Power Supply + Charger for S800

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PeterLester

Member
I am still new to this so bear with me:
The S800 comes with 8 - 360watt motors and will use 40A ESCs with power from a 6S Li-Po. With these items in mind I would like to put together a battery charging system starting with a used/surplus server power supply then the appropriate Li-Po charger/conditioner. My immediate focus is to decide what server power supply specs are needed:

My shop is currently setup with 120 VAC via 15 amp breakers. I can upsize my conduit wiring from 14 awg to 12 or 10 and put in 20 amp breakers if required or put in a 2 pole 30 to 40 amp breaker if the server power supply needs 240 volts.

What kind of specs should I be looking for for the surplus server power supply in terms of wattage or amps output at 24 Vdc?
I assume many server PS's allow for 120 or 240 volt AC connection.
 

kloner

kloner

Aerial DP
there are two main ones we all use.... the most bang for the buck is the dell poweredge server ps 700 - 750 watt, it's these

http://www.ebay.com/itm/DELL-PowerE...=US_Server_Power_Supplies&hash=item2a225c5950

theres also an hp version alot of my friends use.....

http://www.tjinguytech.com/my-projects/diy-24v-47a

at the end of the day, you unhook everything inside with 7 screws and replace them with plastic screws and washers to insulate the board from the housing. it keeps them from sparking if they touch. Work great and the price is always right
 

Kilby

Kilby

Active Member
Kloner, do you have a link to the tutorial on how to set those up. I've seen it posted before, but can't seem to fun it now.
 


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PeterLester

Member
Very useful information..... thanks.

If I go with the Dell PE 2850.... do they put out 24 VDC or do I have to pair two to get that?
It is hard to get all the specs on outputs for these from the internet....
In either case will I need to cut or install jumpers to the back or inside to get the required output voltage as is the case with the HP ESP135 PS?
 


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suddenincline

Member
just curious but why do we need these? what are you guys using them for exaxtly?

I'm just confused this is the first time I have seen this.
 

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Pelted

Member
suddenincline said:
just curious but why do we need these? what are you guys using them for exaxtly?

I'm just confused this is the first time I have seen this.
Click to expand...

Ahaha thanks for asking that. I get that the chargers (like the one I just ordered form HK) need a power supply. I guess I don't get the 24v part since the charger/balancer I thought was only 12. If I'm just charging a couple of 4S packs is this overkill?
 

kloner

kloner

Aerial DP
When you get a large charger, something over 250 watt the idea is to parralel charge with it. the charger is 1kw output, it does 30 amps. that takes 6x 5000mah 6s packs and ballance charges all 6 packs in about an hour and a half. if i used 12 volts in, that'd be like a 32-36 amp draw on the outlet. When i feed it 24 volts, it draws around 15-16 amps (within range of US housing code) most outlets are 15 amp breakers

if you have a couple 4s packs, the icharger 206b is great. you can add a balance board later and it'll do 20 amps out and up to 6 cell packs. the icharger lines numbers are the amps out then the max cell, mines 306b, that's 30 amp, 6 cell max. theres also a 106b, more like a thunder 6 or 250 watt charger. The difference between these and the $30 chineese chargers is the quality of the balance charge. it is spot on and never lies. Them thunder chargers eat batteries. icharger also has a feature that reads internal resistance of your packs, that lets you know there health state and to check new packs coming in before you commit to them and add a battery plug. You can see whats up and still send em back, unlike once you've soldered on a deans



it's like any charger, you can turn em down and charge a 1s 250mah pack or you can crank it up and do 30,000 mah at 1c rate.
 
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kloner

kloner

Aerial DP
even using a system like this. between life, kids and what not, this took me 5-6 hours yesterday to charge. if this was one at a time with a 200 watt charger i'd still be going

i.php
 

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PeterLester

Member
To charge a battery you need a couple of additional volts to overcome the battery's internal resistance. For a 14.8 volt battery that can be charged to 16.8 peak volts you will need about 20 volts! Hence a robust 24 VDC power supply is required. Then there is the current requirement needed to get the job done in a reasonable amount of time. When you convert 120 VAC down to 24 VDC there is also some loss of efficiency, i.e., roughly 15%. The rate of charge is amperes * time, i.e., amp-hours or milliamp-hours.

