Lightest and most compact E-Bike charger 14s(DIY GaN charger research)

I plan on E-Bike Touring and need to keep weight to a minimum.
I will be carrying AC charger with me to top up where possible.
Everything that can be made lighter is welcome and hence focusing on the charger.

Two Batteries is 14s each.

At the moment I use 2x 58.8v 4amps brick chargers either in parallel for one battery (10amp charging current allowed on the cell spec sheet ).

4amps @ 58.8v ~ 233watt
2x233watt= 466watt total on my current setup

1)One option I was considering is to dive in to the electronics and find a way to combine the two in one 8amp charger (shared AC cable, shared DC cable and perhaps clever components hacking)

2) Also considering GaN chargers hacking.
Can't find anything reasonable that's designed around the 58.8v 10a spec - lightweight and no bulk.
That's why my next thought was if I can hack together 4-5 GaN 100watt or so chargers and still come out better in the lightweigh and bulk department.

Looking for input on thoughts, experience and ideas here.
What would be the best way to tackle this?

Here is one 100watt compact GaN charger



Suppose it's possible to remove some of the usb ports if 5 if them are to be hacked into one 500watt, plastic case etc and would look into connecting everything in series to get 58.8v at 10amp. Not sure if it's worth doing on a second thought... possibly there are going to be usb-c protocols and IC communication involved (weight,bulk and challenging schematics ).

I've seen a brick GaN charger which is also more compact than an average brick charger as their own illustration demonstrates

This one is from the automotive EV industry
Reference design

Option 3) Can some of the hub controller circuitry be reused to charge the battery.
Let's say I unplug the hub motor leads and plug AC 230v to another connector on the controller...It's all linked up to the battery anyway :wink:
As far as I understand the GaN stuff is used as a first stage from AC To DC with great advantages over SI MOSFET...

It seems that To(Texas instruments) have interesting GaN charging reference designs.

I am guessing that some of them can be used or adapted for a nice 99% efficient, lightweight and portable charger.

Would appreciate any comments

HLG-600H-54A, get up to 57.6V I believe

Yeah, you need to do better than a huge, heavy, 1000w charger. But three like you have now is a bit of a pain to carry around.

It would be very hard to beat a satiator for a long tour. Decent wattage, but not so likely to pop a heavily loaded plug at some convenience/ gas store. But most importantly, rugged and waterproof enough to just permanently mount on the bike. Its not particularly light at 3 pounds, but priceless to just charge away in the rain. I have mine paired with the fully potted battery from Luna, and the combination is perfect. Both can run in a downpour no problem.

Satiator still only about 450w, but lighter ( I think?) and much more rugged than carrying two of the typical 300w chargers. I finally got my satiator, and felt like a complete dope for waiting so long. Might be a real good plan to carry one satiator for its reliability, and then carry additional slower, but very light chargers that could fail. Basically, carry the satiator and one of your current chargers.

Out on the road, its all about getting that charge fast, but still very reliably. Ideal for me would be two batteries, two satiators. One trick I learned on the road, if you don't have to charge to full to make it to the next plug, don't wait around for the last 10% of charge. That's when the flow slows to a trickle, so at that point you have two 300w chargers, each flowing at 50 w or less. Just move on, rather than wait an hour for a measly 75 watt hours.

One great feature of the satiator, and some of the better air breathing chargers, is that it shows you the rate of charging, so you can stop the charge when it gets stupid to wait. If you don't get that, do carry a cheapo watt meter to show you how much power is actually flowing into that battery. So you don't wait an hour for enough power to ride one mile.

dogman dan said:

Decent wattage, but not so likely to pop a heavily loaded plug at some convenience/ gas store.

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If this is a risk, just create multiple presets. Some with 1/4 the max current you need, some with 1/2, and some with full. Then if you find a plug that seems to be loaded but you don't know how much, and can't risk popping it cuz you don't ahve access to reset it, use the lowest preset. Etc.

dogman dan said:

Satiator still only about 450w,

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Unfortunately it's actually limited to 360w.

