12 Volt Battery Questions

[randy3]

(Mods, if this is not a good forum for this post, please move it. Also, I did a search, but didn't see anything pertaining to non-EV use of battery tenders. If I've acted inappropriately, please delete this post in it's entirety. Thanks)

We've been a two car family for years. But the EV life has reduced our gas car use to just one or two days per month. Now our Honda Insight (2010 model) is registering low cranking amps for it's 12 volt battery. It is 4.5 years old and has the original battery. The report shows 231 cold cranking amps available with 332 CCA's being factory level. The service advisor took this as an opportunity to try to sell me a new 12 volt battery, saying that the battery will likely fail sometime this winter.

Questions:
Should I be concerned about this? Maybe I should just be sure to drive it a little more (once a week maybe)?

If I should be concerned, would buying an inexpensive battery tender solve the problem? Amazon has one for $23. Sounds better than buying a 12 volt battery and then not using the car more than once or twice per month.

Thanks for your help! I appreciate having a place to ask these questions.

 

[JoeS]

Hi Randy,

No worries, as it's a good question and applicable to both your hybrid as well as a seldomly-used BEV and I've moved this post to the Batteries subforum.

Your Insight hybrid uses the 12v battery to power the car's computers and 12v consumers such as lights and radio, but does not "Start" the engine (except in an emergency) as your IMA motor running off the NiMH battery pack performs that function. Just like in the iMiEV, the 12v battery is needed to activate the car's systems, after which the dc-dc converter keeps the 12v battery nicely charged by the larger high voltage battery pack.

The problem with modern vehicles is that even when turned off they consume a small amount of current, typically to power an alarm system. Since the 12v battery in the hybrid and our iMiEV is relatively small, even this small amount of current can deplete such a battery within a month or two.

By far the best thing you can do to keep that battery alive is get a small smart float charger such as a Battery Tender (there are less expensive chargers out there) and simply leave it plugged in when the vehicle is going to sit there unused for weeks at a time. What I do for my seldomly-used ICE cars is use a small solar panel with a small regulator feeding the 12v battery, but for my Gen1 Insights inside the garage I do use a Battery Tender. Hopefully your 12v battery has not sulfated too much by sitting there partially discharged and will recover with a nice steady charge (we won't venture into the merits of desulfators here).

 

[Llecentaur]

Actually, I was going to mention desulfators, which to my experience seem to work.

I have bought a small unit and use it every other month on my jaguar or before putting my convertible in "hibernation".

On the other hand the unit has not been able to restore really hurt deep cycle batteries that do not charge anymore to 14.4 V.

Maybe more experienced users can share their opinions.

 

[Don]

Since the battery doesn't actually start the engine so cranking amps are of no great concern, I was going to suggest installing a smaller motorcycle AGM battery, as they can set for several months without running down . . . . but I see some Insight owners are already doing this

http://www.insightcentral.net/forums/modifications-technical-issues/9229-installation-deka-ext12-12v-agm-battery.html

Don

 

[JoeS]

On that Gen1 Insight forum I had posted my own use of the Odyssey AGM <http://www.insightcentral.net/forum...2-12v-battery-voltage-question.html#post88800>, but it only lasted a couple or three years. I followed up with a Deka Gel cell which is still going strong after more than five years. The early Insights had the voltage regulated to 13.8vdc which was a little too low for the AGMs but perfect for the Gels. Although, as Don pointed out, the self-discharge rate of AGMs is close to zero (i.e., they can sit on a shelf for over a year with no problem), if the car sits unused then the slow current drain by the car's alarm system still has a deleterious effect on the battery. With a rarely-used car, IMO float charging is the solution, and may even keep Randy3's existing Insight battery going for many years to come.

One of these days I'll get around to replacing the FLA battery in my iMiEV with a small AGM as the dc-dc output voltage level is just fine; besides, I hate flooded lead-acid. I kept one of my EVs with 24 6v golf car FLA batteries stored in my garage for a year and the almost-unnoticeable fumes ended up leaving a light coat of rust on all my tools and machinery. :evil:

 

[Llecentaur]

How small could that AGM be? 9 A are really small and cheap.

Interest is that a French iMiev owner installed the Webasto at the place of the battery, which I also find so convenient, next to the heating reservoir.

 

[Don]

If the car is driven daily, I would think the replacement AGM could be pretty small, maybe even as small as 9 AH

I would fit the Webasto as best you can and then see how much room you have left for the starting battery and then buy the largest which will fit - I'd feel more comfortable with something in the 15 AH range than just buying the smallest/cheapest

Don