12 volt battery investigation.

Can someone explain how to interpret the water level in the 12v battery.
The caps have small "cups" built into the bottom of the caps.
If the "cup" is wet does that mean the water level is OK ?
Thanks.
P.S. Those caps were sure put on tight. Plus the one behind the positive terminal is very difficult to access.
2012 Silver ES with Q.C. Picked up Feb.2, 2013.

You can open the caps? Most 12v batteries these days are totally sealed.

Neil, this is a 'Maintenance' battery in converse to a 'Maintenance Free' battery. Why MMC didn't go with a 'Maintenance Free' battery is beyond me unless somehow they felt saving a few bucks was more important.

To answer the OPs question - yes, the water level should be at those little cups and not below them. If low, then fill with 'Distilled Water' only.

Is the battery in our i-MiEVs a deep-discharge battery instead of a starter battery? If so, that would explain the difference. It also makes sense to have a deep-discharge battery -- we have no starter motor to run, just computers and accessories.

MLucas said:

Neil, this is a 'Maintenance' battery in converse to a 'Maintenance Free' battery. Why MMC didn't go with a 'Maintenance Free' battery is beyond me unless somehow they felt saving a few bucks was more important.

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That's disappointing. A big advantage of an EV is its lower maintenance, but if we have to check the battery electrolyte level regularly, some of that low-maintenance advantage is lost. I can't remember the last time I had a car with a battery whose electrolyte level had to be checked.

I don't understand why a deep-discharge battery would be appropriate for an i-MiEV whose 12 v. battery is never discharged deeply under normal circumstances. Likewise, a typical starter battery isn't appropriate for obvious reasons. I will likely replace mine with a small, light absorbent glass mat (AGM) battery like I use in my Honda Insight whose 12 v. battery has never been subject to the large current draw of a starter motor, either. AGM batteries contain no liquid electrolyte, so there's no electrolyte level to check.

Why not replace it with a Li pack of similar voltage not to cause a problem with the original lead battery charger.

I do not know where but quite sure someone having done this replacement.

Also thinking that if the new battery can be very small, the saved space could fit a small Sebastopol type heater. Inspired by a French forum user who installed the webcast in the location of the battery.

Llecentaur said:

Why not replace it with a Li pack of similar voltage not to cause a problem with the original lead battery charger.

I do not know where but quite sure someone having done this replacement.

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The nly reason not to do it would be price I suppose - Why spend several hundred to buy/build a battery which essentially powers nothing?

LOWRACER built one and installed it in his car - I recall when he first posted it looking up the headway cells he used and I think he spent about $400

Check out the last 2 or 3 pictures in this post:
http://myimiev.com/forum/viewtopic.php?f=9&t=694&hilit=battery+replace

Don

MLucas said:

Neil, this is a 'Maintenance' battery in converse to a 'Maintenance Free' battery. Why MMC didn't go with a 'Maintenance Free' battery is beyond me unless somehow they felt saving a few bucks was more important.

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I find this disappointing in the extreme, on two counts. First and most obviously, it's a hassle, and an unnecessary one at that. I just checked the manual and confirmed the instructions to check the battery "regularly" (no clue what that means - it's not like we stop "regularly" at a service station, is it?), and top off electrolyte with distilled water as needed. What brain trust thought THAT was a good idea????

Second and I think more important, my dealer never mentioned this when delivering the car. In an age when virtually all new vehicle batteries are maintenance free, this anachronism is completely unexpected, and customers should be cautioned that they'll need to follow this ancient maintenance ritual. I had no freaking clue, which means this car's battery has never been checked in the nearly six months that I've owned it. I think that annoys me nearly as much as the ongoing headache. Probably not much of an issue with a brand new car, but nonetheless not something to neglect.

A huge thanks to Lithim for asking this question in the first place and piercing the veil of our collective ignorance (I'm sure Neil and I aren't alone in our surprise). If/when someone identifies an appropriate maintenance-free replacement, please share.

