Advice needed for alternator charging of lithium batteries for solar install

[richpatty]

Originally Posted by 10 fan

I finally did a temperature test of the alternator. I duct taped the temp probe to the alternator case and recorded for 8 hours. My 1400 ah of lithiums were at 23% and I let the BIM take controll for 1.5 hours. Temp went up to 185f and stayed there. I stopped and let it idle for 20 minutes and the temp went to 212f. I started driving, hit the latching relay on boost switch for 4 hours and the temp went to 215f. I pulled over and the batteries were 100%. I turned on one AC for the last 2 hours and the temp went to 217f. I drove from Crater Lake,OR to central CA in pretty cool weather, about 85 to 90 outside. With 85a load (about 30%) being the most I have seen with one AC running and 217 deg I am comfortable letting the alternator charge the batteries. So far my system has worked better than I thought.

Great info 10fan! And although I know temperature is an important factor, I would think load would be too. I would be curious to correlate the load with the temperature. I see at one point that you mention 85a load on the alternator. Do you have a meter on that all the time? I have been tempted to get a Bluetooth device that would allow me to measure this as well. What do you use to measure the amp draw?

Thanks

[10 fan]

I bought this on Amazon and it works great. (Thank you Charlie) Clamp it on the alternator output and I put my phone on the bed to record the output, signal won't reach the drivers seat. Used the same meter for temp. and to check a bad capacitor on my roof AC. I have compared the readings to my Fluke and 3 other multimeters and it is the same. I wish I could monitor everything all the time. I have checked alternator output 5 or 6 times while running one AC off batteries while driving and the max so far has been 85a. During those times my solar was close or at the max I have seen (121a). I would think the alternator output would go up when the solar goes down (I can only check solar when I stop) but the recorded amount stays very constant, only varies a few amps.


BTMETER BT-570CAPP Digital Clamp Meter Multimeter, Auto-Ranging Bluetooth Amp Meter for AC&DC Current Amperage Voltage Resistance Temp Electrical Tester with Backlit Continuity
Return and product support eligibility
$47.49

[richpatty]

Originally Posted by 10 fan

I bought this on Amazon and it works great. (Thank you Charlie) Clamp it on the alternator output and I put my phone on the bed to record the output, signal won't reach the drivers seat. Used the same meter for temp. and to check a bad capacitor on my roof AC. I have compared the readings to my Fluke and 3 other multimeters and it is the same. I wish I could monitor everything all the time. I have checked alternator output 5 or 6 times while running one AC off batteries while driving and the max so far has been 85a. During those times my solar was close or at the max I have seen (121a). I would think the alternator output would go up when the solar goes down (I can only check solar when I stop) but the recorded amount stays very constant, only varies a few amps.


BTMETER BT-570CAPP Digital Clamp Meter Multimeter, Auto-Ranging Bluetooth Amp Meter for AC&DC Current Amperage Voltage Resistance Temp Electrical Tester with Backlit Continuity
Return and product support eligibility
$47.49

Thanks. And yes, Charlie is a great help!

I see it now for $37.99
This one?
https://www.amazon.com/gp/aw/d/B07PY8B1JC/ref=ox_sc_act_image_1?smid=A1YAU90U3F1RJ9&psc=1

How hard do you think it would be to get it in there with a rear radiator? I guess that’s a question for Charlie.

[osuallen]

Originally Posted by richpatty

Thanks. And yes, Charlie is a great help!

I see it now for $37.99
This one?
https://www.amazon.com/gp/aw/d/B07PY...0U3F1RJ9&psc=1

Rich

I think it is this one:
https://www.amazon.com/Multimeter-BT.../dp/B07CFWL3SY

[richpatty]

Originally Posted by osuallen

Rich

I think it is this one:
https://www.amazon.com/Multimeter-BT.../dp/B07CFWL3SY

Got it! Thanks.

Will put it on the Christmas list.

[10 fan]

Probably not fun but look up from underneath and follow the wire from the alternator and find an easy place to clamp it on. I would think it goes to the batteries.