Fitting mobility 12volt AGM battery.

When I google this, I get this as the first link, which says it's "Our better flooded, NON-AGM battery".

Maybe the Costco is (different and is) an AGM, but I'd make sure before even looking if the measurements and the terminal-lay-out match up...

Just to be clear, the Prius battery SHOULD be AGM! (Or at least the GEN2 is).

 

Hello Brit Prius,
I don't know if you are still alive and kicking, since these posting are over 10 years old now. Thank you so much for creating this post. As I have just made my own modification to my 2014 Prius V-2. Mossy Toyota in Pacific Beach, CA sold me a used car that had a bad cell. I think it was the original True Start battery. They replaced it with what I thought was a new battery, but I still had problems and have had to tow it to the dealer twice and had the $145 diagnostic performed on it twice with "nothing found " as a result. And gotten my battery jumped over 10 times since owning my car. I think they put a clean used battery in the car and made me assume it was good. Since putting in the deep cell battery, 3 weeks ago, I have had no problems.

One major thing is that the brand of battery you recommended I could not find. But I found an almost exact match on Amazon ... 12V 55Ah Ritar RA12-55 Group 22NF Wheelhchair Replacement Battery (i4 Terminal) SPS Brand
Now $138.60 USD. It came with threaded hole posts that are M6-1.0. The most difficult thing for me to find was the JIS Pencil Post adapters, since it took me over 4 months and contacted many battery suppliers. I finally found it from Odyssey batteries. Even-though I wrote Odyssey directly and they told me they didn't make this adapter. I found a company in Southern California called JHPUSA who couldn't or wouldn't tell me what the bolt size was on the adapter. But said I could buy it and if it wasn't right I could return it. Out of desperation I finally bought it and it fit! These adapters made things so much simpler as I could use the existing battery cable connectors.

The other thing that was major was making of a mounting plate. Because the new battery was just a little too wide for the cradle about 1/4-1/2 in. I decided to use approx 5 X 5 X 1/8 in Stainless Steel plate with three SS 1/4 -20 , 1/2 long Phillips head bolts welded onto the plate. I found that the sheet metal bar on top of the battery had an extra hole 1-1/2in wider than the original position. But the chassis of the Prius had no extra holes for expanding the width of the cradle tray. Why this was done I have no idea. So, I decided to make a plate that allowed me to widen the space for the battery by 1-1/2 in. I had a professional weld shop punch six 1/4in. dia. holes and countersink 5 of them and weld the 3 bolts. Just this work cost $95 USD.

The new battery is only 3/4in taller than the OEM True Start battery. But with the higher battery height and adapters, I can't use the original sectioned plastic tray that goes over the battery. But having peace-of-mind that I have a more dependable battery is well worth not having this. I can still put things there if I really need to. I used a rubber welcome mat that was about 1/4in thick and cut up pieces to wedge in the extra space on the sides and on the top. The M6-1.0 coupling nut I used to increase the height of the fixed side brace with a threaded bar welded on it is 3/4in. long. I had to put a 1/4in. pad between the battery and the top bar to be able to seat the M6-1.0 bolt to the cradle bar on top. I bought four 1/4 X 1 in. nylon spacers to increase the height of the top cradle bar using a M6-1.0 X 40mm bolt.

Thank so much for your explanation and taking the time to prove your theory and put it into practice for all us Prius Owners. It's too bad this idea hasn't caught on by Toyota and other Hybrid manufacturers.

 

Well... You definitely win the prize for most thorough battery mounting job ever!!! I chatted with BrittPruis a couple years back, he's still hanging in there. It's just he's been driving a Lexus for a 1/2 dozen years so not to much interest in Prius anymore. He did say to say hi to everybody when we chatted last.

As for your work, do you have a link or info on those terminal adapters? It'd be nice to buy a box of 'em for our local Prius group because this type of 55 amp-hour 12v now sells for as low as $97 on Ebay these days and sometimes people get confused about what you need to buy at the local hardware store to DIY...

As for your modifications, I've done 12v swaps in both Gen1 and Gen2 Prius and I simply use vise grips and pliers to rebend the sheet metal battery carrier so everything fits. And it might not fit as nicely as your way but my way is free and takes less than 5 minutes.

Anyways, thanks for keeping the message alive about using these batteries... I bought one of these December 2012 and just a couple nights ago forgot to close my rear hatch with interior lights on all night and even after 8 years the battery is still hanging in there. Of course maybe 8 year of no hassles means I shouldn't push my luck and get a new one?

