Portable CTEK Equivalent?

I recently got a CTEK to keep my Cayman battery maintained (been dead a few times because of infrequent driving). The issue is that I don't readily have access to a wall outlet (though I do for emergency/infrequent situations). So it is sort of a solution, but not that great. Rather than use a CTEK to keep the battery maintained, can one use something like this if there is no outlet? My concern is that it wouldn't be "intelligent" charging like the CTEK . Too bad CTEK doesn't make something like this for guys who live in apartments and don't have access to wall outlets :/ https://www.amazon.com/GOOLOO-Porta...le-Starter-Battery-Booster/dp/B017LIE842/ref=sr_1_4?ie=UTF8&qid=1478136249&sr=8

That'll work about as well as the proverbial perpetual motion machine. You want to charge your battery with another battery ? How long will that last? If you park outside, a smallish solar panel with be more than adequate to keep your battery topped-up. That's what I've used on my boat. Something like this Solar Battery maintainer You could put the collector in the rear under the window glass. Or better yet - drive your car more.

If you find an answer, let the world know. Owning a car whose battery tends to die easily is not something you do living in a place with community parking. Without the luxury or your own driveway and access to electricity, you are pretty much out of luck. As to what you point to, go read the consumer reports on the Lithium battery jumpers. When the temp drops to zero, it won't even start the car according to their tests. If you want a portable battery jumper, get a real one like those from Clore.

You are not creating energy, just transferring it. Same concept as charging your cell phone with a portable battery pack. Except you have two things going for you, which are (a) the car battery only needs to go from about 80% to 100% and (b) the portable charger can be a made with a more efficient batter technology. Combined with these factors, the size should be manageable. And just to be clear, this is not something you would leave in your car. You would trickle charge the car battery and bring the portable unit back to your home for a recharge. Repeat the process every couple weeks or so. -- The problem is the cars are in a parking garage so can't use a solar charger. I do try to drive the cars as much as possible, but it is hard to cycle through 3 of them because of my parking situation (each one needs to be swapped out to avoid losing my spaces). Its quite a pain to manage the whole thing and little unit would fit the bill (plus I don't want to drive the Cayman if the weather is bad...so there is a scheduling issue).

Chows4us, Not really looking to jump it, just keep it topped off. I don't think the temperature thing would be an issue. You just keep the trickle charger at home and bring it out when needed. I emailed CTEK about it and they said its not a product they have, but something they may consider in the future. I don't see any reason it can't be done. Its probably just too niche of a market.

If it were me, I would look into a small, portable generator like Generac Power Systems | Portable Power | Generac Power Systems or Honda EU1000i Model Info | Super Quiet 1000 Watt Inverter Generator | Honda Generators . Make sure its sized right but both look more than capable of handling the 4.3 Amp ctek. Plug it in once a week. Let it run a couple of hours, and bring the generator back to the house (outside, not inside).

Hmmm, not that it really matters since no product exists, but I will bounce it off my EE friend as well. I don't see why you can't just adjust the voltage of the source if needed ( voltage regulator ) and just suck the power out til its gone. Seems pretty straightforward. The generator is possible, but I don't really want that in my my place (smaller loft). But I have a loose car battery just sitting in one of the cars that doesn't get used much (just being stored there). I was thinking about hooking up an inverter to that and power the CTEK . But that seems like a lot of electronics. The inverter would be a pure sine wave, as opposed to a modified sine wave version so it should work in theory. Of course, I still have to charge the other battery afterwards, but that is no big deal since it is loose.

This seems like a lot of effort. Why not just start the car and let it idle once in a while?

Yeah, that is another option, but how long and at what RPM for it to charge? And it doesn't sound like it would be good to start the engine up just to charge the battery . I would rather put in a little more effort than put wear and tear on the cars when I don't have to.

Bad idea. How often do I need to use my car to prevent battery death? - The Globe and Mail It takes more energy to start the car than you put back in. Unless, you go drive for a half hour or so. Best thing to do is get that ctek hooked up once a week until its charged. Just gotta figure out how to do that.

What about the option of just disconnecting it the battery if I know it won't drive it for 1-2 months. Sure, I will lose the radio settings, but are there any other issues? Off the bat, I am not too fond of that issue. They make battery quick disconnects, but not sure how reliable that approach is.

