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Open Roads Forum  >  Tech Issues

 > Voltage drop on inverter

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MEXICOWANDERER

las peñas, michoacan, mexico

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Posted: 08/10/19 11:26am Link  |  Quote  |  Print  |  Notify Moderator

Good Lad! Soldered! I have encountered inverters that had issues inside the inverter. Then "floating" connections when stuff is connected BETWEEN NUTS on a terminal. I never hook up a load greater than 5-amps BETWEEN NUTS. The last nut pushes the nut beneath it to float on its threads. Sounds hilarious until it happens to you.

2oldman

Ca

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Posted: 08/10/19 11:28am Link  |  Quote  |  Print  |  Notify Moderator

phemens wrote:

To clarify, I have 2 complete separate sets of bus bars to keep things tidy. One just to collect the wiring from the battery bank - 4 each pos & neg.
It's unusual to not wire the batteries together with very short wire. Why did you do it this way?

Itinerant1

Itinerant

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Posted: 08/10/19 11:46am Link  |  Quote  |  Print  |  Notify Moderator

If your displays for reading voltage is only xx.x instead of xx.xx you would not see the drop as in your example of 13.1 from your batteries if it's starting out at say 13.19v.

You really are seeing a difference in the batteries to inverter voltage lose, .2 is the greatest difference between my lfp battery readings and inverter readings even under load up to 2000w. Now I have seen a .4 difference between the 2 only when the SOC was at 37% pulling 2,867w using microwave, coffeemaker, charging laptops.

phemens

Montreal, Canada

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Posted: 08/10/19 11:47am Link  |  Quote  |  Print  |  Notify Moderator

What’s the advantage in wiring the batteries together vs just wiring them all to a single bus? The wiring between the batteries and the bus is about 1.5 ft each, and it’s all 00. I can it do either way, I just don’t see the difference, total number of wires is the same.


2012 Dutchman Denali 324LBS behind a 2006 Ford F-250 V10 out of Montreal
1 DW, 1 DD, 1 DS, 2 HD (Hyper Dogs)
1Kw solar, 500 AH LIFePO4, Yamaha EF2000 gen, Samlex 3000w Inverter

phemens

Montreal, Canada

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Posted: 08/10/19 11:55am Link  |  Quote  |  Print  |  Notify Moderator

Itinerant1 wrote:

If your displays for reading voltage is only xx.x instead of xx.xx you would not see the drop as in your example of 13.1 from your batteries if it's starting out at say 13.19v.

You really are seeing a difference in the batteries to inverter voltage lose, .2 is the greatest difference between my lfp battery readings and inverter readings even under load up to 2000w. Now I have seen a .4 difference between the 2 only when the SOC was at 37% pulling 2,867w using microwave, coffeemaker, charging laptops.


I’m seeing a much more substantial difference. 11.5 on the inverter panel vs 13.05 on the Victron. I’m not getting any faults on the Samlex. My SoC is around 75%. I guess I’ll need to pull out the voltmeter and check everything when I get back.

DrewE

Vermont

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Posted: 08/10/19 12:26pm Link  |  Quote  |  Print  |  Notify Moderator

A 1.5V drop, at a guessed 100A current, is 150W dissipation. That is quite a bit of power being turned to heat somewhere.





theoldwizard1

SE MI

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Posted: 08/10/19 12:31pm Link  |  Quote  |  Print  |  Notify Moderator

phemens wrote:

Still not sure why the Samlex is showing 11.5V while the Victron holds over 13V, but otherwise it works...
Looks like the voltage readings under load are at odds, but they match when idle.

Not surprising that the difference only shows under load. I think you should pursue this. Both of those items are "above average" quality and I would not expect more that 0.1V discrepancy.

With a load applied to the inverter, check voltage at a) each battery b) the first bus bar c) the second bus bar and d) the input terminals to the inverter.

Another quick check if you have the equipment is check the temperatures at a), b), c) and d). They should all be close to ambient.

LittleBill

Scranton, PA USA

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Posted: 08/10/19 12:33pm Link  |  Quote  |  Print  |  Notify Moderator

do a drop voltage test, this will find the issue.

The other thing bothering me is your saying the microwave is turning off? the inverter isn't? the inverter should be shutting down to low voltage. the microwave has no idea about battery voltage





2oldman

Ca

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Posted: 08/10/19 01:53pm Link  |  Quote  |  Print  |  Notify Moderator

phemens wrote:

What’s the advantage in wiring the batteries together vs just wiring them all to a single bus?
Wire length. Lots of wires to deal with to get somewhere. Perhaps the need for 2 buses.

Electrically it shouldn't make a hoot of difference. It's just that I've not known anyone to do it. Was just curious is all.

* This post was edited 08/10/19 02:05pm by 2oldman *

jharrell

Safety Harbor, FL

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Posted: 08/10/19 05:08pm Link  |  Quote  |  Print  |  Notify Moderator

MEXICOWANDERER wrote:

One positive

One negative

Excellent practice

This is why I despise unsoldered lugs Don't give a **** if they're squeezed till they fart, this would never happen with soldered lugs.

Oh they look good
Tighter than hell
But it doesn't work

There is ZERO protection between the interior of the lug surface and the stranded wires.



I disagree and prefer crimping, these people explain why:

https://www.evdrives.com/category_s/4013.htm

In the marine world crimping is preferred due to oxidation and soldering can prevent flex at the lug joint as well leading to fatigue.


2016 Winnebago Vista 31be - Blue Ox Rear Track Bar - Centramatic Wheel balancers
2016 Jeep Wrangler Unlimited Rubicon Toad - Readybrute Elite Towbar


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