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Jump Starter to Reset BMS?

slo88a

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May 4, 2022
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I've just started in the battery world, and I've gotten a SOK LFP 100ah 12v battery and a 2000watt Renogy inverter. I've found that the Renogy inverter immediately trips the battery's BMS when I turn it on with no load. I've downsized to a 1000watt Renogy inverter with the same result. While I need to figure out this inverter issue and find a working startup method, I also need a better way to reset my BMS. Rebooting the BMS is a pain, as the only method I've found is to connect my AIMS charger and a 12v lead battery to the LFP battery so that the charger will recognize 12v and start charging, thus restarting the LFP BMS.

This is not realistic in the field, where I hope to be running loads from my battery/inverter while camping etc, and I may accidentally overload the BMS and have no good way to restart it without AC power and more gear. SO, i'm wondering if a portable jump starter could do the trick. The lead battery alone doesnt seem to reset the BMS, so I think it needs something more. Perhaps one of these? https://www.amazon.com/gp/product/B...&linkId=3954f93148f549f199255d30efd0c052&th=1

Perhaps this will just have the effect of causing the BMS to shutdown due to overcurrent anyway? Is there some more portable method to reset a BMS?
 
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I think something like the Tecmate / Optimate DC-DC 2A TM-500 V3 charger (it has LiFePO4 bms reset) will do a better job and be more convenient in the field.

Not so much to spend days to charge up the 100ah, but just for bms reset. Possibly useful for charging your lead-acid (motorcycle - vehicle top-off etc) from the LFP when you reset the bms and get it working and you reverse the charge! :)

Just make sure that 2A of current is enough for the Renogy bms to actually reset with.
 
A cool idea -- that's in the right direction; however, it also requires an external power source (eg. a car battery). I'm likely going to be taking my battery setup to some far-flung places where getting back to a car would be hard. Anything you've seen with a portable power source?

Also it's an SOK battery, not Renogy, in case that makes any difference. Renogy is the inverter.
 
It's probably the inrush current filling the inverter's capacitors, try a resister to precharge the inverter. Search the forums for precharge resistor and you'll find some recommendations. Lighter than a jump starter anyway (unless you're using a modified version).
 
Yeah thats what I figure for the inverter tripping BMS, and I'm looking into the resistor solution to reduce inrush (thanks!). The issue will be, what if I trip BMS when I'm out camping and have no way to reset BMS without extra gear and an AC power connection?
 
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The issue will be, what if I trip BMS when I'm out camping and have no way to reset BMS without extra gear and an AC power connection?
Hike it back to someone's car? I wouldn't want to carry a battery around just to restart my other battery's BMS. Might be worth calling SOK, possibly there's some other way to restart the BMS?
 
The car battery should be charging at ~14V with a running engine. I believe you can start the engine and connect the LiFePo4 directly to it to "reset" the BMS. That's valid of course if you have a car with you when camping :) .

The other option should be SCC. The BMS should be able to accept charge from SCC. Try with connected SCC and PVs to see if it will "reset" the BMS.
 
True, a car battery restart may work -- thats a good point. However, we may be hauling this setup deep into the woods to play music or something (rather than a generator), so humping back to a car wont be great. Also I dont plan to have solar w/ me since itll be after dark. I figure if I can get one of these small hand-held jump starters, that'd be a fine insurance policy without bringing a big piece of gear.

Any opinions whether this jump starter approach would work at all, or whether its a terrible/dangerous idea?

I have reached out to SOK for another way to reset, though they're so far pretty slow to respond.
 
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I found that using a small LFP battery (like 5 or 10ah) with some simple jumpers did the trick. This battery happened to have a BMS on it, but I'm thinking of getting a raw 5ah battery to keep around for this purpose. Question is -- should that battery have a BMS on it... I wont be using it besides to reset the big battery; however, other things like short circuit protection would be good to have... hmmm
 
I would try to pay attention to avoid tripping the BMS circuit. 100Ah + inverter + AC gadgets is already a pretty decent weight for going "deep into the woods"

If you still decide to go with the additional battery weight - get a battery with BMS.
 
I got one of these little Li battery packs:

https://www.amazon.com/gp/product/B00ME3ZH7C/ref=ppx_yo_dt_b_asin_title_o04_s00?ie=UTF8&psc=1
51AQN0oQpaL._AC_SL1200_.jpg

And attached a small DC-DC buck converter:

https://www.amazon.com/gp/product/B07VNDGFT6/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&th=1
613lo7nJBuL._AC_SL1500_.jpg


The reason for adding the buck converter is I couldn't find a small boost pack that would put out 14.4V consistently which is what is required to reset my SOK BMSs that have bluetooth for a battery that is fully charged @ 13.6V.

