12 Volt battery is failing, I'm looking for replacement

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jjlink

Well-known member
Joined
Sep 11, 2011
Messages
403
Location
San Francisco Bay Area, CA
My 12 Volt battery is failing and I'm looking for replacement. I have it on a BatteryMINDer to revive it for now. Has anyone found a good replacement AGM battery that will work? I looked around for other posts but not many look like they actually replaced it yet.

I'm looking at my Prius's 12 volt battery and it looks like it could be made to fit.
Optima Yellow Top Battery D51R Starting and Deep Cycle 8073-167

OK, I answered my own question. It looks like this will work:
258e575dea9299cda93004b549ca179e.jpg


Thanks
 
John, I have a whole bunch of Optimas left over from when I converted my Sparrows to Lithium - if you still need it, let me know and I'll give you one. I hadn't tried the Optima in the i-MiEV, and happy to see it fits (thanks for posting the photo) - I'll be replacing my 12v OEM battery the instant I see even the tiniest bit of corrosion at the terminals.

Edit: Oops, just noticed that my Optimas are D34 and the D51 is not only a different form-factor but is 17# lighter. My bad. :oops:
 
According to Firestone Complete Auto Care, on average a car battery lasts 3 to 5 years, and our 2012 Mitsubishi i 12 volt lead-acid batteries are over three years old. However, since our 12 volt batteries are not required to crank out starting amps, I'm hoping they will last longer. I've worked with electrical substation lead-acid batteries that have lasted 20 plus years. My 12 volt i battery terminals show no signs of corrosion, and I checked the electrolyte level was still good.

PS4Xl7sl.jpg



When it comes time to change our 12 volt batteries, BCI (Battery Council International) Group Size 151R should fit with dimensions as shown:

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Note that the "R" stands for reverse mounting of the positive and negative terminals (positive terminal on the right).

Group Size 151R batteries are in stock available at AutoZone, Advance Auto Parts, and Pep Boys.
 
JoeS said:
John, I have a whole bunch of Optimas left over from when I converted my Sparrows to Lithium - if you still need it, let me know and I'll give you one. I hadn't tried the Optima in the i-MiEV, and happy to see it fits (thanks for posting the photo) - I'll be replacing my 12v OEM battery the instant I see even the tiniest bit of corrosion at the terminals.

Edit: Oops, just noticed that my Optimas are D34 and the D51 is not only a different form-factor but is 17# lighter. My bad. :oops:

Joe, thanks for the offer anyway. It looks like the D51R is a good fit and will work fine. I did have to remove the plastic tray under the battery to get the height correct. I don't think the tray is needed anyway. The Optima batteries do have a vent hole. I hooked up to a tube pointed down towards the bottom of the car. Was the vent a concern in your experience with the Sparrows?

I put the old Prius battery back in the Prius after being on a desulfating battery-minder and it looks like it is working fine at least for now. I will put the old I-MiEV on the desulfating battery-minder and keep it for a space for something else.
 
jjlink said:
...The Optima batteries do have a vent hole. I hooked up to a tube pointed down towards the bottom of the car. Was the vent a concern in your experience with the Sparrows? ...
No need to worry about the vent hole in the Optima, as the battery only outgasses when seriously overcharged (>~15.5v), otherwise it is pretty well sealed. I really prefer the AGM over the FLA because there is no maintenance nor corrosive vapors or terminal corrosion. This smaller Optima looks like a great fit for our i-MiEV for someone who regularly plays the radio or uses the 12v for something with the car turned off, or stores the car for long time without plugging in a float charger; otherwise, it's perhaps overkill. :roll:
 
It's official, Bear is the most jealous vehicle I've ever encountered :twisted: :roll: .

My work has a jobsite near Harrisburg, PA. I've been there three times, including today's trip (done with either the parents' hybrid or a company car). Each time after coming home, I've encountered some kind of issue with Bear. After the first trip, I started it the next morning to find my main battery had a failing cell. After the second trip, my LED doorhandle lights started failing.

Today, we just finished eating after I finished up at the site and were at a bike shop across the street. As we were walking out the door to leave, I get a text message. It was the OVMS module warning me of a critical 12 volt battery! I immediately send a DIAG? command to the module. It reports back with a voltage even lower than the warning (warning message said 10 volts, DIAG? response said 9.4 volts). We get home, and sure enough, the car won't unlock with the remote. I unlocked it with the key, popped the hood, and put the 12 volt charger on the battery for a few minutes, then took it off and plugged the car into level 1.

So, now I need to figure out what caused the battery to run flat over a 3-day weekend and how to fix it. There were no lights left on, so that leaves:

A. The radio was stuck in a powered state.
B. The 12 volt battery is weak, both from a year of sitting on the dealer's lot and from running flat a couple of times while the main battery was being replaced.
C. Power draw from the OVMS module, the OBDLink, and the radio is too high for the size battery in the car to last more than a couple of days.

So, does the 12 volt have its own warranty, or is it part of the new vehicle 3-year warranty?
 
