DIY 48V 10A charger for LiFePO4?

Njay

10 kW
Joined
Sep 9, 2010
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Portugal
I'm at the very early stages of converting a motorcycle. I can't find a 48V10A (~480W) on-board charger for a 16 LiFePO4 (TS) pack for less than 130€ to my door, buying directly from China. What really pisses me off is that I can buy a 600W PC power supply for less than 30€ at the store nearby. I'm in Europe.

So I've been wondering: how about building a DC-DC converter to connect to a standard PC power supply to get the 48V10A charger? I would like to know what you guys think of this.

The main challenge I see is that the output power of a PC PS is spread over 3.3V, 5V and 12V outputs. So this converter needs to be Multiple Input and Boost. I've looking at PC PSs and some models provide 2 12V outputs of up to 22A, so that is 528W available power. A Multiple Input power section can be built like this:

miboost.jpg
The schematics is just for reference. I've played with this under simulation. The diodes must be replaced because the ones above don't handle the necessary voltage, so I' inclined to use 60CPW150 (2x 150V 30A). There are other possible selections for the MOSFETs, these ones were just available in the simulator - a TO-220 MOSFET with low Rdson should be able to handle the job. There are some "hidden" values in the schematics, the components there are not ideal ones. The switching frequency is 10KHz. The inductors need to withstand at least some 25A. Dissipation on the each MOSFET is bout 4W and on each diode around 3W. This would be all uC controlled to do the temperature, current and voltage limitation.
There are power supplies with 4 12V outputs, one can play with the number of inputs versus power provided versus number of components versus power dissipation on the converter versus... The 5V rail can provide a lot of power too, but it implies dealing with a lot more current.

What do you think about the feasibility of this? Or, do you know of any source of a decent 48V10A charger for a reasonable price in Europe?
 
I've been working on this myself. I understand many of the guys here use meanwell power supplies to a simliar effect. However, some use server power supplies

http://www.serversupply.com/POWER%20SUPPLY/SERVER%20POWER%20SUPPLY/3000WATT%20REDUNDANT/HP-COMPAQ/253232-001.htm

48v 3000w for $30

I'm probably going to use this as a charger, and throw a tiny 10amp 12v or 5v psu in series for current limiting.

or you can ask your local computer recycler if they have anything you can use.


The thing I'm trying to figure out with the server supplies is: how much can the voltage be adjusted and how can we limit the current with out adding to the complexity with an extra psu?
 
auraslip said:
http://www.serversupply.com/POWER%20SUPPLY/SERVER%20POWER%20SUPPLY/3000WATT%20REDUNDANT/HP-COMPAQ/253232-001.htm

48v 3000w for $30

or you can ask your local computer recycler if they have anything you can use.

The thing I'm trying to figure out with the server supplies is: how much can the voltage be adjusted and how can we limit the current!

I bought one of those 3kW redundants - trouble is, needs 200-240VAC to power up. All I have in my apt is 120VAC but I opened it up and do see a trim pot inside. Dunno what it's for and I may never get this working but $30 is cheap date.

OP - 2qty SP-350-27 Meanwells in series should get you 48V and above 10A rate.
 
Njay said:
I can't find a 48V10A (~480W) on-board charger for a 16 LiFePO4 (TS) pack for less than 130€ to my door, buying directly from China


Have you contacted Ecitypower.com? There 400w charger is $45 USD and the 600w is $73 USD and for smaller items like that I image shipping would be no more than $40 or $50. So total for 600w your looking at ~87 euro. I have had pretty good support from them when I got a bad BMS and shipping is fast. I'm in the USA.
 
I bought one of those 3kW redundants - trouble is, needs 200-240VAC to power up. All I have in my apt is 120VAC but I opened it up and do see a trim pot inside. Dunno what it's for and I may never get this working but $30 is cheap date.

Dang... I'll have to find a 110v 48v power supply
 
Humm, those server power supplies sure seem very interesting (we use 230VAC here)... any idea on their dimensions? Couldn't find dimensions spec; this is for an on-board charger so it can't be too big.

Ykick, those SP-350-27 meanwells look good, if only one were enough... 2 of them will have similar price to the 600W ecitypower charger, also coming from China.

I'm aware of ecitypower, magudaman. But let me show you how a good 600W 53.18€ charger & 50A double pole connector at China becomes a 125€ item at my door. Shipping is 42.74€, totally 95.93€. Then the package flies here and is presented at customs. Customs will fill out some paper work and charge me some 3€ for the papers, plus some "customs rights" percentage (I didn't check what's the percentage for this kind of product but let's assume 0%) making it a 98.95€ charger. Then they will apply 23% VAT on top of it all, so now it is a 121.71€ charger. Finally the national postal service will charge me another 3€ for customs work, and therefore I have a 124.71€ charger. Ah! No, wait, the national postal service will not charge me 3€ because ecitypower uses a fast transportation service (price above was for DHL, the cheaper method); DHL (and UPS and others) will charge me some 30€ for customs work (155€ 600W charger after all).

