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#31
Maintenance and Modifications / Re: Electric a/c for Minis
Last post by MPlayle - October 13, 2026, 07:38:40 AMFrom my research so far, the 12-volt compressors are rated to produce about 6,000 BTU at 2500 rpm and 8,000 BTU at 3000 rpm. That basically falls right into the range of the belt driven compressor of the JDM Minis.
The "kicker" is the higher amperage required at 12-volts versus 48-volts or 350-volts.
I am in communications with WOSP as they are the alternator maker used by a UK company the did electric a/c in a few Mini Saloons. (See the article here: https://www.classicretrofit.com/en-us/blogs/news/electric-air-conditioning-in-singapore-classic-mini-restoration )
I am looking into one of three of their alternators compatible with our Minis: LMA308 (175 amp), LMA420-LO (180 amp) and LMA420 (240 amp). They are not exactly inexpensive, but are supposed to be "direct fit" (upgraded wiring from the alternator to the battery link at the solenoid is required). I have been leaning toward the LMA420 (240 amp) as it's "low rpm output" (idle) tested rating is 160 amps.
The "kicker" is the higher amperage required at 12-volts versus 48-volts or 350-volts.
I am in communications with WOSP as they are the alternator maker used by a UK company the did electric a/c in a few Mini Saloons. (See the article here: https://www.classicretrofit.com/en-us/blogs/news/electric-air-conditioning-in-singapore-classic-mini-restoration )
I am looking into one of three of their alternators compatible with our Minis: LMA308 (175 amp), LMA420-LO (180 amp) and LMA420 (240 amp). They are not exactly inexpensive, but are supposed to be "direct fit" (upgraded wiring from the alternator to the battery link at the solenoid is required). I have been leaning toward the LMA420 (240 amp) as it's "low rpm output" (idle) tested rating is 160 amps.
#32
Maintenance and Modifications / Re: Electric a/c for Minis
Last post by Merlin - October 12, 2026, 07:47:16 PMHere's some data from the AC compressor attached to my JDM mini.
The compressor is a Unicla UP90 (As far as I can tell) The cut sheet is below.
https://www.supercool.com.au/unicla/up90-upf90/
The compressors is designed for 2-3Kw applicaitons which translates to 6,800-10,000 BTU/Hr. This is compressor BTU
Looking at the data in the cutsheet, it gives us power consumption at RPM. The pulley on the compressor is the same as the crankshaft damper (120mm) giving a 1:1 ratio. Assuming that we are steady state at 1,000 rpm the HP consumed is roughly 1hp (750w). Running that backwards into Amps at 13V and adding a 90% eff, that would require 64amps to operate an electrical A/C compressor.
So let's gut check this. There are electrical cars and they don't belt drive their A/C Compressors. There should be a system out there that would work?
https://openinverter.org/wiki/Tesla_Model_S/X_A/C_Compressor
The Tesla units operate on a 350VDC system pulling nearly 4.5kw (6hp!!) which is more than we predicted with the engine driven one above. They offset the need for high Amps by upping the voltage. Checking the chevy volt system as a comparison and its a 350VDC system.
My only thought here is this... Move to a 48V system with its own dedicated battery.
https://www.guchen.com/compressor/48v-electric-ac-compressor-for-truck.html
This unit is capable of 3.5Kw which is at the max of the required need. The cc/rev flow rate is lower at 20cc/rev but it can operate constantly at 6000RPM which means it can move as much freon as the Unicla above. The numbers make the most sense here. Using a 48V lithium battery like the one below would give you the voltage and nearly the amp draw required. The battery states it can do 60A draw, but the BMS says 30A. At full load, the compressor is pulling 33A. We can reel it back a bit, still hit the BTU rate and stay under the battery requirements.
