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Discussion Starter · #1 ·
I don't understand why there is no mention of these batteries on the forum. I did a search for GBS and nothing pops up.

I bought 60 of the GBS 100AH and I have been testing them for capacity at a C/5 rate (20A). Of the 14 I have tested so far the lowest is 101.2AH and the highest is 105.4AH. They have been mentioned on EVTV and are the most different of the prismatic cells. The chemistry is listed as LiFeMnPo4 so there is probably a pinch of manganese in the mix. From a charging and discharging standpoint they are treated just like all the other LFP cells. Out of the box the voltage is 3.3042 to 3.3078 (for these 14 cells) so like the other brands where people bothered to measure out of the box they seem to be almost exactly at a 50% SOC. I have been charging them at 40A to 3.65V (stopping the charge at 2A) and discharging them at 20A to 2.7V. I basically get one per day done. I need to come up with some way to do a 1C or 2C discharge. I can already up the charge rate to 160 amps if I want to but I don't have a way to monitor the current at that level so I might take it to 80A. The discharge and charge curves are quite flat. I will post a plot later.

There are physical differences with these cells. The terminals are flat plates about an inch square and use 4 screws to hold the strap to the plate. With just 2 screws in place the straps cannot rotate and make contact where they shouldn't. The screws are stainless button caps with M4x0.7 thread and 10mm long. They come with a washer and split ring lock washer. The conductive straps used to tie the batteries together are supposed to be silver plated copper. I would call this tin plate and the quality is excellent. They have four of these straps stacked together to carry the high currents. The batteries come strapped four together with an aluminum extrusion endcap and four stainless straps. There is a carrying cord on each end. The terminals are protected with a snap on plastic cover so no connections are visible with the covers in place. The covers have break out tabs for strap access.


I bought the batteries from www.evolveelectrics.com and since they had them in stock they showed up via Fedex ground in 2 days. To me this was worth the extra I had to pay.

Each cell also has a serial number. All the ones I have unpacked start with 110620 which is clearly a date code indicating a June 20 2011 manufacture date. There are 5 more digits after that.

The outside of the cases are ribbed but they also have little alignment pins and dimples molded into them. They sort of Lego together.

The above is the good stuff. I want to preface the rest with the fact that I am very happy with my purchase so far.

The bad stuff is the provided stainless steel button head screws look nice but are pretty soft. They have a 2.5mm socket in the head which I have stripped out trying to take the screws out (a few times). The threads are also not so good. I went to the local hardware store and bought 10 replacements and some different kinds of heads to see what I liked. The provided screws and the replacement button head screws look the best but even the replacements will strip out. I have a snapon torque meter in (in-lbs from 0 to 30). The factory screws strip from 8-12 in-lbs (usually closer to 8). The hardware store replacements will torque to 18 in-lbs a couple of times but eventually will strip out. The stainless socket heads have a 3mm socket and these will max out my torque gauge. I also tried a hex head screw which has a 7mm head. This is what I decided to change to. I also decided to switch to the Nord-Lock (wedge washers). They are kind of pricey but this is one area of the conversion I just don't want to have problems with. A high resistance contact on a battery terminal can ruin that cell. I have not determined what torque to use yet. It looks like from Nord-Lock's web site 17.5 in-lb is sort of the minimum. I've been going to 18 in-lb and I don't seem to be too close to the yield on the threads in the aluminum but the Nord-Locks aren't really locking at this point either. I expect 19 or 20 in-lb will be the point where they start to work properly. I wish the vendors would provide a maximum torque specification.

The terminal pads are not spaced equidistant from the sides and the ends of the cells. This means that a shorter terminal strap is required to connect cells end to end than side to side. This was pretty shortsighted. I would have gone out of my way to make those dimensions the same (its only off by an eighth of an inch or so). I would also have made the length and width a factor of 2 so the cells could be stacked either way. It is not that far off. The 60AH is the same length and width but shorter. This let them use the same terminal straps and the same four cell strapping system.

I am planning on 56 cells giving a nominal pack size of 17.9kwh. I will have four spares one of which I expect to do some sort of accelerated life cycle test. This will prove impractical unless I can automate the testing and do at least 8 cycles per day. I will pick out the worst four of the lot based on capacity. I will probably charge one up fully, discharge one to 2.7V and the third put back to 3.30V and store them this way to see how that affects them. Not sure how often I will test them. In saving out the worst cells I am making an assumption that the cells in the car will age faster than ones sitting in the box. Thus giving me a better balance in a couple of years when I might need to replace a cell for whatever reason.
 

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GBS cells have been mentioned here before, I think its their higher expense that leaves their popularity in use and on the forum to be lower. There is a boat manufacturer that makes a small jet-ski type boat with those cells. I talked to the guy at their booth and he told me that they were considering Valence and asked me if I knew anything about them. I told him that I didn't think Valence were accessible for DIY. I read here that with enough airflow through one of these http://www.harborfreight.com/500-amp-carbon-pile-load-tester-91129.html you can push 300 amps through it continuously. Its rated for 15 seconds of load and a long wait period between tests but there was someone here who said it did the job for a single cell with enough air going through it. They usually go for $70 or $80 but I just snatched one a cuople months back to cycle some cells but I'm only cycling 100 amps or less because I'm testing very small cells.
 

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You can't search on the forum for any word under 4 letters. You should have gotten a message to that effect. This can be a real pain as many important terms exist primarily in abbreviation form (AC, DC, DIY, EV). Google does not have such restrictions, and is also usually better at searching for exact phrases.
 

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Hi Doug. Thanks for taking the time in analysing these cells.