With these factors in mind and a power supply that begins to starve for more current @ 16 amps, a 15 amp household receptacle can't do the job. The 15 amp breaker will trip around 12 to 13 amps load. The purpose of the breaker is simply to protect the house wiring after the breaker from overheating. If you work with two 12 VDC power supplies with outputs wired in series to acquire 24 VDC you can plug each one into a different 120 VAC outlet (each on a separate breaker circuit). In this case each will require only 8 amps makes which is well below the 15 amp breaker trip level. But if you are luck enough to have a 240 VAC subpanel and have wired your 120 VAC downstream circuits with 12 or 10 gauge house wiring, you can simply bump up the subpanel breakers from 15 to 20 amps and use a single 24 VDC power supply to provide the required output power. E=I*R, P=V*I, P=Isq*R.
 

kloner

kloner

Aerial DP
you know i've ran this at home and have 20 amp breakers to full power, but in my trailer at around 23 amp load on the charger she blow my breaker... little travel trailer kinda wiring/breakers.

Most 4 gang outlets use one of each of the 110 leads coming into the house so that splits it across like it was plugged into 220. 7.5 amp draw on each lead, keeps it from being imbalanced. That might not sound important till you run it for 7 hours straight

does canada use 120v 60hz as a standard like us?

I've seen several news stories about houses lighting on fire lately from charging rc batteries. usually an apartment so it's no joke to charge with something like this..... a good garage with 20 amp breakers and 4 gang outlets are all good things to have.
 
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PeterLester

Member
Yes Canada is 120 VAC 60 hertz including 240 VAC for heavy loads including electric range, electric clothes dryers, garage heaters and now for faster recharging of PHEV or Electric vehicles.

Yes I can understand the temptation for individuals into electric RC to discover their 15 amp breaker no longer works properly then substituting it with a new 20 amp breaker from the local hardware store. The breaker is not sized for the load. It is sized only to protect the wiring from overheating. NEC and CEC require a larger wire size to handle 20 amps w/o overheating.
 

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Pelted

Member
Is there any particular reason to have different connectors on my 3s and 4s batteries? The 4s packs I ordered have 4mm bullets and the 3s packs have the XT-60. I'm looking at a balance board from progressiverc and it just seems to make more since to replace the connectors so they are all the same so I do not need different balance board when I'm charging a group of 3s packs or when doing a group of 4s packs. Am I missing something?
 


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PeterLester

Member
Which battery connector

Pelted said:
Is there any particular reason to have different connectors on my 3s and 4s batteries? The 4s packs I ordered have 4mm bullets and the 3s packs have the XT-60. I'm looking at a balance board from progressiverc and it just seems to make more since to replace the connectors so they are all the same so I do not need different balance board when I'm charging a group of 3s packs or when doing a group of 4s packs. Am I missing something?
Click to expand...

IMHO there are several reasons:
1) The primary reason for different connectors is that higher amp-hour batteries need heavier wire and connectors so that they do not get too hot. There is a lot of current moving through these connectors and battery wires during deep cycle recharging and when expending energy at a higher rate.
2) The other reason is that there is not established international standard
3) Parts availability in different countries varies
4) Manufacturers of batteries may also be manufacturing chargers and would like you to buy theirs over others with different plugs.
 

kloner

kloner

Aerial DP
are we all talking about the same thing? your 550 hovers at 20-25 amps, max...... full throttle in atti is about 35 amps

any connector in the planet coming on packs these days does at least 60 amps on a 3s,4s pack that'd fly a 450-550..... xt-60 is a 60 amp rated plug. a 4mm bullet is right about that, maybe more.

1c charge rates are 5 amp on a 5000mah pack,,, were not energizing the time machine
 

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Pelted

Member
Well I get the current rating part, that is pretty obvious but nice to have clarified. I realize there is no "standard" but I want to standardize for my own use. Reading and searching the various forums connector discussions seem to ignite opinion wars on the scale of of religious debate. I think I will stick to XT-60 for my 3s and 4s packs and those brown/red jst connectors for the 2s/1s packs and make this the "Pelted Standard." ahaha.

I don't want to take this topic any further off the OP's question which I hope was answered. I know for me I've now ordered 2 HP power supplies from an ebay supplier. I don't intend to use them in series at the moment, but for the price the 2nd one will be nice to have if I do, but I only have 1 15 amp breaker in my condo's garage so anyway.
 


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