Two Chargers Simultaneous Charging

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Two Chargers Simultaneous Charging

Post by coulomb »

The cable at other end (of the charger) to the output cable and 7-pin round is the mains input. It's unlikely that they have supplied an Australian plug; I've seen some doozies. You can tell your electrician brother that they often use white for active and black for neutral (the opposite of the American standard). Usually they use internationally approved green with yellow stripe for the earth, but maybe they use green for that sometimes (green was the standard before green-yellow). It might be worth checking with a multimeter (brother should have one) for continuity between what you think is the earth wire and the metal of the charger.

Weber tells me that no-one is supposed to use green or yellow any more for any purpose, even ground, in new equipment. So that pesky green cable isn't even compliant. (When searching, I did see some red ones, so maybe they've seen the light, so to speak.) I believe it's OK to use green for signal wires, though, so if the green wire comes from the cable that goes to the 7-pin round connector, then that's OK.

[ Edit: The other end -> The cable at the other end ]
Last edited by coulomb on Fri, 28 Aug 2015, 15:21, edited 1 time in total.
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Post by Paul9 »

Thanks Coulomb and 4Springs.

I have purchased a 40 amp, 12v automotive relay complete with diode. I am keeping in mind that 4Springs said not to connect the 12v (red) wire nor the enable (black) wire to the vehicle's 12v battery.

My proposed wiring for the relay would be as follows:

a) Wire from pos terminal of aux battery to a switch;
b) Wire from switch to lug No 86 on relay;
c) Wire from lug No 85 back to neg terminal on aux battery;
d) 12v (red) wire from charger to lug No 30 on relay;
e) Wire from lug No 87 on relay to 12v socket in BMS; (There are two lugs labelled No 87 on the relay. The lug I reference here is the No 87 lug when relay is in closed position ie. when current flowing.)
f) Enable (black) wire from charger to enable socket in BMS. (This would bypass the relay.)

Don't know if the above is correct so would greatly appreciate your advice. I realise a mudmap wiring diagram would be easier to follow but I have tried numerous times to upload photos and continually stuff it up!

Thanks for your patience,
Cheers
Paul
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Post by 4Springs »

Paul9 wrote: Don't know if the above is correct so would greatly appreciate your advice. I realise a mudmap wiring diagram would be easier to follow but I have tried numerous times to upload photos and continually stuff it up!

No, I think you have the wrong idea. :)

Here you go, I've added relay terminal numbers to the diagram from the manual:
Image
So this is pretty simple, no switch required. Note that we don't use the aux battery either.

Before you do this though, have you checked to make sure that the BMS output is as described earlier?
4Springs wrote:So you need to test your BMS output. You said that there are two wires, check them with a voltmeter and see what happens. My guess is that it will provide 12V to 'enable' the charger, and 0V to disable it.
If this is correct then figure out which wire (from the BMS output) is positive and which is negative. The positive one goes to pin 86 and the negative to pin 85.

Make sure you test it first though, because it might not be 12V (so you'll need a different relay) or it might be 12V to disable it (so you'll need to use different contacts on the relay).
Last edited by 4Springs on Sun, 30 Aug 2015, 17:13, edited 1 time in total.
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Post by Paul9 »

Thanks 4Springs

I'll get my brother over during the week and we will go through it as you recommend.

I'll let you know what happens.

Cheers
Paul
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Post by Paul9 »

Finally got around to doing some testing yesterday. Apart from life getting in the way, the car blew the gearbox and we had to hunt around to find a replacement.

I fitted the new 121v 18amp charger in place of the old 96v 10amp charger and it charges the car at a rate of 17.4 amps but unlike the old charger it doesn't decrease the charging amps as the pack voltage approaches 121v. The new TC charger maintains the 17.4amp charge rate right up until the BMS cuts it out at 121v.

Yesterday I hooked up (but did not install) the old charger and did a simultaneous charge. I turned on the old charger and it charged at a rate of 10.3amps. I then turned on the new charger which delivers 17.4 amps. The total charge amps increased to 27.6 amps and then dropped the charging amps back to 21.4 amps immediately. It maintained this charging rate for the entire charging time. It appears that the new charger delivered its 17.4amps but the old charger dropped its charging rate to about 4amps (not the 10.3 amps I was hoping for).

I assume I will just have to leave the old charger out of the car and keep it as a backup charger in case something goes wrong with the new charger, unless anyone has some other suggestion?

