Return-Path: Delivered-To: craig@dapaero.com Received: from gator4254.hostgator.com by gator4254.hostgator.com with LMTP id 6CAIK1YHc2PJ0Q8AcizydQ (envelope-from ) for ; Mon, 14 Nov 2022 21:28:22 -0600 Return-path: Envelope-to: craig@dapaero.com Delivery-date: Mon, 14 Nov 2022 21:28:22 -0600 Received: from smtprelay0171.b.hostedemail.com ([64.98.42.171]:55904 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 1oumcX-000N9p-VX for craig@dapaero.com; Mon, 14 Nov 2022 21:28:22 -0600 Received: from omf02.b.hostedemail.com (10.5.19.248.rfc1918.com [10.5.19.248]) by smtprelay05.b.hostedemail.com (Postfix) with ESMTP id 11550100329D4 for ; Tue, 15 Nov 2022 03:28:11 +0000 (UTC) Received: from [HIDDEN] (Authenticated sender: andrewscc@nctv.com) by omf02.b.hostedemail.com (Postfix) with ESMTPA id 76C0F8B7BF6E for ; Tue, 15 Nov 2022 03:28:10 +0000 (UTC) Content-Type: multipart/alternative; boundary="------------CxP8sCtUb2oVG3e9s5coKcE0" Message-ID: <636d59a6-dff8-40bf-59d0-4be5ba935cf5@nctv.com> Date: Mon, 14 Nov 2022 19:28:08 -0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:91.0) Gecko/20100101 Thunderbird/91.13.1 Subject: Fwd: 36 VDC 8000 watt inverter-1184 References: <1d549ee2f6c0eedd7b4fa691149582d5@nctv.com> Content-Language: en-US To: DAP AERO From: Curtis Andrews In-Reply-To: <1d549ee2f6c0eedd7b4fa691149582d5@nctv.com> X-Forwarded-Message-Id: <1d549ee2f6c0eedd7b4fa691149582d5@nctv.com> X-Spam-Status: No, score=-5.10 X-Stat-Signature: xf9g53nyjaks5dunp1jp7j4yuqi3ij1y X-Rspamd-Server: rspamout03 X-Rspamd-Queue-Id: 76C0F8B7BF6E X-Session-Marker: 616E64726577736363406E6374762E636F6D X-Session-ID: U2FsdGVkX1+RG/2LOmYN1R/vo/EPy2b9BhIWQO8HWXE= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nctv.com; h=content-type:message-id:date:mime-version:subject:references:to:from:in-reply-to; s=mail; bh=S7G/bf9SmZnBQYcwy2Fj4nS9QEVaVodgsR5qmfzo9C4=; b=VaunfQinaA3ODCd9dDWJ1voiYiTqJ9GEbLY/csTfVPq4INrqP9ur7mJDARsYZRY7xM1aY3PNICiPAwZBUC8n35fywNdV3tVmynWfIPbFKR4xRRy1m06TO1dxYqdXOQupQd0W6HS79IrpezCHrbXHTsNqvUbSFkSsFhE1F+OZH0zuARoEQCrVI6JbaI//CLWq7DmlJWdjmdz9I0hE1NYxJm4kaeyn6ONlx3ka1GkshenLe6lQbrjqLJwXcM19ESyMwwxGbNnlTAMhQx03HvvQOldJs2z7wQFI2XMqtRt3ezkDgURCFIxXStdXLjVS75nx9Fv1wp+3wU7L8rYx8NseiA== X-HE-Tag: 1668482890-535931 X-Spam-Status: No, score=0.2 X-Spam-Score: 2 X-Spam-Bar: / X-Spam-Flag: NO This is a multi-part message in MIME format. --------------CxP8sCtUb2oVG3e9s5coKcE0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit got the two parts for the inverter, when can you work on it? -------- Forwarded Message -------- Subject: Re: 36 VDC 8000 watt inverter-1184 Date: Wed, 19 Oct 2022 12:44:29 -0700 From: Curt Andrews To: DAP AERO 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 >> --------------CxP8sCtUb2oVG3e9s5coKcE0 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: 8bit

got the two parts for the inverter,

when can you work on it?



-------- Forwarded Message --------
Subject: Re: 36 VDC 8000 watt inverter-1184
Date: Wed, 19 Oct 2022 12:44:29 -0700
From: Curt Andrews <andrewscc@nctv.com>
To: DAP AERO <craig@dapaero.com>


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 <andrewscc@nctv.com> 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
 
 
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> 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 <craig@dapaero.com> wrote:

 
 
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 <andrewscc@nctv.com> wrote:

RF740
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