Review: 1200W bulk charger from BMS Battery

[Philistine]

I ordered one of these from BMS battery for bulk charging my 20S4P lipo:

http://www.bmsbattery.com/alloy-shell/29-alloy-shell-1200w-lifepo4li-ionlead-acid-battery-ev-charger.html


I ordered it on 19 October, and it arrived today on 3 November. It was very well packaged, was delivered by DHL, and I was emailed a tracking number etc. from BMS promptly, communication on their end was perfect. With delivery the total cost was (Aus)$192.87

Here it is in the flesh:

charger.jpg (89.58 KiB) Viewed 1658 times

To give it some scale, here it is with a Lyen 12 Fet:

Charger2.jpg (93.95 KiB) Viewed 1658 times

It came with Anderson SB50s, which I swapped for PP75s as that is what I had on my battery lines. It didn't come with a power lead, but it is a standard jug lead, and I just used another lead from an old charger.

I set it up to charge my 20S pack, and it worked perfectly. Charged at 11amps, and final charge was spot on.

I had been hoping that the voltage would be adjustable externally, but the display at the front shows volts and amps, with a switch that switches between the two. I realise I could install my own external pot for trimming the voltage, and I may do this as I wouldn't mind turning the final voltage down a bit for prolonging battery life.

Can't say a bad thing about it so far, but we will see how it holds up over time. But for those looking for an out of the box bulk charging solution it is a pretty good option.

[dnmun]

looks like there is a trim pot right behind the grille, just to the left under the 7. but analyze it before adjusting anything to verify the pot is part of the resistor divider that creates the feedback from the output voltage, and not the current.

[neptronix]

You know it's badass if it needs a handle to be carried.

Please do keep us updated. I'm seriously considering using one of these in place of my meanwell now that the ones being sold are not so easy to modify

[keyne]

How's the 1200W charger going? My 900W version from BMS battery (looks almost the same) blew up yesterday for no apparent reason. In the process of trying to get a replacement now

[miuan]

I drilled holes in top cover of mine to gather access to all the important pots for voltage and current. I'm a lucky bastard, none of their chargers have gone puff on me so far. But some came with reversed polarity recently. Also their new 12 fets (KU123) came without thermal paste, I mean wtf...

[Philistine]

How's the 1200W charger going? My 900W version from BMS battery (looks almost the same) blew up yesterday for no apparent reason. In the process of trying to get a replacement now

Good so far, but to be honest I have only used it a limited number of times, because until I trim the voltage down a bit, I don't like charging and letting it go because it takes my (slightly unbalanced) pack a bit too high (because of the unbalanced cells). I would like to knock it down half a volt at least.

I drilled holes in top cover of mine to gather access to all the important pots for voltage and current. I'm a lucky bastard, none of their chargers have gone puff on me so far. But some came with reversed polarity recently. Also their new 12 fets (KU123) came without thermal paste, I mean wtf...

I have yet to open mine up, how do you know which is the voltage trim pot? Does it say inside? Or do you just have to work it out. I can see a bunch of pots in there when I look through the grill (yet to open the top), but do you just attach a multimeter and start cranking away to see which is which (amps/volts etc..) or are they labelled? Also, how far down can you change the voltage? For example, could my 84V charger be turned down far enough on the voltage to also do 15S? What I mean is, how far is the possible voltage range?

[miuan]

Too lazy to open mine up, but theres an array of about 6 blue pots under top cover. 2 of them are for voltage (one coarse, other fine) and same for current.

More can be seen here:
viewtopic.php?f=14&t=29096&start=15

[dnmun]

How's the 1200W charger going? My 900W version from BMS battery (looks almost the same) blew up yesterday for no apparent reason. In the process of trying to get a replacement now

what blew up in it? do you have pictures inside? can you trace the input voltage through the bridge to the transformer?

[NeilP]

Did you ever see what the voltage output range was ?