I thought of that, but you might want the alarm to be armed. What about a buck-boost converter? Connect your unused lead acid battery to the converter. Set the output of the converter to 14.7V and connect that to your car's battery . https://www.amazon.com/RioRand-Adjustable-Automatic-Buck-Boost-Converter/dp/B00GWCC6S4 Just a quick one I found, not necessarily the most appropriate.

I don't think I am too concerned about theft so maybe I should just disconnect it. I seem to remember something about that not being the best approach though? I could see a voltage regulator being part of the required circuitry, but I think you would want a microprocessor like a CTEK in between. But yeah, that would be the basic concept if company like CTEK went that route. They could have the option to use either an attached smaller battery or just hook up to a larger car battery . Probably just too few people in a situation such as myself to justify developing it. I would feel more comfortable with a battery /inverter and the CTEK (and even then not so sure that is a great idea).

Check this out https://www.kickstarter.com/projects/67854833/jackery-power-pro-solar-ready-mobile-energy-solutif It like your first choice but much more powerful. But you got to match the watts the wattage of the charger and this one is only 300w continuous.

Should I take from this thread that none of the portable ' battery boosters' that work through the cigarette lighter is able to keep a battery near 80-90% or better? [edit to include 'portable' because I left it out]

Not for an extended period. I'm assuming you aren't talking about a plugged-in maintainer/charger

Yeah in that case, just bring the battery inside.

I just really wanted to see if I was missing something. I don't think I am, so it is just a matter of picking an route and going with it. Can anyone confirm that it is OK to disconnect the battery regularly without issue?

A long time ago P9 member L8Apx did and interesting experiment where he measured the current draw from the battery during various operations of the car e.g. lock car, unlock car, open the door, open the frunk etc. Here is the link to that thread http://www.planet-9.com/987-cayman-...vice-and-tech/18024-cayman-battery-load-when-parked.html?highlight=battery+amps . The reason this info is significant in Hozer2's case is it would be nice if you could kind of calculate approximately how much current you are using while the car is idle in between charging the battery or driving the car. Of course the age of the battery is significant to how long it will stay charged but what you do in between driving or charging the battery makes a big difference. For example unlocking and locking the car and opening the frunk could use more current than a device like the GOOLOO could even replenish. According to L8Apx's experiment the car draws .015Amp/hrs when idle after everything is locked and shut down. So when idle the car uses .015Amp/hrs X 24 hours X 7 days = 2.52 Amp/hrs per week. On my 981 with a three year old battery the current going to the car from my battery maintainer is .018Amp/hrs when the battery is fully charged and the car is idle. This is fairly consistent with L8Apx's data. In my case the car is consuming .015Amp/hrs and the battery is consuming .003Amp/hrs. In Hozer2's case one thing that could extend the battery life is to not unlock or lock the car and access the battery externally with something like this BatteryMINDer Quick Connect/Disconnect Ring Terminal Assembly — 15 Amp, RTA-2415 | Battery Maintainers| Northern Tool + Equipment when charging the battery. Also make sure there is nothing like a camera, ipod or radar detector plugged in. Unless the battery is in bad shape or real old it shouldn't get to a discharged state for weeks even months.

This is in the FAQ http://www.planet-9.com/faq.php?faq=techdata#faq_7batterysp However, the batteries are different. Your AGM can discharge deeper than the old style batteries and recover. They also discharge slower and last longer. This change was because of the start/stop. That has to be taken into consideration.

From personal experience, after 2 weeks of sitting, it will start but its a little sketchy. After 4-5 weeks, it is hit and miss. I have gone on vacation for 6 weeks and it started, but barely. Another time, it didn't. Not a huge deal since I can just jump it, but I think this hard on the battery . I seem to have to replace it every 2 years even though it is garage kept and only driven about 3 months of the year. 2006 with 25k miles (sort of a garage queen). That is interesting about the AGM batteries . I just put one in my Cayenne , but the Cayman still has a Walmart H7 (790 CCA). I have been thinking about getting the walmart H8 (900 CCA), which supposedly fits with a little modification. But that is not an AGM battery . Even when fully charged, the H7 doesn't start it right up so a higher CCA battery would be nice. Anyone know of a good AGM battery that may improve the situation (and also has high CCA). And also affordable...haha, not too much to ask right?