If the sun is out, the SCC will reset the batteries, but I had to change my install to use a 1,2,1+2 battery disconnect. I have 2 12V batteries in parallel and if one of them goes into protect, the other one holds the voltage down from any charge source. If I want to reset the other one, I have to unhook it and then apply the reset voltage. That is a PITA. Now I parallel them at the main cutoff switch vs. before. Works like a champ. If the sun is out, I can reset with the SCCs. If I am on shore power, I can reset with the inverter/charger. I can also plug into my truck because I have a Victron DC-DC on the truck charge line. If none of those are available, I use my little jump pack.

Here's my system:

DC wiring 290RL rev 1 tanks.jpg
DC wiring 290RL rev 1 cubby.jpg

You can see the little black box with the red button with the inverter precharge label on it. I have to precharge every time or both batteries will go into protect mode. I sometimes forget. Before the 1,2,1+2 battery main switch, I cursed a lot as I unhooked all the battery cables to get the BMSs to reset. Now, if I have solar, one battery will reset automatically. Then I have to use the 1,2,1+2 switch to isolate and reset the other one.
 
Hi folks. I realize this is my first post here, but have either of you that have the issue with your SOK batteries going into protect mode when you power on your inverter figured out the problem? I am having the same issue with two new SOK 206ah batteries and two different Renogy inverters (1000w & 2000w versions). I pre-charge the inverter caps using Will's recommened procedure with the 25w 30ohm resistor. Check inverter terminals to make sure the caps are fully charged then connect the battery and switch on the inverter......BMS reset dmos every time.
 
Hi folks. I realize this is my first post here, but have either of you that have the issue with your SOK batteries going into protect mode when you power on your inverter figured out the problem? I am having the same issue with two new SOK 206ah batteries and two different Renogy inverters (1000w & 2000w versions). I pre-charge the inverter caps using Will's recommened procedure with the 25w 30ohm resistor. Check inverter terminals to make sure the caps are fully charged then connect the battery and switch on the inverter......BMS reset dmos every time.
I am having the same issue with my 2x12V 206Ah SOKs. They started off with just one going into protect if I forgot to precharge the inverter caps. Now they both go into protect even if I precharge. They are basically junk. So I am going to swap the non-BT BMSs back in. SOK really dorked this one up.
 
I have now went through 3 different brand new Renogy inverters (1-2000w & 2-1000w) thinking the inverters were at fault. I even have a 1500w GIANDEL inverter arriving on Friday to try testing with. I have spoke to Min and explained what I am experiencing and his reply was
; is the battery fully charged, which they have been charged to bms cut off, and he asked that i test with a 12v connection. 12v works fine. I even have a cheapo 200w modified sine wave inverter that works fine. But the renogy inverter resets the bms every dang time, even with pre-charing the caps. Although I will say I also have a 20ah cheapo LFP battery that the renogy will also reset the bms on the same way. I am hoping that maybe the GIANDEL works differently because this is getting old fast. But after hearing from you, I am having my doubts......
 
I've just started in the battery world, and I've gotten a SOK LFP 100ah 12v battery and a 2000watt Renogy inverter. I've found that the Renogy inverter immediately trips the battery's BMS when I turn it on with no load. I've downsized to a 1000watt Renogy inverter with the same result. While I need to figure out this inverter issue and find a working startup method, I also need a better way to reset my BMS. Rebooting the BMS is a pain, as the only method I've found is to connect my AIMS charger and a 12v lead battery to the LFP battery so that the charger will recognize 12v and start charging, thus restarting the LFP BMS.

This is not realistic in the field, where I hope to be running loads from my battery/inverter while camping etc, and I may accidentally overload the BMS and have no good way to restart it without AC power and more gear. SO, i'm wondering if a portable jump starter could do the trick. The lead battery alone doesnt seem to reset the BMS, so I think it needs something more. Perhaps one of these? https://www.amazon.com/gp/product/B...&linkId=3954f93148f549f199255d30efd0c052&th=1

Perhaps this will just have the effect of causing the BMS to shutdown due to overcurrent anyway? Is there some more portable method to reset a BMS?
What I have done to overcome BMS shut-down when I have accidentally tripped a battery usually brought about battery imbalance, is to wire in a switch network driven by a small 12v charger. (Any trickle charger will do). My system is four series connected 12 volt LIPO4 batteries. By wiring positive and negative across each battery via a double pole single throw momentary switch, I can supply enough power to trigger the battery in shut down when I close the switch on the selected battery.
Note: Be careful not to wire across two or more batteries in series. This could cause a serious problem for you when the isolated battery switches on and suddenly you have your 12 volt charger in parallel with a much higher voltage. Things could get very interesting then indeed.
 
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