is the icharger 1010b+ isolated?

[ktm_paul]

As part of a motorcycle project im looking at using Turnigy 5S 5aH Lipo packs. I was going to put 4 packs in series then parallel those chains to make 50aH. Effectively 20S 10P. Iv got 4 packs now for trials.

My plan was to charge/monitor (initially) using two icharger 1010b+ units. If inputs/outputs are isolated i could charge without disconnecting the 20S into two 10s packs. Otherwise I will need to disconnect the 20S into two 10S packs for charging (and possibly monitoring).

So my questions:
- is above logic right?
- are the icharger 1010b+ inputs/outputs isolated? (manual does not say)
- can I test isolation by a conductivity test on the negative terminals? (am away on holidays so cannot do this test)
- is there a mechanical switch that I could use if i need to separate the 20s into two 10s? Would not be under load when i need to open it. Or maybe a connector that can handle up to 400-500A bursts?

Tips appreciated!

Thanks in advance, paul.

 

[ktm_paul]

As part of a motorcycle project im looking at using Turnigy 5S 5aH Lipo packs. I was going to put 4 packs in series then parallel those chains to make 50aH. Effectively 20S 10P. Iv got 4 packs now for trials.

My plan was to charge/monitor (initially) using two icharger 1010b+ units. If inputs/outputs are isolated i could charge without disconnecting the 20S into two 10s packs. Otherwise I will need to disconnect the 20S into two 10S packs for charging (and possibly monitoring).

So my questions:
- is above logic right?
- are the icharger 1010b+ inputs/outputs isolated? (manual does not say)
- can I test isolation by a conductivity test on the negative terminals? (am away on holidays so cannot do this test)
- is there a mechanical switch that I could use if i need to separate the 20s into two 10s? Would not be under load when i need to open it. Or maybe a connector that can handle up to 400-500A bursts?

Tips appreciated!

Thanks in advance, paul.

are there any other icharger 1010b+ users?

wisdom and thoughts appreciated!

 

[ktm_paul]

For those who are interested - the 1010b+ is NOT isolated but is 'safe' to use for monitoring without isolation according to jun si. so i guess its a contactor to separate the packs for charging...

 

[mikehains]

How long are you thinking it will take to charge a 20S 10P pack, with 10A from a 1010B+ ?

I have a 10S 4P pack, and don't want to live with the 1010B+ (too long to charge, and way too long to balance).

I've arranged a CC-CV power supply for 26A at 48V (Meanwell RSP-1000-48). These are superb power supplies, with a good rap.

I'm now arranging shunt balancers similar to those by Goodrum and Fetcher's thread. I note that Mr Goodrum (Gary ?) has posted recently in the Turnigy/Lipo thread about a Lipo Charge Balancer he's created ... that looks superb ... and is scaleable.

Mike

 

[GGoodrum]

There's no problem using the 1010Bs in series, if they are driven by two independent AC supplies that are isolated. I agree, though, it will take eons to charge and balance a big pack like this.

I've got my balancer working pretty well, but even with "only" three packs in parallel (12s3p 45V/15Ah...), with the shunts set at 350mA, it takes quite awhile to get them completely balanced. If you don't charge all the way to 4.2V per cell, and don't discharge down below about 20%, the cells will stay pretty well balanced, but over time, this will change. Anyway, on the next one I do I might go back to at least 1/2A.

I'm also going to make a few other changes. The cell circuit can be simplified by removing the logic that keeps the LED off below 3.80V. I originally was doing this as a full BMS, and so the circuit would have to be connected to the cells all the time. For the balancer, this doesn't matter, so I was able to eliminate four parts per channel. I also played around with the divider values, in order to reduce the full-on shut voltage to about 4.15V. It initially was too low, but then I picked a set that was a bit high, at 4.19V. the lower value is better on the cells, but the main reason I did it was to make sure the high cell don't go too high, before the charger/supply's CV mode kicks in. For now, I'm not using the throttling circuit, to cutoff the charge current when a cell goes to high. It seems that with these high-C LiPo cells, it takes longer for the voltage to drop back under the cutoff voltage, so the FET controlling the charge current stays off longer. As soon as the first cell hit the cutoff, it caused the rest to not get the full shunt current. So, what I did was lower the cutoff voltage, and let the high cells overrun a bit, but they are still under 4.20V. This lets the low cells catch up faster.

Fechter is looking at a replacement for the throttling logic, for the regular BMS board, based on using a PWM chip to control the current, so as soon as he sorts this out, I'll do a new version of the balancer that includes the new charger control section.

-- Gary

 

[ktm_paul]

How long are you thinking it will take to charge a 20S 10P pack, with 10A from a 1010B+ ?

I have a 10S 4P pack, and don't want to live with the 1010B+ (too long to charge, and way too long to balance).

I've arranged a CC-CV power supply for 26A at 48V (Meanwell RSP-1000-48). These are superb power supplies, with a good rap.

I'm now arranging shunt balancers similar to those by Goodrum and Fetcher's thread. I note that Mr Goodrum (Gary ?) has posted recently in the Turnigy/Lipo thread about a Lipo Charge Balancer he's created ... that looks superb ... and is scaleable.

Mike

discharge to 20% then charge to 100%:

(40aH x 74V * 0.8 )/ ( 2 * 300) = 4 hours.

Not great to live with but OK for experimentation.

 

[ktm_paul]

There's no problem using the 1010Bs in series, if they are driven by two independent AC supplies that are isolated. I agree, though, it will take eons to charge and balance a big pack like this.

