Need some education, Jump starting/charging a dead battery Options

[Coondog]

I have read some threads about advising against jumping starting a 914 from car to car. Can someone please explain why this is not a good ideal and is it the same with putting my charger on Hi start power boast mode for 15 minutes which I have done several times. If these have the potential to harm the electrical system then would those hand held battery power boasters also have the potential to cause damage???

BTW....Now I just leave a 1.5 amp trickle charger hooked up. Hope that's ok !!

[McMark]

I've done it all ways and never had a problem. If possible, I prefer to pull the battery out and fully charge it on the bench.

Leave the trickle charger on until it's full.

[Olympic 914]

I think it may have to do with cooking your regulator. if you are jumping from a car/truck with a 85 amp regulator it can burn out your 50 amp regulator.

run into this problem with jumping a motorcycle also.

What I do is, run the engine in the vehicle you are jumping from for about 5 to 10 min, to charge up the dead battery. then shut down that vehicle before attempting to start the dead vehicle. that way you are charging up the dead battery and then just using the battery in the donor vehicle and not its charging system. if it doesn't start right away, shut off the key in the dead vehicle and charge that battery again.

not an electrical wizard but that method works for me.

[screenguy914]

Running the engine with a discharged battery (after a bump or boost start) will cause the alternator to produce max. current output to recharge the battery. This can stress the alternator and shorten its service life.

Recommend to first recharge the battery using a trickle charger, then use a battery maintainer to keep a stored vehicle charged and ready to go.

Sherwood

[Tom_T]

Coondog,

Back in my decade of DD days, I did have to jump start it a few times without any problems, but then they all could've been closer matched amps on both cars (as Olympic1.7 says above).

IMHO - the best option today is to carry one of those little lithium-ion battery pack with you & save both the space of carrying cables, & the hunt for a willing jumper, to help you the jumpee.

You can match the Li battery pack's amps to the car in question, but you do need to keep it charged. An added benefit is that you can recharge them from the lighter socket when the car is running, & they can also recharge your phone, laptop/tablet, run a small 12v LED TV, etc. off of them with their added connectors that usually come with them as a kit.

As for the trickle charger - those only do a slow charge & are "dumb" - so they too can boil a battery, just like a regular charger (or at least damage the battery. So never just leave it on the car, except over night or something short-ish.

I have a small solar trickle charger that I use on camping trips in the Westy & Anion T20 trailer (like an Airstream) to keep their house batteries charged, but they're getting some draw down while camping to offset the constant slow charge. Northern Tool sells a 2-pack of them at a good price when on sale, they're made in China IIRC for Coleman, & are about 6" x 15" & put out about 5A max. IIRC. Handy to have for campers, when you're away from the wall plugs. They are not "smart" maintainers, so they do need to be watched.

What you need is a "battery maintainer" - which has sensors to detect when, how much & how long the battery needs topped-off, then it goes to sleep until next needed - while hooked up continuously.

They also make units to charge multiple cars - so you can also keep that gorgeous SS charged up off the same unit - if both can be parked together!

There are several good ones out there, & everyone has their fav for both the jump-packs & maintainers, so I won't go into names - but you can do some quick online research on them to pick your preference.

Also, you may be able to go online to the KOCE or KLCS local PBS station affiliate up there in A-valley or the overall PBS website, & go to the "MotorWeek" proigram, & look for the Pat Goss segment on trickle vs. maintainer segment from maybe 2014 or 15 for a quick overview on both the battery charger packs & the maintainers (latter was the oldest show).

I'm in the process of equipping all of our vehicles with those battery emergency pack chargers, starting with one for our `88 Westy. In my case I'm getting one from aftermarket suppliers for each car make, since they've used &/or tested them on the particular car. So after trying this first one out for a while, I'll get the one from BavAuto for my `85 325e BMW E30 - unless they say the one below is okay.

So I got the Westy one from GoWesty.com for the Vnagon based `88 Westy, but it may be good on the 914, since they also cover older "Splitty" & "Bay Window" VW vans - the latter of which ran our 2.0 motors (as did the 1st 80-83 Vanagons).

Otherwise, Porsche sells their own branded maintainer if you want the cache of Porsche (try Sunset or Suncoast Porsche for best parts pricing from P-dealers). I'll probably get that one when we finally find that "perfect" lightly used `08-12/13 Cayenne S that we're looking for as a tow vehicle for the Avion.

Good Luck! (IMG:style_emoticons/default/beerchug.gif)
Tom
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[whitetwinturbo]

I'm using a "Battery Tender".........

[tomrev]

I'm using a "Battery Tender".........

Me too, it reads voltage, and shuts off as needed. My Lotus is hooked up all Winter on one.

[stugray]

One thing to keep in mind when jumping any car from another car:

When two voltage regulators fight, bad things happen.
Whenever I jump one car with another, I leave the jumping car running, and THE SECOND the "dead" cars starts, I disconnect the jumper cables (takes at least two people)

When the non-running car gets above a few thousand RPMs its own alternator will kick in and try to regulate the voltage.
If the jumping car is still connected when this happens, the two voltage regulators will each be trying to regulate to their own sensed voltage.
If this goes on for long, one (or both) voltage regulators could be stressed.

It is exciting to watch this when you accidentally connect two different "VREGS" together on a circuit board... fireworks usually ensue spectacularly (followed by some smoke generator action)

And it is not advisable to let a car charge it's own dead battery from completely dead. It does stress the alternator "some".
It might be worse on our old fashioned alternators, but I would bet that newer solid state versions have built in over-current protection.

[Coondog]

Lots of great info...... Thank you

[jcd914]

I've done it all ways and never had a problem. If possible, I prefer to pull the battery out and fully charge it on the bench.

Leave the trickle charger on until it's full.

(IMG:style_emoticons/default/agree.gif)

I have never even heard of anyone having a problem except when some idiot hooks up the cable backward or arks next to the discharged battery setting off the hydrogen gas and blows up the battery.

Jim