Are you able to test voltage sag under load to determine their C rate. Also would be interested to know the average capacity at 1C rate.
 

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Discussion Starter · #8 ·
Hi Doug. Thanks for taking the time in analysing these cells.

Are you able to test voltage sag under load to determine their C rate. Also would be interested to know the average capacity at 1C rate.
I am doing the tests I am doing to satisfy my own curiosity and so I have something to compare against several years from now.

I am using a CBA III and it is not really capable of doing even a 25 amp discharge reliably although they claim 100 watts continuous. At the moment it gives a decent measure of AH at 20 amps (C/5). The recorded voltage is about 0.2V low due to voltage drop in the wires and connectors to the CBA III.

I will probably upgrade my test bench so I can do 150A to 200A discharges and record the results properly. But the C/5 tests are good enough for this initial peek into the cells. There just isn't enough time to make all the neat toys so I'll have to wait for someone to sell the right thing on Ebay.
 

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The terminal pads are not spaced equidistant from the sides and the ends of the cells. This means that a shorter terminal strap is required to connect cells end to end than side to side. This was pretty shortsighted. I would have gone out of my way to make those dimensions the same (its only off by an eighth of an inch or so). I would also have made the length and width a factor of 2 so the cells could be stacked either way. It is not that far off. The 60AH is the same length and width but shorter. This let them use the same terminal straps and the same four cell strapping system.
Anyone know of a source for the terminal straps? Would love some braided ones like EVTV sells for the other "old fashioned TS" types. But for GBS cell, I have done the "googlage" and come up with zippo. Even just blank squares with the 4 holes so I can make the HV cable connects and cell interconnects would be fine. If not I guess I'll have to bite the bullet and fab em myself:confused:...
 

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I'd recommend reading the specs and finding what size you need. Many of the manufacturers use pretty standard sizes, so the straps aren't really TS or GBS specific, but are usually specific to a given cell size/orientation.
 

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Anyone know of a source for the terminal straps? Would love some braided ones like EVTV sells for the other "old fashioned TS" types. But for GBS cell, I have done the "googlage" and come up with zippo. Even just blank squares with the 4 holes so I can make the HV cable connects and cell interconnects would be fine. If not I guess I'll have to bite the bullet and fab em myself:confused:...
The person who sold you the cells should have them, or anyone else who sells the cells. The connection is proprietary and specific to the GB Systems cells and that could be a bit of a challenge if you want to fab 4 holes for every connection on each batteries. That's quite a bit of drill and tapping.
 

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The person who sold you the cells should have them, or anyone else who sells the cells. The connection is proprietary and specific to the GB Systems cells and that could be a bit of a challenge if you want to fab 4 holes for every connection on each batteries. That's quite a bit of drill and tapping.
Exactly why I asked. I've done it before and don't fancy the idea of making them if I can help it. Just heard from my supplier that they should have come with but are on the way. Thanks for the response.
 

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You can also get a distributed BMS for the GBS cells directly from Elite Power Solutions. (One cell board per cell.) They sell it at a loss, just to owners of GBS cells, just to sell their cells, so you can get it at a good price (digital, $ 870). Though I am not sure if they'll sell it to you after you buy their cells from a reseller.

If that doesn't work out, the only distributed BMS that works with those cells is the Lithiumate Lite. (digital, $ 810)

Otherwise, any non-distributed BMS will work, such as Orion (digital, $ 1010) or MiniBMS (analog, $ 726).

Prices are for 56 cells, and come from the Li-ion BMS selector.
 

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You can also get a distributed BMS for the GBS cells directly from Elite Power Solutions. (One cell board per cell.) They sell it at a loss, just to owners of GBS cells, just to sell their cells, so you can get it at a good price (digital, $ 870). Though I am not sure if they'll sell it to you after you buy their cells from a reseller.

If that doesn't work out, the only distributed BMS that works with those cells is the Lithiumate Lite. (digital, $ 810)

Otherwise, any non-distributed BMS will work, such as Orion (digital, $ 1010) or MiniBMS (analog, $ 726).

Prices are for 56 cells, and come from the Li-ion BMS selector.
Got the Lithiumate Lite with the cells from Justin at Evolve, which I should be receiving any day. Had experience with Elithion before in some PHEV conversions and it fit the bill for this job. The owner of this conversion wants a "set it and forget it" setup. Otherwise I would probably have steered him at the Orion which I really wanted to get my hands on. How can you pass up the Android interface? Someday I'll get one for myself when the wife is looking the other way...
 

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Discussion Starter · #16 ·
Anyone know of a source for the terminal straps? Would love some braided ones like EVTV sells for the other "old fashioned TS" types. But for GBS cell, I have done the "googlage" and come up with zippo. Even just blank squares with the 4 holes so I can make the HV cable connects and cell interconnects would be fine. If not I guess I'll have to bite the bullet and fab em myself:confused:...
You should contact the place where you got the cells. I got mine from Evolve Electric and they provided the straps I needed.

A braided version would be nice but normally you use 4 of these thin plates stacked and because they are fairly thin they bend and flex reasonably well.

For the external battery cable I used 1/8" copper bar stock and drilled the four holes for the terminal post and then a 5/16" hole on the other end for the cable lug to attach to. I am considering tin plating them when I am done making them but with noalox it probably wouldn't be necessary.
 

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Was a function of cost for this guy so we went with the Lite. I have an older pro (2009 ish) in my Prius with just a DB9 connector.

Also while you're here... In looking at the Lite when it shipped I noticed the current sensor is to narrow for a 2/0 cable to pass through. I am planning on making a short bar to fit. Is that what you would suggest? Or go bigger on the sensor?
 
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