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Lead acid batteries tend to off gas a lot more than a gel battery and that thing is basically inside the cabin with you. Not behind a firewall under the engine hood like most cars.
Another nasty habit of lead acid batteries is their ability to swell and crack or explode and leak mean, corrosive liquid all over your nice interior.
My parents had an Audi 100 LS ( which was a great car back then) and the battery was under the back seat. That very thing happened to it. The battery cracked and leaked and when we finally spotted it, the damage was done.
In the HS case, I'd say stick with a higher cost gel.
^^^TheAirman, you're right. After researching further, forget the lead-acid (conventional) battery - not worth the risk. Research points to an Absorbent Glass Mat (AGM) battery type for the HS. The challenge so far I'm facing is an aftermarket AGM battery of the appropriate CCA and dimensions.
Not a great pic but it shows the indentations in the tray which I measured with battery in place ~ 8.5" x 6.0" at its narrowest point.
The battery in the HS is in such a hard place to get to, I never remember what it looks like in there.
Sad thing is, when you search for a replacement AGM battery for the HS, it's hard to find. But search for one for the CT or the Prius, there are many choices. That's what happens when they decide to quit making a car model.
The battery in the HS is in such a hard place to get to, I never remember what it looks like in there.
Sad thing is, when you search for a replacement AGM battery for the HS, it's hard to find. But search for one for the CT or the Prius, there are many choices. That's what happens when they decide to quit making a car model.
Do they use the same battery as the HS? The CT and Prius have a smaller engine and traction motor, so I'm wondering if the HS needs a stronger starter battery.
Do they use the same battery as the HS? The CT and Prius have a smaller engine and traction motor, so I'm wondering if the HS needs a stronger starter battery.
That's a good question. The only thing the manual says is "contact your Lexus dealer". And I hate doing that, so I guess I'll climb in there and try to figure out just what size the original battery is.
I think the CT calls for a 440 cold cranking amp AGM battery. Unless the physical size is different, I bet it would work in the HS.
That's a good question. The only thing the manual says is "contact your Lexus dealer". And I hate doing that, so I guess I'll climb in there and try to figure out just what size the original battery is.
I think the CT calls for a 440 cold cranking amp AGM battery. Unless the physical size is different, I bet it would work in the HS.
I've been researching this and CT, Camry Hybrid, and HS, all have different batteries (capacity and size).
Was hoping the Camry Hybrid battery would be the same and fit but it's larger (see here). The HS would be a 55 size (see here) or (see here). Problem is, I have yet to find an AGM battery maker (Exide, Optima, etc.) that produces that size or even a smaller size that would fit, like BCI size "54, 61, 71".
I've been researching this and CT, Camry Hybrid, and HS, all have different batteries (capacity and size).
Was hoping the Camry Hybrid battery would be the same and fit but it's larger (see here). The HS would be a 55 size (see here) or (see here). Problem is, I have yet to find an AGM battery maker (Exide, Optima, etc.) that produces that size or even a smaller size that would fit, like BCI size "54, 61, 71".
Ok, since you are researching, here's a little more to go on.
My online parts manual, (courtesy of the Russians, who like to steal and hack everything) says the original part number for the battery is: 28800-28100
And it is a battery type: S55D23R
It's a good read on how the Toyota Camry Hybrid uses the 12 volt battery and how people are having good luck with a Optima Yellow Top. I don't see how the HS could be much different.
The only thing that troubles me with the original Panasonic battery is that vent tube and being able to fit in that confined space.
The battery issue has become troubling to me, so I pulled everything out of the trunk and climbed in to get a closer look.
The problem with the whole 12 volt aux battery replacement is the space we have to use to replace the battery with. It is crammed in there right next to the traction battery, and it sits in a little tray with not much room to install a different sized battery.
The size of the original Panasonic AGM battery is:
6 5/8" wide
8" high and 9" high with the posts
8 1/2" length
And it sits right in that tray with very little room to move. Height is not a problem because the hold down clamp is adjustable with the nuts. Width is a biggest issue because the traction battery case is on one side, and the 12 volt battery case has these metal holders on the opposite side. To go any wider, you're have to either bend or remove the metal side holders. With the length, if you went any longer than 8 1/2". it would work, but it would kind of sit on top of the the battery tray, instead of in it. So...... width is critical.
The positive and negative cables seem long enough to be placed on either side, so terminal post placement doesn't seem to be an issue.
The vent tube MUST be placed towards the rear of the car and battery so choose a battery with the vent tube provision on the side of the battery.
