Building a Charger for a 180v Lithium Citroen Berlingo

[whereswally606]

I thought I would need to good advice on how best to do this.

My friend Tim has a Long range Citroen Berlingo Converted from original Nicads to Lithium.

His charger at the moment is good for 10amps but to completely charge the pack takes days.

We would like to build a charger which can do 25 to 30 amps.

at the moment we have 10 to 15 hp esp113 server supplies, ready to be modded.

I have already built one fecther limiter board so i know how to do that and set it up. (for this project we may need two and two meanwell 24v 30amps for the compliance)

the other idea we had was to reuse the old Nicad charger which sits dormant in the car and adjust it to do the job of the meanwells. Wondering whether this would be ok?

Other issue is using diodes. Talking to Peter Perkins a while back he said it would be a good idea to have diodes top and bottom at twice the voltage and capable of the amps

the other thing i read from richard fecthers thread was that diode between supplies is a good idea to prevent the stack driving a charger backward if one were to fail.

Question is what size diodes do i need between the psus (the esp 113 ie running 12v 30 amps)?

Thanks for your help and I will do some pictures of the build when we have some.

 

[whereswally606]

Another idea to throw in the mix with the: nicad charger vs two meanwells with v3 limiters vs (new idea)

New idea

Is it possible to run an RC charger in series with the floated DC ground 12v server supplies running in a non- balanced mode?

icharger 3010B will do 30 amps and 12S life

does this have the potential to work?

nice bonus about this is then we will have a decent balancer to balance sections of the 51cells a bit at a time.

 

[dnmun]

i would assume that the balancing charger has current limiting in each stage so the entire thing would be current limited and you could then move the balancing charge down the string of meanwells if the final voltage of each section that the meanwells spanned was the final voltage that the meanwell is set to. but i now think the meanwells would need to be current limited in each section if you do.

the only effective way to do that would be to set each meanwell to a voltage equal to the total voltage on the balancing charger, and then the TOTAL number of cells in series would have to be a multiple exactly of the balancing charger say 14S, and it's final voltage, and the meanwells would also be identical in voltage to the number of cells that they span. no other way i can imagine it working or the voltages on different sections would not work. hope that makes sense.

to summarize, the total number of cells in the series would be a multiple of the balancing charger ports. so a 14S balancing charger would need 28S or 42S, and a 10S balancing charger would need 20S or 30S. and the meanwell final voltage would be equal to the 4.12X14S or 57.68V. using that as the setpoint for the balancer.

edit this, i think you would need to current limit the meanwells in each section also because the meanwell would try to charge the section it spanned at the max current, so the power supply section would be charging faster than the balance charger.

for a 51S pack the balancer would be 17S and the lifepo4 charger or power supplies in series would be a 17S multiple of the 3.65V setpoint of the balancer, or 62.05V which the 48V meanwell can do. the 17S balancer could be a 12S and 5S balancer in series too.

 

[knighty]

the pack must be pretty big for a small van like that ? a good few hundred amp hours, if not 1000+ ?

would it not be best to use any kind of normal transformer to build a bulk charger... and to charge with that first, and then switch over to your balance charging after ?

(something like a modded forklift charger?)

charge up to 180volts with that, and then finish off with the balance chargers ? (or whatever voltage suits it, a simple transformer charger will self limit) you could even charge with them both at the same time ?

where are you going to plug it in ?

seeing as you're in the uk (like me) a normal plug will limit you to 13amps 240volts, or about 16amps charging at 180volts

so you really want a new socket put in for it... (does he have one already?)

it shouldn't be hard to buy (or make/mod) a transformer to put out 180volts... and the nice thing about a transformer is you don't need to do anything fancy to stop it overcharging the pack... it'll just try to put out a constant 180v (or whatever you want) and charge at whatever rate suits the battery.. as the voltage starts to clime the charge rate will fall... until it stops


EDIT:
thinking about it... does he have a higher output socket to plug it into ? or is he having one put in ? when I was talking about a big transformer I was thinking you could run a big one and output 100amps etc.. to do the bulk part of the charge... (I'm assuming the pack is big enough to take that) but now I've just realised there's no way he'll be able to power that at home... 30amps is probably your max... so 15 x server power supplies could do that ?

 

[whereswally606]

OK i think i was not so clear in my last post since I think dnmum misunderstood what i meant.

I have 10 to 15 esp113 HP server which are going to supply up to 168.27 volts give or take. (lowest point of charge of 51 cells of lifepo4)

The 2 meanwells with V3 limiters could do the job of raising the voltage from 168.27 to 180v (i am ignoring here about the lowest compliance voltage of

meanwells so in practice the 168.27v supplied by the server supply string will be lower to accommodate the 40% of 24v of a meanwell (9.6v) or (19.2v for two)

168.27-19.2 = 149.07v supplied by the server string (so 12 supplies supplying 12.42v each roughly)

Then the two meanwell 24v supplies which will take the 149.07v and could supply all the way up to 197.7volts which is 3.8 per cell (0.2v too much)

but they will be trimmed to supply only to 180v or 183.6v at the very most.

