Which 12v battery is the best?

[a_gray_prius]

Looks like a relatively tight fit - otherwise I would have asked why not use a plastic 'bin' for the battery to sit inside so you don't have to fabricate some sort of plastic cover?

[bwilson4web]

Originally Posted by a_gray_prius

Looks like a relatively tight fit - otherwise I would have asked why not use a plastic 'bin' for the battery to sit inside so you don't have to fabricate some sort of plastic cover?

Hummm, my first thought was 'gut' the OEM battery and put the PC925 inside. <GRINS> Sad to say, I've already recycled my old one but the idea has merit. I might do that with our ZVW30 when the time comes.

Bob Wilson

[OptimaJim]

Hello, I noticed your conversation and wanted to offer some assistance, especially to baja454, who just purchased one of our batteries. Although our batteries are sealed, it is important that any lead-acid battery has proper ventilation. ALL lead-acid batteries can vent gas. Traditional wet batteries do this immediately when recharged, since they are not sealed. Sealed lead-acid batteries like Optimas and all other “dry cell” AGM batteries have safety release valves that should only vent if they are seriously overcharged.

Under normal operating conditions, an AGM battery will not vent gas. Since alternators or chargers can fail, the safest and correct mounting method for trunks and passenger compartments is to make sure that any possible gas venting will escape to the outside of the vehicle. All vehicles with original equipment battery locations in trunks or passenger compartments will have a vent provision that should be used. If your battery is custom-mounted in the trunk or passenger compartment we recommend venting the battery to the outside of your vehicle as well. Optima group 27, 51, 78, 34C, and 31 batteries all have ports for connecting a vent hose.

Although people do it anyway, we would never recommend installing an unvented battery in any enclosed space, because there’s a legitimate, albeit unlikely, safety risk involved.

For example, IF there is a voltage regulator failure, and IF the battery is severely overcharged, and IF this goes unnoticed, and IF the battery vents because the internal pressure exceeds the release pressure of the vents, the gasses are both flammable and toxic. This may sound like a lot of “ifs,” but attorneys and engineers get paid to plan for every worst-case scenario.

Jim McIlvaine
eCare Manager, OPTIMA Batteries, Inc.

[jk450]

Thank you for taking the time to contribute to this forum. Much appreciated.

[bwilson4web]

Hi Jim,

Originally Posted by OptimaJim

. . .
Although people do it anyway, we would never recommend installing an unvented battery in any enclosed space, because there’s a legitimate, albeit unlikely, safety risk involved.

Do you offer vented cases for your batteries?

I noticed various marine and other sites offer battery boxes:
Noco Group U1 Battery Box: BatteryMart.com

Do you have any recommended battery boxes for the Optima batteries?

Originally Posted by OptimaJim

. . .
For example, IF there is a voltage regulator failure, and IF the battery is severely overcharged, and IF this goes unnoticed, and IF the battery vents because the internal pressure exceeds the release pressure of the vents, the gasses are both flammable and toxic. This may sound like a lot of “ifs,” but attorneys and engineers get paid to plan for every worst-case scenario.
. . .

I had a voltage regulator on a generator fail many years ago in a Cherokee 140 in flight. By the time I landed and opened up access to the battery, it was venting acidic steam ... not a pretty sight. I pulled the generator circuit breaker and flew home by turning off the master switch and flying VFR.

It looks like my Odyssey PC925L will fit in a U1 box but I'll check with them to see if they have any other recommendations.

Thanks,
Bob Wilson

[bwilson4web]

Originally Posted by OptimaJim

. . . If your battery is custom-mounted in the trunk or passenger compartment . . .
Jim McIlvaine
eCare Manager, OPTIMA Batteries, Inc.

Do you have any 'white papers' or experience with installations that include a stiffening capacitor?

