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31

Automotive headlamps are the obvious, easy 12V choice, being typically in the 45-55W range (don't get LED headlamps.) If you ask the right folks you can often get dual-filament bulbs (high/low beam) with one filament broken for free.


20

Acid cell and Alkaline Batteries function by a process of controlled corrosion of two different elements which creates a voltage potential and a current if the circuit is completed. This process is in continuous motion from the day of manufacture, while it sits on the shelf in its packaging, while installed in the equipment during off/idle periods. It ...


20

Another answer by Fresh Codemonger suggests having two pumps, one on regular power and the other on your inverter. I would like to suggest a similar option that I think is more efficient. As the other answer says, you should have a second pump. However, instead of connecting it to your inverter, your second pump should be one that is designed to run ...


14

You don't need to step up to mains voltage, in fact for experimenting it's best not to. There are such things as 12V car fan heaters that are typically 120-150W. Or you can buy wire-wound load resistors. A 3 Ω resistor would dissipate 48 W at 12 V, so wiring 3 in parallel would work and allow you to adjust the load. I'd buy 100 ...


11

Your hedge trimmer sounds like it has died or is in the process of dying. A quick google search confirms that this can occur with Black & Decker hedge trimmers, although it does not appear to be wide spread. Because you didn't provide the model it isn't possible to give you a more specific reason why it has failed. My opinion is that when you were having ...


10

I think the easier thing to do is to have two sump pump connected. The first on household power and the second on your battery. The first would have a start sensor at a lower spot than the battery sump sensor. This way the battery one only runs if the water reaches above a high spot. This will also give the added benefit that if the household sump pump ...


7

Since you have an old car battery, the cost of damaging it by overcharging isn't much ($40?) and that would only happen if it got a lot of sun over weeks. A small home solar system might have thousands of dollars of batteries, so standard practice has long been for those to always have charge controllers. For small systems the cost of a charge controller ...


6

If you are willing to sacrifice a battery charger, you could gut the charging circuitry out of the charger housing and wire it as a battery dock.


6

Yes on battery removal. I've had better luck with name brand batteries. Before you pitch the lamp, try some vinegar, scraping off the scale ( I used a cotton swab soaked in vinegar) then neutralize with baking soda and finally rinse with water. I just resurrected a kitchen timer this way. I think ( but don't know), that the battery chemistry is more ...


6

Get a UPS No, not that UPS. An uninterruptible power supply, also known as a battery backup. This is a box that takes normal AC (e.g., 110-120V in the US) and uses it to charge a battery and power your devices. If power goes out (technically: voltage out of range) then it uses an inverter to power your devices from the battery. All automatically. You ...


6

You've got a few problems/misconceptions. First there's no such thing as a 100-amp battery; however 100 amp-hour would be typical of a car-battery-sized thing. An amp-hour is an amp for an hour. Second, you can't get 100 amp-hours out of a 100Ah lead-acid battery, at least not for very many cycles. That would be 100% depth of discharge, and that is very ...


6

For 12V DC, you are probably looking for halogen bulbs, not incandescent. You should be able to get a few hundred watts of 12v halogen bulbs for about $10 online, and you could even get them in units of 20W or so if you want to refine your testing.


6

As you know the battery voltage will fall as its charge depletes. Depending on how constant you want the load to be it may need to self-adjust to hold a steady load (wattage). Ham radio enthusiasts routinely require a "dummy load" for testing radio transmitters without actually transmitting anything. These are basically high-power 50 ohm resistors. On its ...


6

Need is not the right word here. Preferred is probably a better choice. 240V is preferred because submersible pumps are often well away from the house and deep down in the hole and you must run a wire there capable of supplying its power needs without too much voltage drop in the line. While you could do this with a large AWG wire at 120V, you can use a ...


5

It is generally always recommended that the batteries be removed from devices that are not in use. Even the device manufacturers recommend this. I'm not sure what actually leads to batteries leaking other than a failed seal. It is possible that a device exposed to wide temperature excursions may make the battery seals more prone to failure. There is more ...


