kill and has killed (in a different model car) someone if not the proper type.

 

there are a lot of safety devices on cars. they all have a purpose and can be useful in some situations.

it is up to each individual as to what is appropriate for them and their passengers.

certainly, any profesional bypassing a device should make the customer aware of the pros and cons, to be sure they are comfortable with the option recommended.

 

2010 Prius HV battery vent tube

 

Well, that's definitely a diagram of a battery vent hose tube for a Gen2 Prius... And while I thought there was some overlap in using that vent tube system in the first year of Gen3 like this part confirms, someone on here who knows way more than I months ago said it wasn't true and that this part does not exist in any Gen3 Prius. So either there's in an error in their search system for parts, or it defaulted to Gen2 part because there's no such thing in a Gen3, or the person who knows more than I on here is wrong. What I do know is my buddy with a 2010 is going to work on his battery pack soon so I'll know for sure when we get to that.

 

For comparison, here's the Gen 2 hose and part number. You can tell it's kind of similar but mirrored, since Gen 2 had it on the other end of the battery.



Yes, the Japanese-to-English part name translation didn't go so well for Gen 2....

 

Well, that second one looks more like the ones I'm familiar with.... It's confusing though because I guess Gen3 started in Europe in 2009 and in the US in 2010... And what's worse way too much of my knowledge is based on reading stuff on PriusChat and there's no thorough correction process if someone gives out bad information, so I'm always on the fence about lots of stuff.

Like measuring internal resistance in modules... Someone on here long ago commented that a module's internal resistance was a simple measure of capacity. It seemed too simple to be true so have been skeptical. But then while watching videos on youtube on how to calculate internal resistance of a battery the person did a load test and showed the mathematical calculation for resistance, and it was essentially a measure of total capacity based on how much of the capacity was lost during a load test. Always more to learn and skepticism is essential to learning

 

You can draw an 'idealized' schematic of a real battery, which has internal resistance, as if you had a 'perfect' battery (constant voltage source, zero resistance) in series with an unknown resistor, where you only have access to measure voltage across the combination.

Then you can easily solve for the value of that 'resistor', by drawing two different known currents, observing the difference in your voltage readings, and using Ohm's law. That's all the internal-resistance calculation is doing.

Capacity is a more complicated subject.

 

Thanks... That's definitely what I'm starting to learn... Are there any PriusChat links that get more into how capacity is a bit more complicated than resistance? I'm still trying to see if I should invest in equipment to measure internal resistance of modules accurately and if that would help find bad modules before they go bad.

Currently my main way I've tried to measure battery resistance is with the crappy Imax SKYrc chargers and all five of these chargers I have will give a different resistance reading on the same module, so I don't even use those numbers on my spreadsheets. But if there was a way to accurately measure that I could afford and it would help to find bad modules before they go bad I want to learn more?

 

Back to the 12v battery replacement. A lead acid battery only spews out sulphur dioxide or hydrogen sulphide if a cell is dead but still try to be charged. The acid splashing out every where, the old VW beetle had the battery under the rear passenger seat and not too many deaths reported from that so .....
But I still prefer the lithium battery replacement for the old technology lead acid battery. It only supplies 12v power to get things going first up when the system is turned on, the HV battery recharges the 12v battery via a DC to DC charger once the system is on so the actual capacity of the 12v battery doesn't need to be anything outstanding. Often wonder if one of those cheapie 18v tool batteries would do the job just as well. They have internal cell balancing, the 14.4v from the DC to DC charger isn't going to over charge an 18v battery and fully discharged they are still 12.5v or so. With a 2.0Ah capacity you couldn't run the stereo for long without the system turned on to get the DC to DC charger working and the headlights would be the same deal, maybe the newer 4.0Ah might be a better choice. Cheap option, no chemicals or acid to spill, it's not like the 12v battery starts the ICE or anything like in any other standard ICE vehicle, that is done by the HV battery in a Prius.

T1 Terry

 

This is what I am thinking. Instead of regressing to very old technology that introduces safety hazards, upgrade the battery technology while you're at it. Personally, I would possibly get a more expensive but longer-life drop-in LiFePo4 replacement, but there are a lot of ways to make it cheaper while sticking with AGM or making it lithium. Possibly, in the long run, buying cheap lead acid batteries and replacing often will be no better than buying Toyota AGM batteries anyway.