Finally the business about nicad charger (to prevent needing to buy a couple of meanwells to do the CCCV part of the charge.) this is because there is already a charger in the car from its original design which had nicad batteries. The hope is that we could alter the charging profile, reduce the voltage to what would be required minus the server chargers and up the current output keeping overall power output the same.

And last but not least. Using an RC charger which can do 30 amps and do it in an UNBALANCED way so not requiring to be a multiple/divisor of the cell string number to do the job of either the meanwells or the nicads.

in summary

option one:

12 servers + 2 meanwells

option two:

12 servers + original nicad charger

option three:

12 servers + Icharger 3010b in unbalanced mode?

option fourwe are looking into this)

15 servers and finding the OVP point and use as many limiter boards as needed to stay within compliance of the charger.

hope this clarified the problem

 

[whereswally606]

Knighty:

we are sticking to 30amps to stay below the 13a@240volt limit

and yes this thing has a big pack.

I am really not sure about the transformer idea. If you transform the AC you still need to rectify it for DC. It might be a possibility but if it is why do they sell such expensive chargers £2000 or more for EV's?

 

[knighty]

13amps at 240volts = 3120watts

3120watts at 180volts = 17.33amps

17amps at 180volts is the most you can charge at from a standard 13amp plug (if you want to charge the whole pack at once)

the idea with the transformer was not to fully charge the pack, but to almost charge it and then take over with something else to slowly/cheaply balance charge it

something like a old forklift charger is essentially a big transformer and then a couple of rectifiers after it... (both bits could be had cheap)

my thinking behind that was it would be easy/cheap to build a 100amp bulk charger... but then I realised you wouldn't be able to power that at home


thinking more about it... for the price the pack must have cost him... if I were him I'd buy some proper balance chargers to charge each cell individually (or each parallel block anyway)

 

[Jeremy Harris]

Do you know what the max voltage is for the built in NiCd charger? My guess is that, because the Berlingo used wet NiCd cells originally, that the built in charger won't be a super clever device. All it probably does is charge at a constant current until a set voltage is reached and then either reduce the current or shut off.

This isn't far off what's needed for bulk charging lithium cells, a constant current followed by a shut off once a set voltage has been reached. It might not allow time for balancing, but you can do that periodically with the smaller charger.

If it were me, then I'd be looking at taking the built in charger out and seeing what can be done with it. IIRC, it's quite a beast, and needs a 16A mains connection, rather than a 13A standard one. There were a few scrap Berlingo Electriques floating around the Southampton area a while ago, when a council got rid of a small fleet they had. I don't know what happened to them but I heard that some ended up in scrapyards - might be a source for a charger or two to play with, to avoid blowing up the one in the converted van.

 

[whereswally606]

yeah it dawned on me we might need a higher amp socket from what knighty was saying.

Also his cells stay in pretty good balance so that is not really an issue at the moment. about scrap berlingos i think they are had to find these days since the new one is coming out in 2013 so its harder to do a internet search for it now. we will look at that as an option for sure, but a bit worried about how integrated it might be.

Thanks for the look in jeremy, knighty and dnmum, Tim and I really appreciate it.

 

[Jeremy Harris]

My gut feeling is that the Berling Electrique wasn't that integrated. It was a pretty modular design, from what I recall. with the the exception of the controller that was tied to the energy display, IIRC. I wouldn't be at all surprised to find that the charger is virtually stand-alone, although I'm pretty sure there is some connectivity to the energy display to allow for the different charge state and charge type options to be displayed (I seem to remember that it does some sort of balancing over-charge periodically).

There was a chap in the Battery Vehicle Society who lived somewhere near Basingstoke, I believe, who had a fair bit of expertise with Berlingo's. I have feeling he had more than one and may well know where spares, like chargers, can be had. I left the BVS a couple of years ago, when it all went a bit pear shaped with some nasty interpersonal stuff, and haven't kept up to date with what they are up to, but if they are still going (Peter Perkins would probably know) then my guess is that they would be a good source for info.

 

[knighty]

even an 16ap socket is only going to give you 20charging amps (and only just)

I'd be tempted to go some something like a 32amp socket wired direct into his fuse box
(I had a quick google but couldn't see any for 'home' use... you can always use a 3phase plug and socket, then just leave 2 pins not connected)


will he want to charge away from home ? I guess it would be nice to be able to run an extension lead and charge away from home (at work, friends house etc..)... not really sure how you could easily charge at 2 different rates without using 2 chargers tho...
(unless you could charge half the pack, then the other half?)