Most cost effective 12v highest a/h lithium battery setup.
- Thread starter eHomer
- Start date
Thanks for the Hobbyking popup tip DrSolly.
I remember seeing it pop up once a few weeks ago, but didn't have any idea of what I wanted to get then. I've tried lurking on the page again, no luck so far, but I will persevere !
I've been collating all the comments and advice on this, and it seems that there's now the possibility of an all-Hobbyking UK supply source now, except the lipo alarm, which I've just bought anyway. (amazingly compact size, much smaller than I thought it would be from the photos).
A Hobbyking parallel charging board was suggested by DrSolly earlier in the thread, so I've amended my schematic to include that instead. Would it suffice in the same way as the direct Chinese supplied ebay one you had suggested Dave ?
So I think that's all the parts needed, aside from the 12v mains supply for the charger ?
I think I could fit the cell packs, balance board and alarm in a waterproof container quite neatly, and just leave the pos and neg output terminals as bolt heads through the case, so that my outboard could be easily connected by it's crocodile clips.
30ah at 14.8 volts weighing about 3.5kg and a recharge cycle count much higher than SLA batteries.
I remember seeing it pop up once a few weeks ago, but didn't have any idea of what I wanted to get then. I've tried lurking on the page again, no luck so far, but I will persevere !
I've been collating all the comments and advice on this, and it seems that there's now the possibility of an all-Hobbyking UK supply source now, except the lipo alarm, which I've just bought anyway. (amazingly compact size, much smaller than I thought it would be from the photos).
A Hobbyking parallel charging board was suggested by DrSolly earlier in the thread, so I've amended my schematic to include that instead. Would it suffice in the same way as the direct Chinese supplied ebay one you had suggested Dave ?
So I think that's all the parts needed, aside from the 12v mains supply for the charger ?
I think I could fit the cell packs, balance board and alarm in a waterproof container quite neatly, and just leave the pos and neg output terminals as bolt heads through the case, so that my outboard could be easily connected by it's crocodile clips.
30ah at 14.8 volts weighing about 3.5kg and a recharge cycle count much higher than SLA batteries.
D
Deleted member 4366
Guest
Nearly sorted. The only thing I'm wondering about is whether with that Hobbyking board, you can get at the tracks to reinforce them. They seem to be on the top side under the solder-resist. There may be access to the connectors at the back. I think I'd go with the Ebay one, which is a known quantity. I see Hobbyking do that type, but not with Deans connectors. It's always the way!
I can see your point about free access from below to the main bus tracks.
I've googled "dean" connector, so I can see they're the red output connectors down the middle across the bus, but I'm confused by the ebay photo. I can't see any cable entry holes, are they blank covers, or plugs, ready to be soldered to the battery leads ?
The Hobbyking battery packs are fitted with 4mm bullet connectors, so I suppose they have to be cut off and replaced with Deans ?
Also, why has the ebay balance board got two 7 pin balance connectors on the end, and 7 Dean plugs down the centre instead of six ?
Are they possibly for daisy chaining another parallel board ?
I've googled "dean" connector, so I can see they're the red output connectors down the middle across the bus, but I'm confused by the ebay photo. I can't see any cable entry holes, are they blank covers, or plugs, ready to be soldered to the battery leads ?
The Hobbyking battery packs are fitted with 4mm bullet connectors, so I suppose they have to be cut off and replaced with Deans ?
Also, why has the ebay balance board got two 7 pin balance connectors on the end, and 7 Dean plugs down the centre instead of six ?
Are they possibly for daisy chaining another parallel board ?
D
Deleted member 4366
Guest
The Ebay board has a removable back, where you have direct access to the tracks. The Hobbyking one is different, but I haven't got one to examine, so I can only go by what's in the photos. You can get that Hobbyking one with T (Deans) connectors too.
On the Ebay one, all the connectors are in parallel. You can do whatever you want with them.
On the Ebay one, all the connectors are in parallel. You can do whatever you want with them.
Are the 6 red deans connectors on the ebay parallel board dummy covers, or plugs that I can solder onto the leads from the battery packs ?
Or would I need to get 6 deans plugs ?
(I can't see any cable entry holes in them.)
(I'm still trying to coax the discount popup on the Hobbyking site )
Or would I need to get 6 deans plugs ?
(I can't see any cable entry holes in them.)
(I'm still trying to coax the discount popup on the Hobbyking site )
D
Deleted member 4366
Guest
They're covers that unclip, because as soon as you connect the first battery, all the others become live, which is why they're covered
Right O, I'll add some Dean's male connectors to my shopping list then Dave.
