SSR for AGM battery
- Thread starter frankz66
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crossy
Solar Addict
Possibly, what's your actual application?
SSRs have a volt-drop and power dissipation (hence the heatsink), exactly what the numbers are should be in the device documentation.
They are (mostly) NOT bi-directional, so if you want charge and discharge currents to flow you need two SSRs in inverse-parallel.
You may actually be better using a nice, meaty, conventional relay.
I also note that yours is marked as 220V DC 50/60Hz
SSRs have a volt-drop and power dissipation (hence the heatsink), exactly what the numbers are should be in the device documentation.
They are (mostly) NOT bi-directional, so if you want charge and discharge currents to flow you need two SSRs in inverse-parallel.
You may actually be better using a nice, meaty, conventional relay.
I also note that yours is marked as 220V DC 50/60Hz
frankz66
New Member
Hi, I know for sure that at the moment they are used to protect solar panels, so the current goes in and out, so unless I have understood the translation correctly, I don't understand what you mean.Possibly, what's your actual application?
SSRs have a volt-drop and power dissipation (hence the heatsink), exactly what the numbers are should be in the device documentation.
They are (mostly) NOT bi-directional, so if you want charge and discharge currents to flow you need two SSRs in inverse-parallel.
You may actually be better using a nice, meaty, conventional relay.
I also note that yours is marked as 220V DC 50/60Hz
crossy
Solar Addict
"Protect" in what way?? Panels only send current in one direction.
The terminals are marked + and - for a reason.
The SSR only allows current flow from the + to the - .
Again, what is your actual application??
The terminals are marked + and - for a reason.
The SSR only allows current flow from the + to the - .
Again, what is your actual application??
crossy
Solar Addict
Is your "storage tank" a water (or sand/rock/salt) heater of some kind or energy storage (battery)?
wpns
Solar Joules are catch and release
So just a resistive heater? That should work fine, but please make sure you have a separate overtemperature thermostat and overtemp/overpressure (plumbing) device and they are functional and also rated for DC.
crossy
Solar Addict
Yeah, assuming that's what he meant, but why the mention of "AGM" which got me going in the battery direction.
Also, I wouldn't want to go over 50% rating on a long-term basis.
wpns
Solar Joules are catch and release
48V AGM batteries and a 48V water heater? The DC thing trips up a lot of people, and hot water tank explosions (*) are nothing to sneer at.
(*) Yes, I know, it requires the primary control device (SSR) to fail on (or the control system hardware/software to get stuck)
AND
The backup/safety thermostat be the original AC-rated model (common mistake) and have it's contacts welded shut as a result
AND
The overtemp/overpressure valve fail in the stuck (or clogged) closed mode
AND
no-one notices that the home-made dump load is running 24x7.
However, the downside is pretty serious, and someone asking the questions above probably doesn't know about all of those fiddly details.
Google is your friend, look for hot water tank explosion.
efficientPV
Solar Addict
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Most of the ones I have seen use an IGBT and there will be a 1.6V or more loss. That is a lot of heat. 100A, who are they kidding.
frankz66
New Member
As written before, it should be used to pass the positive of a 48v battery.
Considering what you wrote and in order to understand, could you make a sketch of the use of the SSR?
frankz66
New Member
I'm sorry but you misunderstood, the water heater has nothing to do with it! I'm talking about passing the positov of a battery through an SSR.
frankz66
New Member
Possibly, what's your actual application?
SSRs have a volt-drop and power dissipation (hence the heatsink), exactly what the numbers are should be in the device documentation.
They are (mostly) NOT bi-directional, so if you want charge and discharge currents to flow you need two SSRs in inverse-parallel.
You may actually be better using a nice, meaty, conventional relay.
I also note that yours is marked as 220V DC 50/60Hz
frankz66
New Member
wpns
Solar Joules are catch and release
Frank, you keep asking questions and when the answer from the experts doesn’t match your expectations you start to argue and treat people like they don’t understand your question.
The simple (if unpalatable) answer is that this is not a good idea for a number of reasons:
Those SSRs may be rated for 100A by the folks who want to sell them to you, but you can’t fit wires with 100A ampacity on those terminals which ought to tell you something.
A relay has essentially zero voltage drop and no dissipated power. An SSR will have a volt or two of voltage drop, you do the math.
Hot water heater dump loads at 48 Vdc require a lot more thought than just swapping out the heating element and hooking it up.
Search the forum for 100A SSR, pretty sure this has been discussed before (including one that failed and was replaced with a relay/contactor).
wpns
Solar Joules are catch and release
Yes, absolutely that works. The results will depend on the load. If that’s a secret then say it’s a secret. If not help us help you by adding some more details.
wpns
Solar Joules are catch and release
Can’t really parse that picture, enable the panels whenever the batteries are connected? And then stay on until the batteries are disconnected _and_ the sun goes down?
frankz66
New Member
I wasn't talking about changing the subject, just the fact that I didn't mention any scoundrels. The intent is to understand if an SSR can make VDC voltage and current flow from a 48V 50 ampere storage tank. I think the problem is traditional from Italian to English unfortunately! I'll attach the video link so maybe you can understand how SSRs are used to protect a system. This is an example, but what I wanted to do is linked to the flow of 48v batteries. I am a beginner and as such I struggle to explain and I want to underline that I am not changing anything, but I insist on a problem of understanding through Google translations. Here is the link to the video which shows just an example of the use of SSR, and from here you got the idea of being able to apply it to the 48V storage if possible. That's all .
efficientPV
Solar Addict
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Don't feel bad. There are only about a half dozen people here who know how to heat water properly. I just scanned thru the video quickly and he came to the conclusion quickly that solid state relays have too much loss. Those with an electronics background can switch electronically for less money and less than 1/2W loss. Those mechanical relays will likely have issues over time.
wpns
Solar Joules are catch and release
Ah, indeed, a translation issue. If you are talking about a BATTERY, that's a whole different question.
Yes, an SSR can switch a DC current (in one direction only).
I really doubt this will work like you think it will, but you still haven't given us enough information to help you properly.
What do you have, and what exactly are you trying to do? The title says AGM, different posts say 50 or 70 amps, if you are switching a battery the current could be (briefly) essentially infinite.
wpns
Solar Joules are catch and release
What device has a 7mv drop at 70 amps? I have an electronics background, but I must have missed something.
frankz66
New Member
Hello and thanks for at least partially understanding. I had inserted agm, because my aim would be to be able to switch two photovoltaic accumulators based on the battery voltage via a dry contact and SSR relays in order to use one or the other as a backup for the inverter. Looking carefully at the video, I noticed that the reason why the negative was connected to the SSR was because it wasn't working. Currently several users use SSR to save the regulator system from sudden storage disconnections. But as written before I would like to make an exchange between the accumulations. I opened another post about this.
efficientPV
Solar Addict
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Someone with an electronics background wouldn't do it this way.
wpns
Solar Joules are catch and release
What are photovoltaic accumulators? And why do you distinguish them from batteries in the same sentence?
Again, connecting batteries together with SSRs invites brief periods of really high currents.
frankz66
New Member
Would you be able to make a sketch?
frankz66
New Member
I mean the word accumulation, my batteries which in this case are 4 12v in series for a certain amount. 48v 110 amp AGM
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