-- Gary

But isnt there a problem with a potential short if the inputs/outputs of each charger are not isolated? Will the 1010b+ balance properly on a floating voltage (effectively 37V to 74V)?

Sorry - if this is a stupid question.

paul.

 

[rhitee05]

But isnt there a problem with a potential short if the inputs/outputs of each charger are not isolated? Will the 1010b+ balance properly on a floating voltage (effectively 37V to 74V)?

Not a stupid question. What Gary meant is that, in order to drive two 1010B's in series (or generally, any chargers in series) are two independent, isolated AC-DC power supplies. Isolated means that the AC and DC sides of the power supply don't share a common ground. If you connect the two AC-DC/1010B pairs in series, the DC ground of the upper power supply will float to whatever mid-pack voltage is (37V in your case). If the grounds weren't isolated, you'd be shorting half your pack to ground and that would be really bad.

 

[ktm_paul]

But isnt there a problem with a potential short if the inputs/outputs of each charger are not isolated? Will the 1010b+ balance properly on a floating voltage (effectively 37V to 74V)?

Not a stupid question. What Gary meant is that, in order to drive two 1010B's in series (or generally, any chargers in series) are two independent, isolated AC-DC power supplies. Isolated means that the AC and DC sides of the power supply don't share a common ground. If you connect the two AC-DC/1010B pairs in series, the DC ground of the upper power supply will float to whatever mid-pack voltage is (37V in your case). If the grounds weren't isolated, you'd be shorting half your pack to ground and that would be really bad.

It turns out I plan on using two P350 power supplies from Jun Si (http://www.hillrc.com/UploadFiles/P350.pdf)

How can I know if they are isolated? Wouldnt they have to be for AC/DC power supply?

 

[rhitee05]

Wouldnt they have to be for AC/DC power supply?

Most are, but they don't have to be. It just depends on whether internally the DC ground is connected to the input ground (earth ground). It's a little cheaper and easier to build non-isolated, but isolated allows more freedom with the output (like your usage). There's very little difference in the circuit, but if you want to give an isolation spec, the layout has to have certain spacings, the components you use have to have their own isolation specs, etc. Hoops someone making low-budget supplies for certain applications might not want to bother with.

How can I know if they are isolated?

Generally, the data/spec sheet should say. Here's an example of a Meanwell 24V supply:

http://www.meanwell.com/search/RS-150/default.htm

If you look down a bit under the "Safety and EMC" section there's an item for "Isolation Resistance". That's a tip-off, and the spec here says it's good for up to 500V (meaning your DC ground could be floating up to 500V above earth ground, or 500V below). Sometimes they'll outright say it's isolated as one of the features.

Looked at your spec sheet and it doesn't seem to say anything. Safe course would be to e-mail and ask them. Or, if you already have a supply you're not sure about, you should be able to measure the resistance between the output V- and AC or earth ground. If it's isolated, it'll be really high, probably so high your meter says open. Non-isolated would be ~0 ohms.

 

[ktm_paul]

That is _extremely_ helpful - thanks. That clarifies a lot of ideas for me.

Unfortunately I have already ordered the power supplies - and the supply is in the mail - so I will both ask the company now and test once they arrive.

 

[rhitee05]

Glad to be of help.

As a backup plan, if you get them and they don't seem to be isolated, there is a plan B. If you can find a 1:1 AC isolation transformer, that would let you make the upper supply isolated. It would have to be a pretty beefy transformer, rated for the full input current of those supplies, 3 A or so. If you use that transformer to connect the AC line and neutral from the wall to the supply, it will isolate it from the external ground (neutral is "sort of" ground for household power). Just make sure not to connect the AC ground wire to anything on that supply. It won't exactly be UL-rated, but it should be sufficient for your application, keeping in mind that the chassis and "ground" of that upper supply will now be at 37V!

It could take some work to find a suitable transformer, though. Isolation transformers are pretty common for low-power stuff like audio, but not so much for power. With some searching you should be able to find something if you need it. It is possible to build your own, but that's a whole other can of worms... :?

 

[ktm_paul]

Glad to be of help.

As a backup plan, if you get them and they don't seem to be isolated, there is a plan B. If you can find a 1:1 AC isolation transformer, that would let you make the upper supply isolated. It would have to be a pretty beefy transformer, rated for the full input current of those supplies, 3 A or so. If you use that transformer to connect the AC line and neutral from the wall to the supply, it will isolate it from the external ground (neutral is "sort of" ground for household power). Just make sure not to connect the AC ground wire to anything on that supply. It won't exactly be UL-rated, but it should be sufficient for your application, keeping in mind that the chassis and "ground" of that upper supply will now be at 37V!

It could take some work to find a suitable transformer, though. Isolation transformers are pretty common for low-power stuff like audio, but not so much for power. With some searching you should be able to find something if you need it. It is possible to build your own, but that's a whole other can of worms... :?

I think as a backup ill just use a contactor to seperate the packs... iv got an extra ev200 and i think i can find space for it on my motorcycle conversion. then i guess it is safe to connect each 1010b+ to its own P350 and then to the mains...

i do hope the P350 power supplies are isolated though...

 

[ktm_paul]

Got an answer from the manufacturer:

"Our engineer has do this experiment according to your description, and it works.

The P350 power supplies are isolated, but since there is a 0.01μ static bleed capacitance to ground wire, and we are not sure if there is some risk. In this way, we still suggest you'd better split your pack for charging."

What does it mean?

 

[ktm_paul]

rhitee05/gary - is this isolated? Diagram from the 'engineer' at icharger...