 

I missed Britprius here, especially his contributions.

 

Thanks so much for the comments... I started a FaceBook page called "LOW MPG TOYOTA PRIUS OWNERS AND USERS" because my Prius was getting 28MPG. I changed the plugs a few weeks ago. I think this did the trick. But I'm filling up the tank again to verify that I'm getting around 45MPG... I started the page because Toyota washes it's hands of anything by saying "Mileage may vary" and it's dependent on the driving habits of the operator, which is Bullshit... 2 salesmen told me I would be getting over 40MPG. And when I tried to have the dealer take the car back they told me the salesmen didn't ever say they "guarantee" the mileage. Even-though the computers records the MPG which they knew it wasn't working to full capacity. They have diagnosed my Prius twice and both times they found nothing wrong. And if the computer doesn't catch anything then they can't fix a problem they don't see. They didn't see that my plugs were not working to full capacity? Anyway... this is a blog to call attention to the Hybrid market not having enough correct S/W & test equipment and expertise to solve problems. And that's where the future is headed...

As for the adapters they are available through, JHPUSA - 5057 Walnut Grove Ave., San Gabriel, CA 91776 or call 626-287-5000 M-F 9AM-5PM PST / Closed Weekends & Holidays. They have a free "will call" pick-up.
One Pair, Odyssey JIS Battery Terminals cost $29.95, $10.96 S&H, $3.89 CA Tx, T= $44.80 USD. Since I don't own the car and still making payments I wanted to be able to revert it back to original design while still using the original cradle. In a "pinch" I would do what PriusCamper did and use the strong-arm pliers method. The adapters from M6-1.0 to SAE terminals are a whole lot easier to find. I was just about to give up and have a machinist make the adapters. Glad I found them. The cost would've been astronomical as you can tell from my simple extension plate.
See attached mechanical drawing that I found while searching for the JIS terminal adapters.
As for the average life expectancy of the Deep Cell batteries, I have not researched this. From PriusCamper's experience they must be super reliable. Most lead-acid batteries on the market are warrantied no more than 3 years now. Over the years I have noticed that places that tested batteries went from a multi-cycle test lasting 3 hours to now it's done in 15 minutes. So, not sure how thorough these tests are now and if they can really tell you the condition of the battery. I would rather have that 3 hour test done.

 

Wow... That's expensive. I think I'll stick with simply putting in longer bolts and big thick washer on the top and bottom of each terminal. As for MPG, the quickest fix for that is tire pressure. Keep adding 1 or 2 psi in each tire until the tires start slipping slightly on most common road conditions you drive, then back off a few psi, to regain the lost traction. On my Prius I have Ecopia running at 47psi in front and 45 psi in the rear.

 

@Marcel Gomez Did the mileage improve after replacing the battery. I suspect that was the solution as opposed to the plugs.

 

I still have Low MPG with the new battery and new spark plugs, There's something else wrong that neither Toyota nor I can detect.

 

You may want to start a new thread in a Prius+ MPV forum rather than go off-topic in this thread. I doubt there is the cross-over experience here in the Gen 2 forums to be able to help you. I know I can't be of much help to you.

 

Thanks folks for an awesome ride! This thread rocks. My 05 with SKS is now sporting the 33ah flavor sealed AGM mobility and I couldn't be happier. Props to all those who went before me!

Here in the USA, a vented mobility delivered for a decent price seems unavailable. I envy you folks abroad, we can't get those batteries...
So, for my fellow comrades trapped with me on the USA Titanic, here's an update of what I found: MightyMax 33ah. (Unable to post link per forum, I guess you have to Google it)
This bad boy has the coveted internal threads. One block of wood underneath to match the battery clamp down was all I added to the mix. It's a neat and tidy installation.

I chose to use a clip to hold the air vent of the battery compartment itself open. Outgassing has been discussed ad nauseam, and I am no longer concerned of venting, but I am of course interested in your opinion. Pic attached.

I'll mention that I don't use my SKS, with button off I assume drain is eliminated. Thus my comfort with the 33ah flavor battery. They sell the 55ah flavor for $130 shipped.
We shall see. I sure am happy with my $75 shipped one this far.
She'll be experiencing some Rocky Mountain High style winter temperatures coming up if all goes well. So I'll be putting that smaller battery to the test in the extreme temps as well as elevations.

You folks here have been very inspirational.