I didn't actually see the battery temperature sensor, but according to the Toyota Camry Hybrid forums, not hooking it up correctly will give you the "check hybrid system" light.
Since the HS does not use the 12 volt aux battery to start the engine, it uses the traction battery to start the car, cold cranking amps (CCA) is not an issue in battery selection. The 12 v battery only starts the computers and radio and alarm system and door locking functions, so deep cycle battery is a better choice.
And since the battery is there with us in the passenger compartment you really don't want a convention lead acid battery that might leak or vent gasses.
Here's one that might work. The Exide Edge AGM battery in either Group 25 or 35. The length is an issue but it would just sit on top of the tray as described above.
^^^ Thanks for the additional info. A little tied up these days to study this further than I have but I plan on changing the battery well before winter. My key challenge still is finding a battery that fits into the confined space, within the tray which due to its shape, makes for a narrower curved base than the top of the battery, closer to a max 8 1/8" length is my guesstimate (didn't remove the battery for exact measurements).
Did you notice if the tray is also curved along the width thereby narrowing the battery below the 6 5/8" width?
Do we need a vented battery if AGM? From the few AGM aftermarket batteries I've seen that are close to the size we need (but a bit too big), there is no venting tube so not sure how this would be retrofitted, if at all needed.
Yeah, we don't need a high CCA battery. In fact, a 360 CCA is the minimum requirement for the HS which is met by all 12V car batteries I've seen. Problem is the smallish size requirement.
The tray isn't really curved, but the traction battery on the left in your picture, won't move. On the right, and you can just see it in your picture in the post above, is 2 small curved side brackets. They are about 3" tall. I imagine you could probably squeeze a little bit more than a 6 5/8" wide battery in there, but you would have to bend the two curved side brackets.
Looking at it again, we are probably better getting a 6 5/8" wide battery but maybe a little longer that will sit over top of the metal end of the tray in your picture. The Exide Edge AGM fits that way.
And most of the AGM batteries have a provision for a vent tube. You might just have to order it when you order your battery and transfer the original tube over. You can see in your picture, the tube and the 90 deg plastic elbow just click into the side of the battery.
Venting is not an issue if the battery was up near the engine behind the firewall, but in the passenger compartment, if the charger would happen to overcharge the battery, it might send out some deadly fumes. I'm going to vent my new one, everyone else can make there own choice, because some say you really do not have to vent a AGM battery.
Last edited by TheAirman; 08-16-16 at 05:19 PM.
Reason: spelling
I might try the Exide when the time comes to replace, but I don't see any difference between the 25 and the 35 series except for the price. Current prices on Amazon:
Exide Edge FP-AGM35 Flat Plate AGM Sealed Automotive Battery $224
Exide Edge FP-AGM25 Flat Plate AGM Sealed Automotive Battery $167
I wonder if there is room to put a 3/4" piece of plywood under the battery so it would be fully supported and sit higher in the tray.
Anyone know if there is a vent connection on this battery?
Is there a temperature electrical sensor connection on the Panasonic?
This would sure save a lot of money.
I found this link for the FP-AGM35 for $170 with free shipping from Chicago: https://www.batteryservice.com/produ...umber=FP-AGM35
They claim it has "Special Pressure Venting System to Reduce Water Loss" but I don't see a vent connection.
Any thoughts?
I found this link for the FP-AGM35 for $170 with free shipping from Chicago: https://www.batteryservice.com/produ...umber=FP-AGM35
They claim it has "Special Pressure Venting System to Reduce Water Loss" but I don't see a vent connection.
Any thoughts?
The difference between the 35 and 25 should be size, because each "group" number should be a different size. But in this case I agree with you, I don't see any difference between the two group sizes 25 and 35. Maybe there is a difference in the case design.
Over at greenhybrid.com, people have been using the Exide group 35 with much success on their Toyota Camry Hybrids, which has almost the same battery box set up as we do. According to all the write-ups, the Exide Edge 35 does have the battery vent hook ups and you can buy the connector from the Exide dealer. Try taking a look at one at your local Home Depot. They usually carry them. The vent from our original battery should just pop out and fit into the new Exide battery.
The plywood base sounds like a good idea. The new Exide might just fit on the lip of the original battery box, but I am not sure until I try it myself.
I have not located the temperature sensor on my battery yet, because I have not removed the original battery. Maybe we do not have one ??? I did see something mounted right next to the battery. Maybe that is it ?? Maybe someone else that has changed theirs can help us out.
06-25-16, 07:02 PM