As a matter of interest the new charger did not come with any fan(s) to help keep charging temperature down. I took 4Springs advice and bought a fan from Jaycar and a 50degree thermostat and hooked those up to the new charger. I also attached two heat sinks with double sided thermal transfer paper. From the pictures 4Springs posted, mounting fans on the charger appeared to involve some work. I noticed some small screws on the charger which appeared to attach the heat sink fins on the top of the charger to the charger itself. The holes at the four corners of my fan just happened to be exactly the same width apart as the screws on the charger. I purchased longer, but same diameter, screws and used those to attach the fan to the charger using the existing holes in the charger. My fan is the 12v 80mm fan Jaycar part number YX2513.

Cheers
Paul

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Post by 4Springs »

I'm jealous with the neat mounting of your fan!
How did you measure the current being put into the battery?
It sounds like perhaps the new charger was charging so fast that the voltage was raised high enough for the old charger to start limiting its current. Was the battery very depleted to start with? It might put more in if it was further discharged?
21 Amps is better than 17.4. By one fifth!
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Post by Paul9 »

4Springs - I am able to measure current with both the TBS Pro I had from my "lead acid" days and the BMS we installed with the lithiums. They both agreed on the current being charged so I assume my figures are accurate.

The battery was down to about 75% to 80% SOC when charging commenced. I wondered about the scenario you suggested and I will get the battery down to, say, 50% SOC in the next couple of days and give it another go.

Mounting the fan was a bit of luck on my part! Not having the skills you and many others have, I have to look for "easy" ways to do things! Once in a while I actually find an "easy" way!

Thanks
Paul
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Post by Paul9 »

Hi 4Springs

Got the SOC down to 51.2% yesterday and did a simultaneous charge this morning. Looks like your theory is correct. Unfortunately the SOC only got up to 55% and the charging rate went down to 24amps. Then SOC got up to around 60% and the charge rate went down to 21.4amps.

Looks like the new 17.4amp charger gets the voltage up quickly which causes the old charger to drop its charging rate. Still, as you say, 21.4amps is better than 17.4amps.

Thanks muchly
Paul
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Post by 4Springs »

The other day I was inspired by Paul to try out my lead-acid charger temporarily to see if it works. Here are the results for the edification of anyone reading - mainly me in the future when I try to remember what exactly it was that I did...

I have two ways to measure what is going on:
I have a Watt meter that I can plug something into on the 240V mains. This gives me a reading in kW.
I have the Zeva fuel gauge driver plus (FGD+), which drives a gauge showing me the current entering or leaving the battery. This is an analogue gauge so it is great while you are driving but not very useful for reading relatively small currents while charging.

In the car is a TC charger configured for my 48 lithium cells (let's call that 160V). When I plug the car into the wall my meter shows that it is drawing 2.1kW.
So 2.1kW/240V = 9A being drawn from the socket.
2.1kW/160V = 13A being delivered to the battery.

I have a lead-acid charger as well that has been sitting in the shed. I hooked it up in a temporary manner the other day and plugged it into a different 240V socket. I measured:
2.1kW on the TC charger.
1.3kW on the lead-acid charger.
So 3.4kW means that I was drawing 14A from the power points, and I was delivering 21A into the battery.

When I had the lead-acid pack I had written down what the charger did at what pack voltage. Referencing this (here, oh future self), it seems that my charger will deliver full current up to 172V. This is pretty-much full for my lithium pack, so I don't think I'll have the same problem that you have Paul with it throttling back the current. But my test was with a fairly discharged pack, so I can't be certain.

I'll need to figure out some way of turning off the lead-acid charger with my BMS. The BMS throttles back the current by talking to the TC-Charger. When that happens I want it to switch a relay to disconnect the lead-acid charger. I'm pretty sure there are no digital outputs left on the BMS so I'll have to think about how to do that.
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Post by Paul9 »

Hi 4Springs

My extremely limited knowledge of how my BMS works includes that it has three pos-neg connections so it can handle three separate chargers. My new charger has wires coming from it's "other end" to connect it to the BMS.

If I read your post correctly you are having problems with connecting both chargers to the BMS?

My old lead acid charger however does not have any wires to connect it to a BMS. I don't know how my mates connected it so it is controlled by the BMS but I'll ring them Monday and ask them to explain it to me (if in fact this is the problem you have??)

