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High voltage alarm?
Hi all, awesome site you've got here!

Anyways, I'm planning on building a 100p14s bank to be charged off solar (60A Mppt controller).

Searching for a suitable cheap BMS is giving me a headache so I was thinking instead of a BMS I could just use low voltage alarms and high voltage alarms to let me know if my pack goes out of balance. Charge at 4.0V and set the alarm to 4.1V

I think I would actually prefer it that way since I can then fix the root of the problem instead of relying on balancing to "safely sweep the problem under the rug".

I've seen a lot of cheap low voltage alarms like these around:

Question is, where do I find equivalent high voltage alarms?

Or maybe it's possible to modify a low voltage alarm to become a high voltage alarm by just switching some wires around?

Seems like it should be fairly trivial to change the direction but I just don't know enough about electronics to even begin to figure that one out...
I'm with you - I employ audio/visual critical event alerts (instead of cut-off) on my APC 7s7p packs. I bought a few of these (that you show above) but they're pretty crude - so I upgraded to ISDT BattGo. The ISDT BattGos are $30 but have hi/low volt audible+visual warnings (beep and red led) and balance and easy to see voltage readings on one screen - an all around nicer package. Have been using 4 of them for a year (continuous) with no problems.

Here's an AMZ listing -
A cheap bms is cheaper and easier tham just getting an Audible alarm.... Bms cost 30usd and Up and have all functionality
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The tenergy cellmeter 6 has low and high voltage alarms, low is programmable to 3 volts, high voltage is set to 4.22 volts (not adjustable), these cost about 12 dollars on amazon, you would need several for a 14s.

I would seriously think about getting a chargery bms16 (cost about 110 on ebay) its the only bms I would use with solar, low/high voltage are programmable and it also has audio/visual alarms. I've been using the chargery bms8 on my 4s lifepo4 for the past year and works great. It uses mechanical contactors/relays to disconnect the solar panel when limits are reached.

The cheaper bms that use mosfets will produce voltage surges if they activate to stop the charge. They are better then nothing but I could never get use to the voltage surges, no matter how low you set the charge controller, eventually the bms would activate.

I would definitely use some sort of bms to protect from out of balance pack or controller failure, alarms could also fail. 

Ibiza likes this post
Thanks a lot guys! Great info here.

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