Using a lipo as a field battery for 2xPL6 + Bump? - RC Groups
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Jul 10, 2017, 04:36 PM
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Using a lipo as a field battery for 2xPL6 + Bump?


Is it reasonable to power revo chargers in the field using a large 6S lipo?


Guessing it's impractical for most uses. For me though, I'm a surface guy who currently runs small packs in 1/10 scale stadium trucks: 2S ~4000mAh. Also small drones. I built a portable bump charger setup with dual PL6s and a bump controller.

If I used something like a Revo 6S 10Ah battery, that should give me plenty of charges for my small packs in the field. Then, at home, I'd charge that large pack up using wall power.

Looks like most people use deep cycle lead acid, which I can certainly do, or a generator, which is overkill for me. Just thought I'd look at the possibility of a lighter setup. I'm guessing this isn't typically done because it's a bit pricey, and doesn't help more typical use cases with big packs. And regenerative discharge is (presumably) not an option. But is there any other reason for me not to try it?

One issue I know I need to solve is powering my exhaust fans this way, since they are 12V.

Thanks!

p.s. Yes, I know my charger setup itself is way overkill for my current use. What can I say, Revo chargers rock. Also, I'm planning on expanding my collection to bigger surface stuff and drones eventually.
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Jul 11, 2017, 09:59 PM
Michael
A 6S LiPo will work just fine; especially given your description of how you plan to use it and charge it back...

As for the 12V fan, one possibility is to swap for a 24V fan and the other possibility, as fans do not draw much current, is to search eBay for a step-down regulator. I have one that goes from 24V to 12V to power my fan (two cases, one w/12V fan and other w/24V fan.)

They are quite inexpensive, IIRC. Mine is buried inside the case and it would take some effort to open it up and find the specific step-down regulator I am using. However, if you cannot find one, let me know and I'll see if I can find the make/model.

Michael
Quote:
Originally Posted by kdaq
Is it reasonable to power revo chargers in the field using a large 6S lipo?


Guessing it's impractical for most uses. For me though, I'm a surface guy who currently runs small packs in 1/10 scale stadium trucks: 2S ~4000mAh. Also small drones. I built a portable bump charger setup with dual PL6s and a bump controller.

If I used something like a Revo 6S 10Ah battery, that should give me plenty of charges for my small packs in the field. Then, at home, I'd charge that large pack up using wall power.

Looks like most people use deep cycle lead acid, which I can certainly do, or a generator, which is overkill for me. Just thought I'd look at the possibility of a lighter setup. I'm guessing this isn't typically done because it's a bit pricey, and doesn't help more typical use cases with big packs. And regenerative discharge is (presumably) not an option. But is there any other reason for me not to try it?

One issue I know I need to solve is powering my exhaust fans this way, since they are 12V.

Thanks!

p.s. Yes, I know my charger setup itself is way overkill for my current use. What can I say, Revo chargers rock. Also, I'm planning on expanding my collection to bigger surface stuff and drones eventually.
Jul 11, 2017, 10:10 PM
Registered User
Quote:
Originally Posted by kdaq
Is it reasonable to power revo chargers in the field using a large 6S lipo?


Guessing it's impractical for most uses. For me though, I'm a surface guy who currently runs small packs in 1/10 scale stadium trucks: 2S ~4000mAh. Also small drones. I built a portable bump charger setup with dual PL6s and a bump controller.

If I used something like a Revo 6S 10Ah battery, that should give me plenty of charges for my small packs in the field. Then, at home, I'd charge that large pack up using wall power.

Looks like most people use deep cycle lead acid, which I can certainly do, or a generator, which is overkill for me. Just thought I'd look at the possibility of a lighter setup. I'm guessing this isn't typically done because it's a bit pricey, and doesn't help more typical use cases with big packs. And regenerative discharge is (presumably) not an option. But is there any other reason for me not to try it?

One issue I know I need to solve is powering my exhaust fans this way, since they are 12V.

Thanks!

p.s. Yes, I know my charger setup itself is way overkill for my current use. What can I say, Revo chargers rock. Also, I'm planning on expanding my collection to bigger surface stuff and drones eventually.
Yes, no problem with doing that, but just make sure you set your low voltage cutoff to protect from over discharging your LiPo. And of course if u forget and leave the case powered from the lipo, its the same as leaving it plugged into an ESC - it will eventually drain it completely dead and ruin the pack.

