[fotomoto]

Or do you have to open your hood to connnect/disconnect?

I keep the hood open, thus no (realistic) way to accidentally move vehicle while still hooked up. The quick connect remains connected to the under hood charge points and is capped (as designed) when not in use.

I thought a bright yellow extension cord leading out to the lefthand side of the Prius in the driveway would be enough but, umm, no it wasn't. For lawn mowing reasons, the cord was eventually moved to the right side of the vehicle and thus out of sight (and out of mind).

 

[Sienna25AE]

duplicate deleted.

 

[Sienna25AE]

I keep the hood open, thus no (realistic) way to accidentally move vehicle while still hooked up. The quick connect remains connected to the under hood charge points and is capped (as designed) when not in use.

I thought a bright yellow extension cord leading out to the lefthand side of the Prius in the driveway would be enough but, umm, no it wasn't. For lawn mowing reasons, the cord was eventually moved to the right side of the vehicle and thus out of sight (and out of mind).

Great experience shared! May I also ask how many amps of a charger are you using? I have a Noco 10amps charger and hesitate to use it. I plan on getting the Noco 2 (2amps) charger for this purpose avoiding the risk of friying the ECU.

Currently my 2012 Sienna (parked in driveway) and Nissan Juke (Parked in the Garage) are permanently plugged in using a Noco 2D (direct mount) charger for the purpose with a cable sticking out of the hood since the one in the garage is acceptable to do so, while the 2012 Sienna I have yet to figure out where route the cable outside the hood. Reason is it would be cumbersome to open and close hood every time I drive this van.

Some side questions. You said you take short trips with you Prius prompting you to trickle charge. How short are your trips and how often do you drive it in a week?

I too have very short trips on weekdays (less then 2 miles on weekdays x2 per day) and a total of about 30 miles on Sundays. My 2023 Sienna is modified with mobility access seat with 3 motors sucking a lot of power. The 2023 Sienna will loose about 10-15% charge (SOC) overnight everyday. If I don’t drive it two days in a row, the charge will go down to the low 40’%s. Is this the case with your hybrids as well?

 

[fotomoto]

Great experience shared! May I also ask how many amps of a charger are you using for the charger?

Battery Tender Jr. Trickle-charger, 1-2amps. Battery maintenance is a HUGE deal in the motorcycle world (RV, boats, etc too) where folks have "seasons" in which the battery isn't used. These are made to slowly trickle charge the battery and the maintain a float charge for possibly months or years on end. They are NOT made to jump start (high amps) other vehicles; I have one of those chargers for that too. Folks with multiple bikes typically get a BT, Jr for each one.

We live in a small town so most every trip is about 3 miles (or less). I also have a PHEV Escape and even with it's "small" EV battery and even driven almost daily I am at coming up to 8 months on the same gas tank (1/4 left).

My father in law was a paralyzed WWII vet with a large wheel chair and Chrysler van with lift. If you don't already, please have the hybrid in the ON/Ready mode whenever you use the lift motors. My poor old MIL somehow had the belief that having the car ON was somehow hurting it while the lift was being used. DOH! They lived in a large city and also only needed to travel a few blocks to the store and only a mile or two to the doctor(s) at a large medical complex. Their longest drive was about 4 miles to church. Yep, they had weak 12v battery issues too.

I believe the battery side of the quick-connect lead would be long enough to fish out the front grill/headlight area so one would not need to open the hood but you'll need a good fail-safe for that; especially if used on a near daily basis.

Good Luck!

 

[wscan]

Great experience shared! May I also ask how many amps of a charger are you using for the charger? I have a Noco 10amps charger and hesitate to use it. I plan on getting the Noco 2 (2amps) charger for this purpose avoiding the risk of friying the ECU.

You will not fry the ECU if you use the connection points as recommended in the Owners Manual. I use a 10 amp charger on the under hood positive connection with negative on the passenger side engine lift hook (as stated in the owner manual) on the engine without a problem.

I have also used a Battery Tender Jr. (output is 0.75 amps) to maintain the battery. I rarely see the LED turn to green (indicating a full charge and the tender dropping the charge rate). Battery Tender is also connected per the Owners Manual.

