Hank the Tanks Dodgy battery and solar system

[merl]

it charged up a single one in next to no time then it will charge two still over the course of a day quite easily

A 100W panel would take 10 hours to deliver 100Ah and that's at 100% efficiency (which your PMW isn't) and perfect conditions with full overhead continuous sun. If you're topping up your battery in just a few hours then mathematically you're actually not taking a great deal out of it.

 

[merl]

Twenty one pages!

Thank goodness it's not a discussion about something truly important!

What like 8 pages about a cork

 

[Pudsey Bear]

I still think you need more solar and a MPPT jobby if you add a battery for the way you use it without moving for so long and no ehu.

 

[barryd]

A 100W panel would take 10 hours to deliver 100Ah and that's at 100% efficiency (which your PMW isn't) and perfect conditions with full overhead continuous sun. If you're topping up your battery in just a few hours then mathematically you're actually not taking a great deal out of it.

You don't realistically take a battery down to flat though although lithium I think you can do 80 or 90%. Last year our 120ah (the new one) would typically drop to between 12.1v and 12.5v by bed time. It was the 12.1v that worried me. If the forecast the following day was poor we had nothing to play with but generally even from 12.1 if it was sunny ish it would be back up to fully charged by lunchtime. Then of course the charger switches off and just tops up when necessary. So most days in summer its done its work by mid morning to mid day. If there was a second battery even with one panel it would have time to top both batteries up to full and once they are full its unlikely two full 120ah (240ah) would ever fall as low as 12.1v in one evening thus giving me more breathing space if the following day is dull.

This is just my gut feeling based on living with it not science.

 

[barryd]

I still think you need more solar and a MPPT jobby if you add a battery for the way you use it without moving for so long and no ehu.

Remember though we did make it work most of the time. I think in August we managed 4 weeks off grid before we had to move without moving the van with just one battery although it did drive me nuts at times. I agree, it would be better to have more solar and a different controller but is it necessary right now and is there a controller with a second output for the engine battery?

 

[Robmac]

You don't realistically take a battery down to flat though although lithium I think you can do 80 or 90%. Last year our 120ah (the new one) would typically drop to between 12.1v and 12.5v by bed time. It was the 12.1v that worried me. If the forecast the following day was poor we had nothing to play with but generally even from 12.1 if it was sunny ish it would be back up to fully charged by lunchtime. Then of course the charger switches off and just tops up when necessary. So most days in summer its done its work by mid morning to mid day. If there was a second battery even with one panel it would have time to top both batteries up to full and once they are full its unlikely two full 120ah (240ah) would ever fall as low as 12.1v in one evening thus giving me more breathing space if the following day is dull.

This is just my gut feeling based on living with it not science.

To be honest Barry, I can see what Merl is saying and I can see what you are saying.

I have seen results from batteries that fly in the face of what the science would say. I used to run my fridge for 3- 4 days without switching it off (as well as lights, TV Etc. and I didn't have solar back then) yet people would tell me that this is impossible. Same with driving a short distance to top the batteries up, I was told you would need to drive for half an hour or whatever but often I didn't.

I know that displayed voltage isn't the be all and end all of a battery's condition but as long as it kept on performing I didn't care.

I've practically been called a liar before now but what would I have to gain by lying?

 

[gasgas]

As for the controller I was always a big fan of MPPT and loved my old controller and really didnt like this one.......

If I was changing vans - which I was - I would remove the nice MPPT controller that I loved, and replace it with a cheapo wottevver controller - which I did. I was part exchanging a camper at a dealer and I extolled the virtues of all the accessories my van had. The dealer said "accessories count for nothing. You can take them off if you like". So I spent a few days removing tow bar, spare wheel, MPPT, second LB, bike rack and everything that didn't prevent it from moving or working. Later I found out that a dealer makes between £10,000 and £15,000 mark up on a used motorhome. I have no sympathy for them, if the customer insists on a spare wheel included in the price or a second battery, they will fit them. They can afford it out of the mark up they will be making. Just look round the back at the staff car park of a big dealer. You will find lots of very expensive cars.
I had agreed prices with a dealer on one motorhome, and on the morning of taking it there I was reversing round a corner, and a tree branch sticking out over the road pierced and broke the habitation side window. I took it to the dealer and apologised. He said don't worry it makes no difference.

