Return-Path: Delivered-To: craig@dapaero.com Received: from gator4254.hostgator.com by gator4254.hostgator.com with LMTP id mB1JBqhTUGNb1A0AcizydQ (envelope-from ) for ; Wed, 19 Oct 2022 14:44:40 -0500 Return-path: Envelope-to: craig@dapaero.com Delivery-date: Wed, 19 Oct 2022 14:44:40 -0500 Received: from smtprelay0230.b.hostedemail.com ([64.98.42.230]:43436 helo=smtprelay.b.hostedemail.com) by gator4254.hostgator.com with esmtps (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.95) (envelope-from ) id 1olEzX-003ufb-LY for craig@dapaero.com; Wed, 19 Oct 2022 14:44:40 -0500 Received: from omf08.b.hostedemail.com (10.5.19.248.rfc1918.com [10.5.19.248]) by smtprelay05.b.hostedemail.com (Postfix) with ESMTP id 3B084100348F2 for ; Wed, 19 Oct 2022 19:44:30 +0000 (UTC) Received: from [HIDDEN] (Authenticated sender: andrewscc@nctv.com) by omf08.b.hostedemail.com (Postfix) with ESMTPA id E1F3318BDC165 for ; Wed, 19 Oct 2022 19:44:29 +0000 (UTC) MIME-Version: 1.0 Date: Wed, 19 Oct 2022 12:44:29 -0700 From: Curt Andrews To: DAP AERO Subject: Re: 36 VDC 8000 watt inverter-1184 In-Reply-To: References: Message-ID: <1d549ee2f6c0eedd7b4fa691149582d5@nctv.com> X-Sender: andrewscc@nctv.com Content-Type: multipart/alternative; boundary="=_ea50ad8fe134399d27f2fe3717adca90" X-Spam-Status: No, score=-5.10 X-Stat-Signature: nbs8j4gsfjetjmxyi5nasjpttxehgi3o X-Rspamd-Server: rspamout04 X-Rspamd-Queue-Id: E1F3318BDC165 X-Session-Marker: 616E64726577736363406E6374762E636F6D X-Session-ID: U2FsdGVkX1/HjY49ArAr3d0IVG2krr7dsbkv8nxFepI= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nctv.com; h=mime-version:date:from:to:subject:in-reply-to:references:message-id:content-type; s=mail; bh=wldwxNry6KPsJM0BhwPpKYR+/G3b8FANmXZFXyulE3o=; b=Fm2TBwf+PYopH8WUlmj0kBi3j8D66Y/bSW/fLBiVmOWmN+Ao77Az6L9IJhgXPIFSOXEE81SEOFE8fsHelLVkJFCeDAIhQrtwNIIV2tgm89OkqrdbHDL3iPuCF1quEqweV7e+f1E03FnxkONhw4UZRDj0pHO/yMzlZDywlH+VPA1YR8tV05Dyj6ypkQCT7kGY+aJDkxbZtBekS6BtgzBNxsSN7adO8QRIm+lO2T6gHVkz5f4ckHJLz29tUQQqeJVPmS9yb9Z9x0mXSA6JPnz4Q4Bcea+SxmAwY95nBaxQXsEEoanRMwjYVF7GGlnuoWadQuuSXbzGxcbNc5Jj4iD7OQ== X-HE-Tag: 1666208669-874628 X-Spam-Status: No, score=0.2 X-Spam-Score: 2 X-Spam-Bar: / X-Spam-Flag: NO --=_ea50ad8fe134399d27f2fe3717adca90 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=US-ASCII; format=flowed we went through the whole grounded issue, as the negative battery, 120 neutral and ground are all bonded together to car. Yet the ground of the inverter is in the middle of the 120 volt sine wave, or 60 volts! so i had the case isolated even though they said i did not need to. They have never asked about the charger, but 20 amp charger was probably on during the first failure, but was not on second smoked one. second smoked one was not connected to any output, i was just testing with battery connected. --- Curt Andrews 1336 E Oak Othello WA 99344 509 346 8108 On 2022-10-19 09:55, DAP AERO wrote: > The second and third units have burned up with or without a load? > 12 mosfets seems excessive but then if it is pure sin wave maybe that > is the way they do that. > > Is the battery completely floating or is the negative taken to the > chassis? Then does the charger take the negative to ground? Was the > charger connected when the inverter blew? > > My first guess would be something about the charger/ battery/ inverter > is not what they are expecting. > >> On Oct 19, 2022, at 9:45 AM, Curt Andrews wrote: > > I do not think they know what the problem is, but i have two failed > units and they hesitate to replace again. > The first one I ran for a few hours and it totally burnt out four of > the 12 large mofets on the back side. I have that one all torn apart. > They sent a replacement and i turned it on and the 5 watt resistor > started to smoke immediately and i turned it off. so it is still > intact. So you can live test that one. > The problem in the second unit is in the control circuity, not the high > amp stuff. Something in the controls is simply pulling too much load > through the resistor. > > I would ask for my $1200 back, but i have not found another > manufacturer of a 36 volt pure sine wave inverter over 5000 watts. > Everyone has gone to 48 volts. > > --- > Curt Andrews > 1336 E Oak > Othello WA 99344 > 509 346 8108 > On 2022-10-18 19:25, DAP AERO wrote: > > If 4 more it is an H bridge so it is directly driving the big > transforme, probably like this > > https://www.homemade-circuits.com/easy-h-bridge-mosfet-driver-circuit-for-inverters-and-motors/ > > They must be confident the problem is not in the H bridge part > > On Oct 18, 2022, at 7:19 PM, DAP AERO wrote: > > Oh wait, are there four more of these mounted on the other side of the > board? > > On Oct 18, 2022, at 7:12 PM, DAP AERO wrote: > > https://www.vishay.com/docs/91054/91054.pdf > > Gate should be isolated from other two leads > Freewheeling diode from source to drain, maybe 2v drop in diode test. > diode is reversed from drain to source so diode test should show no > current. > > In operation, the drain to source current is nearly zero until the gate > voltage gets between 2 and 4 volts and the source/drain resistance will > quickly go down as gate voltage increases. When the device is full on, > the source/drain resistance will be less than 0.5 ohm. > > Maximum source/drain current is 10 amps but that will dissipate 55 > watts from the internal 0.55 ohm resistance so it can only be on for a > moment to drive current into the step up transformer. It then turns > off, probably switches on and off in the kHz range and adjusts this > frequency and duty cycle to get your AC output of the inverter. > > Frequency is very high so transformer is smaller than you are probably > expecting. > > On Oct 18, 2022, at 6:41 PM, Curtis Andrews wrote: > > RF740 --=_ea50ad8fe134399d27f2fe3717adca90 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=UTF-8

