Modern Vespa

Can anyone recommend a good Portable Jump Starter? I know at least one of the cars needs 900amps of cranking power.

I live in a sky rise with no access to an electrical outlet. Both my car batteries at times would be dead. Since I got my scoot, I've been neglecting both cars. I try to take them out once in awhile, but if I do not drive them after a week, they will not start.

I think Sears sells something like that, for a quick start when you battery is low.

http://www.mysears.com/DieHard-2-40-200-amp-Manual-Battery-Charger-reviews

no bueno. Not going to work. I have no AC plug near by. I kind of want to stay away from sears. Their battery products really sucks nuts.

If the batteries are too low to start the vehicle you really need to get them on a charger. You are going to kill your Alt using it to charge a dead battery, if you do that very often.
Get them started then take them someplace you can plug a charger in.

Wayne B

Here's a whole passel of them on Amazon:

Portable Jump Starters

If you read the reviews on Amazon or any other source of these things there are a lot more negatives than positives. I really wanted one and read all the bad raps and just got discouraged and didn't buy anything. The lead acid batteries in them seem to be the weak link. They are real cheap and don't last more than a year or two. If your situation is such that you absolutely must have one I would get it from a local source that has a good return policy so that you can get a new one when it fails prematurely, and then just expect to have to replace it every couple of years. Don't waste your money on the ones with all the extras, compressor, lights, radio; when the battery
dies, that all goes in the can together.

I'd suggest:
Get both car batteries fully charged first.
Get another leisure battery (that can be deep discharged without killing it), and use a DC-DC converter to trickle charge them in turn. The leisure battery can be carried upstairs and re-charged every so often.
If the cars have a view of sunlight, consider solar battery trickle-chargers.

Also consider selling one of the cars.

having the scooters around is definitely a (car) battery killer. I've seriously killed three car batteries out of neglect. I now have dongles on all my vehicles to facilitate quick hookups to battery tenders.

Imo, if you want to do as you propose, it's still going to be a bear of a "system" to keep up with. My first impulse is to avoid it if at all possible. And by that I mean I would make a serious effort to find a 120v outlet *somewhere* near your car. *any* 120v outlet. It might not be "yours" but if it's the apartment's, perhaps you could "borrow" it once or twice a month.

2nd point: you're not not not interested in a jump starter. If you've let your battery get down so far as to need a jump start, you're going to kill your battery after only a dozen or so cycles of this, which means about one season of use. What you *really* want to consider is a portable *trickle charger* so that it never gets so low that you need a jump start. lead acid batteries (even the deep discharge batteries) were never intended for applications where their charge gets down so low. Even deep discharge batteries are best kept above their 60% level as much as possible. Check out www.batteryuniversity.com for background info on lead acid batteries. The difference between an abused battery (a few dozen cycles before failure) and a well-maintained battery (upwards of several thousand cycles) is *huge*.

Ok, so if you're going to do this...imo, what you're really interested in is powering up a battery tender from a portable power source instead of the conventional 120v power source. There's a few ways to go about this. Is the car ourdoors? If so, I'd go solar. It's pricey, but it's sure to work, and the most efficient. cost wise...huge upfront cost, but if you consider that you won't actually be replacing dead batteries quite so often it might seem more reasonable.

If the car isn't outdoors, you are forced to consider more idiotic setups.
There's the idea that you could buy a sacrificial deep draw battery that you charge the others up with. This has some advantages, but larger drawbacks. It is, imo, the 2nd worst option save for the jump starting idea). On the upside, it's a relatively simple concept to implement. You hook up a charged battery to charge a depleted one. The charge levels even out, and voila. But it's downsides are imo large. It doesn't do a good job of charging, because charging a 12v battery actually takes a higher voltage gain on the charging end to push the charge across to the depleted battery. You'll never actually get the depleted battery up to a full charge in this manner. The sacrificial battery will not give all its charge to the depleted battery...they'll just equalize. You'll have to manually guess whether it's given as much juice is it's got, and in the end...it kills a battery to keep a battery, which, imo, is inane.