My car turns 4 this month (built in Feb. 2012). I guess lead acid likes the abuse of a starter motor better. The battery in the Cavalier I drove before lasted 10 years before it needed replaced. Of course, care was taken to never run the battery down in the Cavalier. It's been used to jump other vehicles, but hasn't needed a jumpstart itself.

I'll be looking for a replacement, but I'm still going to try to track down what power drains I have and see if de-sulfating the current battery helps at all. One of my door lights is suspect, since it recently quit working, and touching it would cause it to light before it quit, so I'm thinking that light has a short somewhere (there's a resistor in-line, so a soft short could be continuously running the battery down without blowing any fuses).

I know LOWRACER did a LiFePO4 conversion at the very beginning of the Preperation for Cold Seasons thread (http://myimiev.com/forum/viewtopic.php?f=9&t=694). Someone else did this, too. I'm wondering how that has been working out, as I have 2 LiFePO4 12 volt packs from my old eBike available to put in the car.

Also, a side note regarding the MCU warning light. It seems that if one tries to start the car with a dead battery, the light will be triggered and have to be cleared by the dealer, but if the battery goes dead and it is recharged by a 12 volt battery charger before starting the car is attempted, the light won't be triggered. Last year at a show, just after getting Koorz, the battery went dead from the lights. My friend tried to start the car to recharge the 12 volt battery, but it wouldn't start. The warning light was set. Last night, I charged the battery in Bear before trying to start it, and the light has stayed off.
 
Anyone buy a 12v battery local or has everyone had to get it on line?

I looked locally but did find it. Maybe I need to look harder.

Some places have outrageous prices for these little motorcycle batteries.
 
How about one of these? http://www.ultrabattery.com

It looks idealistic, but see this:

http://www.hybridcars.com/alabc-ultrabattery-hybrid-surpasses-100000-miles-of-fleet-duty/
 
I recently had to get a new 12 volt for my 6 year old prius. No local parts stores had it in stock. They all wanted to order me a Yellow top battery which was indicated on their computers. They wanted about $75 more than I was able to get it for online. The dealer wanted something like $400 for an OEM...and maybe that was installed, but still. I think I paid about $140 online.

Actually turned out that my old battery was probably still good, because after I installed the new one, I found the overhead dome light on...wife had been in the car the day before. Had I known, I probably would have charged it up and given it a whirl, but I had made that assumption that once a battery is over 5 years old, you might as well replace it.

Be wary of replacing the 12 volt batteries in cars like iMiev and Prius with "bigger" "better" batteries than they came with. This means the car has to supply more electrical charge to keep the 12 volt up to speed...taking away juice from the traction battery. You may not notice it at first, but when that bigger battery starts to decline in 5 years, it will hurt MPGs. (or eMPGs as the case may be).

So I guess what I am trying to say if the iMiev battery is a standard lead/acid battery, I would replace it with such, same size, same specs. The Prius had an AGM battery to start with.
 
It looks like the same size I had on my 1100 Motorcycle.

Still looking for a list of other manufacturers that make this battery size. All the other 'books' that cross reference never list the 'i' as a car {rolls eyes}
 
BMW K-bikes use a big 12V battery, nearly the size of the jellybean's.

So if using a bigger battery puts extra load on the pack, then does using a tiny one put less load?
 
In a way, yes. There are less floating losses with a smaller lead acid battery. It takes less to bring a smaller battery up to system voltage and maintain it.
 
Guys, dc-dc could provide about 80A current, so any big battery would be charged properly!
I don't see why bigger battery would take much more energy. It will take depends of how battery was discharged before. For battery 35Ah and 50Ah and I-miev consumption - it will be not so big difference, especially that dc-dc is taking all consumption in ready mode.
Better choose it's to use LiFePO4 battery because it shows almost same capacity in discharge and charge mode, so it will take less energy from HV battery.
 
PV1 said:
In a way, yes. There are less floating losses with a smaller lead acid battery. It takes less to bring a smaller battery up to system voltage and maintain it.

Yes (mostly), and beyond this an AGM charges more efficiently and has lower standby losses than a standard type flooded battery. A number of AGM batteries will fit in the car but not without some changes here or there. For warranty purposes IMO it has to fit without alteration to the car. But I will definitely be replacing mine with an AGM when the time comes (I'll alter the battery not the car). I had to take the stock battery out to do a good job of filling and checking it when I got the car. Doing that twice a year is not on my preferred approach list!

Aerowhatt
 
OK, time to beat this topic to death. Let's review our 12v battery - it lives a very benign and happy life, never has the stress of having to provide hundreds of amps starting current as for an ICE. Thermally, it is not sitting next to a high-temperature ICE; however, it is indeed exposed to brutally-cold northern climes.

