Budget Models with Amazing Future Power; some DIY required

[svetz]

You can get a slick looking solar generator for pretty cheap, work those biceps, and have your first DIY Battery build project in a few years!

Here's how
Head on down to your a HomeDepot or similar store and walk right by the over-priced solar generators. Instead, get a Jump Starter as if you were getting it for a car. They're inexpensive, compact, and generally spiffy looking. Get it with all the features you want. Next year, when the lead acid battery is dead, remove it, measure the interior, and calculate how many prismatic cells or 18650 cells you can squeeze in there for your first DIY battery build project (or just use a drop-in LiFePO4 replacement battery of the correct size). You can actually plan that out ahead of time as the manual will typically tell you what size lead acid battery is in side.

Heck, you probably already have one of these dead in your garage...so no need to go to the store and you can skip to the good part!

If you can find one that has a Cigarette lighter connected directly to the battery, you can plug the solar charger in there (make sure it doesn't have regulated voltage). Although it's not strictly necessary...you can always use the convenient jumper cables to connect it to your MPPT or add your own connector. All you need are solar panels and a solar charge controller and it can double as the heart of one of Will's DIY Solar Generators.

I know this works as I just I just got done replacing the lead acid battery in a dead Peak Jump Start with some lithium cells; it went from 216W (18 AH) to 400W. The built in charger is a bit undersized now, but otherwise it works great and is lighter! The only modification I made was to move the AC adapter from the built in circuit board to the BMS I added.

Here's a $70 model version. Different models have other options (lights, tire inflators,etc).

But wait... don't solar generators have 120V?

Here's a 140W inverter for $17. You could affix to the case with some VHB tape.

DeWalt has one with a built in 1 kW inverter for $269 from home depot: You'll be buff after lugging this guy around all summer!

Here's a Schumacher with a 400W inverter, usb, light, etc. for $120.

Note: Beware ones with built-in inverters, they don't generally seem to be pure sine wave - which may or may not be okay for your needs.

Jump Starter Projects members have built

• Svetz's Peak Jump Start
• Bob's Duracell Powerpack 600 Jump Starter

 

[Will Prowse]

Smart idea!!!! Bravo bravo. I want to build one haha

But at that point you could build one yourself really. I guess it is really nice to have the enclosure though.

 

[PHoganDive]

Great idea!...just so happens I have an old one in the garage that the battery is pretty dead in at this point....just haven't brought myself to throwing it out (I tend to be a pack rat)...time to repurpose it.

 

[Rider]

lol... I had one from Harbor Freight. When the battery died, I scavanged it for parts to use in my home-grown solar charger.

 

[svetz]

Originally I didn't plan on it ending up this way. Like @PHoganDive I had a dead one in the garage and like @Rider I was going to scavenge it for parts (cables, switch, etc.). But once I had it apart it was hmmmm... these batteries can easily fit where the old battery is... and I get a sweet convenient case, the meter, lights, and switches are already mounted, soldered in, and working...

 

[svetz]

Will says if you don't show it, it didn't happen... so uploaded some photos and information on the Show and Tell forum: The Peak Jump Start

 

[Wiley]

OK experts: So couldn't one build one out of an old UPS? That way it would have the 120 volt charger as well as low voltage cut off (if one connected it to a gel cell battery... which is also connected to controller and panels)? The inverter might not be sine wave but probably better than most as it uses a transformer.
But would a long run time pose over heating issues with the UPS?
Would there be electrical issues at the controller if connected both to the grid via the internal charger and to the controller/ panels?
Thoughts?

 

[svetz]

Haven't tried rebuilding a UPS, but why not? Definitely not an expert, but let's see about those questions, off the top of my head...

Q: would a long run time pose over heating issues with the UPS?
A: Interesting! LA batteries have a higher IR so produce more heat electrically, but the discharge reaction is endothermic (heat absorbing) offsetting that. Lithium is exothermic on discharge so both add together to make a hotter battery. Plus UPSes typically have a high current rate, so that would compound the problem. Pack design to leave spacing and a fan might be needed. In The Peak Jump Start, those cells have no fan and are packed simple cubic structure; over 3.6 hours they build up to 110F at ~200W, they're also the much thicker 32700 cells and I believe have slightly higher IR than 18650s. eBikers use them, and they have high current draws so perhaps someone else can say more?

Q: The inverter might not be sine wave
A: If you'll be running sensitive electronics, you'll want one with a pure sine wave. Anything meant for computer equipment should be fine.

Q: Would there be electrical issues at the controller if connected both to the grid via the internal charger and to the controller/ panels?
A: If that was the way the UPS was designed to work, replacing the battery shouldn't affect that.

 

[svetz]

Stanley has a 19 lb 500 Watt inverter version, 228Wh, with 5 hour recharger for $148:

Certainly lighter than DeWalt's $269 40 lb, 1000 watt inverter, 500 wh, 6 hour recharge time.

 

[svetz]

If these things are made to run power tools, does that mean they have pure sine wave inverters? You'd think they'd say so if they did.

Update: Comments on Amazon seem to indicate they're modified sine-wave.

 

[Batman]

You can get a slick looking solar generator for pretty cheap, work those biceps, and have your first DIY Battery build project in a few years!

Here's how
Head on down to your a HomeDepot or similar store and walk right by the over-priced solar generators. Instead, get a Jump Starter as if you were getting it for a car. They're inexpensive, compact, and generally spiffy looking. Get it with all the features you want. Next year, when the lead acid battery is dead, remove it, measure the interior, and calculate how many prismatic cells or 18650 cells you can squeeze in there for your first DIY battery build project. You can actually plan that out ahead of time as the manual will typically tell you what size lead acid battery is in side.