48v version (what the OP would want to use) is max of 8A, and max of about 60v-ish, but not both at the same time. So for example, with 14s packs full at 58.8v (as OP uses) then the max charge current at an empty battery (about 45v-ish) is 360w / 45v = 8A, but by the time it's about half full (52v-ish), it's dropped to about 7A. By the time it's nearly full, about 58v, it's down to about 6.2A. (this also depends on the pack's internal resistance; if it's high enough it'll drop the current down on it's own by raising the voltage across the pack).

but lighter ( I think?) and much more rugged than carrying two of the typical 300w chargers.

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It is definitely more rugged (cant count how many times I've dropped it, or the dogs have run full tilt thru the cords and sent it flying across the yard), but I don't know about lighter. I haven't directly weighed both, but I have a largish 5A "52v" charger with aluminum shell, from an EM3EV A123 pack, that seems a bit lighter than the Satiator...volume is about the same between the two, but Satiator is fanless and water-resistant (maybe waterproof; I've used it to charge the trike's lighting pack with both sitting out in the rain), while the other charger uses a fan and is not even dust-resistant, and would drown with any water exposure.

It isn't heavy, however. But it is very expensive.

The potted meanwell HLG series is even tougher, and comes in up to 600w per unit, though I've got the one on the trike setup so it's about 700w output and it's survived that for at least a couple of years now, even in the summer heat, bolted to the wood on the bottom of the trike.

But they're heavier--about 7lbs each, and the size of a narrow but thick trade paperback book, or maybe even a hardback. But they are cheaper, perhaps a quarter of the price-per-watt of the Satiator, though you don't get any "programmability". (you only get a voltage and current adjustment pot set, under plugs for waterproofing, if you get the HLG-xxx-xxA version)

do carry a cheapo watt meter to show you how much power is actually flowing into that battery.

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Alternately, wire the charger to the controller side of the shunt used for whatever power meter you already have, if your battery's BMS has the same port for charge and discharge. For instance, my Cycle Analyst setup uses an external shunt between battery and controller, so I have the charger input on the same side of it as the controllers, and when I charge it just looks like regen current to the CA.

Came across these poking around the web today, reminded me of this topic - not sure if they could be configured to your specs, but they get close have ready to go PMBus and are GaN based:
https://www.digikey.com/en/product-highlight/t/tdk-lambda/pfh500f-28-series-ac-dc-power-modules

These are components intended to be incorporated into a professionally designed product, not ready to use by consumers.

If someone here has the knowledge & skills to help us be able to make use of this type of gear that would be fantastic.

I'd even help pay for that info if necessary.

john61ct said:

These are components intended to be incorporated into a professionally designed product, not ready to use by consumers.

If someone here has the knowledge & skills to help us be able to make use of this type of gear that would be fantastic.

I'd even help pay for that info if necessary.

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I'm not sure they are really that far off, they won't exactly come with any end user support or manual but they seems to work on a similar principle to the many Mean Well supplies, with control of their parameters from their pin outs and with 'standard' PMBus interface.

I would expect it would be a whole lot simpler than wiring together 5 USBC chargers in any case!

All depends on ones skillz.

The AC input needs conditioning, don't even know how well they'd go serial'ing / paralleling, etc.

If you find the appnotes and it seems straightforward to you, please make a HowTo.

The 1000W 48V versions are very interesting to me, have an Israeli source sells them pretty cheap and 48V is my backbone voltage for most projects.

And yes, USB is only suitable for little portable packs

All depends on ones skillz.

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Indeed!

If you find the appnotes and it seems straightforward to you, please make a HowTo.

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No it's not something I would be able to do without guidance, just seen projects around these forums that strike a layman as more complex.

I did just spot the manual though, which doesn't seem to be linked on Digikey: https://www.manualslib.com/manual/1506759/Tdk-Lambda-Pfh500f-28-Series.html

The 1000W 48V versions are very interesting to me

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Is there a 1000W of the PFH or do you mean the PFE series? I actually just looked up the difference and they were already pretty impressively dense power supplies. The older PFE500 is 70x12.7x122mm and the newer PFH500 is 61.0x13.3x101.6mm.

PFE1000F-48

This is the sort of unit to look out for on eBay, all assembled ready to go

https://www.ebay.com/itm/264779848510

Of course still not a charger, just a PSU, need to automate the stop-charge logic