pgrange

Yes battery tech is making massive moves pushed along by Ev's. When I started building my battery pack 18650 cells were the way to go. Now lifepo4 has come along and changed the game again. I'm waiting for 26650 (A123) cells to come down in price then I'll make another powerwall based on those.

Hello Tom Chargery have just released a DC contactor that works specifically with the BMS. It only requires the one contactor which works with faults on either the charging and discharging cycles of my Li. The real benefit is that it only consumes 11ma which is a massive improvement on my current setup and simple plug and play install ? Peter

This is interesting. Forgive me I'm completey ignorant when it comes to electronics. Would the 12v my BMS provides to close relays if put through this circuit would it latch a relay closed? Similarly when the BMS cuts the 12v the relay would latch open. Does that make any sense? ?

Peter

I made 8 packs in total so I could swap one out should it need balancing or servicing

Yes it took some time. Each battery was soldered to a cable bus bar and each +ve end has an individual 5A glass fuse. If I did it again I'd invest in a spot welder. That would have sped up the job tenfold.

Yes sorry 500ma is what I should have stated ?

Hello No it doesn't support a pulsed trigger and your correct with both the ssr and 200a relay there is a constant current draw. I do prefer using NO relays and the small current draw I have keeping them open is not an issue for me. I haven't actually measured it but the specs would suggest a draw of around 50ma or 12w. Not an issue for my setup . I use 18650 lipo cells.

For those interested in the Chargery BMS I'll give you a brief run down. I have the BMS8T. The main unit itself incorporates a 1.2A balancing circuit, remote display /programming unit and a current shunt. The main unit has a separate charge and discharge circuit to trigger relays should any of the set paramaters be met. For both charge and discharge circuits parameters can be set such as over /under voltage, over /under current over /under temperature range etc. I have wired my charge /discharge circuits in series using 2 low power solid state relays which in turn trigger a 200A 24v relay. I have tested the unit to disconnect the load at certain points and it works as expected. The voltage and current it measures reflects that of my inverter and is fairly accurate give or take a few milivolts/amps. To measure the temperature the main unit has 2 temp probes that I have placed inside 2 of the packs. Again the accuracy is pretty much bang on. The unit costs just over £100 delivered and comes from China so expect a few issues. The soc accuracy is appalling. You set the kw/h and AH of the pack manually and unit after a number of discharge and charge cycles works out the soc and gives a rather naff graphic displaying it. However it just doesn't work and gives a false reading. I think the issue being I only charge to 4.0v per cell and discharge to 3.6v per cell. The bms looks at this range and assumes that is the full capacity of my packs even though I have programmed the kw/h and AH. It doesn't bother me too much as but I need to set the soc disconnect parameter to 0% to prevent the unit disconnecting my load. All in all it appears to be a solid unit for the money and the safety features work well. Maybe future firmware updates will solve the soc issue. Hope that helps some people here. Peter

So far it seems a nice bit of kit. It incorporates a 1.2A balance circuit so it's essential the packs are balanced beforehand. I top balanced my packs before installing and the Chargery BMS keeps everything balanced nicely. In my case I only have a 45 to 75mv difference between my 7 packs.

Thanks for that. A quick Google shows they do make a 24v version for about £60. So I maybe able to control the field power wire with my voltage relay. Interesting. I'm going to have a deeper look into that. ?

Good morning everyone. I have been reading this thread with interest. I have just installed my diy powerwall made from 420 recycled 18650 cells to form a 7s60p 24v 120A setup. Taking into account the cells are recycled my own tests suggest I have 100A usable. I've installed an Iconica 3KW hybrid inverter together 1000w of solar panels. I'm using a Chargery BMS to look after the Li. The BMS has a number of safety features including the ability to control a relay offering protection against over charging over discharging, high and low temp cut off all configurable. The part of the puzzle I'm having issues with is charging the batteries from the alternator. Reading here it looks like quite a conundrum. I've seen people mention the Sterling AtoB which looks like a nice piece of kit but at £350 a bit pricey for me. My beta marine runs 2 separate alternators so I'm thinking of swapping out the existing 12v for a 24v model and using a simple voltage controlled really to switch the charge on and off. Will this work? I'm not familiar with the workings of an alternator but does it require always being connected to a load? If so could I simply dump the load to a 24v La battery when the Li have hit the correct voltage? All suggestions and help truly appreciated. Many thanks Peter

Just on a side note I read a post on here from some time back that rang bells. Direct from the heater I have 2 T joints which go to my calorifier, one flow one return. Could it be that the heated water is going to the calorifier coil and back to the heater still hot before its had a chance to get to the front of the boat? . The calorifier valves were originally wide open. I have throttled them back as per sea dogs recommendation but I'm unsure by what amount or the method. Thanks Peter

Had a listen to it this morning and yes its clicking away 1 a second if not slightly faster. I'll check the actual amount of fuel it delivers tomorrow when I have more time.

OK thanks Mick I'll give that a go and report back.