https://www.vevor.com/batteries-c_14008/vevor-48v-electric-scooter-battery-20ah-ebike-lithium-battery-pack-with-30a-bms-p_010464838800?adp=gmc&utm_source=google&utm_medium=cpc&utm_id=23748664457&ad_group=195029942043&ad_id=805057579869&utm_term=&gad_source=1&gad_campaignid=23748664457&gbraid=0AAAAACq8bLWtC1hNskacoNW9DoBg0woRN&gclid=CjwKCAjwirLWBhBBEiwAlItbEuIBtaDomHAmvgcrCeKXxLTSTMPrkprE89vUj1LKlKCh8-2bSbIyBBoCy9MQAvD_BwE
Battery states 20AH, which would be about a 40 min run time. The compressor would not run constantly so this could be an option for shorter trips. Adding a DC/DC charger could help offset. This could add 400W to the system, which could be used for demand or for charge. Adding batteries could be used to double or triple that range if require at the cost of weight. https://expion360.com/products/orion-tr-smart-12-48-8a-380w-non-isolated-dc-dc-charger?variant=46373429739683&country=US¤cy=USD&utm_medium=product_sync&utm_source=google&utm_content=sag_organic&utm_campaign=sag_organic&utm_term=&utm_campaign=WP+-+PMax+-+NOCO+%2B+Victron&utm_source=adwords&utm_medium=ppc&utm_id=23326401726&hsa_acc=4475371194&hsa_cam=23326401726&hsa_grp=&hsa_ad=&hsa_src=x&hsa_tgt=&hsa_kw=&hsa_mt=&hsa_net=adwords&hsa_ver=3&gad_source=1&gad_campaignid=23331492140&gbraid=0AAAAACkQ-wRiaIQCjat0gIUycjFaZMGsg&gclid=CjwKCAjwirLWBhBBEiwAlItbEkhGua-m08o-TtJApp0b-Nd-S22CeR_3s8Dboh0sq6nB-sFrst4Q8xoCSzMQAvD_BwE
This is math problem limited by physics. 12,000BTUs of cooling require ~1.5hp. How you get it is up to you.
The compressor is a Unicla UP90 (As far as I can tell) The cut sheet is below.
https://www.supercool.com.au/unicla/up90-upf90/
The compressors is designed for 2-3Kw applicaitons which translates to 6,800-10,000 BTU/Hr. This is compressor BTU
Looking at the data in the cutsheet, it gives us power consumption at RPM. The pulley on the compressor is the same as the crankshaft damper (120mm) giving a 1:1 ratio. Assuming that we are steady state at 1,000 rpm the HP consumed is roughly 1hp (750w). Running that backwards into Amps at 13V and adding a 90% eff, that would require 64amps to operate an electrical A/C compressor.
So let's gut check this. There are electrical cars and they don't belt drive their A/C Compressors. There should be a system out there that would work?
https://openinverter.org/wiki/Tesla_Model_S/X_A/C_Compressor
The Tesla units operate on a 350VDC system pulling nearly 4.5kw (6hp!!) which is more than we predicted with the engine driven one above. They offset the need for high Amps by upping the voltage. Checking the chevy volt system as a comparison and its a 350VDC system.
My only thought here is this... Move to a 48V system with its own dedicated battery.
https://www.guchen.com/compressor/48v-electric-ac-compressor-for-truck.html
This unit is capable of 3.5Kw which is at the max of the required need. The cc/rev flow rate is lower at 20cc/rev but it can operate constantly at 6000RPM which means it can move as much freon as the Unicla above. The numbers make the most sense here. Using a 48V lithium battery like the one below would give you the voltage and nearly the amp draw required. The battery states it can do 60A draw, but the BMS says 30A. At full load, the compressor is pulling 33A. We can reel it back a bit, still hit the BTU rate and stay under the battery requirements.
