I have a 2007 RX8 with just under 20K miles, so you probably know where this is going. I have been replacing batteries about every two years and was told a while back that I don't drive the car enough to keep the battery charged correctly. I really only drive it short jaunts 2, maybe 3, times a week. I was advised to get a battery maintainer and did some research on them. I think the Deltran Battery Tender Junior 12V, 750MA might be enough for my needs. It has an automatic shut off, so I can plug it into my battery when it is sitting in the garage until I use it the next time. Will this one be enough, or do I need to go to one with more amps? Thanks!
https://www.deltran-global.com/junior

 

This is fine. You don't need more amps if you're just maintaining. The car draws about 20 milliamps while off for alarm and stuff.

 

How's your alternator? I have an Optima Redtop, with an Optima charger, maintainers. Maintainers are good if your car is sitting awhile. When you drive do you do any high reving? I would assume that that will keep your battery charged. I always rev high, up to the 9k rpm mark, which will keep your engine alive longer, in my opinion.

 

By the way, short trips will kill these cars pretty quickly. If all it's doing is warming up and putzing around town, you get carbon build up and fuel in you oil. Wind it out, let it breathe.

 

Yep, have had carbon cleaned out at least once, maybe twice.

And thanks about the Battery Tender Junior.

 

I've been using this setup for years. Battery Tender

The thing that I do with all of my cars is attach the hardwire kit to the battery and run it around the battery box and along the small coolant line that attaches to the battery box. I then run 2 zip ties to that hose as well.

With this hardwire option I just attach the tender whenever the car is going to be sitting for awhile. You don't need crazy amperage.. I like the low amp versions and have had no issues for the 6+ years I've been using them.

 

Thought I already responded, but must not have hit the post button... So, even though you use the 1.25amp, you still think the 750mAh is sufficient?

I was planning on leaving the ring terminals on the battery and then just hooking those lines up to the tender but was wondering how to affix/tie down the terminal lines - will look at your coolant line/zip tie option for sure.

 

Excuse the dirty engine bay.. but the car sees long road trips when in use. But this is how I route the charging cable. Easy for long storage. Each car is setup the same way, the hardwire kit can be purchased separately.

 

I have that same tender
Covercraft noah cover?

 

went with the California car cover brand.. this is the “dust force” cover since it’s indoor only.

 

I have the same battery tender. Always plugged in when its stored over the winter (from November 1 to mid-April). And if I am going away and not using it for like a week, I will plug it in.
These cars go through batteries like crazy. I just put a new one in this spring too.

 

This is a little more permanent installation that I have. It is hard wired onto the battery and the line cord tucks nicely it the space between the fuse box and the fender. Remember, for longer battery life, install the correct size when replacing. There needs to be some extra airspace around the battery due to the extra heat in the engine bay that the rotary engine produces.

 

Thanks. I've been using a temporary connect up and it seems to be fine as I am not charging it very often and can do so each time overnight. The airspace around the battery is what is "offered" given it has a cover that I leave in place other than when I am charging the battery.

 

The reason I use this set-up is two fold:

1. There are times my RX-8 will sit for a few weeks and all that time there is a small drain on the battery from the onboard items that continue to draw a trickle of power even with the ignition off. I definitely notice a slower operating starter on those occasions.

2. Here in the Great White North, I store my car from about mid November thru mid March as the road salt kills all cars eventually (I have seen a number of rust-bucket RX-7s over the years)! I leave the battery minder plugged in during that time to maintain its health.

I do the same thing with my motorcycles; saves me having to constantly remove and install the batteries or the battery tenders. As a caution: you still need to keep the electrolyte levels up as there always is a small amount of evaporation through the heat and charging process.

The best way is to observe the levels is thru the filler caps. While most so-called maintenance-free batteries have them covered with a decal, they are easily accessed by gently heating the label with a hair dryer and peeling it back. I have saved numerous batteries from being replaced by just topping them up with distilled water. Of course a totally sealed AGM battery doesn’t have this issue.

Remember… exposed lead plates KILL a battery and the manufacturers want to sell you a new battery!

 

I've done the battery tender thing in the past.

New thing to do imo, is get an Anti-Gravity with RE-start. Been using them with great success in both my cars (yep I own two of these fancy batteries, ha).

https://antigravitybatteries.com/pro...s/restart-oem/

 

Never heard of them so I checked out the link and a Group 35 for an RX-8 is listed as $949 USF! Are you kidding me? That is about $1350 CDN! Little rich for my retired budget!! And there is shipping on top of that; I’ll stick with my $45 battery minder thanx!!!

 

Wow that is expensive. I don't remember them being so pricey. I purchased years ago before they really gained traction in the industry. Also might be able to substitute another battery with appropriate CCA rating for their recommended battery at a better price point.

 

I don't know whats wrong with my car, in 13 years of owning it I replaced the battery 3 times and for 8 of those years she rarely got driven.
Standard old Auto Zone or Walmart batteries.

 

Couple of thoughts here:

1. I think a lot of the batteries we buy are not up to the same quality standard of years ago. I replaced an 18 month old battery last year purchased from Costco for my RX-8. One cell went completely dead; fortunately they have a 2-year replacement and a full warranty on the new battery.

2. Any battery will slowly degrade over time if it just sits. The car still needs a tiny amount of current for some electronics even with the ignition off. The voltage will drop and eventually it just fails. That’s why a battery tender is a must; it maintains the battery at peak voltage and recharges it as the car uses some power.

If you had the car stored outside in the cold those 8 years, that’ll kill it as well. Use the car more regularly, install a battery tender and think of a battery as a consumable just like tires!