Motobatt - any good?

[sime66]

Anybody used Motobatt sealed glass mat batteries?
Anybody any opinion on them?
I don’t need a battery or even a full sized one, but decided I would anyway as I’m doing the reg/rec and 12v supply. I thought a sealed battery would be preferable to conventional. SIP sealed 12v 9Ah battery is currently out of stock everywhere as far as I can see, but Motobatt have a couple of options, but I’m wondering why the suggested one to replace a YB9-B is actually a 7Ah battery. Trying to get any sense about why 7Ah is supposed to replace 9Ah is becoming a pain – they have data sheets, but no one to ask the Chinese any questions. If I don’t get some sense I’ll give them a miss, and I suppose I can either do it all and leave the battery out for now, or use a conventional battery. Anyone tackled this Motobatt discrepancy before?

[sbwnik]

What are you using it for? Sat Nav/Phone?


7Ah will be enough if so

[sime66]

Two 12v outlets – one on top of toolbox for satnav and camping/breakdown light, and one inside toolbox for more secure/waterproof charging (phone, camera etc.). Plus maybe some other bits, possibly off spare fused connections. I think I can put a better than standard strangled horn in too if I’ve got a bit more grunt.
I only ended up putting a 16.5 Amp R&B through with a 10Amp fuse, but it's quite easy to increase, now I know how. I just thought it was a bit like a 90% job if I only put a 7Ah in.
I did sketch it out, then simplified it a bit:

[sbwnik]

diagram looks good but I'd not do return earths, just straight to chassis. It works as well with less risk of harm.

[sime66]

I wondered if it was necessary, now I’ve got a spare wire, which is handy.

What do I do with the ‘C’ connection on the Reg/Rec though? I’ve seen several different answers. My understanding is that it will match the DC in to give the correct DC out (B+) to the battery, so needs DC to charge battery correctly. I’ve also read just to leave it unused. I’m not sure what to do with it.

[sbwnik]

can't remember.. I'll have to look at mine when I get ten minutes.

[sime66]

I’ve looked at several schematics now for different scooters with batteries and DC.

The DC from the battery seems to go to ignition switch, and a DC seems to come back from there, through switch, to ‘C’ on the regulator – this seems to complete a DC circuit between ‘B+’ & ‘C’. This ties in with two statements that I’ve picked up from reading everything I can find:
· That it works like a DC ‘earth’.
· That the input at ‘C’ regulates the output at ‘B+’.
That makes sense for a DC scooter, but as I will not always have any DC circuit active, but will still want to be charging my battery, I’m wondering if either:
a) I should connect from the ‘+’ side of the battery to ‘C’, but would this will still make a circuit when the scooter isn’t running and discharge the battery? Or worse, bugger my shiny new rectifier or battery.
b) I should use a source of 12V AC instead as a control at ‘C’, which might explain why I have also come across the statement that an AC from the indicator relay works. This would only have 12V when the scooter is running, which I suspect is what I need, but is AC not DC.
It is also possible that none of this is important, and
c) It works fine with no connection at all, which keeps it simple.

I’ve had a good look at it and I’m not sure if it’s very simple or very complicated now.

[sime66]

Last post today – Honest!

Here’s what I reckon:
· Inside the Reg/Rec, the Rectifier part provides DC to charging circuit via ‘B+’
· On a DC scooter (Top diagram) the voltage at ‘C’ enables the Sensor to determine the voltage, and hence the charge required to battery. There is no circuit unless scooter is turned on at ignition switch. If there was a circuit when ignition is off, the battery would be able to drain to Earth. (If that is not true then there is no problem).

· On an AC scooter with an added battery (Bottom diagram), there is no ignition switch to break the circuit, so if battery would drain to Earth then ‘C’ cannot just be connected to + side of battery.
· There will not always be a DC circuit being used, so I can’t connect as a DC 'Earth' (my now unused black wire), UNLESS it is OK only to have battery charging when it is being used.
· It may also be true that if no signal comes to sensor via ‘C’ then battery will just trickle charge to capacity and no further, but I don’t know.

