I've been researching batteries for about a month now due to a failing house bank.
What I've learned so far:
Solar doesn't produce near as much as it seems.
555W solar = 166ah a day (100W panels
produce about 33ah on a good day
have more usable energy.
3 105ah house batteries = 315 ah / 2.2 efficiency multiple = 143 usable ah
200ah lithium / 1.2 efficiency multiple = 166 usable ah
" Warning levels are more conservative than Protection levels, HVC = 14.2V "
" Cell level protection disconnects the bank if overcharged to 15.0V "
Tristar Sealed Lead charge settings:
Absorption Stage: 14.15
Float Stage: 13.70
Equalize days: 28
Mahe alternators charge at ~14.4v
Most lead shore chargers also charge ~14.4v
Based on this discharge curve, charging
at this level would charge the batteries to near 100%.
At first I was planning on building my own LifePo4
battery bank. Here's a parts
list based on current
LifePo4 prices - they fluctuate quite a bit. Tesla being the largest consumer and ramping up production has sent prices up in the past year. However Tesla is opening up a huge LifePo4 manufacturing facility, which should bring prices down significantly.
LifePo4 200ah - Balqon (need 4 batteries to = 12v, each battery 3.3v)
1. HouseBMS (battery management system) = $75 (so you dont overcharge, undercharge battery bank)
2. Cell Balancing - 3 * $12 = $36 (protects individual cells from overbalancing / undercharging)
3. Battery Box
- Todd Box - $70
4. 200ah Balquon Lifepo4 - $220 x 4 = $880
5. Battery monitor display - $175
6. Contactor / Relay that is triggered by HouseBMS to disconnect if battery bank is overcharge / undercharged - $90 x 2 = $180
total for DIY: $1416 + tax + shipping
Add another $1000 and you can get it prebuilt w/ a few more options, one contact if something goes wrong, and in a nice tight tested package.
I like the pre-built box because it's got some good idiot proofing - like protection from reverse polarity. It is also setup to be able to connect cells in series if you want to add more cells later. Individual cells are bolted into place, so if a cell goes bad it can be replaced.
Low Voltage Protection Switch - Automatically disconnects at 8V
Over Voltage Protection Switch - Automatically disconnects at 15.8V
Short Circuit Protection Switch - Automatically disconnects
Reverse Polarity Protection Switch - Automatically disconnects
Internal cell balancing - Automatically balances cells
Charge Balancing - Independant balancing for multiple batteries connected in parallel or in series.
I'd like to hear any arguments to the counter from those educated in the world of LifePo4. Besides price
, these batteries seem to be a good chose for replacing house leads.
I did find two negative reviews
: 1. Someone didn't like the installer on Amazon, seems he was too dependent on someone else's knowledge of his systems. 2. A competitor on this forum said they were not good, but gave no details.