Cheers
Paul
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Post by 4Springs »

Paul9 wrote:If I read your post correctly you are having problems with connecting both chargers to the BMS?Paul

The problems are all in my head at the moment. :)
I have a very different BMS to yours Paul. Mine is custom made so I'll need to customise it a bit more. I gained enough information from my experiment to know that I do want to put in the second charger - I just need to figure out the fiddly details. Another detail is exactly where to fit it. Not a lot of space left...
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Post by Paul9 »

Oh yeah ..I understand the "space available" problem!!!!

When I ordered and received my 2kw charger I should have thought about its physical size! I took out the old charger and placed the new charger in the same spot and realised the new charger was about 75mm longer than the old one. All the mounting brackets under the bonnet had been built to mount the old charger. One end of the new charger could go on one bracket and the only thing I could bolt the other end to was fresh air!

I eventually came up with the idea, on the "fresh air" end, of using 2 springs (that's half of 4 springs!), hooking one end of each spring into the mounting holes on the new charger and the other end of each spring is hooked under the closest mounting bracket (about 100mm away).

Feeling quite proud of my problem solving abilities, I put all my tools away and went to close the bonnet. As I am closing the bonnet, I look down and realise for the first time that the new charger is also 40mm higher than the old charger!! Would the bonnet close and what the hell was I going to do if it didn't??

I have never closed anything so gently in my life! The final "click" when the bonnet closed without hitting the charger was wonderful!

I don't know the gap between the closed bonnet and the top of the charger but I am sure it can only be measured in 100th's of a millimetre!

Hope it all works well for you,
Cheers
Paul
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Post by Peter C in Canberra »

I have two 1.5kW TC chargers operating in parallel. Their endpoint voltages are nominally the same but actually not quite identical. Their output is 8A each up to not quite 165V (45xLiFePO4). One charger gets to its endpoint so the current drops over a short time to 8A as that charger tapers down the current then stops, then the voltage rises slightly further then the second charger also tapers down current and stops.
Both are controlled by having 240VAC applied to their inputs. My old EVPower BMS has a mains rated relay to pull the power if a problem is detected. With both running the current drawn from the mains might be a bit more than 10A though under 15A. For a very 10A-friendly option one charger can be left off by using a switch to have its two wire remote control open rather than closed.
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Post by Paul9 »

Thanks Peter,

That might be an option for my set up!

Cheers
Paul
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Post by Paul9 »

Thought I might update this thread a bit in case anyone has similar problems to mine.

Up until recently my plan was to fit the new 18amp (actually 17.4amp) charger and just leave the old lead acid charger as a backup. Just to recap, I wanted to fit both chargers but the old charger didn't have any signal wires to attach to the BMS to allow the BMS to control it.

I was hunting the interweb to find some IEC cable for the new charger and lo-and-behold found a "Y" shaped IEC cable which has one male connector to two female connectors (Jaycar Pt no. PS4104).

This allows me to have both chargers in the car, both connected through the BMS to the one existing cable.

My concern though still was that the two chargers would pull too many amps and the rear circuit breaker would "shut off". I hooked them both up (without actually installing the old charger) turned on the juice and they both started charging. The charge from the old charger quickly went from 10amps down to 4amps as I explained previously in this thread but nothing switched itself off.

I did some feeling around to see what may be getting hot and found the 10amp extension lead was getting quite warm as was the male end of the IEC cable. The IEC cable is also rated at 10amps. Both chargers pull less than 10amps at 240v but combined, I am guessing, pull about 11 or 12 amps. Unfortunately Jaycar said there is no 15amp "Y" shaped IEC cable.

Swapping the 10amp extension lead for a 15amp lead solved the problem of warmth with the 10amp lead. The male end of the IEC cable was also getting warm whereas the two female ends were not at all warm. This made sense to me as it is only the male end which handles the full load of both chargers. The male end of the cable is about 18inches (450mm) long so I assumed shortening it may reduce the resistance and thus the build up of heat. I have now shortened the 18inch male end to about 4 inches. Haven't had a chance to try it out yet.

Just thought I would put this out there in case anyone has a similar problem to mine and may be unaware of the existence of the "Y" shaped IEC cable.