 

[Sienna25AE]

You will not fry the ECU if you use the connection points as recommended in the Owners Manual. I use a 10 amp charger on the under hood positive connection with negative on the passenger side lift hook (as stated in the owner manual) on the engine without a problem.

I have also used a Battery Tender Jr. (output is 0.75 amps) to maintain the battery. I rarely see the LED turn to green (indicating a full charge and the tender dropping the charge rate). Battery Tender is also connected per the Owners Manual.

So is it safe to assume it won’t fry the ECU if connecting a battery tender 1-2amps to the battery in the back directly?

 

[Sienna25AE]

Battery Tender Jr. Trickle-charger, 1-2amps. Battery maintenance is a HUGE deal in the motorcycle world (RV, boats, etc too) where folks have "seasons" in which the battery isn't used. These are made to slowly trickle charge the battery and the maintain a float charge for possibly months or years on end. They are NOT made to jump start (high amps) other vehicles; I have one of those chargers for that too. Folks with multiple bikes typically get a BT, Jr for each one.

We live in a small town so most every trip is about 3 miles (or less). I also have a PHEV Escape and even with it's "small" EV battery and even driven almost daily I am at coming up to 8 months on the same gas tank (1/4 left).

My father in law was a paralyzed WWII vet with a large wheel chair and Chrysler van with lift. If you don't already, please have the hybrid in the ON/Ready mode whenever you use the lift motors. My poor old MIL somehow had the belief that having the car ON was somehow hurting it while the lift was being used. DOH! They lived in a large city and also only needed to travel a few blocks to the store and only a mile or two to the doctor(s) at a large medical complex. Their longest drive was about 4 miles to church. Yep, they had weak 12v battery issues too.

I believe the battery side of the quick-connect lead would be long enough to fish out the front grill/headlight area so one would not need to open the hood but you'll need a good fail-safe for that; especially if used on a near daily basis.

Good Luck!

Thanks for the detail insight. I do put the van in Ready mode when operating the auto access seat. According to what you said, it’s indeed the low mileage driving that is causing the low battery issue. I will definitely install a 2amps battery tender instead of using a the 10amps I have just to be on the safe side.

 

[wscan]

So is it safe to assume it won’t fry the ECU if connecting a battery tender 1-2amps to the battery in the back directly?

Correct. The reason that the ECU sometimes fries is because the ground path for the external charge takes the path of least resistance. This is through the ECU if the ground connection is too close to the ECU which is located close to the fuse box under the hood.

 

[Sienna25AE]

Correct. The reason that the ECU sometimes fries is because the ground path for the external charge takes the path of least resistance. This is through the ECU if the ground connection is too close to the ECU which is located close to the fuse box under the hood.

Thank you! I am now confident enough to go ahead and start my project. I have the materials ready, and just wanted to be absolutely sure since this is my first Hybrid and don’t know much about it after almost owning it for almost 2 years.

I will try to photo document my project and report back here for all to see and do away with the worry of not able to jump their van when their battery drains.

 

[Sienna25AE]

Is it actually plugged or is that small opening a vent. It could be a vent for the battery.

Nox Vidmate VLC​

That pipe/tube in the rear is the a/c condensation drain. The “plug” thingy with the “slit” is a plug the size of a pinky in diameter that plugs a hole. This plug is definitely not the battery’s vent. Unless that’s the other fail safe vent in case the original vent fails.

There is no piping connected to in on the inside of the van. The battery has a tube connected to it and it routes out somewhere else.

I plan on routing my charge/jump cable out the a/c drain hole and change the current plug with another one that will accomodate both the a/c drain and my charge cable.

The harder option would be to drill a new hole to route my cable out of the van.

 

[Sienna25AE]

I have done it! So far so good. It works!

Drilled/Cut an one inch hole between the rear A/C drain line and the unknown plug to route a SAE/eyelet cable out the van right above the rear muffler. An 1 inch grommet is used to buffer the SAE cable and plug the hole. I intent to modify the grummet part using some other material so that the cable can be tucked back into the van when not in use. This cable serve as charger cable, and battery jump point as well eliminating the use of the front jump points.

