FridgeFreezer Posted July 31, 2020 Share Posted July 31, 2020 ...just to add a few notes to the video as the forum software wouldn't let me; Chronologically stepping through: You can see the fridge is running (-4.3A) When I turn the ignition on the heater fan is running on low and the MS wakes up and primes the fuel pump (-11.5A) When the fuel pump is primed we drop back to -3.8A to spin the heater. You can see the starter current (-225A) Once started, the alternator comes up to 14.1v and the starter battery replenishes (30A) - you can see how quickly this drops off to almost nothing too. Once the main battery voltage has been stable for a few seconds the split charge kicks in and 41A flows into the "house" battery. Bear in mind this is an AGM starter-type battery so will accept a lot more amps than a caravan battery. With the split charge in and the starter battery still replenishing, the total current is 14A + 41A = 55A By only 30 seconds in, the main battery is down to 5A and the house battery is drawing 26A and both are still tailing slowly off. That video shows a fairly typical start after a day of sitting around with the fridge running. You can see how the alternator voltage dips a tad under the load, that's the regulator doing its thing as it can't sustain full amps at tickover - but if it was struggling the battery light would be on & the voltage would be down to 12v not 13.8. There's also clearly some losses in my wiring / inaccuracies in the reading but the broad picture is correct. I will say that I have seen that AGM battery draw 80A very briefly and 50A for a period of maybe 15 minutes after a particularly hard thrashing but your alternator will regulate things the same as mine, dropping the charge voltage a tad until the draw is sustainable. And, again, most leisure batteries won't take 50A+ out of your alternator. Another thing to note is how quickly the charging currents taper off - the main battery is down to 4A by the end of the video and the house battery is down to 24A already - it's not accurate to just do amps * hours for recharge times but driving for half an hour or more is certainly going to put a hell of a bulk charge back. 2 Quote Link to comment Share on other sites More sharing options...
Snagger Posted July 31, 2020 Author Share Posted July 31, 2020 Wow! That main battery draw drops much faster than I would have expected after starting - I thought it’d be at 10-15a for up to ten minutes. Very useful. Quote Link to comment Share on other sites More sharing options...
Mo Murphy Posted July 31, 2020 Share Posted July 31, 2020 I like that guage FF ! Mo Quote Link to comment Share on other sites More sharing options...
smallfry Posted July 31, 2020 Share Posted July 31, 2020 The Thor engine has a 150 amp alternator, AND on the V8 its nice and high up, out of the way, probably the only good reason to have a Rover V8 Freelander TD4 also has a 150amp unit, but with a different mounting arrangement. To my simple mind, would make more sense to avoid the complexity of two alternators, and have a solar panel or two instead. Or maybe a little generator, which is very useful for other things too. I drove my Renault Master back from Cumbria to Kent at night with a genny running in the back after the alternator died on the way up. 1 Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted August 1, 2020 Share Posted August 1, 2020 17 hours ago, Mo Murphy said: I like that guage FF ! Mo If enough people liked it enough to spend ~£200 on it I'd make a run of them. It does two batteries, true voltage & current readings up to 1000A. Quote Link to comment Share on other sites More sharing options...
Mo Murphy Posted August 1, 2020 Share Posted August 1, 2020 Thanks fridge, I suppose it's not that bad a price as it does amps too. What size is the finished article ? Mo Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted August 1, 2020 Share Posted August 1, 2020 5 hours ago, Mo Murphy said: What size is the finished article ? 52mm 2 Quote Link to comment Share on other sites More sharing options...
Mo Murphy Posted August 2, 2020 Share Posted August 2, 2020 Blimey have you mounted yours in an ashtray ! Mo Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted August 2, 2020 Share Posted August 2, 2020 9 hours ago, Mo Murphy said: Blimey have you mounted yours in an ashtray ! Nope, that's the housing, I did it on the lathe for the prototype, didn't have the heart to paint it black! Quote Link to comment Share on other sites More sharing options...
vulcan bomber Posted August 10, 2020 Share Posted August 10, 2020 I run 2 65 amp alternators on my 110, and I just use an ignition live, through the 24volt warning light on the dash to the 2nd alternator to excite it. Perk of 2 alternators is you just keep driving when one breaks. Theres many ways of charging batteries in a vehicle but I see a pair of alternators the easiest to obtain spares for in the wilderness, hence why I chose that route. Quote Link to comment Share on other sites More sharing options...
Snagger Posted August 10, 2020 Author Share Posted August 10, 2020 1 hour ago, vulcan bomber said: I run 2 65 amp alternators on my 110, and I just use an ignition live, through the 24volt warning light on the dash to the 2nd alternator to excite it. Perk of 2 alternators is you just keep driving when one breaks. Theres many ways of charging batteries in a vehicle but I see a pair of alternators the easiest to obtain spares for in the wilderness, hence why I chose that route. That was one of the big attractions for me. Charge rate of relatively cheap and low rated units so that a short drive would be enough for full charge, near complete separation of the two systems and built in redundancy. At work, I have 10 generators, including backups, and the new model will have at least two more! 😄 Quote Link to comment Share on other sites More sharing options...
vulcan bomber Posted August 10, 2020 Share Posted August 10, 2020 6 hours ago, Snagger said: That was one of the big attractions for me. Charge rate of relatively cheap and low rated units so that a short drive would be enough for full charge, near complete separation of the two systems and built in redundancy. At work, I have 10 generators, including backups, and the new model will have at least two more! 😄 Dont get carried away wiring them in, just an ignition live off the main loom, to a bulb, to the 2nd alternator. 1 Quote Link to comment Share on other sites More sharing options...
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