Thanks
Paul
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Post by 4Springs »

Paul9 wrote: Swapping the 10amp extension lead for a 15amp lead solved the problem of warmth with the 10amp lead. The male end of the IEC cable was also getting warm whereas the two female ends were not at all warm. This made sense to me as it is only the male end which handles the full load of both chargers. The male end of the cable is about 18inches (450mm) long so I assumed shortening it may reduce the resistance and thus the build up of heat. I have now shortened the 18inch male end to about 4 inches. Haven't had a chance to try it out yet.
Is the male end an IEC male plug? If so it is probably a 10A version, and may be the source of the heat. There are 16A versions of IEC plugs & sockets - would it be possible to replace the plug and the socket that it mates with? Search for IEC C19 on ebay, and have a look at the wiki.
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Post by Paul9 »

I hadn't thought of that 4Springs.

Correct me if I am wrong, but I gather you are saying that it may be the plug which is causing the heat in that section of the cable and not the cable itself?

I will do a search on the Jaycar website to see if they have 15amp IEC male plugs which I assume would have a different size to the 10amp male plug - therefore I would also need a 15amp female plug?

Thanks
Paul
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Post by 4Springs »

Paul9 wrote:I gather you are saying that it may be the plug which is causing the heat in that section of the cable and not the cable itself?
If both are rated at 10A, then it is possible that both will heat up. I wouldn't recommend using anything over its rating, but if you must, shortening the cable will help.
Paul9 wrote:I will do a search on the Jaycar website to see if they have 15amp IEC male plugs which I assume would have a different size to the 10amp male plug - therefore I would also need a 15amp female plug?
Yes, they are a different size so you will need the pair. I couldn't see any on Jaycar but I did find them on ebay. Search for IEC C19.
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Post by Paul9 »

Thanks 4Springs - shall do!

Cheers
Paul
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Post by Johny »

Hi Paul and all. Just curious - how did you pay for your Chinese stuff?
I have had three experiences so far paying TTs and each time have been hit with extra bank charges which had me paying fees for yet-another TT because a bank (other than the one I used) stripped off some cash on the way through.
I'm thinking of using Western Union.
Any experiences anyone?
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Post by Paul9 »

Hi Johny

I paid by electronic transfer straight from my bank account to their bank account listed on their invoice. In US dollars of course.

I think there was a $30 fee charged by my bank.

Cheers
Paul
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Post by Paul9 »

Hi people,

I thought this thread had reached its conclusion. All I had to do was get some of the terminals which 4Springs told me about and all would be good. I haven't had a chance to hunt those terminals down but my brother happened to be free this afternoon so we decided to actually install the old lead acid charger - that job needs 4 or 5 hands to move wires etc.

The lead acid charger was installed and he was curious about how warm the wires got so we hooked up both chargers and turned on the juice. As I explained earlier in this thread, the two chargers, when tested prior to installing the lead acid charger, got me up to 27.4 amps quickly and then the old charger quickly dropped its current to about 4amps and the combination of the two would charge at about 21.4amps.

No, not this time! This time the combined charge got up to 27.4amps and stayed there? Within two minutes the circuit breaker clicked off and charging ceased! The lead acid charger did not drop its charging current.

Twice I had tested the two chargers together with the same cable as this afternoon and everything worked fine. The only difference this afternoon was that the old charger was actually installed in a spare space under the bonnet.

My brother suggested that, as the old charger was installed on its side, maybe all the electrons had sunk to the bottom of the charger and thus the current at the bottom of the charger was stronger. I think he was pulling my leg!

We are going to change the circuit breaker to a 15amp breaker as well as buy the terminals which 4Springs suggested. My primary confusion is why the chargers would act differently between the two tests and the installation?

Any ideas?
Thanks
Paul
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Post by Adverse Effects »

in all the tests where the cases common ground (IE:- both bolted to the same metal structure) or was the old charger sitting on the floor next to the car or sitting on a board on the car or something like that
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Post by Paul9 »

Hi Adverse Effects,

When I tested the combination of the two I had the old lead acid charger sitting on a piece of rubber sheeting sitting on the top of the front edge of the engine bay.

Would this make a difference?

Thanks muchly
Paul
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Post by Peter C in Canberra »

Parallel output from two identical chargers should be fine. I would not be so sure about two non-identical chargers. Things could go wrong. Eg. One charger might have its -ve output referenced to the mains earth. The other charger could have its output deliberately isolated.
I have two Elcon 1.5kW chargers connected in parallel, hard-wired into my car, and it works just fine. I would not be so confident about dissimilar chargers with unknown internal configurations.
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