VERY IMPORTANT! Anyone reading this post. Please point out any potential danger / mistakes / issues with this mod is greatly appreciated.


Original under body

Hole drilled

Positive cable attached to positive battery post. Negative cable attached to chassis negative post point.

Cable routed out with grummets

 

[fibber2]

I would do a little experiment before adding a plug-in item like a trickle charger on a permanent mount basis.

In an ideal world, when you plug in your trickle charger it will provide low current power to keep the battery topped off. But what happens if you don't plug it in every time?

Ideally, charge should flow one way. A diode or other device should prevent power from being 'consumed' by the charger (drawn from the car battery) when the charger is not plugged in to 120v. I'd expect it to be OK to keep a decent quality / properly designed charger connected to the vehicle full time and not draw more than a few milliamps max. But it's worth checking. Cheap designs or an internal component failure can cause your top-off aid to become your new vampire load when your vehicle is parked at the airport for a week.

A little ammeter work can verify if you've created a new problem....

 

[Sienna25AE]

I would do a little experiment before adding a plug-in item like a trickle charger on a permanent mount basis.

In an ideal world, when you plug in your trickle charger it will provide low current power to keep the battery topped off. But what happens if you don't plug it in every time?

Ideally, charge should flow one way. A diode or other device should prevent power from being 'consumed' by the charger (drawn from the car battery) when the charger is not plugged in to 120v. I'd expect it to be OK to keep a decent quality / properly designed charger connected to the vehicle full time and not draw more than a few milliamps max. But it's worth checking. Cheap designs or an internal component failure can cause your top-off aid to become your new vampire load when your vehicle is parked at the airport for a week.

A little ammeter work can verify if you've created a new problem....

Never thought about that. I have permanent Noco 2D chargers installed in my other two cars that's always plugged in. One of those cars are hardly ever driven. Both of these are plugged right back in after being driven.

The install I am detailing in this post does not have the charger permanently installed. Only a cable is installed and routed outside to the bottom of the van with no trickle charger of any short attached. The charger has to be unplugged when the van is driven. I hope a cable alone does not drain the battery.

How do I verify if my mod creates a battery phantom drain? Can you detail how I can verify this? I suppose using a multimeter. I just bought one and have no clue how to use it.

 

[fibber2]

Got it. Just prewired for the charger. I saw the Ancel monitor and other wiring and thought that the trickle charger was back there too.

No, just a wiring stub should cause no issues. Just keep the cap on the exposed connector so it doesn't get wet/salty.

There are several threads out there about vampire loss detection. Basically you insert your ammeter between the negative terminal and the battery (meter in series so that all power flows thru it). At first you'll likely record up to a half amp draw as systems power down and go to sleep. After 20+ minutes you should reach full sleep mode and draw should be 50-75 millamps. If it's much more, you need to go look for the offending circuit.

But... on the Sienna with the battery in the back, I'm not sure how you'll handle the tailgate door. The van will likely know the gate is open, so the Security system won't rest even if you can turn lights off. Maybe there's a latch trick that will do it. Camper mode?

 

[Sienna25AE]

Got it. Just prewired for the charger. I saw the Ancel monitor and other wiring and thought that the trickle charger was back there too.

No, just a wiring stub should cause no issues. Just keep the cap on the exposed connector so it doesn't get wet/salty.

There are several threads out there about vampire loss detection. Basically you insert your ammeter between the negative terminal and the battery (meter in series so that all power flows thru it). At first you'll likely record up to a half amp draw as systems power down and go to sleep. After 20+ minutes you should reach full sleep mode and draw should be 50-75 millamps. If it's much more, you need to go look for the offending circuit.

But... on the Sienna with the battery in the back, I'm not sure how you'll handle the tailgate door. The van will likely know the gate is open, so the Security system won't rest even if you can turn lights off. Maybe there's a latch trick that will do it. Camper mode?

Thank you for the testing instructions. I will try what you told me in testing. In terms of testing parasitic drain. My 2012 Sienna XLE van does that and I want to find out what is causing it. Can you give me some pointers on that?