we went through the whole grounded issue, as the negative battery, 120 n= eutral and ground are all bonded together to car.   Yet the groun= d of the inverter is in the middle of the 120 volt sine wave, or 60 volts! = so i had the case isolated even though they said i did not need to. &n= bsp;

They have never asked about the charger, but 20 amp charger= was probably on during the first failure, but was not on second smoked one= =2E  

second smoked one was not connected to any outpu= t, i was just testing with battery connected.  


=

---
= Curt Andrews
1336 E Oak
Othello WA 99344
509 346 8108

On 2022-10-19 09:55, DAP AERO wrote:

 
The second and third units have burned up with or without = a load? 
12 mosfets seems excessive but then if it is pure sin wave= maybe that is the way they do that.  
 
Is the battery completely floating or is the negative take= n to the chassis? Then does the charger take the negative to ground? Was th= e charger connected when the inverter blew?
 
My first guess would be something about the charger/ batte= ry/ inverter is not what they are expecting.

On Oct 19, 2022, at 9:45 AM, Curt Andrews <andrewsc= c@nctv.com> wrote:

I do not think they know what the problem is, but i have two failed unit= s and they hesitate to replace again. 
The first one I ran for a = few hours and it totally burnt out four of the 12 large mofets on the back = side.  I have that one all torn apart.  
They sent a re= placement and i turned it on and the 5 watt resistor started to smoke immed= iately and i turned it off. so it is still intact.  So you can live te= st that one.
The problem in the second unit is in the control circuity= , not the high amp stuff.  Something in the controls  is simply p= ulling too much load through the resistor. 

I would ask fo= r my $1200 back, but i have not found another manufacturer of a 36 volt pur= e sine wave inverter over 5000 watts.  Everyone has gone to 48 volts.&= nbsp;      

---
Curt Andrews
1336 E Oak
Othello WA 99344
509 346 8108

On 2022-10-18 19:25, DAP AERO wrote:

 
If 4 more it is an H bridge so it is directly driving the = big transforme, probably like this
 
 
They must be confident the problem is not in the H bridge = part

On Oct 18, 2022, at 7:19 PM, DAP AERO <craig@dapaero.com> wro= te:

 
Oh wait, are there four more of these mounted on the other= side of the board?

On Oct 18, 2022, at 7:12 PM, DAP AERO <craig@dapaero.com> wro= te:

 
 
Gate should be isolated from other two leads
Freewheeling diode from source to drain, maybe 2v drop in = diode test.
diode is reversed from drain to source so diode test shoul= d show no current. 
 
In operation, the drain to source current is nearly zero u= ntil the gate voltage gets between 2 and 4 volts and the source/drain resis= tance will quickly go down as gate voltage increases. When the device is fu= ll on, the source/drain resistance will be less than 0.5 ohm.
 
Maximum source/drain current is 10 amps but that will diss= ipate 55 watts from the internal 0.55 ohm resistance so it can only be on f= or a moment to drive current into the step up transformer.  It then tu= rns off, probably switches on and off in the kHz range and adjusts this fre= quency and duty cycle to get your AC output of the inverter. 
 
Frequency is very high so transformer is smaller than you = are probably expecting. 

On Oct 18, 2022, at 6:41 PM, Curtis Andrews <andrewscc@nctv.com&= gt; wrote:

RF740
--=_ea50ad8fe134399d27f2fe3717adca90--