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I have a Husqvarna pressure washer that has an electric start powered by a 12v rechargeable battery. The battery is recharged using a power converter that plugs into a standard 120v AC outlet. The battery is only charging to 11.48 volts DC even after being connected to the charger over night. It won't turn the 3.5 HP engine over to start it with only 11.48 volts. Would it be unwise for me to connect my standard 12v battery charger to the posts of the sealed battery and put the charger on engine start mode to see if it will turn the engine over? I would essentially be bypassing the charging system so I don't see how that would be an issue but I'm unsure about the seal rechargeable battery being subjected to the amperage engine start mode might send to it. I thought about just retrofitting a stardard 12v lead acid lawn mower battery to it (I would have to modify the bracket/battery compartment). I've included a photo of the battery in the pressure washer... would the lawn mower battery be a better solution? No more often than I use the pressure washer I just don't get much life out of a the rechargeable batteries and their a little pricey ($75). Thanks for reading and I welcome your comments.
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That looks like a standard Sealed Lead Acid (SLA) battery. Maybe a 12Ah size? Do you know the specs on it? They should be printed on one of the sides.

It looks like the battery has nut & bolt (NB) terminals. Unfortunately, batteries like that cost a bit more. Here's one for about $45, delivered.


You could drop down to a somewhat smaller capacity battery of 9Ah. It's a bit smaller in dimensions and should fit, if there is a way to secure it. It will give you fewer crank attempts before it runs down, but if the engine starts easily, it should be just fine.


They usually last 5 years or so, if you keep them charged all the time. That's important - if you let them discharge too deeply, it will kill the battery. If it will only charge to 11.48V, that's a bad sign. You might have a dead cell.
 

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How old is the battery? Maybe it is done and won't accept any more charge.
You could try another 12 volt charger on it.
If you disconnect the battery terminals how much voltage do get on the disconnected cables from the charger?
 

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By the looks of the online manuals, that is a standard lead acid battery (probably gel or absorbed glass mat), 12Ah. Fully charged it should be around 12.6v so you might have a bad cell. The washer doesn't have a charging system - the charger is a wall wart you plug into the port.

Those small utility batteries don't last forever, particularly since they generally only see sporadic use. OEM replacements are stoopid expensive (like in the range of $150) but I saw an online battery site for around $35.The odd thing is it looks to have side posts. If you take some measurements, you should be able to find replacement. I can't see what's above the tray to know whether there is room for more typical top posts. You might have to re-arrange the cables.
 

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You can check the discharged batt. by charging it at 12Ah/20hr = 0.6A, "the C/20 rate".

Connect it to any car battery with a 2 ohm, 2W resistor from Amazon & wait 20 hours. Run your car at a fast idle occasionally. The resistor will be hot at first.
12.0v is half charged, after 10 hrs. Check the voltage after 5 hrs.

If it charges then the charger is the problem.
 

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Discussion Starter · #6 ·
How old is the battery? Maybe it is done and won't accept any more charge.
You could try another 12 volt charger on it.
If you disconnect the battery terminals how much voltage do get on the disconnected cables from the charger?
I hadn't thought of checking that... thanks for the tip!
 

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Discussion Starter · #7 ·
That looks like a standard Sealed Lead Acid (SLA) battery. Maybe a 12Ah size? Do you know the specs on it? They should be printed on one of the sides.

It looks like the battery has nut & bolt (NB) terminals. Unfortunately, batteries like that cost a bit more. Here's one for about $45, delivered.


You could drop down to a somewhat smaller capacity battery of 9Ah. It's a bit smaller in dimensions and should fit, if there is a way to secure it. It will give you fewer crank attempts before it runs down, but if the engine starts easily, it should be just fine.


They usually last 5 years or so, if you keep them charged all the time. That's important - if you let them discharge too deeply, it will kill the battery. If it will only charge to 11.48V, that's a bad sign. You might have a dead cell.
I hadn't thought of looking for an equivalent on amazon or ebay... thanks for the links! I'm sure I'll be able to find a replacement.
 

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I agree it's a standard SLA, Unfasten it, pull it out, get the numbers and dimensions.

It's possible they dimensioned it for a standard lawnmower battery. More likely they dimensioned it for standard SLA sizes.

Husqvarna doesn't make batteries, so they aren't going to commission an oddball design just for them. But they do make units private-labeled for other manufacturers (e.g. Craftsman) and those other makers don't like "oddball single-source".


I hadn't thought of looking for an equivalent on amazon or ebay... thanks for the links! I'm sure I'll be able to find a replacement.
Both those channels are awash in cheap Chinese garbage.
Make sure the battery is from a reputable manufacturer, or at the least sold by Amazon proper (as distinct from the many, many, items "Sold by jackasses / Ships from Amazon with Prime".
 

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I hadn't thought of looking for an equivalent on amazon or ebay... thanks for the links! I'm sure I'll be able to find a replacement.
Your call but quite frankly I would first try a local battery retailer, even a small engine shop. Take some measurements or take it with you. You often never know what you are getting off Amazon or Ebay. Personal experience only but I have had zero luck with Interstate.

Obviously, up here all of our yard stuff is seasonal. I started putting the lawn tractor on a battery tender all winter and I think I'm into year 6 or 7. My motorcycle sits on a tender all winter and I got five years. That charger is probably acting like a trickle charger - no logic circuit - which slowly, over time if left connected can ruin a battery.

Good luck
 

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The other thing I'd say is once you have the battery sized, you do not need the seller's assistance matching the unit to the battery size. So a listing that says "... for Husqvarna 123456" or whatever" is useless to you, even dangerous because those guys' marketing plan is to target people who want help matching up battery size, not to sell quality.

What you need is the best quality battery you can get for a sane price.
 

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11.48 volts is pretty close to 12v. It's within nominal operation range. It really depends on the type of battery. A starting battery is designed to put out a ton of current in a short period of time and then be recharged. A deep cycle battery is designed for sustained loads over a long period of time. The battery is probably not good.

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