 

[merl]

You don't realistically take a battery down to flat though although lithium I think you can do 80 or 90%. Last year our 120ah (the new one) would typically drop to between 12.1v and 12.5v by bed time. It was the 12.1v that worried me. If the forecast the following day was poor we had nothing to play with but generally even from 12.1 if it was sunny ish it would be back up to fully charged by lunchtime. Then of course the charger switches off and just tops up when necessary. So most days in summer its done its work by mid morning to mid day. If there was a second battery even with one panel it would have time to top both batteries up to full and once they are full its unlikely two full 120ah (240ah) would ever fall as low as 12.1v in one evening thus giving me more breathing space if the following day is dull.

This is just my gut feeling based on living with it not science.

Yep, I understand exactly what you're saying and your reasoning Barry. What I'm saying is that all of your logic is based on voltage readings to establish the amount of power that's in the battery and I think that's flawed because with a 110w panel on a PWM controller I'd estimate you'd get maybe 25Ah max by lunchtime during your particular break this year.
Did you EVER actually take the battery to flat so that it wouldn't power anything? I'm guessing not?
When did you get the voltage readings from?

 

[trevskoda]

Remember though we did make it work most of the time. I think in August we managed 4 weeks off grid before we had to move without moving the van with just one battery although it did drive me nuts at times. I agree, it would be better to have more solar and a different controller but is it necessary right now and is there a controller with a second output for the engine battery?

What part of votronic can you not get the head round, one amp to starter battery, and its got its own fuse, it also can be switched to lith when or if you go down the path to that, open the wallet tight ar-e.

 

[barryd]

Yep, I understand exactly what you're saying and your reasoning Barry. What I'm saying is that all of your logic is based on voltage readings to establish the amount of power that's in the battery and I think that's flawed because with a 110w panel on a PWM controller I'd estimate you'd get maybe 25Ah max by lunchtime during your particular break this year.
Did you EVER actually take the battery to flat so that it wouldn't power anything? I'm guessing not?
When did you get the voltage readings from?

Initially all we had to go on was the Swift control panel above the door which just has a series of lights which gives you a clue as to where it is and then after five days it went into the red and beeped an alarm and I noticed the solar controller battery status had also gone red. This was the start of this thread. When @yeoblade came to the rescue and we fitted the new battery we also fitted two direct to battery quality trailing 12v sockets and a plug in voltage tester so I used that ever since. It seems pretty accurate. On the new battery I dont think it ever went below 12v. 12v has always been my limit before I think we are going to need to do something before the battery starts to get damaged. I think actually its lower than that but yes, if it got that low it would take a fair bit of time to get back up to full again but generally it was fully charged in summer by midday. Not always if it was a bit cloudy. It was those circumstances that drove us nuts as we had to be super stingy with power.

I reckon though the PWM controller was just as fast at charging the battery as my old MPPT Controller was though.

 

[Robmac]

What part of votronic can you not get the head round, one amp to starter battery, and its got its own fuse, it also can be switched to lith when or if you go down the path to that, open the wallet tight ar-e.

If Barry wants to go to MPPT Trev he would be better off spending just a little more and getting a Victron unit which would be far better.

 

[barryd]

If Barry wants to go to MPPT Trev he would be better off spending just a little more and getting a Victron unit which would be far better.

I might point out this isn't just about saving money if its about that at all. Its about doing what is necessary and possible on my own. I dunno what Trev is on about. Maybe he is on about me wiring something to the engine battery. Why would I do that when I already have a controller thats wired into the engine battery? Unless I have misunderstood.

 

[Robmac]

I might point out this isn't just about saving money if its about that at all. Its about doing what is necessary and possible on my own. I dunno what Trev is on about. Maybe he is on about me wiring something to the engine battery. Why would I do that when I already have a controller thats wired into the engine battery? Unless I have misunderstood.

