I do try to drive my 914 all year, but it will have some down time when snow and salt are an issue.
"Finally" getting a battery tender.

question:
when hooking up the charger, is it safer or good practice to disconnect the ground?
I have a switch, so easy enough to do.....

I have several vehicles with permanent tender plugs attached to the battery. I have never had a problem.

Odyssey recommends that you do not charge the battery for seasonal 6 month storage, just disconnect the ground. This is my 4th year on a 680 and disconnecting the battery is all I've done.

I usually take customers and my batteries out and I have a battery storage/charging bench then I trickle charge them about every 6-8 weeks.

i use an Optima Red, got about 8 years out of my last one, maybe because of this modification. Since I drive my teener in fair weather only and often on short trips, I put a tender on it whenever it's in the garage. I got tired of opening the engine cover and attaching it all the time, so I did the following modification. Now I pull in the garage and "plug in" the car...

http://www.914world.com/bbs2/index.php?sho...&hl=battery

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Hard wired tenders to everything that might sit for a few weeks. If it won't be driven for months, pull the ground, no tender and trickle charge every few months.

When I had an optima battery, I had to trickle charge it or it would be dead if the car sat for a week. I hard wired the cigarette lighter with a fuse to the battery. This made it easy to plug the trickle charger into the cigarette lighter. Since switching to an AGM battery, i no longer need the trickle charge. But recently I bought another 914 with an optima battery. This one has the battery in the front trunk, so I just wired the included plug to the battery.

I disconnect the ground with a marine quick disconnect, and do a trickle maybe 2-3 times over the winter here in NJ.

@Steve …
Optimas are AGM batteries, no? Or am I confused?

You're correct, I saw this as well, an Optima is an AGM battery.
More likely the battery was on it's last legs and a small drain (like a clock radio) and the new battery fixed the issue.

I have multiple hobby cars, and now have a tender on every one. I wire up the included plug tail to the battery for the best connection. My previous standard battery for the 914 lasted 15 years doing this.

I have also installed a basic battery disconnect on the ground side of all of my vintage vehicles. I added the disconnect after reading a story about someone who had a vintage car and had an electrical short start a fire that burned down the garage (and almost took the house as well). Seemed wise to spend such a small amount of money to disconnect the power on a 40+ year old car and provide peace of mind. On my newer cars, I don't worry about the disconnect being required.

Jim

Correct, the Optima battery in my 3.2 914 was well over 10 years old. Now that we have other AGM battery options in the stock size, I just replaced it. Nothing changed on the car, but it still starts after two weeks or more of sitting. The yellow optima battery in the v8 914 i just bought also dies after one week of sitting, but it did have lighted electric window buttons that went directly to the battery and were on all the time. I wired up an accessory toggle switch, so I can shut it off when I'm not driving it. We shall see if it still dies.

Prior to my 914, I always took the battery out of my classic Mustang and brought it in the house, on the tender all Winter. It can get really cold here in OH and remember reading years ago that this would help increase battery life. Batteries have lasted 10+ years.

Do you think this is a waste of time for the 914? It's kind of a bitch getting it out of the car because my charcoal canister is attached to the tray. Should I just leave it in, on the tender?

But after reading about disconnects on the negative side or ground, what's the recommended procedure? Don't need the place burning down!

https://www.amazon.com/TKDMR-2Pack-Battery-...6355&sr=8-5

These are the basic disconnects I use. I imagine there are fancier ones out there, but these were fine for me. I leave the batteries in all my cars when they are on the tender (they are all garaged). The nice thing about the 914 is the engine lid can stay up and not be intrusive.

My optima sucks . I have to keep on a trickle charger as well . It will be dead within a few days .
This is my second optima. I thought the first one was bad so I bought a new one and they both suck. Meanwhile my van can sit for over a month and fires right up .
10’yr old no name battery….

Similar experiences, my '81 Ford truck has an ancient lead cell that never fails, the AgM only lasts a few days in cold weather as now, 24F right in East Oregon this morning.

I have the exact same model optima battery in all of our cars, with the exception of the SUV. I have not had to replace the battery in it yet.

To keep them active when we are not driving the car, I mounted Battery Tenders hanging from the garage door opener. We have cutoffs on all the batteries, and have the pigtails hard wired on the battery side of the cutoff so they can be run with the rest of the electrical system disconnected. We have a portable one I can use to keep a battery live when out of the car (That's the battery for Betty's 914 that's in the body shop).

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I need to lengthen the one going to the red car, but otherwise it works great.

Unfortunately we don't get to drive them as often as we like, so this keeps the batteries alive.

Clay

Last winter I never charged my 680 battery for 5 months (in heated shop) and it was good.
Three weeks it's been cold storage, plus I now have a clock radio and it didn't have enough juice to start. To be fair even a with a big optima it was hard to start, I may have flooded it, okay once I got it running.
It's above freezing but she wasn't happy waking up, she's going back into the heated shop for the winter.

I have a PC1200 for my 914 which is sitting on the bench in the shop while the 914 undergoes paint. After reading this, I think I'll put the battery in the Pantry. Wife will just love that.

With the PC680 I'm starting a 3.0 twinplug high CR engine with a lawn tractor battery.

I could have gone with a PC680 for the 914. That's what I run in my two Bugs and they work great. I think I went with the PC1200 just because I had the space on the stock battery tray.

I like the PC series, not the cheapest, but they've done me well over many years.