Battery air pump replacement

[asavage]

The RAV4 EV, the Mercedes Electric Drive/B250e, and the electric Smart cars, they all have a desiccant pack in the battery.

The RAV4 EVs have some kind of little air pump on top of the battery cover, it's under the driver seat area, and it's quite noisy. It's one of the loudest things you hear when you plug in to charge. You think you're hearing coolant pumps, but you're usually hearing that air pump.

The last few months, mine has been getting noticeably louder.

Is there any information on repairing/replacing this pump?

I believe I read somewhere in the past where somebody cut a hole in the floor of the car to access the pump for repair, rather than dropping the battery!

Jimbo69NY has a YT video on the pack, and pointed out the thing.

 

[asavage]

Mine has gone silent, about a month ago.

 

[xyzzy]

On my car it runs noisily after the car has been driven in rain or humid weather, then goes silent when things dry out. I don't know if it only runs if a sensor says it is necessary (so only on or off), or if there is a variable speed.

 

[asavage]

Mine always buzzed when first plugged in to charge, in any weather. Now, it's silent; I can hear a coolant pump, and sometimes the radiator fan comes on/off, on low speed, which I only notice if I happen to be in the driveway working on something else when it happens.

 

[Johan]

@asavage I think you were referring to this post on Facebook by Xuye Li. After zooming in on the photo with the air pump (see below) and doing a quick Google search, I think it's the following product:

• Manufacturer: Mabuchi Motor Oken
• Type: "Rolling Pump"
• Model: P54E-0012RG
• Specsheet: https://okenseiko.com/en/wp-content/themes/oken_en/pdf/air/P54E12RG.pdf

 

[asavage]

I think you were referring to this post on Facebook by Xuye Li.

Nope. That's a private FB group and I've never seen a single post there.

 

[Johan]

Nope. That's a private FB group and I've never seen a single post there.

Hmm OK. So far, I have found the following discussions regarding the 2012-2014 RAV4 EV battery dehumidifier:

• asavage in this thread,
• Xuye Li in this post on Facebook by (as mentioned in my previous post; not accessible for some bc private group),
• James Klafehn on Youtube (here and here) and asking around in this thread (diyelectriccar.com),
• Samli on this forum here (maybe that's the one you were referring to?)

I'm trying to figure out if an aftermarket dehumidifier can be made for EV batteries in general (not for a specific make/model) because it seems that a large fraction of EV battery failures is related to moisture ingress. For example, count these cases, accross many makes and models, on youtube.com/@CarRepairVideos. The RAV4 EV is one of the few EV models (that I know of) that has both desiccant and desiccant regeneration capabilties. The dehumidifier won't solve most of the consequences of things like leaks of course, but it can remove water vapor from the battery "breathing in" vapor as a consequence of altitude (pressure) and ambient temperature changes.

 

[asavage]

• Samli on this forum here (maybe that's the one you were referring to?)

This one is the one I was recalling. Thanks for that complilation.

 

[asavage]

I've got my pack dropped for a BMS_f038 contactor replacement.

 

[asavage]

For the search engines: Okenseiko P54E01R, motor stamped N24225.

Mabuchi Motors bought Okenseiko around Dec2022. Okenseiko specialized in pumps for vacuum, air, and liquids and have been used in medical devices, MB seat lumbar supports, and bidet pumps. The P54E-0012RG (presumed to be similar; it's both brushless and the same 27mm dia.) "datasheet" lists 12v but not inputs, and this is a three-wire device. That complicates unit testing. Some P54s have brushes, some are brushless.

The P54E-0012RG, which is called a "high durability" model, is rated for 3000 hours service life, with 2000 hours "guaranteed". 3k hours is . . . not a lot.

The heater plate is positioned (suspended) to be nearly in the middle of what I presume to be silica beads (desiccant). I'm not seeing any controller logic on that PCB; I assume the BMS has a schedule or triggers, and then sends 12v to this collection of parts, which then runs blind. I don't see a humidity sensor. The beads have worn off the markings on what looks like it may be a thermostat in series with a fuse on the heater plate.

This is a model of the P54 line which has both inlet and outlet hose nipples, so it's harder to source. It can apparently be had for under $200 from one source*, and for well over $320 from another (NLA).

[I later ordered one @ USD$195 after "processing fee", about two weeks lead was promised, and the next day they wanted to raise the price to about $400. I canceled the order.]

 

[asavage]

Now you know the source of that buzzing noise when charging.



The pump apparently pulls air from the desiccant chamber, and pushes it out this brass hose barb.




Nice high-temp RTV here . . .




The pump comes apart easily, once you score the paper tag. On mine, the rotor's upper plain bearing (bronze-colored) is shot and the rotor moves almost 1/8" (3mm), so it binds on the stator I assume. It does not turn when I tried using my fingers.

 

[asavage]

The supplier I'd ordered the pump from tried to more than double the price, after I'd paid for it.



So, I'm still looking for one.

I filed off the four crimped areas at the rear of the motor, pulled off the driver from the load end, desoldered the three coil wires (two of them broke) using copper braid and new flux, and instead of finding the load end bearing worn out, the shaft has much of the wear instead. Normally, in a plain bearing, you engineer a softer fixed bearing material to be mated with a harder rotating/moving part, but not here.



I'm not thinking of a way to rescue this one. And I'm not finding any brushless examples of Oken Seiko air pumps, either, outside of their model listing. Plenty of 2-wire, none with this six-pin connector.