If you can find one that has a Cigarette lighter connected directly to the battery and you can plug the solar charger in there. Although it's not strictly necessary...you can always use the convenient jumper cables to connect it to your MPPT. All you need are solar panels and a solar charge controller and it can double as the heart of one of Will's DIY Solar Generators.

I know this works as I just I just got done replacing the lead acid battery in a dead Peak Jump Start with some lithium cells; it went from 216W (18 AH) to 400W. The built in charger is a bit undersized now, but otherwise it works great and is lighter! The only modifcation I made was to move the AC adapter from the built in circuit board to the BMS I added.

Here's a $70 model version. Different models have other options (lights, tire inflators,etc).

But wait... don't solar generators have 120V?

Here's a 140W inverter for $17. You could affix to the case with some VHB tape.

DeWalt has one with a built in 1 kW inverter for $269 from home depot: You'll be buff after lugging this guy around all summer!

Here's a Schumacher with a 400W inverter, usb, light, etc. for $120.

 

[Batman]

Can you please describe how you would use a solar panel to charge it?

 

[svetz]

... Can you please describe how you would use a solar panel to charge it?...

...If you can find one that has a Cigarette lighter connected directly to the battery... you can plug the solar charger in there. Although it's not strictly necessary...you can always use the convenient jumper cables to connect it to your MPPT. ....

So you'd get an SCC to match the number of panels and configuration you like. Plug the panels into the SCC and then connect the SCC to the battery either via a port (e. g., cigarette lighter) or via the jumper cables. Worse case, add your own connector.

Let me know if you or @WSix still have questions!

 

[Batman]

If you plug the solar panel directly into the 12V terminal or the jumper leads, will I need to worry about overloads or anything else?

 

[svetz]

That's the nice thing about these, except for the SCC, the on /off switch, display, fuses, case are built in.

An SCC normally connects to a battery, sometimes with an external fuse. So the trick to doing this is to do the same... but with the internal battery. Absolute worst case is drill a whole in the case to add your own connector wired directly to the battery.

You might need something between the SCC and panels, the manual for the SCC should tell you. Make sure the SCC is setup for the correct type of battery.

There are some things to watch for...

There are some models of jump starters that do not connect the jumper cables directly to the battery, instead they use the car's weak Battery to charge a capacitor and it slowly builds up enough charge to jump the car, so stay away from those types, they don't even have a battery.

In the old days, cigarette lighters could handle some serious amps. But now that they're used for everything but lighting cigarettes they often have wussy wires. If you want to charge via that port you should confirm the wire gauge is sufficient for the SCC current and augment it if necessary.

Similarly, you might find a cigarette lighter has a regulated output. This is so the port outputs 12v even when the battery is under 12v, but it also means there isn't a direct connection, in which case it can't be used. You typically only see regulated ports on high end models. Easy to test by checking the port voltage when the battery is depleted.

These units won't typically have a low voltage cutoff which will hasten the demise of the lead acid battery. You could add one, but easier to just replace it with a lifepo4 that has a bms with a low voltage cutoff when the time comes .

Finally, keep in mind the ones with built in inverters typically aren't pure sine wave. If you're running sensitive electronics off it, get one without an inverter and add on an external one

 

[svetz]

Just curious if anyone else has re-purposed a jump starter and if so their experience with it, for details on my build see https://diysolarforum.com/threads/the-peak-jump-start.535/.

 

[Bob142]

Ha, that reminds me that I've been sitting on the shell of an old Duracell Powerpack 600 for a while now trying to figure out how much effort I want to put into it. It's a great rugged case, but has a modified sine wave inverter and a built-in charger that take about a century to charge the 26Ah AGM. I have to figure out if the Anderson-like connector is a true SB120 or a knock-off. I was thinking I could use that jack in an external charger and SCC.

So thanks, you've just distracted me from the other projects I've been working on and now all I want to do is convert this to LFP with a pure sine wave inverter.

 

[Bob142]

Oh it's on now, @svetz! So roomy inside without the giant AGM and the chunky 400W modified sine wave inverter.



Hopefully I can beat the original full charging time (I'm definitely keeping that sticker on it for the humor factor).



I'll start a Show and Tell thread when I rebuild it. This post is just to put pressure on myself to do it. ?

 

[svetz]

Go Bob GO!!!!! That is positively cavernous... I bet you'll have a lot more watts than the original!

 

[svetz]

...One thing that I need clarification though is cleaner way to connect the solar panels to the jump starter. Is there a guide you can refer me to that uses a standard plug instead of the alligator clips for the connection?

If you don't want to use the alligator clips, anything directly connected to the battery would do.

For example, if it has a non-regulated 12V cigarette lighter (e.g., direct battery connection, usually only fancy ones have a regulated output), you could plug the SCC output into there.

After that it depends on what sort of connectors are available on the jump-start. Anything 12V connected to the battery would work.

Worse case, cut through the case and add your favorite style of connector (e.g., an Anderson).

Or, just two small machine screws if there isn't much room inside: The washers on both sides of the case add strength to the "connector", inside nut holds the screw and battery connector (ring terminal) in place, outside nut holds the ring terminal from the SCC securely. Might want to use red nail polish on the positive nut.​

You can put the fuse inside or out if your SCC needs one.

@Rider notes that you can get sealed "thru-studs" here.