I think he's still saying that you should switch to MPPT Barry but if you were to I wouldn't go for that particular one when the best (Victron) doesn't cost much more. But if you've got something that works why bother? as you have said you can always get a proper Lithium install at a later date if you so choose to.

I'm only switching because I want to go all electric. I wouldn't have had a clue how to do what I am doing on my own without loads of advice though - it simply has to be right and I don't want to have any anxiety about it.

I never thought it was about money, I've seen what you've spent on the van - and you ain't been reduced to busking just yet, even if you are using Cava corks for most of your mods!

 

[merl]

I reckon though the PWM controller was just as fast at charging the battery as my old MPPT Controller was though.

Short answer to that statement is "It can't be" MPPT is measurably significantly more efficient.
I think the reason why you've come to that conclusion is because you're not discharging the battery as low in Hank II compared to Hank I. This is why you also suspected that Hank II is less efficient and probably has a higher parasitic/standing current draw than Hank 1.
Essentially ALL of your reported issues and inconsistencies can be explained by inaccuracies/differences in display readings you're relying on for information re battery capacity and thus Hank 2 doesn't appear to be operating to quite the same level of efficiency as Hank1 was. In reality all you're doing is not discharging Hank 2's battery quite as much as Hank1.

 

[Nabsim]

If Barry wants to go to MPPT Trev he would be better off spending just a little more and getting a Victron unit which would be far better.

What makes you think it would be better? I have one x Votronic 250 duo and 1 x Victron 100/20. In operation while harvesting there is no difference, (each having an identical 150W panel). The Votronic send a trickle to the starter battery that the Victron does not. The Votronic units are tiny compared to Victron but do not suffer heat problems. The Victron has bluetooth built in that my Votronic don't.

The Votronic has been in use now for 6 years without a single problem, cant remember when I added the Victron, maybe 3 years, again with no problem.

In my opinion Victron is NOT better than Votronic. They do make different things, or do it in a different way so a lot of things are not a straight comparison. Votronic are used a lot in emergency vehicles across Europe.

 

[Nabsim]

Barry, I am a great believer in buying bugger all until I know I need to change something. If you want a second battery same as your first just get it added.

As I posted earlier you can add folding panels to your setup if you need to, some of these will have a controller built in and it can be as simple as connecting crocodile clips when you want to use them. I would wait until you know you need them if it was me as well. IF I was to be buying anything for the electric side though I would be making sure it is compatible with lifepo4 in case you want to change at a later date

 

[rugbyken]

when we were last at goosnargh i had 2 x 100A renogy solar panels from amazon. delivered on site the panels were £70 each and i ordered a victron controller bits silkaflex gaskets etc all for less than £130 took a couple of hrs to fit the panels and about an hour for jeff to wire it up , i know lithiums are going down in price but panels now are ridiculously cheap i. believe robmac got a 300+ for about the same price

 

[Pudsey Bear]

Remember though we did make it work most of the time. I think in August we managed 4 weeks off grid before we had to move without moving the van with just one battery although it did drive me nuts at times. I agree, it would be better to have more solar and a different controller but is it necessary right now and is there a controller with a second output for the engine battery?

Of course you did make it work but that isn't what you are wanting to do going forward, you want to have spare capacity for when it pisses down for 5 days no scooter riding so sat twiddling your phumbs not daring to switch anything on in case it never shines again and you are not on EHU.

You need to get another (at least one) panel, an MPPT and add a second LA battery, that for me would be the rock bottom minimum setup for parking it up and no worries at least until you see how that works.

And none of this I can fit a panel either, it is two wires a chimp could do it, whether you're fit enough is another thing, but you could always chuck Michelle up there though.

 

[Nabsim]

No Kev, what he needs is a realistic daily use figure then he can plan properly lol

I don't think he uses a lot of power, remember being a bit shocked when he first mentioned lithium lol

There are people can manage fine on a single 100/120Ah lead acid battery for several days on end in darkest Winter in the UK

 

[Pudsey Bear]

Yeah we only have 85w and 100ah.