The 12v battery is fed by a dc-dc converter which provides a constant voltage. I suspect (but have not measured) that this voltage is temperature-compensated. For example, I just measured 14.48vdc when I turned the car on in my 45degF (7.2degC) garage - I had left the door open overnight. Incidentally, our high yesterday was 75degF (23.9degC). :cool:

The 12v battery only provides three lightweight functions:

1) Provides the current to activate the car's systems when the key is turned on (Ready).

2) Provides current to run the various 12v accessories with the key turned to the first notch: radio, fan, dome lights, etc. I measured 9.6A current draw with the fan in the midway position on my SE Premium with nav unit and radio and hard drive running. YMMV.

3) Provides a tiny trickle current to keep the alarm system active when the car is Off. I couldn't measure this with my clamp-on ammeter, but suspect it's under 50ma. Let's see, 30 days idle at 50ma is 30*24*.05= 36Ah … oops, dead battery, so it must be much less than that. I'll measure power-off current draw when I go to replace mine.

As RobertC identified, the battery is BCI Group Size 151R. Mitsubishi calls it a 34B19L(S). From the Yuasa website, this is shown as 33Ah at the standard 20-hour rate (i.e., a constant 33/20=1.65A) before it drops to 10.5vdc, whereas all the BCI ratings use CCA and Reserve Capacity about which we don't care.

For completeness, for the 34B19L(S), Yuasa shows L = 185mm (7.3"), W = 125mm(4.9"), H = 202mm(8"), Overall H = 224mm(8.8")

All right, so what does all this mean? The stock battery size is already excessively-large, IMO, but your usage determines the battery capacity you need. For example, you may wish a higher capacity -

1. If you go away for weeks at a time not using the car and don't plug in a float charger.

2. If you spend a fair amount of time sitting in the car listening to music or with your laptop or other gadgetry plugged into the accessory socket.

I consider the most stressful thing you can do to our 12v battery is to simply leave the car sitting untouched for a few weeks - the gradual battery depletion results in sulphation of the plates which, in turn, never get a chance to recover because the battery never gets an "equalizing" (higher-voltage) charge to clean the plates. Auto dealers murder 12v batteries when the cars sit on their lots untouched for weeks at a time.

Choices -

The car comes with a flooded-lead-acid (FLA) battery. It's advantage is that it is cheap, but the fluid level should be periodically checked and eventually it will result in terminal corrosion and maybe a bit of rust around it due to the acid fumes. Alternative is a 'maintenance free' FLA - I don't even know if one is available in this size range. I personally will not replace my FLA battery with another FLA.

AGM (Absorbed Glass Mat) - this is a sealed battery that is very suitable for this application. Usually, AGMs don't like to see more than 14.4v at room ambient (exceptions being Optima and Odyssey AGMs), but it seems that our dc-dc puts out voltage right at this limit so I don't see a problem.

Gel - also a sealed battery and actually would be very good in this application as Gels do well in deep-cycling which would be the case if the car was left unused for weeks at a time; unfortunately, the traditional Gels don't like to see a voltage much over 13.8v, so I wouldn't put one there. Don't even know if there's anything available in that form factor.

Lithium - sure, you could stick four LiFePO4 cells in there - for example, four Headways strapped together or even higher capacity like the 3P4S configuration LOWRACER did (http://myimiev.com/forum/viewtopic.php?p=4035#p4035), and it would work BUT I wouldn't put those in there without an individual-cell BMS. Lead-acid is very abuse-tolerant, whereas Lithium is not. Also, 14.4v from the dc-dc results in 3.6v per cell, which is close to the LiFePO4 upper limit of 3.65v - not good for longevity to keep it that high continuously.

For myself, since I usually put a float charger on my i-MiEV's 12v battery when we go away for a few weeks and I can't recall ever sitting in the car for any amount of time while not charging (the dc-dc is activated when the car charges, so you can run the accessories indefinitely while charging), I'll install a small (much less than 33Ah) inexpensive motorcycle AGM when the time comes. I did that on my Honda Insight a decade ago and it's still going strong.
 
Before dropping two Benjamins on an Optima, I'd experiment with a Lithium battery, especially since 18650 and 18500 cells are pretty ubiquitous and affordable. I found 66 new LiFePo4 18500 cells for $33 last week simply because they has a 2012 mfg date. So far, they're testing out good.
 
jray3 said:
Before dropping two Benjamins on an Optima,
I was thinking more along the line of a $25 12Ah battery...
jray3 said:
I'd experiment with a Lithium battery, especially since 18650 and 18500 cells are pretty ubiquitous and affordable. I found 66 new LiFePo4 18500 cells for $33 last week simply because they has a 2012 mfg date. So far, they're testing out good.
Oooh, at that price worth experimenting. Strap them all in parallel and top balance them (for a few days?) and then put together a 16P4S 20+Ah pack and you're in business with no BMS, at least for a while.:geek:
 
JoeS said:
jray3 said:
Before dropping two Benjamins on an Optima,
I was thinking more along the line of a $25 12Ah battery...

Yes I was thinking the same.
Or a Motorcycle battery, I just don't know where to find one that will match.... ok ok I am just too lazy to look that hard
 
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