Thanks,
Bob Wilson

[OptimaJim]

Hi Bob,

Unfortunately, we do not offer vented boxes or other accessories for our batteries and cannot “officially” recommend products manufactured by other companies or offer specific advice on custom applications. I can tell you that any custom application should consider these guidelines-

· Hood Clearance – There should be at least ¾” clearance between the top of the battery terminals and the underside of the hood. When we do our fitment studies we put a ball of clay on top of the post, and VERY carefully close the hood to make sure that nothing makes contact. By measuring how much the clay is squeezed down when the hood is closed, we can know how much hood clearance we have.
· Trunk/Interior Mounting – As previously mentioned, if your battery is mounted inside the passenger compartment or trunk, the battery must be vented to the outside of the vehicle. Optima group 27, 51, 78, 34C, and 31 batteries all have ports for connecting a vent hose.
· Side Terminals – Optima 34/78, D34/78, 75/25 and D75/25 batteries have both top and side terminals. If you are using one of these batteries in a vehicle that uses the top terminals, it is important to ensure that the side terminals can not come into contact with anything metallic (for example, the firewall or fender well), thereby causing a short. We suggest keeping the post protectors on the terminals you are not using. Do not connect a winch to the side terminals.
· Battery Modifications – Cutting, drilling, trimming or otherwise modifying your Optima battery may present a safety hazard and will void the warranty.
· Mounting – Your Optima battery must be securely mounted. The terminals are not intended to be used to secure the battery. Using the terminals in this way will damage the battery and void your warranty.
· Heat – Protect your battery from high heat, such as turbochargers or exhaust manifolds

If you have any other questions, I’ll do my best to answer them.

Jim McIlvaine
eCare Manager, OPTIMA Batteries, Inc.

[Kanshome1]

We are just now getting into this forum and because we are having issues with our '01 model, I have begun researching several things. As of today I was told by a very qualified mechanic (at an independent garage, not Toyota) that the Prius needs the original style 12 V battery because the internal design works with the slow (low amperage) charging system used on the Prius. The 12v battery is apparently charged through the HV battery. Overlooking the problems with adapting a different sized case, and the wiring concerns, I think I'm going to have to go with the dealer-sold part, because my friend's argument made sense to me. But that's why I signed on to this forum, I'm open to any and all information. Again, forgiving the size issue and assuming the wiring is not rocket science, does another style of battery hold up to the Prius needs? I have several street rods and usually run Optima batteries and knowing how good they are, (I'm still running one that was installed in 1995) I wonder if that capability is masking some pending issue?? As in, is the solid core battery just keeping up with the use and will fail because of charging rates, or is it really living with the Prius electronics as it should?
Sorry for the long post. Keith

[bwilson4web]

Originally Posted by Kanshome1

. . . As of today I was told by a very qualified mechanic (at an independent garage, not Toyota) that the Prius needs the original style 12 V battery because the internal design works with the slow (low amperage) charging system used on the Prius. . . . .

I've done load testing of our NHW11 as part of installing a 1 kW inverter and it delivers a solid, 1 kW.

Originally Posted by Kanshome1

. . . The 12v battery is apparently charged through the HV battery. . . .

More accurately through the power inverter. Although 'OptimaJim' is concerned about a runaway alternator and I have experienced a runaway generator, there is a quantum leap between those primitive systems and our Prius inverter. I'm not worried about either over voltage nor over loading our liquid cooled, power inverter but I've tested mine to the 1 kW limit.

Originally Posted by Kanshome1

. . . I think I'm going to have to go with the dealer-sold part . . .

My OEM battery lasted about 6 years and yours, 9 years. Given the average USA fleet age is (or was) close to 9 years, this isn't bad at all.

Bob Wilson

[orange4boy]

The Prius does not use any exotic charging technology. It charges just like a standard alternator system, by the overall voltage of the 12V supply. In this case it is supplied by the DC-DC converter which has a 100 amp fuse so it is designed to supply up to roughly 80 amps. without too much trouble. It will have no problem charging an Optima.

The reason the Prius has a small battery is that since it does not need to start an ice a small battery is all that is needed to boot the computer and supply a bit of juice before the ready indicator is lit. Small means light which means better fuel economy. I'm an Optima fan as well. Go for it. They are a much better battery for the money.

Any car that is used on short commutes will tend to under charge any battery which will lead to stratification in a flooded battery. Optimas do not stratify which is probably one of the reasons they last so long.