I am in conversation with BMS at the moment, asking them what the range is, but they do not seem to understand the question. The usual language problem I guess

[Philistine]

Did you ever see what the voltage output range was ?

No, I have yet to adjust the voltage, but I have had discussions with Miuan who has adjusted his to have two pots and a switch to go between two voltages with a switch (rather than adjusting the pot each time). I would suspect that the course voltage would let you move between (say) 50V and 84V, because when they quote you the options of voltage, the amperage is obviously just a function of whatever voltage you choose along all possible voltages to reflect 1200W. So I presume that it is the same charger they sell, they just adjust the voltage and amps between all possible voltage ranges before shipping. I will post up when I get around to opening up to adjust the voltage, but at this stage I just want to adjust it from 84V to 83V, but I will have a play and see what it can do.

But I can confirm it is a good charger, I have been using it to bulk charge 20S and it has worked a charm. I also found postage (cost and time) was perfectly reasonable. I bought from BMS Battery.

[NeilP]

Great, thanks

I have had two mails from Judy at BMS this morning, and so far all they are saying is that they are not adjustable and we are not allowed to do it ourselves...all the usual liability stuff.

Am trying to convince her to give me spec for them, and said that if we had that then there would be many more people would maybe buy them if we knew more about them. So lets just see what happens.

I run a string of up to 10 scrap PC supplies at the moment so i do have a 2kW system at the moment..but it is a bit ungainly

[999zip999]

So if you turn it down to 50v it run 24amps = 1200w. That's charging at 24a. ?

[Philistine]

So if you turn it down to 50v it run 24amps = 1200w. That's charging at 24a. ?

No, it has a current/amp pot as well. But yes you could if you wanted to run it at 24amps when at 50v, but if you are just "modding" the voltage pot, that is all you will change (current/amps) will stay the same.

EDIT: What I was trying to say in my earlier post (I can see your confusion from my post), is that they give these options of different voltages, and then corresponding amps, to meet 1200W, which suggests it is the same charger they sell for 1200W, they just adjust the voltage and amp pot before shipping. This is confirmed by Muian who over in the DocBass thread explicitly says he mods the voltage pot with a switch, to switch between 50V and 84V with the same amps.

[miuan]

While I have successfully adjusted the voltage, I strongly advise against the proposition of 1200W at ANY given voltage. I doubt that all the chargers are the same. There may be 2 or 3 different models for different voltage ranges that use different fets, caps etc. Therefore when I tune the voltage down, I don't raise the amps by same amount, actually I barely ever adjust the current.

[nonlineartom]

Mine just arrived in the post, same success story, less than 3 weeks from ordering to arriving in the UK. Volts are spot on as requested and it came with andersons as requested but I'll swap those for bullets.

I've asked this elsewhere but never got a diffinitive answer, charing a 12s2p pack with this charger will mean that the charger is putting out 50V 24A (roughly), Trunigy Lipo is supposedly rated at 2C charge rate which would mean 20A maximum charge rate, am I going to shorten the life of the pack or risk puffing cells if I'm charging above 2C ?

[Philistine]

Mine just arrived in the post, same success story, less than 3 weeks from ordering to arriving in the UK. Volts are spot on as requested and it came with andersons as requested but I'll swap those for bullets.

I've asked this elsewhere but never got a diffinitive answer, charing a 12s2p pack with this charger will mean that the charger is putting out 50V 24A (roughly), Trunigy Lipo is supposedly rated at 2C charge rate which would mean 20A maximum charge rate, am I going to shorten the life of the pack or risk puffing cells if I'm charging above 2C ?

I presume going over the rated charge C rate would shorten life, but I don't know really what I am talking about, I have often wondered myself what is the uppermost reasonable charge current. It has never been an issue in the past as my chargers have never been able to put out enough current.

You can lower the current with the current pot if you want, and knock it down to (say) 20A.