We offer a case on bumpcharger.com that does exactly what your doing with a large 6S LiPo, but also includes a complete low-voltage disconnect to ensure the pack can never be overdischarged:

http://www.bumpcharger.com/shop.html...egory=16195245

If interested, i could try to assemble a DIY electronics package for that low voltage cutoff controller.
Jul 11, 2017, 10:14 PM
Registered User
Quote:
Originally Posted by RevoKelly
Yes, no problem with doing that, but just make sure you set your low voltage cutoff to protect from over discharging your LiPo. And of course if u forget and leave the case powered from the lipo, its the same as leaving it plugged into an ESC - it will eventually drain it completely dead and ruin the pack.

We offer a case on bumpcharger.com that does exactly what your doing with a large 6S LiPo, but also includes a complete low-voltage disconnect to ensure the pack can never be overdischarged:

http://www.bumpcharger.com/shop.html...egory=16195245

If interested, i could try to assemble a DIY electronics package for that low voltage cutoff controller.
As you might imagine, that case is my own go-to case for micro and FPV ... every bell and whistle i could ever want !!!
Jul 11, 2017, 10:29 PM
Registered User
Michael, good call on the stepdown, I'll look into that. I have a specific type of fan that I rather not try to find a 24V variant of.

Kelly, those bumpcharger.com cases are absolutely gorgeous! My approach is...well, I don't want to say the exact opposite, but pretty philosophically different. I put together a functionally similar case that required zero soldering work, and zero case work. Laziness as a virtue, if you will. At least, that's what I'll keep telling myself.

To stay with the spirit of my project, I think I'd opt out of a custom-built low voltage cutoff controller, but I greatly appreciate the offer of help with that.

Overall, it sounds like 6S power is feasible for me. Thanks!
Last edited by kdaq; Jul 11, 2017 at 10:54 PM.
Jul 11, 2017, 10:52 PM
Registered User
Quote:
Originally Posted by kdaq
Michael, good call on the stepdown, I'll look into that. I have a specific type of fan that I rather not try to find a 24V variant of.

Kelly, those bumpcharger.com cases are absolutely gorgeous! My approach is...well, I don't want to say the exact opposite, but pretty philosophically different. I put together a functionally similar case that required zero soldering work, and zero case work. Laziness as a virtue, if you well. At least, that's what I'll keep telling myself.

To stay with the spirit of my project, I think I'd opt out of a custom-built low voltage cutoff controller, but I greatly appreciate the offer of help with that.

Overall, it sounds like 6S power is feasible for me. Thanks!
Here's something good that will help - we will be adding a feature to the Bump Controller that will optionally sound a continuous alarm sound when the battery supply drops below the configured low voltage cutoff, or is idle for a specified timer, while running on a battery supply. It won't automatically disconnect and save your battery, but at least makes it less likely that you'll walk off an forget about it.
Jul 11, 2017, 11:11 PM
If it flies, I can crash it.
rocketsled666's Avatar
You can get smaller-sized Gel or AGM lead/acid batteries and not worry so much about low voltage cutoff. I have a 18Ah AGM battery in a 50-cal ammo can with a PL8 charger. It's lighter than it'd be if the box was actually full of ammo, but it's still kind of heavy. The PL8 is pretty much exactly as wide as the ammo box, and there's room below the PL8 for the battery. Plus room for my charging harnesses. Everything is held in place with brackets I made from Aluminum angle stock I bought at Home Depot. Drilled and stuck together with cap screws and locknuts. Hacksaw and a hand drill was all that was required. The cover closes and latches without touching anything. If I put some silicone around the holes I made for the cap screws, it'd be water tight when closed and latched.

It's rigged with a toggle and pushbutton switch that lets me power the charger directly from an external PS without connecting to the internal battery (how it's running in this picture) or off the internal battery, or to charge or discharge the internal battery with an external charger without powering the PL8.

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Jul 11, 2017, 11:12 PM
Registered User
Quote:
Originally Posted by RevoKelly
Here's something good that will help - we will be adding a feature to the Bump Controller that will optionally sound a continuous alarm sound when the battery supply drops below the configured low voltage cutoff, or is idle for a specified timer, while running on a battery supply. It won't automatically disconnect and save your battery, but at least makes it less likely that you'll walk off an forget about it.
Oh, and here's the 24v to 12v converter that we use in our cases.
These have proven to be extremely reliable and handle up to 30v lead acid sources without a problem.
They are available from many sources, but we stay away from Chinese sources as I worry about cheap clones of lesser quality.

http://www.bumpcharger.com/shop.html...egory=16200430


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