DIY 30A dual battery charger. Build one for $175

efoils – Electric Hydrofoil Surfboards
#1

Hey guys.

After getting some ride time on my latest build (Jsonnett's Latest East Coast Build) I’ve been frustrated with my wayyy underpowered RC style charger (https://www.amazon.com/gp/product/B07LF1SC63/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1) and started looking for a better charging solution for the large batteries used on these boards. I know I’ve seen others asking around with this same problem and I wanted to share what I came up with.

I wanted something with some power. Something capable of at least 10A. I run two 6s ~24Ah batteries in series so a dual-channel setup that lets me charge/ balance both batteries at once was a must. I also wanted something fairly affordable as high power chargers and power supplies can get pretty pricey. I also am too impatient to wait for stuff from China so if I could find everything off of amazon then BONUS!

Here is what I came up with:

  • All in it cost me about $170 to build.
  • Super easy to assemble and build.
    -Everything can be had thru Amazon Prime.
  • Capable of charging at 15A continuous PER battery, 30A total (chargers capable of 20A each but might toast these power supplies). It RIPS (to me at least)
  • Can handle up to 8S (watch your currents and stay within power supply rating).
  • 1.5A/cell balance current.
  • Really nice/clean user interface.

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It uses:

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STL files for the chassis can be found here:https://www.thingiverse.com/thing:4689369

Airflow thru both power supplies is drawn in from holes in center portion of the chassis. The hot air is blown out of either side. Make sure you note PS fan orientation when assembling and make sure fans are on outside. Chargers are tilted at an angle so that hot air from the one in the front doesn’t blow right into the intake of the one in the back.

8 screws hidden under the chargers and underside of base thread into the PS and sort of sandwich everything together. I used stick-on velcro to attach the chargers to the chassis.

I hope some of you find this useful. Im really pleased with it so far. Its awesome to be able to casually charge 2 batteries at 10A each without even breaking a sweat while my last charger would only charge at about 3A each running wide open (and eventually burning up). I can easily get two rides in a day with this thing and can charge my 2 6s8p 30Q packs in about 3 hours at 10A but could even go up to 15 if Im in a hurry.

10 Likes
#2

Nice work!

Thanks for sharing.

#3

Hi Jsonnett

I have been searching around the forum gathering info before I build my electrical system and came across your post. I was thinking of doing something very similar with 2 x 6S13P batteries connected in series. I see you can actuall get an ISDT twin output charger that will simultaneously charge two batteries at the same time. This single charger would then effectively do what you’ve created.

A couple of questions for you if I may please.

You are balance charging each 6S with each charger, so I take it that you don’t have/need a BMS on each battery. Is that correct?

Do you have any photos you could share of your batteries?

Thanks
Mark

#4

Hi. That’s correct. No bms needed if running balance chargers. One less thing that could fail on the board and made it a little easier to fit everything inside the waterprooof enclosure I was working with.

Below are pics of the batteries. Thought I had some pics with the covers off to show the nickel plates and balance lead wiring but this is the best I could find.

Good luck!

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2 Likes
#5

Nice effort! But why, it seems so complex for little gain?
just bought this: 50.4V 15A Charger
https://a.aliexpress.com/_mOEFfKs

It’s 30% cheaper than the kit total, (no building fun though if you’re looking for that). It’ll be at my door in about three weeks normally.

#6

But you need a bms inside the battery with this simple charger.
The Hobbycharger can balance the cells, so no need for bms.

1 Like
#7

True, i always use smart BMS nowadays, i think it’s good practice. Have had some incidents with damaged or dead batteries on BMS-less builds. User errors but as they happen they need to be countered.

#8

Thanks Jsonnett
I like your setup. I am thinking of an dual output charger such as this one https://www.aliexpress.com/item/1005002039702015.html?gatewayAdapt=4itemAdapt

It should effectively provide the same outcome as what you have achieved.

Regards
Mark

#9

yep. that looks like a good one. The Q8 chargers i used could supply 20A each but i never really ran them at more than 10A. Just make sure you power that puppy with a large enough power supply.