[NeilP]

Well it is possible that you will, but you are not massively over the 2 C rate.
The other Turnigys I have are rated at 5 C or one pack has a 10C label.

Yes it would be nicer if it was a bit lower..but I would not be worrying too much over it.

For the first couple of charges I would monitor and see what actual current the charge really does put out, as opposed to what it is supposed to put out.

If you see that is is going way to high at start of charge, you could maybe wire a light bulb in series for the first 15 mins of charge, to drop it down a bit to start with.

Or find out if there is an easily adjustabel pot to lower the voltage and or current limit.

if you can find the current pot, then turn that down a bit.

if not then there must be a voltage pot..you could maybe either bring it out to the front so you can lower voltae for start of charge, then up it again as the pack charges, or remove it , measure it and get a second identical one. have one set to a lower value, so you start in one position, and as charge progresses, switch to the main position for topping off

[nonlineartom]

Thanks for that Neil.

I plan to use this for my commuter setup so I don't have to disconnect any of the hardness between charge and discharge, I'll use a pair of battery medics to balance and check the cells, but even after 4 weeks of daily use the packs never go more than -.3V out of whack.

[atom1025]

So I am looking to commit to a purchase of one of these bulk chargers from bms. I want to get some clarity before making my order.

So I have a 15s2p 5000mah 25c pack. My commute eats up 5amps WOT. So I currently must limit Watt usage. I run about 18mph avg. and use 3.5amps each way. So I would like to give it a charge at work. I don't want a full charge just a boost.

When selecting voltage I was thinking 4.1v per cell so 61.5v cutoff sound right.

Now I don't need a quick charge so will the 400w model be fine? Maybe the 600w?

[nonlineartom]

I just used my 1200W charger for the first time just now, here are my observations....


charging 12s 4p pack, 49.8V 20A output. I only just noticed the printed label on the charger itself says 49.8v meaning they really do go the extra effort to mark the charger as per your custom order which is nice. A switch on the front switches between volts view and amps view, a check with the multimeter confirmed it is outputting the correct voltage

Charging through a PP45 connector @ 20A the charger remained cool but the PP45 connector itself got over 40 degrees C. When the fan kicked in it really kicked in, there is a LOT of airflow through this charger, any bits of detritus in the vicinity will be drawn in by the suction of the fan. Charged the pack scarily quickly, I used a pair of battery medics to make sure the cells were staying in check.

General rule from now on, how do you know when you've got a good charger? when you turn it on and the house lights go dim. Aw yeah.

[NeilP]

Well the 600W puts out 8 amps at 60 volts...and the 400w does 5 amps

If you are at work for longer than 1 hour a day, then even the 180W charger will be enough.

You say you use 3.5Ah each way..so the 600 and 400 Watt units will fully charge your pack in less than an hour to full charge

If money is an issue just get the smaller 180 W unit//that will put out 2 amps at 60 volts, so a little less at your required voltage... So a three hour charge will give you a fully charged pack to go home

and they are smaller and weigh less

[NeilP]

General rule from now on, how do you know when you've got a good charger? when you turn it on and the house lights go dim. Aw yeah.

Gulp...hope you are joking..if not you need to re wire your house....1.2kW is still less than a house-hold kettle

I ordered the 2Kw at 148 volt...

How long did yours take to arrive from China?

[nonlineartom]

2 weeks i think from order to arrival, well packaged and the label on top lists the ampage and voltage and polarity of the cables. Can't argue with that can you

[zombiess]

I just ordered one last night after being in a hurry and accidentally touching the wrong two connectors together for a split second. Now today the joy of replacing the connectors. User error on my part and I was being a cheap ass, but now that I run a 30s3p pack reconfiguring for charging is a real pain and error prone. Time to simplify since I'm standardizing on 30s for my bikes.

[nonlineartom]

I've only used mine a handful of times now but I don't regret it at all. I only wish the balancers would work quicker.