That’s where I’m at with it. I won’t be doing this until next weekend (Not bothering with Isle of Wight), so I’ve got a long weekend to sort it all out. 

DC scooter


AC scooter with an added battery


Diagram from www.vespamaintenance.com/elec/charger/

[sbwnik]

I'm going entirely from memory here, so bear with me if I'm wrong, but I just thought I'd offer this.

IIRC On a battery model P range there are two separate DC circuits. One for the starter motor and one for the horn. The battery feed runs the starter, the other feed running the horn.


There is no need for a control circuit as the regulator does this by it's design (Again, IIRC) and the widely fluctuating AC output from the stator couldn't be relied on to do this - The AC out put is only around 14v at most, and the design of the regulator as illustrated shows a clipper with inverting capacity (There is a name for this kind of rectifier, but it's 6.30 on a Sunday morning and I can't remember...). Also, the AC input to the DC side comes AFTER the regulator has limited the voltage.

My understanding anyway, could be wrong. Do you have any links to the suggestions of other design?

[sime66]

Thanks Nik, I’ll put some links below, but as it becomes clearer to me I think some of them are red herrings, and some of them confused me before I realised that a DC scooter would be wired differently around the rec & battery to an AC scooter with a battery added, because there is not a simple source of DC for the ‘C’ connection.

You’re right that the starter motor is off the battery circuit, and the rest is via the ignition switch, including the ‘C’ connection and the horn (I don’t know what year yours is). I’m uncertain whether the yellow circuit is fed from ‘C’ (as a separate DC cicuit), or is fed from the ignition switch and goes back at ‘C’ though, it seems to depend how the ignition switch is wired:



This, from Piaggio, shows ‘C’ connection coming off the DC ignition, which is now clearly correct for DC scooters:



This from Beedspeed, which didn’t really clarify it:



I reckon it’s true that no control circuit is required just to trickle charge a battery on an AC scooter, and it has to be the first option for my installation, then I can just measure if it’s charging or not, and rethink if it isn’t. I’m sure using AC at ‘C’ is wrong too, so forget that one.

Much better to understand it, rather than just plugging it in where it seems to work without understanding why. I spent hours yesterday investigating my scooter wiring, and got engrossed with the subject, and probably went astray in my thinking at times during the process.

Links:
(I know Forum discussions can be an unreliable source unless you know who’s posting, but here goes)

youngguns.team-talk.net/t1191-fitting-a-battery
(Piece of p**s – ‘C’ to + on battery, - on battery to Earth)

www.forums.ilambretta.com/viewtopic.php?f=2&t=10630&start=0&sid=5307514bbe86dd72383a20de16e9b062&view=print
(Discusses draining battery, and not connecting anything to ‘C’ just to trickle charge.)

modernvespa.com/forum/topic110635?highlight=adding+battery
(Discusses battery not charging without ‘C’, draining battery, and then gets lost in switches and stuff)

www.vespalabs.org/User:Internetscooter/Notes/Regulator_Wiring
(Describes ‘C’ as DC Earth)

I’m having trouble finding two other British ones. One of them says to plug into the flasher relay, which could be true for a DC scooter, but is not an option for me. The other says to leave it alone – it doesn’t need it. There are also your posts on SBW!

After gathering it all together, it’s still not clear, and I’m still curious, but I think the best plan will be to initially go with no connection at ‘C’. Unless I find the answer in the week, in which case I’ll definitely post it because it must be quite a common question. I’ve still got to get the battery too.

[sbwnik]

The beedspeed picture confirms my theory. Leave C out of the equation.

[sime66]

Thanks for your brain-work on this Nik,
(especially early Sunday - that's dedication!)
I'll confirm when it's all working.