No, the optimal solution here if no sunlight is involved is to run a portable power source that has a built in inverter so it can produce 120v power so you can plug in trickle charger into the portable power source and do a legitimate trickle charge. This way, you get several benefits. First, the power reserve in the portable power source is now fully on tap, so it can deplete completely (rather than just reaching equilibrium). Not a good thing for the longevity of the power source, but it's what you need it to do to fully top up the depleted battery. 2nd, you get the benefit of legitimate charging logic from the battery tender, preventing overcharge. You probably have the urge to keep things small when it comes to the choice of which power supply, and my recommendation to you is that that urge is dead wrong. You need to go large, because it's an extremely inefficient and taxing job you're asking the power supply to handle. You're taking 12v power and inverting it to 120v power (an inefficient transformation), and then powering an AC adapter converting that BACK to a 12V charge (again, inefficiently)! Why bother, one would ask? Well, in the process, you buy yourself the charging logic in the battery tender's circuitry. To overcome all this inefficiency, and still have enough capacity in the power supply to 1) give enough juice to depleted battery, 2) power the AC adapter, and 3) not kill itself in the process, you need a BIG portable power supply. And I havent' done the math on it, but I hazard the guess that you really would be most successful w/ the biggest you can get...like...right now I see Duracell has one called the Duracell Powerpack 600...something along those lines.

Like I said, though, my very 1st impulse is to avoid this at if at aaaaall possible. It's alot of hoops to jump through for a rather preventable situation. Running a car for 20 minutes every two weeks or so (at speed...not just at idle), is a decent alternative, or 100ft of outdoor extension cord & a trickle charger every two or three weeks...

Costco sells solar trickle charges. Last time I saw them they were pretty cost effective.

Also, if you are not driving the cars very often, it may be easier to simply bring the batteries upstairs to your unit and placing them on the charger on you balcony. When you know you need the car, place the charged battery back in the car and you're ready to go. You may want to invest in the RV or boat posts that disconnect form the cables via wing nut.

Do the cars have a large power drain? Why do they kill a battery in less than a week? Alarm?

2 each for $39.95 http://tinyurl.com/yhlb5te

lead acid batteries are cheap for sure, but imo they don't last more than a year or two because it's largely a misapplication of the technology. If the consumer actually kept up with the maintenance of their accessory battery...it'd last for years! But that's kind of a catch-22, isn't it? If you had the intention of keeping up w/ a battery's maintenance in the first place...you wouldn't need an accessory battery would you? The other comment wrt this is that the average consumer infallibly under-sizes their power supply in an effort to keep things small, not taking into consideration how it affects the longevity of the device. This is partially the consumer's fault, and partially the fault of "optimistic" marketing. But it's really not the technology's fault, per se. That's not going to stop consumers from getting on a website and trashing their reviews though.

Why not just a simple DC-DC converter built for the job? e.g.:
http://www.powerstream.com/WC.htm - but there are some far cheaper ones around.

Ah, of course...I shoulda checked powerstream. I didn't know DC input chargers even existed! It's a nice twist to the concept, bcs it takes out one (unnecessary) transformation. So instead of a 120v battery tender + portable power supply + AC Inverter, you just go with a DC Input battery tender + portable power supply. It's definitely more efficient.

What do you think, though, in terms of sizing the portable power supply? I still kind of think the larger the better for the sake of minimizing how deeply you discharge the power supply which I tend to expect is itself a sealed lead acid arrangement.

Lets assume a constant trickle charge of 50ma with no conversion losses (in reality it will be bursts of say 750mA with long intervals between from a decent intelligent charger) - that should be plenty for a good condition (low self-discharge) large truck 12V battery. A common portable leisure battery with carry-handles is 75Ah. Lets also assume we don't want this to go much below 50% capacity.

The converter will (reality averaged) take 20 hrs to deliver 1Ah, so in 800 hours will deliver 40Ah. So over 30 days before needing to be re-charged.

My guesses at the charge delivered may be out by quite a lot - so a weekly re-charge of the leisure battery should do it.