I hadn't come across those before, but after Googling them and seeing how they're soldered on Youtube, they look straightforward enough, and change the battery pack output bullets connectors.
I hadn't come across those before, but after Googling them and seeing how they're soldered on Youtube, they look straightforward enough, and change the battery pack output bullets connectors.
I'm all set to place the order with Hobbyking, at the full price (can't get the damn popup to appear )
Just one last incentive for me, am I right in thinking that my existing two 12v 14ah SLA batteries in parallel are only giving me 14ah of usable power per charge ? ( am I right in saying that SLA gives 50% discharge per cycle ?)
So these six lightweight Hobbyking 4S Lipos will give me the full 30 a/h ?)
)Just one last incentive for me, am I right in thinking that my existing two 12v 14ah SLA batteries in parallel are only giving me 14ah of usable power per charge ? ( am I right in saying that SLA gives 50% discharge per cycle ?)
So these six lightweight Hobbyking 4S Lipos will give me the full 30 a/h ?)
D
Deleted member 4366
Guest
The SLAs can do more than that, but the lower you go, the faster they wear out. There's no BMS, so unless your motor has LVC, you'd run them down to flat and get the full 28aH. You shouldn't go lower than about 10V, so a voltmeter would help.
D
Deleted member 4366
Guest
All of the parts arrived from Hobbyking very quickly, just a couple of days.
I assembled the six 4s 5 amp packs into a "clip and lock" waterproof lunchbox.
The packs are snugly fitted together, separated by 8mm thick foam sheet, cut from an exercise mat.
All of the output leads are paralleled together and the 4s balance leads, using the balance board.
I tried it with my electric outboard in a test tank, at full speed, and it ran for 65 minutes before the lipo alarm went off, showing that the first bank of cells were down to 3v. (so that's the first cell of each 4s pack, paralleled up to 6p, via the balance board. The other three banks were still showing 3.5 volts, and they all started at 3.8v.
I've put the charger on in balance charge mode, 4s, and set the current at 0.5 amps, (trying to be very cautious here !) It's been on for a couple of hours now, and the balance display shows all four voltages at 3.52 at the moment, so presumably it's levelled out.
I'm getting a little nervous now, and having second thoughts about my 30 amp pack though.
I made the mistake of looking at some of the frightening youtube videos of just one 5amp 4s lipo pack, in a black plastic rectangular case, just like these units. The amount of flame was frightening, and I was thinking that if just one of mine went up, it would set off the other five, and I now have visions of my plastic lunchbox suddenly vaporising, and dropping through my canoe hull like the China syndrome !
I do all of my charging in the garage, with the batteries in my home made fireproof sack, sewn up from a fire blanket folded in half. I've been reading about lipos suddenly going off during use while discharging though, such as dropping below 3v.
The "12v" lithium pack is a great success otherwise, 30 a/h of usable power at around 15 volts, driving my little 12v electric outboard very strongly. The pack in the clip seal box is watertight, with the power take off as bolt studs outside the casing, just like an SLA battery. The 4.5 litre volume of the box even means that it would actually float, just.
I assembled the six 4s 5 amp packs into a "clip and lock" waterproof lunchbox.
The packs are snugly fitted together, separated by 8mm thick foam sheet, cut from an exercise mat.
All of the output leads are paralleled together and the 4s balance leads, using the balance board.
I tried it with my electric outboard in a test tank, at full speed, and it ran for 65 minutes before the lipo alarm went off, showing that the first bank of cells were down to 3v. (so that's the first cell of each 4s pack, paralleled up to 6p, via the balance board. The other three banks were still showing 3.5 volts, and they all started at 3.8v.
I've put the charger on in balance charge mode, 4s, and set the current at 0.5 amps, (trying to be very cautious here !) It's been on for a couple of hours now, and the balance display shows all four voltages at 3.52 at the moment, so presumably it's levelled out.
I'm getting a little nervous now, and having second thoughts about my 30 amp pack though.
I made the mistake of looking at some of the frightening youtube videos of just one 5amp 4s lipo pack, in a black plastic rectangular case, just like these units. The amount of flame was frightening, and I was thinking that if just one of mine went up, it would set off the other five, and I now have visions of my plastic lunchbox suddenly vaporising, and dropping through my canoe hull like the China syndrome !
I do all of my charging in the garage, with the batteries in my home made fireproof sack, sewn up from a fire blanket folded in half. I've been reading about lipos suddenly going off during use while discharging though, such as dropping below 3v.
