Battery that heats itself

[cruising7388]

Originally Posted by wincrasher

Well it depends on how you are parsing it.

The load on an instantaneous basis is probably the same. In aggregate, it probably is not. I think we all understand the benefit to having a much shorter run time to charge the batteries - not only in wear and tear on the engine, but in the noise created.

So I'll take the choice to go 48v any day of the week and twice on Sundays.

The Volta load the engine sees may be a bit more than the Nations/Delco setup but isn't there still a significant net savings in fuel consumption with Volta?

[avanti]

Originally Posted by cruising7388

The Volta load the engine sees may be a bit more than the Nations/Delco setup but isn't there still a significant net savings in fuel consumption with Volta?

Why would that be?

..and, wouldn't it be more than a "bit" more? If it really does exceed the MB spec, that is a serious matter.

[Boxster1971]

Originally Posted by TooMuchHair

The MB specification of 8500 watts is "Input watts". The Volta Power 8000 watt alternator specs show the efficiency of that unit to be "80% typical". So that would be require 10,000 watts of input.
https://voltapowersystems.com/wp-con...ts_3.16.18.pdf

I'm not trying to split hairs, but they are exceeding MB's limits.

Plus there already have been many reports of belt issues using alternators with much lower output than the one we are talking about. Many of those include an engine overheat due to the loss of the water pump drive, that to me is an even bigger concern.

Love the forum and appreciate all of your well informed posts!

Good info - thanks. Those Volta alternators are certainly higher output than the commonly used Nations unit at about 4000 watts.

Guess it would depend on which level of B-van kit Winnebago and ARV are using since the level 2 kit has a 6000 watt alternator. The level-3 kit uses the 8000 watt alternator.
https://voltapowersystems.com/wp-con...1.8.17_WEB.pdf

https://voltapowersystems.com/wp-con...1.8.17_WEB.pdf

Volta does say both level 2 and 3 kits are compatible with the Sprinter, Promaster and Transit vans. Did notice that specs for the 6000 watt alternator lists "Ford, MB and other small diesels". The 8000 watt unit lists "GM, Ford and others". The actual load can be adjusted by pulley diameter. Both alternators list custom external regulators on the spec sheet. Without specific details of each installation can't be sure if limits are exceeded. I'd imagine Winnebago and ARV have made adjustments to keep the load withing the MB limits.

Here is a setup from the audio junkies with real belt problems.

https://www.youtube.com/watch?v=2OHQUa28wLA

[cruising7388]

Originally Posted by avanti

Why would that be?

..and, wouldn't it be more than a "bit" more?

I don't know how much more a "bit" more is which is why I asked. But assuming the same battery ah capacity and depth of discharge for comparison purposes, while doubling the alternator power delivery will incrementally increase engine load and presumably fuel consumption, isn't this happening for only one half the time? So. my question is whether with respect to fuel consumed using Volta compared to Nations et al, when you are recharging at idle speed, are you ahead or behind at the completion of the charging cycle with Volta or is it just a wash?

[GeorgeRa]

Personally, I would consider the difference of higher fuel consumption at shorter time versus lower fuel consumption at longer time a wash without actual data. I also agree that exceeding the manufacturer's maximum power spec for PTO is asking for some serious problems.

[avanti]

I suppose it is true that if you stipulate that you are charging at idle, then taking more power at a time is probably marginally more efficient, since there most likely is some overhead involved in merely keeping the engine running, so running twice as long probably costs a bit more. But, charging at idle is a pretty bad idea. But if we are talking about charging while under way (which is pretty much all I ever do), then I doubt that there is a significant difference.

[cruising7388]

Originally Posted by GeorgeRa

Personally, I would consider the difference of higher fuel consumption at shorter time versus lower fuel consumption at longer time a wash without actual data.

Well, my initial thought was that it would be a wash but I wonder if that assumes that the relationship between horsepower engine efficiency and external load levels is linear. Since the engine at idle is operating at its peak inefficiency, perhaps operating time influences total fuel consumption more than the level of the alternator load at engine idle. Where is an automotive engineer when ya need one