[sbwnik]

No problem, and night shift is a good time to do stuff like this! :-)

[vespasian]

here is the correct battery 9amp too

www.ebay.co.uk/itm/320923690220?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

[sime66]

Thanks, you're right that is the correct conventional battery, but I’ve got my heart set on a sealed battery, on 9Ah, and on having it in the standard place on the standard bracket, so it must be no wider than 135mm. Getting a battery that meets all three criteria is proving trickier than I expected:
· Battery 12V 9Ah
· Sealed
· Not exceeding 135Wx75Dx140H (There are loads of 150W, but they don't fit the bracket)
The only one I can find is the SIP (reference is #8504600), and they are out of stock.
www.sip-scootershop.com/en/products/battery+12v9ah+sip+_85046000
If anyone knows who has SIP ones in stock, or knows of an alternative that meets the criteria I’d be very grateful, because I can’t get my hands on one. I’m not going to put a 150wide one on its side or in the glovebox, so I’m going to hang on until they are back in stock, or use a 7Ah (not ideal), or go conventional (not ideal), or temporarily wire into the +B on the Reg/ Rec until they are. it's all sorted except buying the battery, and I can do all the wiring, but I might have to be patient with it. I'm trying to get one now for the weekend.

I'm actually just reading up on what 9Ah vs 7Ah actually means in terms of watts down a wire.

[sbwnik]

9Ah/7Ah doesn't refer to the output so much as expected drain over an hour. If you put a 1A load on a 9Ah battery then it'll last 9 hours, a 7Ah one 7 hours. 2A load 4.5hours and 3.5 hours respectively etc..
All this doesn't allow for recharge rate.


In short, a charger won't even drain a 7Ah battery. In theory, anyway!

[sime66]

I’ve just gone back to my ‘O’ Level Physics for a couple of days!
I knew it wasn’t crucial, but just wanted to understand it, and wanted it right. The Dick I was talking to insisted that I wanted a 7Ah for a PX150, which I knew was wrong, although I accepted you had said it would be OK, which is true, especially for my planned use. I also sussed out that battery data, as presented, is really given for a battery that isn’t charging as you say, which makes it difficult to follow.
I’ve sorted it out anyway and it was simple in the end. I probably didn’t need to spend the money, but there are two Motobatt sealed AGM that fit in the bracket: MB5.5U (7Ah) & MB9U (11Ah). After all the messing about with it the discharge table (which seems more like cranking data) and the extra weight make it a toss-up which is best anyway.
If anyone is interested the SIP one is meant to be back in stock mid-September, but they said mid-July before.
As I’ve dug the info out, and in case anyone else is looking at a sealed battery for a Vespa, the comparison, dimension and discharge data for Motobatt are below. I’m giving them a go and mine will arrive on Thursday, so it’s sorted.

[sbwnik]

I assume the P200ARC is a DC model, no electric start? I can't think of any other use for a 5.5Ah battery on a scooter. That'll be for powering a DC horn and (I'd guess) sidelight (US markets often ask for them to be fitted as parking lights) so with that level drain, I think it would be enough for the job you need it for.

[sime66]

You have a keen eye; I was waiting to see if you picked up on that. I think it’s an error, which caused the fruitless discussion I’ve been having, and sadly, although I’m still curious, there is no one sensible to ask. Do you know any P200 that didn’t have a YB9-B equivalent? Everywhere in the documents a YB9-B cross references an MB9-U. Anyway, I understand your point about the starter motor being the big load, but loads of scooters don’t have starters, and I am sure you’re right that the MB5.5U is adequate, but who wants adequate! I’m going for the big grunter. It is certainly more than adequate for all needs, and when I’m able I prefer doing things as well as I can, rather than as cheap as I can. Over-engineering to compensate for ignorance maybe, but I had to make my mind up to get one for the weekend, a tenner over the life of a battery isn’t worth worrying about, and if I’m wrong I’ll learn from it.

[sbwnik]

I'll check with my mate who runs a scooter shop near New York, but 5.5 can only be for a non electric boot bike

[sbwnik]

Definative answer from Gene at Scooters Originale:

US spec P series use a 12n5-3b (not the 5.5 that is a much bigger battery)

He suspects the 5.5 is a misprint too BTW, so good spot!

[sime66]

I’m just finishing some jobs and tidying up threads, before Wollacombe next week.
Thanks to all who advised during these jobs.
I need to cut a hole for my top power outlet, so this all needs a tidy when that’s done. Theres a couple of fused relays for future, and I fitted in all on a little board that fits in the only empty space in my toolbox.

[sbwnik]

That's a beautifully done set up you've got there. Very nice.