The "12v" lithium pack is a great success otherwise, 30 a/h of usable power at around 15 volts, driving my little 12v electric outboard very strongly. The pack in the clip seal box is watertight, with the power take off as bolt studs outside the casing, just like an SLA battery. The 4.5 litre volume of the box even means that it would actually float, just.
D
Deleted member 4366
Guest
Confession time...
That photo is actually the mark one version, with Hobby King's parallel balance board with the same connectors as the battery packs.
I wasn't happy with the way the wires laid in there, some were quite taught etc., so I changed things around and built the mark two version.
This is the same box, but dispenses with the balance board and uses two 6 way harness leads to connect all of the packs in parallel. One for the 4s balance leads, and one for the power connections.
I also noticed that some "deluxe" balance boards had individual fuses between the battery pack power leads, so I thought I'd take that as an additional safety precaution, and I incorporated seven blade fuse holders that clip together, one for each pack, and one for the main output. I fitted those new fuses that glow an led when they blow, so it's easy to see if an individual pack fuse does blow.
The "6 way" breakout leads are much easier to run neatly in the plastic box. rather than the parallel board.
As I say my main worry now, is that the six packs are very closely packed together, so I've get 30 a/h of 15 volts that might all go up if just one pack swells and melts.
That photo is actually the mark one version, with Hobby King's parallel balance board with the same connectors as the battery packs.
I wasn't happy with the way the wires laid in there, some were quite taught etc., so I changed things around and built the mark two version.
This is the same box, but dispenses with the balance board and uses two 6 way harness leads to connect all of the packs in parallel. One for the 4s balance leads, and one for the power connections.
I also noticed that some "deluxe" balance boards had individual fuses between the battery pack power leads, so I thought I'd take that as an additional safety precaution, and I incorporated seven blade fuse holders that clip together, one for each pack, and one for the main output. I fitted those new fuses that glow an led when they blow, so it's easy to see if an individual pack fuse does blow.
The "6 way" breakout leads are much easier to run neatly in the plastic box. rather than the parallel board.
As I say my main worry now, is that the six packs are very closely packed together, so I've get 30 a/h of 15 volts that might all go up if just one pack swells and melts.
Last edited:
D
Deleted member 4366
Guest
If possible, you should set your lipo alarm higher. They drop very very quickly once they go below about 3.5v per cell. Just running for an extra minute after 3.0v can brick them. If you can, keep them between 4.15v and 3.6v for long life.
Well I was very wrong there then, I was going by the instructions that came with the charger.
It said for Lipos:
Voltage level 3.7v per cell
max charge voltage 4.2v per cell
allowable fast charge current 1c or less
discharge voltage cut off level 3.0v/cell or higher
I had therefore changed the LVC alarm's low voltage setting to 3 volts.
I'll change it to 3.6 volts as you suggest.
My other mistake then was in assuming that the initial reading of the batteries at around 3.85 volts per cell was that they were fully charged, but if you say 4.15v is a safe max, then my hour's worth of full speed test was with a partly discharged battery.
I've been googling to find any info about charging and using six lipo packs in close proximity, but have found nothing so far.
It said for Lipos:
Voltage level 3.7v per cell
max charge voltage 4.2v per cell
allowable fast charge current 1c or less
discharge voltage cut off level 3.0v/cell or higher
I had therefore changed the LVC alarm's low voltage setting to 3 volts.
I'll change it to 3.6 volts as you suggest.
My other mistake then was in assuming that the initial reading of the batteries at around 3.85 volts per cell was that they were fully charged, but if you say 4.15v is a safe max, then my hour's worth of full speed test was with a partly discharged battery.
I've been googling to find any info about charging and using six lipo packs in close proximity, but have found nothing so far.
Here's the mark two version, with the breakout leads and blade fuse holder.
I've got 30 amp fuses at the moment, but I was thinking of dropping it down to 10 amps for each individual pack, and having a 30 amp for the combined output circuit, do you think that would be about right ?
It seems much safer than leaving all the packs connected to each other unfused.
Here's the balance reading on the charger at the moment, around 3.7v per cell.
I've set it to Lipo 4s, so hopefully it will shut off on or before 4.2v !!
I've got 30 amp fuses at the moment, but I was thinking of dropping it down to 10 amps for each individual pack, and having a 30 amp for the combined output circuit, do you think that would be about right ?
It seems much safer than leaving all the packs connected to each other unfused.
Here's the balance reading on the charger at the moment, around 3.7v per cell.
I've set it to Lipo 4s, so hopefully it will shut off on or before 4.2v !!
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