It sounds like the car batteries in this case are knackered anyway, if they can't be left for one week without failure. They should be able to last unattended for months and still be able to start the car.

Sounds about right, with a reasonable margin for error.

I agree, the charge delivered is usually much less than rated. It's my understanding (as always, derived from that Cadex site) that the batteries are rated using rather slow current draw, to be as optimistic as possible. Plus, there're other factors that aren't ideal, like temperture, sulfation, etc.

Keeping the power supply above 70% is what I'd aim for, though. Generally speaking, the folks at Cadex have this to say:

http://www.batteryuniversity.com/partone-16.htm So, to take a different view...if I were interested in a 30-day solution, w/ the 50mA trickle charger, we'd burn through 36Ah over the course of a month. If we stick with Cadex's recommendations of 30% discharge for sealed lead acid batteries, then at a minimum, you're interested in a power supply that's rated @ 120Ah.

That Duracell Powerpack 600 I mentioned earlier is spec'd at a paltry 28Ah despite the fact that it's the largest offering Duracell provides us. Recharging that power supply up would definitely be a weekly routine, unless you wanted to buy a new one every season.

I don't think that site was addressing leisure batteries, which are differently designed, and can tolerate deeper discharges, but not high current draw (so don't use them to jump-start). These are the batteries typically used in motorhomes to power the 'home' part rather than the 'motor' part.

That's true, deep discharge batteries do differ in design from regular flooded lead acid (thicker plates help guard against the effects of sulfation, for example), and are designed to withstand it better. I've seen anything from 50-60% cited from RV & marine resources when talking specifically about deep draw batteries. 50%...60%...70%...it's all a bit large for the more portable options (obviously, Jim, I'm referring to the ones that were designed for hauling around like an appliance, rather than the larger items).

This:



as opposed to this:



But of course, there's nothing wrong w/ the larger straight-up battery, if you're willing to haul around three stones.

Based on a few hours research, the Duralast Gold Top Batteries offer the best cost/performance/warranty out there. I used to think Optima ruled but not so much any more. Read the warranty terms carefully before you buy, that Duralast is hard to beat at least in my application. I believe they are available at AutoZone.
Here is a good link http://www.batteryfaq.org/ you'll find lots of info there.

Wow. Thanks for the battery lesson. Positive Karma given to every person on this thread.

I just finished replacing SUV battery, battery was 5 years old. Dealer wanted $250 installed, but I opted to do it myself for $170 (had no other option but to purchase battery from Benz dealer). My Infinity battery is still dead. I was able to jump start it using the Benz, but of course it did not start up again after turned it off. I'll probably jump start it tomorrow and take it in to work.

So after reading this thread, I'm leaning to get a battery charger. I do see a 120v plug about 80 feet away from me, but there is no way our building management will let me use that plug. I would have run a wire across driveway and a few stalls where cars/people would run over the extension cord. They will view it as a hazard. Our building security is serious and they patrol our parking area every 45mins (underground, no sunlight )

So I'm thinking I would have to get a charger, and drive down to my friend's house or work and utilize their 120v and charge up the Infiniti's battery (I replaced that 3 years ago). Then the hard part is to use these vehicles throughout the week and using the Vespa a lot less.

Sounds like your batteries were on their way out anyways. 3-5 yrs is a decent length of time for them.

I can definitely see a vigilant building mgmt throwing up red flags when they see a power cord strung across the garage (the watchful guys in golf carts at my SO's apt were simultaneously a blessing & a curse). There're (possibly) ways to make the idea more palatable for them. If I were a contractor working at your place, the bldg mgmt would require that I use an extension cord cover or cable protector intended for vehicular traffic if cars are going to be passing over them. Heavy duty ones look like this (but aren't that cheap).



You can get two 12' lengths of light-duty stuff for like $80 bucks, which, imo is probably good enough. If it were me (and of course...I'm not recommending this, per se) I'd just pick the "garage floor" color and see if they notice. That's a relatively big added cost. But hey...24' of rubber just might last longer than a poorly maintained power supply, imo!