https://www.vevor.com/batteries-c_14008/vevor-48v-electric-scooter-battery-20ah-ebike-lithium-battery-pack-with-30a-bms-p_010464838800?adp=gmc&utm_source=google&utm_medium=cpc&utm_id=23748664457&ad_group=195029942043&ad_id=805057579869&utm_term=&gad_source=1&gad_campaignid=23748664457&gbraid=0AAAAACq8bLWtC1hNskacoNW9DoBg0woRN&gclid=CjwKCAjwirLWBhBBEiwAlItbEuIBtaDomHAmvgcrCeKXxLTSTMPrkprE89vUj1LKlKCh8-2bSbIyBBoCy9MQAvD_BwE
Battery states 20AH, which would be about a 40 min run time. The compressor would not run constantly so this could be an option for shorter trips. Adding a DC/DC charger could help offset. This could add 400W to the system, which could be used for demand or for charge. Adding batteries could be used to double or triple that range if require at the cost of weight. https://expion360.com/products/orion-tr-smart-12-48-8a-380w-non-isolated-dc-dc-charger?variant=46373429739683&country=US¤cy=USD&utm_medium=product_sync&utm_source=google&utm_content=sag_organic&utm_campaign=sag_organic&utm_term=&utm_campaign=WP+-+PMax+-+NOCO+%2B+Victron&utm_source=adwords&utm_medium=ppc&utm_id=23326401726&hsa_acc=4475371194&hsa_cam=23326401726&hsa_grp=&hsa_ad=&hsa_src=x&hsa_tgt=&hsa_kw=&hsa_mt=&hsa_net=adwords&hsa_ver=3&gad_source=1&gad_campaignid=23331492140&gbraid=0AAAAACkQ-wRiaIQCjat0gIUycjFaZMGsg&gclid=CjwKCAjwirLWBhBBEiwAlItbEkhGua-m08o-TtJApp0b-Nd-S22CeR_3s8Dboh0sq6nB-sFrst4Q8xoCSzMQAvD_BwE
This is math problem limited by physics. 12,000BTUs of cooling require ~1.5hp. How you get it is up to you.
#33
Daves Garage / Re: Mini ST Hotrod
Last post by MiniDave - October 12, 2026, 02:03:56 PMI took the floor brace out and as expected the worst rust was under it, just like on the right side. I'll butt the rear section I have up against the front and weld it all up, then make a filler patch for the back edge. But first I'll need to remove the upper and front parts of the roll cage to get it out of the way, then once the floors are all done I'll need to make a new cross brace - my plan is to make it smaller in cross section but out of stronger material, maybe 18 gauge. and I may make 2 - one that goes across in front of the seat attachment and one under the seats......not sure on that yet.
#34
Maintenance and Modifications / Re: Wheel bearings?
Last post by MPlayle - October 11, 2026, 01:02:43 PMDid a bit more prep work on the hubs today. I installed the new bearing kits into the new hubs. I am using genuine Timkin bearing sets and paid special attention to keep the bearings matched to their respective outer races and center spacers.
#35
The Lounge / Re: What did you do in your sh...
Last post by ADRay - October 11, 2026, 04:58:49 AMyesterday I put the finishing touches on rebuilding the head, and after a couple hiccups, had it out for a drive by 2 pm. It's been off the road since early June.
#36
Maintenance and Modifications / Re: Electric a/c for Minis
Last post by MPlayle - October 10, 2026, 06:52:53 PMMost of the BTU ratings I have seen on the 12 volt compressor kits turn out to be the rating of the evaporator versus the capability of the compressor.
I am still trying to figure out/learn the differences and relationship between the two.
I am still trying to figure out/learn the differences and relationship between the two.
#37
The Lounge / Re: What did you do in your sh...
Last post by 94touring - October 10, 2026, 05:37:38 PMMy tundra gets it's air from the fender also.
#38
Maintenance and Modifications / Re: Electric a/c for Minis
Last post by MiniDave - October 10, 2026, 05:25:22 PMLooking at several different brands and suppliers it seems I was wrong, none of them use a heat strip for heat, they all use the engine's coolant. That's a disappointment as I was hoping not to have to plumb water to the unit.
I've seen BTU's of 12K, 13,800 and 18K.....makes me wonder just how much I would actually need for 1/2 of a Mini interior? (no back seat in the hot rod)
I've seen BTU's of 12K, 13,800 and 18K.....makes me wonder just how much I would actually need for 1/2 of a Mini interior? (no back seat in the hot rod)
#39
Cars for sale/wanted / Re: ‘68 Mk2 Austin Cooper on B...
Last post by MiniDave - October 10, 2026, 05:02:48 PMSaw that! Didn't realize it was yours! 
#40
The Lounge / Re: What did you do in your sh...
Last post by MiniDave - October 10, 2026, 05:01:39 PMQuote from: Jims5543 on October 08, 2026, 09:51:26 AMNut/Stud on top is for the engine vanity cover, I always take them off my cars.
There is a large factory hole to the left of the new K&N filter in the fender, the TRD box had a opening that reached into the hole, you can see it on the top pic of the TRD box, the K&N just shields the air filter from the engine bay with the air coming in from the hole in the fender.
Don't worry about getting rain/spray in there? reason I ask is that I may have to do something similar on my hot rod Mini - ie: pull intake air from under the fender