Charging LI from 12V DC source?

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Charging LI from 12V DC source?

Postby flagman1776 » 23 May 2019, 18:20

The TravelScoot's official charging system is a dumb charger to charge the official LI battery which has BMS. Input power in the USA is 120V AC. I suspect it may also accept 220V AC by switching the power cord. I'd need to check but I think the plug at the battery pack is a 3 pin plug.
It would be useful to have a 12 V DC input charging system. I wonder is there an easy way to charge off a 12 V DC source? A step up transformer perhaps?
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Re: Charging LI from 12V DC source?

Postby Burgerman » 23 May 2019, 18:27

PL8 obviously. Input voltage 10V up to 30V.
Output, can charge anything from .1A to 40A. From 1.5 to 35V. 1 cell to 8 lithium. 12 cell lead. Any chemistry, in this case 7S lithium ion.

You would need to tell it its charging a lead battery instead, to charge a 7x 4.200V or 29.4V with BMS. You would then choose LEAD, 12S, and 2.450vp cell. Thats the same 29.4v. But it does not need the balance connections and will rely on the useless BMS.
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Re: Charging LI from 12V DC source?

Postby flagman1776 » 24 May 2019, 22:13

I was hoping for a low tech solution since the TravelScoot LI battery has a BMS.
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Re: Charging LI from 12V DC source?

Postby Burgerman » 24 May 2019, 23:58

Well theres hundreds of ways. You just need a 29.2 to 29.4 power supply. Anything of any power level, around 2 to 5A will do. Theres lots of laptop style bricks, that could be used with an ebay CC/CV circuit board that is configurable for very cheap! The PL8 though is simple. It can use just 2 wires. And is designed for exactly that...
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Re: Charging LI from 12V DC source?

Postby Burgerman » 25 May 2019, 11:22

This for e.g. would allow you to choose an output of CC/CV of your choice. So set it to 29.2V, 3A, and power from anything. E.G. an old laptop charger. Or a battery. Etc.

https://www.ebay.co.uk/itm/DC-DC-Boost- ... 100623.m-1
or
https://www.ebay.co.uk/itm/4A-DC-DC-Boo ... 2635056884
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Re: Charging LI from 12V DC source?

Postby flagman1776 » 25 May 2019, 16:26

YES! That's what I'm talking about. Just add a 3 pin plug & run it directly off an RV house battery.
THX!
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Re: Charging LI from 12V DC source?

Postby shirley_hkg » 26 May 2019, 06:59

Or something better looking CC /CV one .
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Re: Charging LI from 12V DC source?

Postby flagman1776 » 26 May 2019, 15:06

shirley_hkg wrote: Or something better looking CC /CV one .


Is there a matching case for this?
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Re: Charging LI from 12V DC source?

Postby Burgerman » 26 May 2019, 15:56

Yes. Its called a hobby charger.

Theres thousands of cheap stuff like this for e.g. https://www.banggood.com/ToolkitRC-M8-D ... rehouse=CN

Dont ask me how good/bad it is. But its the size of a paxk of cigarettes.
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Re: Charging LI from 12V DC source?

Postby ex-Gooserider » 28 May 2019, 02:09

Might be a matching case, ask Shirley, but if not it's pretty easy to deal with, as from the picture it is a simple 'panel mount' design - get box of whatever size / shape / material you like (as long as it is bigger) make cutout to fit the panel - bolt in... If weather resistance is needed, choose a box with gasket, and / or seal it up w/ silicone or Shoe-Goo type sealant to get as much resistance as the panel offers...

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flagman1776 wrote:
shirley_hkg wrote: Or something better looking CC /CV one .


Is there a matching case for this?
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Re: Charging LI from 12V DC source?

Postby shirley_hkg » 28 May 2019, 04:43

That is a step-down model . drunk2

Below is a step-up one.
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Re: Charging LI from 12V DC source?

Postby shirley_hkg » 28 May 2019, 05:18

5A / 250W max.
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Re: Charging LI from 12V DC source?

Postby Mechniki » 06 Jun 2019, 21:09

I would just use an inverter and run off my normal charger, I have 3 inverters.12V to 220/240V 150W (200W Peak), 12V to 220/240V 200W (300W Peak) and a 12V to 110/220/240 1500W (don't know the peak on that), But have never used the larger Wattage ones.
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Re: Charging LI from 12V DC source?

Postby flagman1776 » 07 Jun 2019, 02:13

The OEM LI WITH BMS... charger is set for overnight charging. If camping off the grid... without a generator... Are you seriously suggesting running a inverter all night?
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Re: Charging LI from 12V DC source?

Postby Mechniki » 09 Jun 2019, 13:40

flagman1776 wrote:The OEM LI WITH BMS... charger is set for overnight charging. If camping off the grid... without a generator... Are you seriously suggesting running a inverter all night?

Yes. As I am assuming your RV has 3 leisure batteries as well as it's normal batteries, which I assume you have them charging whilst the RV is running or use a wind generator and Solar panels. Even my friends converted VW Transporter RV WAV,has two 175 Ah Marine grade batteries that can be charged by the engine or by the solar panels that are on the opening roof section. His family only uses a wind generator when they are off grid as it has to put on it's mount and extend the pole.. They also use an Otto Bock and never mentioned any problems in their several weeks away camping. They also have a small caravan (think it's a POD) for their children. Everything in their RV is electric, even the ramp and hoist. Not so sure about the POD, I know that that also uses solar and a wind generator. His children sleep there. He has ALS and MND
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Re: Charging LI from 12V DC source?

Postby flagman1776 » 10 Jun 2019, 02:54

Unfortunately, not. Unit is a trailer, only has 2 house batteries & no charging off grid. Off grid, we mainly run on propane with a few LED lights at night & the gas refrigerator controls. There's no need for 120V AC and the installed inverter has never worked since we've owned the trailer.
The whole idea was to direct fast charge the "10 ah" LI battery pack.
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Re: Charging LI from 12V DC source?

Postby ex-Gooserider » 11 Jun 2019, 00:18

Mechniki wrote:I would just use an inverter and run off my normal charger, I have 3 inverters.12V to 220/240V 150W (200W Peak), 12V to 220/240V 200W (300W Peak) and a 12V to 110/220/240 1500W (don't know the peak on that), But have never used the larger Wattage ones.


This is generally a BAD idea - you will waste a LOT of power..... Any time you go from AC-to DC or the other way, you are looking at probably only 60-80% efficiency per step.... DC-DC converters are much more efficient, but even then you want to avoid as many changes as you can.... Remember that the inefficiencies add up - if you are running at 75% and put in 1000 watts, you get 750watts out, the next step gets 75% of 750, or about 500W or HALF what you stared with...

If at all possible, you want to do at most ONE conversion from whatever the source is to whatever you need for the output. In that case you only have one conversion loss...

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Re: Charging LI from 12V DC source?

Postby flagman1776 » 11 Jun 2019, 16:18

Exactly!
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