The 12 volt battery is a bit of a weird bird - Officially, it's a Yuasa 34B19L and was used in several small cars, most of which were not imported here. You can Google that part number and read about replacements available elsewhere in both flooded and AGM chemistries. If you want an EXACT AGM replacement, I think it's going to be difficult (and maybe expensive) to find

One of my other cars is a Mazda Miata which came with a sealed AGM battery mounted in the trunk. Checking the dimensions of both batteries, it appears a Miata battery will drop right in and give you what you want . . . . namely, a small, sealed, maintenance-free, AGM battery

Several vendors sell various brands of Miata AGM replacements - You can Google Miata AGM and find all sorts of listings. There is one for sale at Amazon.com for about $100 including shipping. Also, WestCo batteries have been very popular replacements with the Miata crowd for more than 20 years, over which time their price has risen from about $60 to more than double that today. It's not unusual for a Miata battery to last 10 or 12 years

As to why Mitsu didn't use one of these in the first place, I'm assuming it came down to cost. The flooded battery they chose probably cost them about 1/3rd of what a quality AGM would have. I'm guessing that by the time they added up all the numbers, they were trying to save where ever and how ever they could

Don

I've had mine for a year and never checked it - I had no idea I needed to!

Jenn

Checking battery electrolyte levels shouldn't need to be done too often. My Dad's Cavalier (when I was driving it before I bought the i) had the original battery fail last year. That battery was almost 11 years old. Never once have we checked the electrolyte levels, or needed to. The battery simply gave out because it was at the end of its life, reduced current output caused by plate deterioration from all the high current starts. My smaller AGM batteries haven't even lasted that long.

Now deep cycle FLA's that are used as deep-cycle batteries do need to have their electrolyte checked regularly because they are exercised much more. A starter battery has the 3 second high-current blast, followed by varying lengths of full charge; hardly used at all. Our batteries have an even easier life. Nearly always at full charge, and only spending very little time with any sort of load, and not much of a load at that. I'll have to measure 'READY' voltage, but as long as the DC-DC converter isn't going over 14.4 volts, the electrolyte won't boil.

If you feel that you should check your electrolyte, then check it, by all means. I'm just saying that we've never had the need to do it, fortunately.

Off-topic: Isn't it strange how many Miata components work/fit on the i-MiEV?

PV1 said:

Checking battery electrolyte levels shouldn't need to be done too often. My Dad's Cavalier (when I was driving it before I bought the i) had the original battery fail last year. That battery was almost 11 years old. Never once have we checked the electrolyte levels, or needed to.

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Unless I'm misunderstanding something, I think this is exactly the point. The battery in your Dad's Cavalier was maintenance free, which is why you didn't need to check electrolyte levels. The owner's manual for the i specifically instructs the owner to check electrolyte levels "regularly" without ever defining what that means (e.g., is weekly too often? monthly? quarterly?). Leaving this potential failure point out there and doing nothing to warn owners about it is not going to make a lot of friends when dead 12V batteries leave cars unable to start. I can just imagine the idiot press coverage now - "Mitsubishi EV battery failures strand frustrated owners", which I think we could all agree would leave a very misleading impression.

Don said:

One of my other cars is a Mazda Miata which came with a sealed AGM battery mounted in the trunk. Checking the dimensions of both batteries, it appears a Miata battery will drop right in and give you what you want . . . . namely, a small, sealed, maintenance-free, AGM battery

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When I had my Honda Insight in Honolulu, I used a Miata battery rather than the flooded-cell Civic battery that Honda recommended to replace the small Yuasa OEM battery. However, the orientation of the terminals was reversed from what the Insight was designed for, so I had to relocate the ground cable. Is the orientation of the terminals of the OEM i-MiEV battery the same as the Miata battery? If so, that's a good replacement. If not, it might still be a good replacement if the cables can be made to reach without too much bother.

Yes, the terminal placement on the Miata battery is the same as our battery. The length and width are correct but the Miata battery isn't quite as tall - You may need a small block on top of the battery for the hold down clamp to work correctly. The amp hours are the same

I'm pretty sure you could also put a group 51R AGM in the car. The height and depth are the same, but the 51R is about 2 inches wider. It looks to me like it will fit OK, but you wouldn't be using either the bottom tray or the top cover. Using this battery, you would have considerably more amp hours and there are deep cycle 51R's if you'd prefer to go that way

BTW - There are already reports of the 12 volt battery failing and disabling the car - I've read about two such instances on-line

Don

Hi Don,

Thank you for the information.

I am not sure if this came out clearly in the thread, do we need a normal car battery or a deep cycle one ?

Further, I saw some LiFe or LiPo motorcycle batteries for about 250 USD with now amp information. Wondering how to choose if the price is indeed around 200 rather than 400?

For the paranoid, could we carry a smallish 12V battery with some alligator clips on it that could at least be used to get the car started? I wonder how much current we need to run everything... or at least enough to get the car running.