Your intuition is correct, you could boost the voltage of the auxiliary battery thus enabling you to transfer virtually all of its energy to keep the car battery fully charged. But let's run some numbers. Others have reported the car consumes 15 mA at rest. Let's convert this to Watts since we're going to be transferring energy from a different voltage source: 15mA*12V=180 mW. Lets assume you want the auxiliary battery to maintain the car battery at full charge for 2 months. 180mW*24hours*61 days=263Wh. Then we need to account for the inefficiency of converting the voltage - say 80%. So we'll need an auxiliary battery of at least 330 WHr. Looking at battery-based jump starters on the web, the larger ones are rated at something like 18000mAh though this is at the native voltage of the cells, likely around 3.7V. Thus this would only be 67Wh, so you would need 5 of them! (Plus I don't believe the capacity claim because they say they can only charge an iPad mini 1.8 times which would be more like 36 Wh.). So we see the problem is getting enough capacity. Thinking about it, a better technology for this application might be fuel cells. I've never looked into them, but here's something I found with a quick search: FCHP-02: Horizon Fuel Cell Technologies : MiniPak Handheld Hydrogen Fuel Cell Power Supply : Electronic Kits & Projects Sent from my iPad using Tapatalk

The thought is that you would do the recharge every week or two (as opposed to every 8 weeks). So with a 4X-8X multiplier, the math works out. And if your source is another full size battery (alternate option), it would have plenty of juice for every 4-8 weeks. Ideally, you would have a 12V CTEK equivalent + Li-Ion battery pack + alligator clips to hook up to an alternate source. That way, you could cover all the bases. Clearly not as good as wall socket, but would be useful for guys who don't have that option. The other option would just be to do repeat the process 2-3X in a row if you skipped a few weeks. Again, not ideal, but better than nothing.

My calculation is valid regardless of how frequently you connect the auxiliary battery - it's just based on how much energy has been consumed and needs to be replenished. And conventional lead-acid batteries unfortunately cannot be discharged fully without damage, so aren't the best choice for this application, which is low rate/high capacity as opposed to starting a car which needs the opposite. That's why a fuel cell is an attractive possibility. Sent from my iPad using Tapatalk

Right, my point is that if you use your calcs you have 330/8 = 41 W*hr/week. This means you need to charge it every 1.5 weeks with the portable battery pack. This seems about right and is also a reasonable timeframe. It could be done twice if you let it sit for a few weeks. If you use the regular car battery , you wouldn't need 100% of the energy. Assuming the car is at 50% and your source is at 100%, you only need half. Besides, the source can just be a used or cheap battery (essentially a throw away). My point is that this is feasible with off the shelf standard electronics and CTEK (or anyone else) could build one. But I mainly want something with a microprocessor to control the flow...and that is the problem. Anyway, its all just hypothetical at this point.

I see, yes, if you're willing to disconnect the auxiliary battery and bring it inside to charge every week then this could work. And you could piece this together with available parts by putting a 110V inverter between the jump starter battery and your trickle charger. It would be more efficient to avoid this extra conversion with custom hardware, but the advantage is limited because all we're likely talking about is a mild difference in how often you need to charge the aux battery . I'd think the best market opportunity would be a tweak to the trickle charger allowing it to operate from a 5V or 12V input as well as AC mains voltage. This should only add a few dollars of cost and could be pretty handy given the proliferation of medium sized batteries available. Sent from my iPad using Tapatalk

Yeah, I would think it would be simpler because you are going directly from DC to DC. And yeah, CTEK could probably just make that adjustment to existing hardware with relative ease. Of course most people don't have access to a spare battery , hence the desire for a smallish Li-Ion. I asked CTEK about the inverter idea a while back and they said it would work. My concern was I probably need a pure sine wave inverter (as opposed to a modified sine wave) and those can be costly and unreliable. That is about the time I started this thread...since that approach seemed convoluted and I was wondering if there was something more direct. Guess not.

I doubt you need anything sophisticated for the inverter, as the battery charger is just going to step down, rectify and filter the AC anyway. Sent from my iPad using Tapatalk