 

The reason you can't find a vented mobility battery is because the vent is entirely not necessary... Battery design has advanced enough to no longer need it. Of course the delusional paranoids will be happy to cite all kinds of baseless claims for why it is needed, but don't listen to them, they're crazy.

Can you post the link so it doesn't behave like a link so we can see that $75 battery you bought? That's a great price!

 

I liked his comment so he should be able to add links now.
My battery is showing around 12V with a temperatures plummeting every day. It's 7-8 years old. My car has SKS and they still equipped it with 35Ah (UK).
I am going to buy 60Ah Power-Sonic tomorrow. Issue is that the battery tray is small and I need to hack it.

Model PG-12V60
Hopefully it will fit.

 

It looks a bit tall? Which generation of Prius are you putting it in? You can get away with deleting the battery tray to make it fit better, but depending on which generation Prius you have, you may have to figure out mounting hardware hack.

 

My 55Ah (of which I don't know the exact measurements) barely fits. I think the tray above it is lifted 1-2mm. I think I did not cut any plastic off to make it fit like that. Iirc I did have to lengthen the thread or bolt that straps it down in the battery compartment.


If you look past the tape in the pic below it seems to say 245x154x245mm. I'm hoping that's the battery, not the box
Is yours bigger in any direction?
(in inches it's close to 9 5/8 times 6 1/16 times 9 5/8)


EDIT: same seller (Netherlands-Europe) seems to have 60Ah deep cycles that are slightly smaller.

 

I'm needing a battery and was looking for cheaper options. What model number have you got and what battery posts did you install in it?
Thanks

 

I'm sorry but the forum will not let me post the link as a new member, if you Google this word salad you should go direct to the manufacturer for $75 delivered after tax!
"mightymaxbattery 12v-sla-batteries 12-volt-35-ah-sla-internal-thread-battery"
Note: the company offers many options. My AGM is not the gel cell they offer, and I'm a huge fan of those awesome internal female threads for posts! They make for the sweetest install!

 

My 33ah needed a block of wood under it. Don't modify anything! Get the right battery to fit. I had a couple pieces of hardware left over from stock, I used absolutely nothing new to install. It's a match made in heaven.
If you want the 55ah you can easily find one which will bolt right in no mods.
My experiment is Gen 2 and I've seen success in Gen 3.

 

It is just a tad taller (207 mm) than OEM (200 mm) but with clamps, YUASA 35Ah has 245 mm in height (positive) so still some space for hacks.


I did not purchase yet as it found that the PG series is Long Life and not Deep Cycle battery which I thought it is.
PG: PG Series - Long Service VRLA Battery, UPS/Telecom | Power Sonic

There is a specific series that is described as Deep Cycle Gel (DCG)
DCG: DCG Series, 12V Deep Cycle Gel Batteries | Power Sonic

I drive Auris TS (kind of Corolla in the UK) which is third gen HSD.
Toyota Auris Touring Sports (2013) - pictures, information & specs

I must say that after a few weeks of research the Ritar batteries are the best from the lot as their capacity was stated as C10 where everyone else shows C20 which is always higher. Also, the design life claimed is far greater than the competitors.
https://www.ritarpower.com/uploads/ueditor/spec/RA12-55.pdf
https://www.ritarpower.com/uploads/ueditor/spec/EV12-55.pdf
I cannot find them in the UK though.

I also found that Ritar RA used by OP @Britprius was not advertised as a Deep Cycle battery.
RA: AGM VRLA Batteries from 33Ah to 260Ah_Ritar Power
EV: Electric Vehicle VRLA Batteries_Ritar Power

There is a DC or DG series marked as Deep Cycle
DC: AGM Deep Cycle VRLA Batteries_Ritar Power
DG: Deep Cycle GEL VRLA Batteries_Ritar Power

Should I go with 60 Ah Long Life AGM
PG-12V60 12V 60Ah Long Service Life VRLA Battery | Power Sonic

or 50 Ah Deep Cycle Gel (same size)
DCG12-50 12V 50Ah Deep Cycle Gel Battery | Power Sonic

or just much smaller 32 Ah one that will fit 100% with no modifications?
DCG12-32 12V 32Ah Deep Cycle Gel Battery | Power Sonic


Thanks.

 

Do the posts come with it and then it's just pull the old battery , drop in the new?

 

12 Volt (12V) 55 Amp (55Ah) VRLA AGM Sealed Lead Acid Battery 55 AMPS HIGH CAP | eBay