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LiOn PP3 Rechargables

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LiOn PP3 Rechargables

Postby Sam Spoons » Sat Nov 17, 2018 8:22 pm

Looking at the latest in battery tech for stomp boxes, particularly for my Boss RC-3 looper which uses a single PP3 9V battery. Has anybody tried lithium Ion PP3s? They seem to be too good to be true, 1.5x the capacity to an alkaline, rechargeable and only 2x the price.

https://www.amazon.co.uk/Rechargeable-Batteries-Lithium-ion-Self-Discharge-High-Energy-3-Pack-Charger/dp/B078JMHHF8/ref=pd_lpo_vtph_23_tr_t_2?_encoding=UTF8&psc=1&refRID=5X480Q1S6SRQXWFHC0F8

Also, I guess the sustained voltage will be 7.2-7.4V as LiOn cells have a native voltage of 3.6-3.7V. Would my RC-3 work on this reduced voltage (I will try to devise a way of trying it out without going to the expense of buying some, it's days like today that I wish I'd bought a bench PSU.....)?
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Re: LiOn PP3 Rechargables

Postby Wonks » Sat Nov 17, 2018 8:36 pm

The description says "initially 8.4v". Not tried them.
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Re: LiOn PP3 Rechargables

Postby Sam Spoons » Sat Nov 17, 2018 8:41 pm

Yeah, spotted that, seems unlikely they will hold that for long as the correct charging voltage is 4.2V per cell. It's a bit like your car battery reads 13.8V just after you take the charging leads off it but as soon as you load it it quickly drops to under 13V.
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Re: LiOn PP3 Rechargables

Postby James Perrett » Sat Nov 17, 2018 10:36 pm

Wonks wrote:The description says "initially 8.4v". Not tried them.

That's the fully charged voltage which falls off pretty rapidly as can be seen in the diagram below.

Image
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Re: LiOn PP3 Rechargables

Postby ef37a » Sat Nov 17, 2018 10:43 pm

Two problems come to mind.
Yes the voltage is lower than an alkaline and not only will this reduce the analogue headroom (and a PP3 does not give you a lot to start with!) but the digital side of the looper probably runs at 3.3V and from a regulator and so the latter will "drop out" earlier with a lower differential across it. Result? You might not get any longer per battery than a bog standard Leclanche!

The other issue is common to all rechargeables, they have massive current capacity. Not a problem until there is a fault then complete destruction. We used SLAs in meters at Bs and a meter developed a short and the battery just kept delivering until the meter was a molten plastic mess and the battery swollen and stuck fast. If there is room I would fit a 20mm, 100mA in line fuse.

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Re: LiOn PP3 Rechargables

Postby Sam Spoons » Sat Nov 17, 2018 10:59 pm

James Perrett wrote:
Wonks wrote:The description says "initially 8.4v". Not tried them.

That's the fully charged voltage which falls off pretty rapidly as can be seen in the diagram below.

Image

Thanks James, That was my reason for asking the question. I seem to remember hearing about some LiOn PP3s that delivered 9V by virtue of having three cells and a voltage regulator inside the package. Can't seem to find them via Google now though.

ef37a wrote:Two problems come to mind.
Yes the voltage is lower than an alkaline and not only will this reduce the analogue headroom (and a PP3 does not give you a lot to start with!) but the digital side of the looper probably runs at 3.3V and from a regulator and so the latter will "drop out" earlier with a lower differential across it. Result? You might not get any longer per battery than a bog standard Leclanche!

Yeah, see above Dave.....

The other issue is common to all rechargeables, they have massive current capacity. Not a problem until there is a fault then complete destruction. We used SLAs in meters at Bs and a meter developed a short and the battery just kept delivering until the meter was a molten plastic mess and the battery swollen and stuck fast. If there is room I would fit a 20mm, 100mA in line fuse.

Dave.

Hadn't thought of that (despite having a NiCad PP3 short itself on a coin on my pocket some years ago :oops: )
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Re: LiOn PP3 Rechargables

Postby Hewesy » Sun Nov 18, 2018 7:23 pm

Just a thought, perhaps a Pedaltrain Volto (or similar) might be an option if you want to keep to batteries?

Rechargeable still, designed for the task and you could just have some long life Duracell batteries if you wanted a backup.

Not cheap perhaps but should remove some of the concerns above.

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Re: LiOn PP3 Rechargables

Postby Sam Spoons » Sun Nov 18, 2018 7:56 pm

Yeah, good suggestion, I have a Volto and two Rockboard LX packs :thumbup: (Rockboard is cheaper but slightly frustrating as it has no switch). I'm looking for an "in the pedal" solution for the RC-3 so I can just chuck it in my gig bag when I'm off to an open mic or similar. If I can't find a suitable PP3 replacement I guess I'll just bulk buy Alkalines.........
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Re: LiOn PP3 Rechargables

Postby Hewesy » Mon Nov 19, 2018 7:16 pm

Fair enough, what about a lithium? Should last longer and be a useful backup if the Volto dies.

I'm a fan of rechargeable batteries in the right application but I'd be worried about remembering to charge it between gigs (or the voltage dropping mid gig).

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Re: LiOn PP3 Rechargables

Postby Sam Spoons » Mon Nov 19, 2018 10:56 pm

Yeah, it's a thought :thumbup: I won't be using the internal battery for anything mission critical, I have the RockBoard and Volto power packs for that but it would be good for the odd open mic or couch session.
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Re: LiOn PP3 Rechargables

Postby James Perrett » Tue Nov 20, 2018 1:38 am

The great thing about lithium ion rechargeables is that they retain their charge for years. We had some never used ones that were nearly 10 years old yet were still charged when I checked them. So you can keep a spare one charged up and know that it will be usable. They also don't mind being charged when only partially discharged which is something that will reduce the performance of nickel metal hydride batteries over time.
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Re: LiOn PP3 Rechargables

Postby Sam Spoons » Tue Nov 27, 2018 8:24 pm

Ive finally got around to connecting a battery clip to my new bench PSU and gradually wound the voltage down on the RC-3 while it is playing back an earlier recording. The battery warning pops up when it drops below 5.9 volts or thereabouts but it continues functioning as normal and it eventually shuts down at 4.5V. Anyway it looks like the LiOn PP3s will do the job nicely.

Thinking about it I suppose the logic circuitry runs at 5V or 3.3V, the analogue buffer will probably be the first to suffer but it seem fine even down to well below 6V playing a loop and live guitar over it, record and overdub worked fine too, didn't try storing an overdub but it's hardly a disaster of Brexit proportions if one of my inane noodlings goes AWOL.
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Re: LiOn PP3 Rechargables

Postby Sam Spoons » Thu Nov 29, 2018 6:17 pm

They arrived this arvo and, fully charged with no load they measure 8.33V. Will report back WRT longevity in the RC-3.
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Re: LiOn PP3 Rechargables

Postby Hewesy » Fri Nov 30, 2018 12:43 pm

Not only great feedback/update but a sublime mic drop. My hat is truly doff'd Sir.

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