The iMiEV's 12v battery lives in such a benign environment that I would be surprised if it needed any fluid for five or ten years (I'm still using some FLA batteries from the mid-90's which I've never topped up). As I see it, there are only three possible electrical stresses in its existence:

1. When the car is left alone for a few weeks there is a gradual 12v battery depletion (I think primarily due to the alarm system - I have yet to measure this standby current).

2. When the key is turned and the radio is left playing for a few hours or the accessory socket is used for something

3. If someone inadvertently leaves a light on.

I don't recall an outright 12v battery failure in an iMiEV on this forum, but I wouldn't be surprised to hear that one of the above conditions has resulted in a depleted battery, preventing the car from starting.

Can't imagine needing a deep-cycle battery for this small amount of use - compared to an ICE car, our battery experiences extremely "shallow" cycling.

My motivation for converting to AGM (yes, I will do it one of these days) will be to simply avoid the corrosive results of any slight acid leakage or even fumes, as I'd like to keep my iMiEV pristine. Haven't done it yet, but first I would want to verify that the dc-dc does not go over 14.4v at room ambient and I wonder if the dc-dc varies this voltage with temperature as on a hot day the AGM would prefer a lower voltage. If the voltage is higher, then I might want to use an Odyssey AGM battery.

As for lowracer using Headways (LiFePO4) - I wouldn't do that in the iMiEV without a serious BMS capable of managing each cell individually:
1. Our dc-dc output feeding the 12v battery would need to be further regulated to match the Headways' needs
2. In my limited experience so far, Headways unaccountably seem to get out of balance, unlike others' experience with large-format cells which, once balanced, seem to stay that way for a long time. I'm presently building a test fixture to parallel 64 Headway cells and perform a properly-stabilized balance - and peterdambier and I can have a discussion over exactly what voltage level this should be performed at

The Leaf Forum has an extensive thread on this subject (which I haven't read yet): 12 Volt Lead Acid Battery Replacement

It will be interesting to see how the OEM battery holds up - I'm not all that confident that it's going to last several years

Ideally, a flooded battery likes being hooked to a 'smart charger' which recognizes when the battery is full and switches it to a lower, float voltage. This prevents gassing, which consumes water. Our DC/DC converter has no such provision and it holds the battery right at 14.4 volts all the time, which is right on the threshold of gassing the battery

Since I have already read about two instances of a bad accessory battery stranding the car, I think I'm going to replace my battery sooner rather than later - I'm not fond of walking and over the years, my wife has grown to really appreciate the fact that I have never had her driving anything which might involve some walking :lol:

After some more research, I suspect I'll probably opt for a group 51R AGM . . . . probably before the end of the summer - If I wait too long, you guys will be the first to know . . . . but since nobody here has had a problem yet and some of you have far more than the 8,000 miles we have on the car, I don't feel there's any great rush

First thing to do though, is remove the battery and check the water - *IF* they thought using a battery which requires some maintenance was a good idea, they sure could have put it in a better place. It's almost impossible to check it properly with it still in the car

Don

Vike said:

Unless I'm misunderstanding something, I think this is exactly the point. The battery in your Dad's Cavalier was maintenance free, which is why you didn't need to check electrolyte levels.

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That battery had caps on it, so does the one I replaced it with. So it was maintenance free in the sense that I never had to do anything with it, but it had caps on it so that water could be added.

Vike said:

The owner's manual for the i specifically instructs the owner to check electrolyte levels "regularly" without ever defining what that means (e.g., is weekly too often? monthly? quarterly?). Leaving this potential failure point out there and doing nothing to warn owners about it is not going to make a lot of friends when dead 12V batteries leave cars unable to start. I can just imagine the idiot press coverage now - "Mitsubishi EV battery failures strand frustrated owners", which I think we could all agree would leave a very misleading impression.

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No doubt it could make bad press. That may be the reason it's in there in the first place. The battery could also be on the checklist during the annual service visit. For checking it yourself, once a year should be plenty, right before the weather cools off for winter.

Touching on the owner's manual, this car's manual is much more daring (if that's the right word) than other manuals I've read. Most manuals won't mention half of the more detailed specifics of driving the car, whereas our manual freely tells you how to use the different driving modes, for example.

I checked today the battery level by removing its cover and putting a flash light behind and slightly shacking the car. Otherwise it is impossible to see the level.

Here is a link I found for LiFePO4 car batteries, 40A would be 260 area.

Maybe a 30 A would get closer to 200 and we could make a group ordering ?

http://qdhipower.en.made-in-china.c...UQ/China-Auto-Start-Battery-12V-12V40AH-.html

One of motivations would be to reduce the battery size in order to check of a Webasto Hester can fit right there on top of the Battery...