Grid Charger Build
 

Hi guys.
I have a 2007 HCH.
I would like to build myself a grid charger. I am comfortable working with electrical and electronics.
I have been reading every thread I can about this and have come to the understanding that one can be built for apprx $100. However, most of the info regarding building your own charger seems to be too old or has been removed.

If anyone can point me in the right direction to help me find the power supply/ies I would need (Ebay or Amazon or whatever) I would greatly appreciate it.
Thanks in advance.

Re: Grid Charger Build
 

Never mind, I found it:
[POWERNEX] MEAN WELL NEW APC-35 35W Single Output Switching Power Supply

Ebay link: https://www.ebay.com/itm/POWERNEX-ME...r=552930681411

Re: Grid Charger Build
 

Never ever grid charge the battery without active cooling. You will cook it.

Re: Grid Charger Build
 

Got that Steve, thanks.

Found a better place to get the power supplies: https://www.digikey.com/product-detail/en/mean-well-usa-inc/APC-35-350/1866-1127-ND/770257

Looking at this grid charger build, does anybody know what the 1 Megohm resistor is for? http://projekt.com/locouki/Website/insight/grid-charger-discharger.html#construction

Re: Grid Charger Build
 

I figured it out, it limits the charging current.

Re: Grid Charger Build
 

Doubt it. There is no charging current limitation. The PSU are constant current LED supplies that will put out 300mA in their operating range.

A 1MΩ resistor is almost an open circuit. I suspect it's used in conjunction with the diodes between the poles of the individual power supply output leads to help dampen any voltage oscillations/current irregularities when charging at very low voltages following discharges.

Re: Grid Charger Build
 

Well, 300mA is the total current output by the power supplies. However, charging the battery pack at a lower current is better for it. This 1 MegaOhm resistor bypasses some of that current. So does the other branch containing the neon lamp and 220K resistor.
If you look at the note top left of the schematic, it says 255 mA is the current charging the battery pack. Hence the remaining 45 mA passes through those two afore mentioned branch circuits.
I had missed that little note before too.

Re: Grid Charger Build
 

(1) not a true statement.
(2) This can be calculated. the 1 MΩ resistor pulls 0.18mA of current when the supplies are running at 180V. The 220KΩ resistor pulls 0.82mA. The sum of these is 1mA (again at max voltage - less when the PSU are putting out less than 180V total).
(3) I didn't miss the note. I read the whole diagram. The note is wrong. If you look at the diagram, you can see the DISCHARGE circuit is labeled 255mA. The PSUs are rated at 300mA, and there is nothing in circuit to limit the output current beyond the PSUs normal ability to operate at 300mA constantly. He has it backwards in the note.

The 1MΩ resistor, the diodes (per the narrative, they are not necessary due to the supplies you bought) and the NE2 bulb/resistor combo are not necessary for the design to function.

Re: Grid Charger Build
 

You are absolutely right, my bad. I just assumed the note must be right. Thanks for pointing that out.
The purpose of the 1Mohm resistor is still unknown then. As you say, I will just leave it out. Wasn't planning on using the neon lamp either.
So the diodes are not required too? Could you point me to a schematic specifically for HCH2 grid charger, or have the plans all been bought by grid charger manufacturers? I've been looking all over but couldn't find any.
I appreciate your help, Steve.

Re: Grid Charger Build
 

Wire the APC inputs in parallel to 110VAC. Serial the output, PSU1 (+) to battery. PSU1 (-) to PSU2 (+), PSU2 (-) to battery. Put a single diode in the positive output of PSU1 per D1 in the diagram (stripe on battery side).

Just to bring it up again, do not attempt grid charging without active cooling - either driving the fan at max (WITH the IPU lid on), or outside of the car with a fan blowing through it, etc.