5

Buy a (petrol-fired) air compressor and pneumatic tools, or go for a bigger generator. (Good) Inverter can cost nearly as much as a generator, also remember that an inverter rated for 2kW has a substained rate of about half. I found on Amazon this 3kW inexpensive inverter, check if it may be good for you. Anyway, with an inverter it's important that the ...


5

Officially what you are actually asking for is a constant current sink: something which uses the same current even if the voltage drops. A light-bulb does that somewhat as it has a PTC thermistor characteristic (The resistance increases when it gets hot). If you really want constant current you would need to build something electronically. That is ...


5

You don't want to do that. An inverter powerful enough to start a sump pump will also have high standby losses. It will burn your battery down in short order. When you're dealing with a 12V system this small, you want all the loads to be DC. It might be tolerable if you only spun up the inverter for the second per day the pump was actually in ...


5

I found this page which stated: The second oldest style keypads have a pin hole at the bottom of the keypad cover. You will have to insert a small Phillips screw driver into the small hole at the bottom of the cover and gently pull outward to loosen and slide the cover down to remove. Below is a picture you can reference. But strangely, the picture didn't ...


5

No reasonably-sized and priced 20V PSU will be able to deliver the power that your 20V tools need. You are trying to design a corded tool that can last through a big job. The correct solution is to buy actual corded tools. Just the ones that you actually need for such big jobs. Plan B would be to buy more, bigger, batteries and a multi-battery charger ...


4

The neck style battery pack typically held an extra 1-2 NiCad cells in that neck portion. With the transition to higher voltages, they want to make at least some change in design so you can't use the wrong battery like @Henry Jackson stated. But the main reason you don't see any is the way lithium-ion packs are constructed, yes they do still have a few ...


4

The Powerwall is/will be based on the lithium ion battery technology used in the Tesla cars, so instead of a few large lead acid batteries (like in PV battery banks) it will contain a zillion tiny 18650 cells, which work better if you put them in series and let the voltage soar. This keeps the current low while still allowing the same amount of power output ...


4

You have the basic concept down. Your challenge will be sizing. What's the minimum possible load you can put on the system? For instance, don't use an inverter to run lighting. Run the lighting direct off 12V, and there's a huge variety of 12 volt LED lighting: from screw-in bulbs, spot or flood lights, LED strips that let you freestyle your lighting, ...


4

Measure each battery individually, you can still do that with the wires you have added attached to the battery. I suspect your batteries don't have a full charge. Your logic is correct.


4

That charger device clearly states that it is for NiCd and NiMH rechargeable batteries only. It would be a risky proposition to put other batteries in that unit whether they be lithium or alkaline types. I think it would be just too easy to put the unit into the wrong mode. What you want to do instead is get yourself a digital multimeter that can measure ...


4

3% hydrogen to air is explosive. Even sealed batteries discharge some hydrogen gas when charged--they have to release the pressure or they will break the case. The seal is accomplished with a rubber (or silicone like material) over the port and usually a plastic shield welded in place to keep the seals in place. These batteries are not designed to be ...


4

There are 'off the shelf' battery tester/electronic loads which handle up to 20 A/150 W at a fairly nominal price (considering that they have some degree of monitoring built in) - assuming that you are not really interested in designing your own here. These use some sort of power FET coupled with a fan/heatsink and constant current control. For clarity, ...


3

The unit in question has two large current-carrying wires which connect to the positive and negative terminals of the battery, and a sense wire which is designed to connect to a probe supplied with batteries manufactured by the same company. The probe is a thin metal rod that sticks through a special hole in the top of the battery; the hole is placed so as ...


3

There have been a lot of changes in batteries for tools over the years. Different chemistries, voltages, capacities. Obviously the tool makers don't want you sticking a 20V lithium battery into an old 12V nickel-cadmium drill, so they make the shapes different. Maybe some of the discount manufacturers try to turn over their battery types regularly to force ...


3

AC power cannot be stored because AC is dynamically changing (to be more precise, alternating). It requires very expensive hardware to arbitrage it for other types of energy which are storeable, and in the sizes you need, the cost of that hardware is well beyond the scope you established in your question. That leaves: Hand tools. Exercise your arms. ...


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