That's why my battery went down when I was doing the drilling while the back hatch is open. Maybe lock up myself in the van that long to test if I don't suffocate in it? 🤓

PS. The other two cables

The other cable with the red fuse cap is the positive cable for my Mobilty seat where the negative is connected to the chasis's negative point (black cable alone on left). I don't like how they wired the mobility seat. I wonder why they did not tap either the front or rear fuse box for it. Is it possible for me to tap this positive to one of rear live fuse box sockets instead? The battery positive pole is pretty cluttered as you can see. (Live because they claim the seat's computer board needs constant power to hold programming) The seat has 3 motors and claim will deactivate 1 minutes after use) Any insight on that?

The other cable with yellow eyelet on the negative chassis end is to add 3 USB ports (USB module is located towards the right bottom of the battery compartment picture) for my 3 rear dash cams instead of occupying the rear USB ports. It's positive is tap to one of the the rear fuse box non-live-when-ignition-off sockets.

The Ancel will drain power. Just wonder how much and if anyone has any insight on that matter?

 

[fibber2]

A few threads possibly worth reading. Anything like your mobility seat that needs constant power will be a longterm drain on your battery. There may be others, if you are actively having trouble.

One consideration. Do you have factory sensors attached to the battery posts? If so, make sure you make all connections AFTER these sensors (where factory wiring connects). That helps your charging system see and account for all loads in it's recharge algorithm.

https://www.siennachat.com/threads/parasitic-draw-and-battery-discharge.10010/?post_id=62209#post-62209

https://www.siennachat.com/threads/finally-measured-the-parasitic-draw-on-my-2022-sienna-xle-530-milli-amps.77424/?post_id=478595#post-478595

https://www.siennachat.com/threads/parasitic-battery-drain-how-much-is-too-much.4612/?post_id=35099#post-35099

 

[Sienna25AE]

A few threads possibly worth reading. Anything like your mobility seat that needs constant power will be a longterm drain on your battery. There may be others, if you are actively having trouble.

One consideration. Do you have factory sensors attached to the battery posts? If so, make sure you make all connections AFTER these sensors (where factory wiring connects). That helps your charging system see and account for all loads in it's recharge algorithm.

https://www.siennachat.com/threads/parasitic-draw-and-battery-discharge.10010/?post_id=62209#post-62209

https://www.siennachat.com/threads/finally-measured-the-parasitic-draw-on-my-2022-sienna-xle-530-milli-amps.77424/?post_id=478595#post-478595

https://www.siennachat.com/threads/parasitic-battery-drain-how-much-is-too-much.4612/?post_id=35099#post-35099

Thank you very much for the reading materials. I will go over reach thread carefully.

What are the factory sensors attached to the battery? I don't know for this is the first time I have heard such devices. What I can tell you is that the negative side does not seem to have anything attached to it. the positive side have something other then the battery contact that is part of the positive cable. currently my cables are connected to the battery post contact screws.

 

[fibber2]

Shunts for measuring voltage and current at the battery are becoming pretty common sights on vehicles these days, but as I don't own a Gen-4, I don't know if you have one. Maybe someone else can confirm?

I do see an assembly on the positive terminal in your photo. That could be a master fuse or a sensor for helping your alternator optimize the charge process. If you add a load directly to the battery post and bypass a sensor, you are working against battery optimization. A factory Service Manual check will help you get this right.

 

[Sienna25AE]

Shunts for measuring voltage and current at the battery are becoming pretty common sights on vehicles these days, but as I don't own a Gen-4, I don't know if you have one. Maybe someone else can confirm?

I do see an assembly on the positive terminal in your photo. That could be a master fuse or a sensor for helping your alternator optimize the charge process. If you add a load directly to the battery post and bypass a sensor, you are working against battery optimization. A factory Service Manual check will help you get this right.

So given if what you said is fact, then the Mobility seat positive cable (red cable with red fuse) should have been attached at or after the assembly you mentioned? Also my prewired charging cable should have been attached at or after the assembly point? Maybe @yonah can give some insight into this since she modified the battery end extensively.

 

[Sienna25AE]

Looked up @yonah thread and found his pictures detailing the battery posts. What are those? Are they sensors you are mentioning.

Courtesy @yonah