By the way auraslip, been playing a bit with your 12V DC-DC converter, and they're not 12V anymore, now they're 13.8 to charge a 12V battery :). Simple resistor change, most (if not all) such converter/chargers have a feedback on a resistor divider.
 
By the way auraslip, been playing a bit with your 12V DC-DC converter, and they're not 12V anymore, now they're 13.8 to charge a 12V battery :). Simple resistor change, most (if not all) such converter/chargers have a feedback on a resistor divider.

Very cool! I noticed that those units put out only 11.5v and that's fine for most uses, but cranking it up to +13v would make my halogens SUPER bright!

Humm, those server power supplies sure seem very interesting (we use 230VAC here)... any idea on their dimensions? Couldn't find dimensions spec; this is for an on-board charger so it can't be too big.

It's funny because LFP said he uses two of those as portable chargers. I looked up the spec sheet on the servers they are meant for, and the space for the PSU is like 2'x1.5'x5". It's pretty big and would definetley not "mobile." I'm in the same position as you right now. In need of a mobile 48v charger and not wanting to pay crazy shipping from bmsbattery.

It'd be awesome to find a 300-500w (less than 10amps so no current regulation needed) 48v psu that can be adjusted up to 58v. One that runs on 110v and is small enough to carry around.
 
Njay said:
Humm, those server power supplies sure seem very interesting (we use 230VAC here)... any idea on their dimensions? Couldn't find dimensions spec; this is for an on-board charger so it can't be too big.

Ykick, those SP-350-27 meanwells look good, if only one were enough... 2 of them will have similar price to the 600W ecitypower charger, also coming from China.

I'm aware of ecitypower, magudaman. But let me show you how a good 600W 53.18€ charger & 50A double pole connector at China becomes a 125€ item at my door. Shipping is 42.74€, totally 95.93€. Then the package flies here and is presented at customs. Customs will fill out some paper work and charge me some 3€ for the papers, plus some "customs rights" percentage (I didn't check what's the percentage for this kind of product but let's assume 0%) making it a 98.95€ charger. Then they will apply 23% VAT on top of it all, so now it is a 121.71€ charger. Finally the national postal service will charge me another 3€ for customs work, and therefore I have a 124.71€ charger. Ah! No, wait, the national postal service will not charge me 3€ because ecitypower uses a fast transportation service (price above was for DHL, the cheaper method); DHL (and UPS and others) will charge me some 30€ for customs work (155€ 600W charger after all).

By the way auraslip, been playing a bit with your 12V DC-DC converter, and they're not 12V anymore, now they're 13.8 to charge a 12V battery :). Simple resistor change, most (if not all) such converter/chargers have a feedback on a resistor divider.


Holy crap that is terrible! On my next Europe trip I will load up an extra bag filled with just chargers and bring them with me ;)
 
Njay said:
Humm, those server power supplies sure seem very interesting (we use 230VAC here)... any idea on their dimensions? Couldn't find dimensions spec; this is for an on-board charger so it can't be too big.

Ykick, those SP-350-27 meanwells look good, if only one were enough... 2 of them will have similar price to the 600W ecitypower charger, also coming from China.

Sorry, I didn't catch the part about onboard charger - 48V 3kW HP server supply I picked isn't anything to carry around. Probably 2ft long and very heavy but it is 57A max.

2qty SP-350-27 MW's in series will provide about 13A charge rate. That's not something you would want to carry with you and it's twice the expense.

However, SP-350-48 should be able to provide 6A maybe 7A from a single package. That's pretty fast charge time compared to what most of us were using a year ago and I've carried it around in my backpack a few times. It wasn't too big or heavy IMO. I wouldn't want to carry 2qty though.
 
Be aware that most of the server PSU's are "hot swop" designs which need a control voltage signal to power up the outputs.
Not a big deal , but you will need to figure out the "pin out" logic to find the control signal pins in the multi pin connector.
I have some Dell DPS 500CB PSU's that are 500w (12.6v, 41A ) that work fine , but it took a bit of searching to find the right combination of pins to jumper.

25237395-260x260-0-0_Dell+DELL+PE2650+POWER+SUPPLY.jpg
 
Ykick said:
However, SP-350-48 should be able to provide 6A maybe 7A from a single package. That's pretty fast charge time compared to what most of us were using a year ago and I've carried it around in my backpack a few times.

Well, you see, this is to charge a 3KWh pack, 10A is already a bit slow. The pack is 48V 60Ah, at 10A that's already at least 6h for charging.
 
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